JP5312265B2 - Optical communication system, station side device, and subscriber side device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical communication system which provides low consumption power of an ONU (Optical Network Unit) even when mixing and transmitting a streaming data frame and a non-streaming data frame in a downward signal. <P>SOLUTION: In the optical communication system, an OLT (Optical Line Terminal) is provided with a frame discrimination means which classifies frames into the streaming data frames and the non-streaming data frames and a downward signal transmission means which arranges the streaming data frames to a first section to be continuous and non-streaming data frames to a second section, and then transmits them to ONU3<SB>1</SB>to 3<SB>n</SB>. The ONU3<SB>1</SB>to 3<SB>n</SB>shift to a sleep state at the time zone in which a streaming data frame of a different kind from that of streaming data frame requested for viewing and listening is transmitted. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical communication system, a station-side apparatus, and a subscriber-side apparatus that handle a signal in which data that needs to be continuously received on the receiving side, such as streaming data, and non-streaming data are mixed.

  2. Description of the Related Art In recent years, a PON (Passive Optical Network) system, which is one type of FTTH (Fiber To The Home), has rapidly spread in access networks that connect stations and user houses.

  In the PON system, a station side device (OLT: Optical Line Termination) and a plurality of subscriber side devices (ONU: Optical Network Unit) are connected via an optical splitter that branches signal outputs to a plurality of optical fibers. is there. The ONU is a device installed in the user's home, and a TE (Terminal Equipment) is connected to the ONU via a LAN cable. TE includes HGW (Home Gate Way), VoIP-TA (Voice over Internet Protocol-Terminal Adapter), PC, and the like.

  In the PON system as described above, since the ONU always establishes a link with the OLT and the TE even during standby when data communication is not performed, there is a problem that power consumption is large. Therefore, studies have been made so far for methods for solving such a problem of power consumption (for example, see Non-Patent Document 1 below).

  In the method described in Non-Patent Document 1 below, when there is a sleep request from the ONU, the OLT notifies the sleep approval and causes the ONU to sleep for a specified time, and then the ONU starts intermittently and continues. By selecting whether to sleep automatically (sleeping for a specified time again) or starting, and when starting, unnecessary control is performed by executing a control operation to notify the OLT to that effect. I try to save power.

ITU-T SG15Q2 Intended type of document (R-C-TD): GR04, “ONU power-save annex”, PMC-Sierra

  However, in the conventional method disclosed in Non-Patent Document 1 (method for reducing power consumption), a frame (streaming data frame) that the ONU needs to always receive, such as streaming data of a video distribution service, for example. ) And non-streaming data frames mixedly transmitted. Therefore, there is a problem that the conventional method cannot be applied to a system in which streaming data frames and non-streaming data frames are mixed and transmitted from the OLT, or that sufficient power consumption cannot be expected even if applied. there were.

  For example, when the above-described conventional method is applied to a system configured to transmit streaming data frames and non-streaming data frames mixedly from the OLT, the ONU may change the streaming data frame in the state of transition to the low power consumption mode. Can not receive. That is, once the transition to the low power consumption mode (sleep state) is permitted, the streaming service cannot be provided to the user thereafter. On the other hand, in the state where the streaming service is provided, the ONU continues to receive the streaming data frame, and thus cannot make a transition to the low power consumption mode and cannot reduce the power consumption.

  In addition, in a situation where streaming data frames and non-streaming data frames are mixed, it is possible to reduce the power consumption by operating the ONU to sleep in units of frames. In this case, the ONU comes to the ONU. Since it is necessary to frequently exchange control frames between the OLT and the ONU in order to know the arrival time for each frame, bandwidth efficiency is reduced and frame transmission control is complicated. In addition, it is necessary to frequently perform ONU activation and sleep frequently in units of frames, and the rise time for transitioning to the ONU activation state and the fall time for transitioning to the sleep state are integrated. It cannot be reduced.

  The present invention has been made in view of the above, and in the case where a streaming signal frame and a non-streaming data frame are mixedly transmitted in a downstream signal, an optical communication system capable of reducing the power consumption of the ONU, and the station side An object is to obtain a device and a subscriber side device.

