JP2016051978A - Band allocation method, band allocation system, subscriber side termination device, and station side termination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DBA technique to shorten a delay time in uplink communication.SOLUTION: A band allocation method according to the present invention performs the following in sequence: a monitoring and acquisition procedure of a station side termination device connected with a plurality of subscriber side termination devices monitoring downlink traffic to the plurality of subscriber side termination devices, and obtaining downlink traffic information; and an allocation procedure of determining the permissible amount of transmission according to traffic information obtained from a monitoring result of a subscriber side termination device monitored by the monitoring and acquisition procedure among the plurality of subscriber side termination devices, and the amount of transmission requests or the amount of transmission from the subscriber side termination devices, and allocating the permissible amount of transmission to the subscriber side termination devices n times, where n is one or more.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a bandwidth allocation method, a bandwidth allocation system, a subscriber-side termination device, and a station-side termination device according to a dynamic control technology of a traffic band from a subscriber termination device to a station-side termination device in a PON (Passive Optical Network). .

  In a passive optical network (PON), as shown in FIG. 1, an end-side terminal device (OLT: Optical Line Terminal) 12 installed in the accommodation station 11 and a plurality of subscriber terminals 14 are installed. It is composed of an optical distribution network (ODN) 16 that distributes a single optical fiber from the OLT 12 connected to a terminal unit (ONU: Optical Network Unit) 15 into a plurality of optical splitters 13 by an optical splitter 13. . Communication between the OLT 12 and the ONU 15 is multiplexed by a time division multiplexing method, a frequency division method, a wavelength division method, etc., and a single OLT 12 is shared by a plurality of users, so it is possible to provide a service at a low cost. is there.

  In the case of the current PON using time-sharing control, communication between the OLT 12 and the ONU 15 is realized by using, for example, a control protocol called MPCP (Multi-Point Control Protocol) (see, for example, Non-Patent Document 1). Unlike the communication from the OLT 12 to the ONU 15 (hereinafter referred to as downlink), the ONU 15 to the OLT 12 (hereinafter referred to as upstream) communication causes a signal collision when a plurality of ONUs 15 emit light at the same time. The ONU 15 can transmit by permission (assignment slot) for designating.

  There are fixed bandwidth allocation (FBA: Fixed Bandwidth Allocation) and dynamic bandwidth allocation (DBA: Dynamic Bandwidth Allocation), and DBA is indispensable for effectively using the PON upstream bandwidth. In the DBA, the OLT 12 determines the permission time based on the transmission request amount from the ONU 15 or the past uplink transmission amount.

  For example, in MPCP, the transmission request amount is transmitted to the OLT 12 by a REPORT message. Based on the request, a permission GATE message is transmitted to the ONU 15, and then data is transmitted to the OLT 12 at the time and length specified by the GATE. (FIG. 2). Note that a GATE for sending a REPORT is periodically allocated separately from the OLT 12 at a fixed period or a variable period.

  In recent years, studies have been made on increasing the distance of PON and increasing the number of branches in order to further improve economic efficiency. Thereby, if attention is paid to the upstream data of a certain ONU 15, the cycle of the transmission timing becomes longer. This is because the response time (RTT: Round Trip Time) of the MPCP message is increased due to the longer distance, and the number of ONUs is increased due to multi-branching, and the transmission timing is opened to one ONU 15.

IEEE 802.3-2012 64.3 Multipoint Control Protocol (MPCP)

  In downlink communication, the OLT 12 can send data to the ONU 15 at an arbitrary timing, while in uplink communication, the ONU 15 once asks the OLT 12 for transmission permission, so the delay until the permission is given lowers the network quality. There is a problem. In particular, due to the recent trend of longer transmission timing cycles, the delay time is further expanded and the network quality is lowered.

  The present invention is characterized in that the traffic state of downlink communication is used for bandwidth control of uplink communication. In many communications, upstream and downstream communications are often performed in unison, not just upstream or downstream unidirectional communications. Therefore, when downlink traffic is found by the OLT 12, it is expected that uplink communication will occur.

  In the network above the PON, the statistical multiplexing effect of traffic occurs, so the correlation between uplink and downlink is low. However, in the PON, there are many forms where individual subscribers are connected to the lower part of the ONU 15 and the traffic bursts. The statistical multiplexing effect is low, and the correlation between uplink and downlink is high.

  Therefore, when downlink traffic occurs for a certain ONU 15, the OLT 12 gives transmission permission such as GATE even if there is no transmission request such as REPORT from the corresponding ONU 15. As a result, it is possible to suppress a delay in uplink communication that is highly likely to occur immediately.

  In order to solve the above-described problems, an object of the present invention is to provide a DBA technique for reducing a delay time in uplink communication.

  In order to achieve the above object, in the present invention, when downlink traffic is generated for an ONU, the OLT grants transmission permission such as GATE even if there is no transmission request such as REPORT from the corresponding ONU.

Specifically, the bandwidth allocation method according to the present invention includes:
A monitoring acquisition procedure in which a station-side terminal device connected to a plurality of subscriber-side terminal devices monitors downlink traffic to the plurality of subscriber-side terminal devices and acquires information on the downlink traffic; and the plurality of subscriptions The amount of transmission permission is determined according to the traffic information acquired from the monitoring result of the subscriber-side termination device monitored by the monitoring acquisition procedure among the subscriber-side termination devices and the transmission request amount or transmission amount from the subscriber-side termination device Then, an allocation procedure for allocating the transmission permission amount n times (n is 1 or more) to the subscriber-side terminal device is sequentially performed.

In the bandwidth allocation method according to the present invention,
The monitoring acquisition procedure includes:
Monitoring downlink traffic to the plurality of terminal devices on the subscriber side, and determining the first transmission permission amount according to traffic information of the downlink traffic;
The allocation procedure is as follows:
Using the transmission permission amount determined according to either the transmission request amount or the transmission amount from the subscriber-side terminal device as the second transmission permission amount, the first transmission permission amount and the second transmission permission amount A transmission permission amount is compared, and if the first transmission permission amount exceeds the second transmission permission amount, a first transmission permission amount is assigned, and the first transmission permission amount is the second transmission permission amount. If the value is less than 2, the second transmission permission amount may be allocated.

In the bandwidth allocation method according to the present invention,
The allocation procedure is as follows:
A sum of the first transmission permission amount and the second transmission permission amount may be determined as a transmission permission amount, and the transmission permission amount may be allocated.

In the bandwidth allocation method according to the present invention,
The monitoring acquisition procedure includes:
Monitoring the transmission permission amount for each bandwidth allocation period and downlink traffic to the plurality of subscriber-side terminal devices, and acquiring the transmission permission amount and the information of the downlink traffic,
The allocation procedure is as follows:
The transmission permission amount may be allocated by determining the transmission permission amount according to the current transmission permission amount and the traffic information, the transmission permission amount of the past allocation period, and the traffic information.

In the bandwidth allocation method according to the present invention,
The allocation procedure is as follows:
The transmission permission amount may be continuously allocated over a plurality of bandwidth allocation periods while gradually decreasing the transmission permission amount determined according to the traffic information or the transmission amount from the subscriber-side terminal device for each allocation period. .

In the bandwidth allocation method according to the present invention,
The allocation procedure is as follows:
When the transmission amount from the subscriber-side terminal device is smaller than the transmission permission amount of the initial allocation period continuously allocated in the past, the transmission permission amount allocated to the initial allocation period as a value smaller than the transmission amount or 0 A decision may be made.

Specifically, the subscriber-side termination device according to the present invention is:
A control signal that is transmitted from a station-side terminator connected via an optical fiber and that includes traffic information of a plurality of subscriber-side terminators and a transmission permission amount determined according to any of a transmission request amount and a transmission amount A receiving unit for receiving;
A transmission unit that transmits communication data to the station-side terminal device in an allocation slot acquired by referring to the control signal.

Specifically, the station side termination device according to the present invention is:
A monitoring acquisition unit that monitors downlink traffic to a plurality of terminal devices on the subscriber side connected via an optical fiber, and acquires information of the downlink traffic;
The traffic information acquired from the monitoring result of the subscriber-side termination device monitored by the monitoring acquisition unit among the plurality of subscriber-side termination devices, and transmitted according to the transmission request amount or the transmission amount from the subscriber-side termination device An allocating unit that determines a permitted amount and allocates the permitted transmission amount n times (n is 1 or more) to the subscriber-side terminal device.