  In order to solve the above-described problems and achieve the object, the present invention provides an optical communication system including a station-side device and one or more subscriber-side devices connected to the station-side device via an optical fiber. The station side device is arranged in the first section so that the frame input from the host device is classified into a streaming data frame and a non-streaming data frame, and the streaming data frame is continuous. And a downstream signal transmitting means for transmitting the non-streaming data frame to the respective subscriber-side devices by arranging in the second section, and the subscriber-side device is different from the streaming data frame for which it has requested viewing. It shifts to a sleep state in the time slot | zone when the kind of streaming data frame is transmitted, It is characterized by the above-mentioned.

  According to the present invention, since the station side device arranges each data frame so that the same type of streaming data frame is continuously transmitted, the subscriber side device can reduce power consumption. Play.

FIG. 1 is a diagram illustrating a configuration example of a first embodiment of an optical communication system according to the present invention. FIG. 2 is a diagram illustrating an example of a timing chart of downlink signals in the optical communication system according to the first embodiment. FIG. 3 is a diagram showing a downlink signal transmission / reception sequence in the optical communication system according to the first embodiment. FIG. 4 is a diagram showing an example of downlink time slot information. FIG. 5 is a diagram illustrating an example of downlink time slot information. FIG. 6 is a diagram illustrating a configuration example of the OLT according to the first embodiment. FIG. 7 is a flowchart illustrating an operation example of the OLT according to the first embodiment. FIG. 8 is a diagram illustrating a configuration example of the ONU according to the first embodiment. FIG. 9 is a flowchart illustrating an operation example of the ONU according to the first embodiment. FIG. 10 is a diagram comparing the power saving control operation in the system of the first embodiment and the power saving control operation in the conventional system. FIG. 11 is a diagram illustrating a downlink signal transmission / reception sequence in the optical communication system according to the second embodiment. FIG. 12 is a diagram showing an example of downlink time slot information. FIG. 13 is a diagram showing an example of downlink time slot information. FIG. 14 is a diagram illustrating a configuration example of the OLT according to the second embodiment. FIG. 15 is a flowchart illustrating an operation example of the OLT according to the second embodiment. FIG. 16 is a flowchart illustrating an operation example of the ONU according to the second embodiment. FIG. 17 is a diagram illustrating an example of a timing chart of downlink signals in the optical communication system according to the third embodiment. FIG. 18 is a diagram illustrating a downlink signal transmission / reception sequence in the optical communication system according to the third embodiment. FIG. 19 is a flowchart illustrating an operation example of the OLT according to the third embodiment. FIG. 20 is a diagram illustrating another configuration example of the optical communication system according to the third embodiment. FIG. 21 is a diagram showing a downlink signal transmission / reception sequence in the optical communication system according to the fourth embodiment. FIG. 22 is a flowchart showing an operation example of the OLT according to the fourth embodiment. FIG. 23 is a flowchart illustrating an operation example of the ONU according to the fourth embodiment. FIG. 24 is a diagram illustrating an example of a timing chart of downlink signals in the optical communication system according to the fifth embodiment. FIG. 25 is a diagram illustrating a configuration example of the OLT according to the fifth embodiment. FIG. 26 is a flowchart illustrating an operation example of the OLT according to the fifth embodiment. FIG. 27 is a diagram illustrating an example of a timing chart of downlink signals in the optical communication system according to the sixth embodiment. FIG. 28 is a diagram illustrating a configuration example of the OLT according to the sixth embodiment. FIG. 29 is a flowchart illustrating an operation example of the OLT according to the sixth embodiment. FIG. 30 is a diagram illustrating a configuration example of the OLT according to the seventh embodiment.

  Embodiments of an optical communication system, a station-side device, and a subscriber-side device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of an optical communication system according to the present invention, showing an example in which a PON system is configured by a station side device (OLT) and a subscriber side device (ONU). ing.

As shown in the figure, the optical communication system of the present embodiment is connected to the OLT 1 capable of streaming delivery, the optical splitter 2 connected to the OLT 1 via an optical fiber, and the optical splitter 2 via an optical fiber. ONUs 3 _{1 to} 3 _n that can receive streaming data distributed from the OLT 1, HGWs 4 ₁ to 4 _n that are connected to each ONU and connect the communication carrier and the user's home network, and personal computers that are connected to each HGW PCs 5 _{1 to} 5 _n that are information terminal devices and STBs (Set Top Box) 6 _{1 to} 6 _n that are connected to the respective HGWs and generate video information that can be played back by the TV based on the received streaming data frames, TVs 7 _{1 to} 7 _n connected to the STB and displayed on the screen using the video information received from the connected STB.