  The above inventions can be combined as much as possible.

  According to the present invention, when downlink traffic occurs for a certain ONU, the OLT gives transmission permission such as GATE even if there is no transmission request such as REPORT from the corresponding ONU. Thereby, it becomes possible to suppress the delay of uplink communication and to improve the quality of the network.

It is an example of the block diagram which shows the structure of the passive optical communication network which concerns on related technology. It is an example of the timing chart which shows the transmission system in MCPC which concerns on related technology. An example of the timing chart of the band allocation method which concerns on related technology is shown. An example of the timing chart of the band allocation method which concerns on related technology is shown. An example of the timing chart at the time of the response delay generation | occurrence | production in the band allocation method which concerns on this embodiment is shown. An example of the timing chart at the time of the continuous generation | occurrence | production of the response in the bandwidth allocation method which concerns on this embodiment is shown. An example of the timing chart which avoids duplication of the transmission permission in the band allocation method which concerns on this embodiment is shown. An example of the timing chart which allocates the total value of the transmission permission in the band allocation method which concerns on this embodiment as a transmission permission amount is shown. It is an example of the block diagram which shows the structure of the band allocation system which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
The bandwidth allocation system according to the present embodiment includes a plurality of subscriber-side termination devices and station-side termination devices, which are connected to each other via a passive optical communication network. The bandwidth allocation method sequentially performs a monitoring acquisition procedure and an allocation procedure. The subscriber-side termination device includes a reception unit and a transmission unit. The station-side terminal device includes a monitoring acquisition unit and an allocation unit. The receiving unit in the subscriber-side terminating device receives a control signal by a GATE frame or the like transmitted from the station-side terminating device connected via the optical fiber, and the transmitting unit obtains the transmission permission acquired by referring to the control signal Communication data is transmitted to the station-side terminal device in the slot.

  FIG. 9 shows a passive optical communication network (PON) using the bandwidth allocation method and the termination device of this embodiment. The terminator refers to the OLT 12 or the ONU 15. The OLT 12 is connected to one optical fiber, branched into a plurality of optical fibers by the optical splitter 13, and then each optical fiber is connected to the ONU 15. There are a plurality of optical splitters 13 on the path, and the number of optical fiber branches may be increased stepwise.

  In the passive optical communication network, different wavelengths are assigned to downlink communication and uplink communication, and a plurality of ONUs 15 can communicate with each other by time division multiplexing in uplink communication and downlink communication. In FIG. 9, the wavelength λ1 is assigned to the upstream signal and the wavelength λ2 is assigned to the downstream signal, but a plurality of wavelengths may be assigned to the upstream signal and the downstream signal. In downlink communication, communications addressed to different ONUs 15 are arbitrarily time-divided by the OLT 12 and delivered to the ONUs 15. Each ONU 15 selectively acquires only communications addressed to itself, thereby realizing a plurality of transmission paths from the OLTs 12 to the ONUs 15 To do.

  In upstream communication, if the ONU 15 arbitrarily sends communication data, a collision occurs when the ONU 15 is multiplexed by the optical splitter 13. Time). Information regarding the transmission timing and the bandwidth is sent from the OLT 12 to the ONU 15 in the downstream communication. The present embodiment relates to uplink bandwidth control.

  The present embodiment is characterized in that the traffic state of the downlink communication is used for bandwidth control of the uplink communication. In many communications, upstream and downstream communications are often performed in unison, not just upstream or downstream unidirectional communications. Therefore, when downlink traffic is found by the OLT 12, it is expected that uplink communication will occur.

  Therefore, the OLT 12 (station-side terminal device) monitors the traffic from the station-side terminal device 12 to each subscriber-side terminal device 15 and acquires traffic information, and the monitoring and acquisition procedure for monitoring and acquiring the information. On the basis of the traffic information obtained in the above and the transmission request amount from the subscriber-side termination device 15 or the transmission amount from the subscriber-side termination device 15 for the traffic from each subscriber-side termination device 15 to the station-side termination device 12. Thus, a bandwidth allocation method having an allocation procedure for allocating a transmission permission amount so as to give transmission permission over a single or a plurality of bandwidth allocation periods is provided.

  A specific example is shown in FIG. When the OLT 12 detects downlink data for the ONU 15, the OLT 12 transmits the downlink data to the ONU 15, and sends an authorization allocation (GATE) for uplink communication to the ONU 15. The ONU 15 transfers the downlink data to, for example, a terminal connected to the ONU 15. The terminal receives the downlink data, generates uplink data in response to the data, and transfers it to the ONU 15. The ONU 15 transfers the upstream data to the OLT 12 at the time allocated by the GATE from the OLT 12.

  In the case of the related technology, as shown in FIG. 4, the ONU 15 that has received the upstream data sends a REPORT to the OLT 12, waits for a GATE from the OLT 12, and transfers the upstream data to the OLT 12 at the time allocated by the GATE. Therefore, a delay occurs. According to the present embodiment, the delay time can be reduced.

  In addition, the technique in the present embodiment does not give permission for GATE based only on downlink data, but the amount of transmission requests from the subscriber-side termination device 15 by normal REPORT or the like, or from the subscriber-side termination device 15 It can be used together with the related technology allocation method based on the transmission amount.

  In the present embodiment, GATE can be continuously set over a plurality of allocation cycles instead of once after detecting downlink data. This is because it is assumed that there is a certain delay in the response of the terminal (FIG. 5) or that the response of the terminal is continuous (FIG. 6).

  The number of transmission permission allocation periods and the transmission permission amount given to the ONU 15 are determined based on the traffic information obtained by the monitoring acquisition procedure to be monitored. Specifically, the presence / absence of downlink traffic, the number of frames, the frame size, Information such as the total value, packet and frame priority (ToS value, Cos value, etc.) is used.

  For example, the simplest is a method of granting transmission permission for a fixed amount of transmission permission amount or the number of assigned cycles depending on the presence or absence of a downstream frame. In addition, when the number of frames and the total size of the frame are large, the transmission permission amount and the allocation cycle number are increased, or a higher transmission permission amount and the allocation cycle number are given to high priority traffic. There is also. Furthermore, there is a method in which transmission permission is not given to downlink traffic of a certain size or less.

(Embodiment 2)
Here, the present embodiment is based on the transmission permission amount 1 based on the traffic information obtained in the monitoring acquisition procedure to be monitored and the transmission request amount from the subscriber-side termination device 15 or the transmission amount from the subscriber-side termination device 15. The transmission permission amount 2 is compared in the allocation procedure, and when the transmission permission amount 1 exceeds the transmission permission amount 2, the transmission permission of the transmission permission amount 1 is given, and when it is lower, the transmission permission of the transmission permission amount 2 is given. Also good.

  That is, two allocations of transmission permission amount 1 based on downlink traffic detection and transmission permission amount 2 based on transmission request amount from subscriber-side terminal device 15 such as REPORT or transmission amount from subscriber-side terminal device 15 occurred simultaneously. Sometimes, the larger of the transmission permission amount 1 and the transmission permission amount 2 is assigned as the transmission permission amount given to GATE.

  This method basically complements the allocation by allocation based on downlink traffic detection based on the allocation method of related technology such as REPORT. When the transmission permission amount 1 is allocated multiple times, the same uplink data On the other hand, since the transmission permission amount 2 by REPORT or the like is assigned, there is an effect of avoiding a loss band due to the duplication.

  In FIG. 7, the upstream data 1 is already transferred from the ONU 15 to the OLT 12 in the GATE 1 and the requested amount due to the REPORT of the upstream data 1 is also considered in the GATE 2. In this case, in order to avoid waste due to duplication as much as possible In addition, the larger one of the transmission permission amount 1 and the transmission permission amount 2 is adopted as the transmission permission amount of GATE2.

(Embodiment 3)
On the other hand, the present embodiment is based on the transmission permission amount 1 based on the traffic information obtained in the monitoring acquisition procedure to be monitored, the transmission request amount from the subscriber-side termination device 15, or the transmission amount from the subscriber-side termination device 15. The transmission permission amount 2 may give a transmission permission of the sum of the transmission permission amount 1 and the transmission permission amount 2.

  That is, two allocations of transmission permission amount 1 based on downlink traffic detection and transmission permission amount 2 based on transmission request amount from subscriber-side terminal device 15 such as REPORT or transmission amount from subscriber-side terminal device 15 occurred simultaneously. Sometimes, the transmission permission amount 1 + transmission permission amount 2 is assigned as the transmission permission amount given to GATE.

  When the transmission permission amount 1 is assigned a plurality of times, the transmission permission amount 2 by REPORT or the like is assigned to the same uplink data, so that the loss bandwidth due to the duplication increases, but as shown in FIG. When there is another upstream traffic before the downstream traffic occurs, when the downstream traffic occurs, the data can be transmitted from the ONU 15 to the OLT 12 with little delay with respect to the upstream data 1.

(Embodiment 4)
Furthermore, in the present embodiment, there is a monitoring acquisition procedure for monitoring the transmission permission amount for each allocation cycle and the traffic volume from each subscriber-side terminal device 15 to the station-side terminal device 12, and the allocation procedure in the monitoring acquisition procedure in the allocation procedure The transmission permission amount based on the traffic information obtained in the monitoring acquisition procedure may be changed during communication from the difference between the transmission permission amount and the traffic amount for each transmission or the difference between the past transmission permission amount and the traffic amount. .

  The transmission permission by downlink traffic may cause an allocation time during which uplink data is not actually transmitted, resulting in a decrease in bandwidth utilization efficiency. This reduction in bandwidth utilization efficiency depends on the transmission permission amount based on the traffic information obtained by the monitoring acquisition procedure and the number of assigned cycles. That is, if a larger amount of transmission permission and the number of allocation periods are given as GATE, the delay can be reduced, but the bandwidth utilization efficiency is lowered.

  Therefore, if the bandwidth utilization efficiency is obtained from the difference between the transmission permission amount and the uplink data actually transmitted from the ONU 15 to the OLT 12 and becomes worse than a certain threshold, the transmission permission amount or allocation based on the traffic information obtained by the monitoring acquisition procedure By reducing the number of cycles, it is possible to control so as not to improve the bandwidth utilization efficiency or to reduce the bandwidth utilization efficiency beyond a certain level.

(Embodiment 5)
Further, the present embodiment may be characterized in that the allocation procedure adjusts the transmission permission amount for each allocation cycle based on the information obtained from the traffic information obtained by the monitoring acquisition procedure. That is, the transmission permission amount given by GATE1 and GATE2 shown in FIG. 6 can be changed.

(Embodiment 6)
In the present embodiment, the allocation procedure may be characterized in that, for transmission permission based on traffic information, the transmission permission amount in a plurality of allocation periods is gradually decreased every time the period passes. That is, in FIG. 6, GATE2 gives a smaller transmission permission amount than GATE1.

  There is a stepwise gradual reduction method such as giving the same amount of transmission permission over a plurality of periods and then reducing it. Since the degree of correlation of uplink data correlated with downlink data decreases with the passage of time, a decrease in bandwidth utilization efficiency can be prevented by reducing the transmission permission amount.

(Embodiment 7)
In this embodiment, when the allocation procedure is such that the transmission permission based on the traffic information has a smaller traffic volume from the subscriber-side terminal device 15 to the station-side terminal device 12 than the transmission permission amount in the past initial allocation period. The transmission permission amount in the initial allocation period may be 0 or a small amount.

  This is because if there is a delay in the uplink data corresponding to the downlink data from the terminal, the downlink data is observed by the OLT 12, and if the GATE is assigned immediately, the allocation time may be wasted. It is taken into consideration. If the upstream traffic is monitored by the method described in the fourth embodiment, the downlink data is observed by the OLT 12, and the transmission permission immediately assigned with GATE is often wasted, the response speed of the terminal under the ONU 15 is slow. This is a technique for making a determination and allowing a delay before transmission permission by GATE. In the above-described embodiment, the subscriber-side terminating device 15 sets the subscriber-side terminating device 15 in the power saving mode during the transmission permitted time from the acquisition time when the control signal with the determined transmission permitted time is acquired. The power saving mode may be canceled as the transmission permission time elapses.

  Note that the gradual reduction method described in the present embodiment and the sixth embodiment may be combined.

  The present invention can be applied to the information communication industry.

11: Containment station 12: OLT
13: Optical splitter 14: Subscriber home 15: ONU
16: ODN (passive optical communication network)

Claims (8)

A monitoring acquisition procedure in which a station-side terminal device connected to a plurality of subscriber-side terminal devices monitors downlink traffic to the plurality of subscriber-side terminal devices and acquires information on the downlink traffic; and the plurality of subscriptions The amount of transmission permission is determined according to the traffic information acquired from the monitoring result of the subscriber-side termination device monitored by the monitoring acquisition procedure among the subscriber-side termination devices and the transmission request amount or transmission amount from the subscriber-side termination device And an allocation procedure for allocating the transmission permission amount n times (n is 1 or more) to the subscriber-side terminating device;
A bandwidth allocation method characterized by sequentially performing the steps. The monitoring acquisition procedure includes:
Monitoring downlink traffic to the plurality of terminal devices on the subscriber side, and determining the first transmission permission amount according to traffic information of the downlink traffic;
The allocation procedure is as follows:
Using the transmission permission amount determined according to either the transmission request amount or the transmission amount from the subscriber-side terminal device as the second transmission permission amount, the first transmission permission amount and the second transmission permission amount A transmission permission amount is compared, and if the first transmission permission amount exceeds the second transmission permission amount, a first transmission permission amount is assigned, and the first transmission permission amount is the second transmission permission amount. The bandwidth allocation method according to claim 1, wherein a second transmission permission amount is allocated if the transmission permission amount is less than. The allocation procedure is as follows:
The bandwidth according to claim 1 or 2, wherein a sum of the first transmission permission amount and the second transmission permission amount is determined as a transmission permission amount, and the transmission permission amount is allocated. Assignment method. The monitoring acquisition procedure includes:
Monitoring the transmission permission amount for each bandwidth allocation period and downlink traffic to the plurality of subscriber-side terminal devices, and acquiring the transmission permission amount and the information of the downlink traffic,
The allocation procedure is as follows:
2. The transmission permission amount is determined by determining a transmission permission amount according to the current transmission permission amount and the traffic information, a transmission permission amount in the past allocation period, and the traffic information. 4. The bandwidth allocation method according to any one of items 1 to 3.
The allocation procedure is as follows:
The transmission permission amount is continuously allocated over a plurality of bandwidth allocation periods while gradually decreasing the transmission permission amount determined according to the traffic information or the transmission amount from the subscriber-side terminal device for each allocation period. The bandwidth allocation method according to any one of claims 1 to 4. The allocation procedure is as follows:
When the transmission amount from the subscriber-side terminal device is smaller than the transmission permission amount of the initial allocation period continuously allocated in the past, the transmission permission amount allocated to the initial allocation period as a value smaller than the transmission amount or 0 6. The bandwidth allocation method according to claim 1, wherein the determination is performed. A control signal that is transmitted from a station-side terminator connected via an optical fiber and that includes traffic information of a plurality of subscriber-side terminators and a transmission permission amount determined according to any of a transmission request amount and a transmission amount A receiving unit for receiving;
A transmission unit that transmits communication data to the station-side terminal device in an allocation slot acquired by referring to the control signal;
A subscriber-side terminating device comprising: A monitoring acquisition unit that monitors downlink traffic to a plurality of terminal devices on the subscriber side connected via an optical fiber, and acquires information of the downlink traffic;
The traffic information acquired from the monitoring result of the subscriber-side termination device monitored by the monitoring acquisition unit among the plurality of subscriber-side termination devices, and transmitted according to the transmission request amount or the transmission amount from the subscriber-side termination device An allocating unit that determines a permitted amount and allocates the permitted transmission amount n times (n is 1 or more) to the subscriber-side terminal device;
A station-side termination device comprising:

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