Here, in this embodiment and each embodiment described later, it is assumed that the streaming data frame is an IP multicast used for video distribution or the like. Moreover, streaming data frame after being transmitted from the OLT to ONU 3 ₁ to 3 _n, is passed to the STB 6 ₁ to 6 _n via respective HGW4 ₁ ~4 _n, where it is converted into a video signal, TV7 ₁ ~ 7 _n is data for reproducing the video signal and displaying the video.

  Further, the non-streaming data frame is a data to be transmitted to the PC assuming a frame other than the streaming data frame as described above. However, the type of streaming data frame is not limited to the above.

  Next, the overall operation of the optical communication system according to the present embodiment will be described. In the optical communication system having the configuration shown in FIG. 1, when each TV (user) selects a viewing channel, the information is passed to the STB connected to the TV on which the viewing channel is selected. The STB generates a channel viewing request for the viewing channel indicated by the received information, and outputs the channel viewing request to the ONU connected via the HGW. Upon receiving a channel viewing request from the STB, each ONU transmits the received channel viewing request to the OLT 1.

As a premise for the following description, ONU 3 ₁ transmits a channel viewing request for ch ₂ to OLT 1, ONU 3 ₂ transmits a channel viewing request for ch 1 to OLT 1, and ONU 3 _n transmits a channel viewing request for ch 4 to OLT 1. It shall be. The PCs 5 _{1 to} 5 _n are assumed to be in an activated state. However, these are examples for explanation and are not limited to this.

  The downlink signal received by the OLT 1 from a higher-level device (not shown) is a signal in which streaming data frames and non-streaming data frames are mixed. Then, the OLT 1 aggregates the streaming data frame and the non-streaming data frame for each channel by separately buffering and aggregating the frames, and transmits the frames by type (details of the frame transmission operation by the OLT 1 will be described later). To do).

  FIG. 2 is a diagram illustrating an example of a timing chart of a downlink signal when the OLT 1 collects each frame received from the higher-level device according to type.

  The OLT 1 sets the band update period of the downlink signal shown in FIG. In this example, it is assumed that the bandwidth update cycle is from several microseconds to several milliseconds. However, in actual application, this is not limited to this. You may make it set.

  Further, the OLT 1 sets a streaming data slot and a non-streaming data slot within the band update period. In addition, in the streaming data slot, a slot (corresponding to the channel slot shown in the figure) is further set for each channel (for each type), and streaming data frames belonging to the channel are aggregated in each channel slot and transmitted to each ONU. To do. That is, OLT 1 arranges and transmits in a channel slot so that streaming data frames received by the same ONU (streaming data frames of the same type) are continuously transmitted. FIG. 2 shows, as an example, a state in which the streaming data frames of ch1 are aggregated in the channel slot for ch1. Although not shown, the same kind of streaming data frames are aggregated in the channel slot for ch2 and the channel slot for ch4 as well as the channel slot for ch1. On the other hand, in the non-streaming data slot, non-streaming data frames addressed to each ONU are mixed according to the transfer rule based on the frame priority set by the operator or the like.

FIG. 3 is a diagram illustrating a downlink signal transmission / reception sequence in the OLT 1 and the ONUs 3 _{1 to} 3 _n of the optical communication system according to the present embodiment.

  As shown in FIG. 3, in the downlink signal transmission / reception operation, each ONU first transmits a channel viewing request to the OLT 1, and then the OLT 1 determines a downlink time slot configuration and starts a band update period. .

  The OLT 1 first transmits downlink time slot information to all ONUs at the beginning of the bandwidth update period. Here, a configuration example of the downlink time slot information is shown in FIGS. FIG. 4 shows an example of downlink time slot information transmitted by the “downlink time slot information notification (A)” shown in FIG. On the other hand, FIG. 5 shows an example of downlink time slot information transmitted by the “downlink time slot information notification (B)” shown in FIG. The downlink time slot information includes, for example, streaming data slot information, non-streaming data slot information, and channel slot information. The streaming data slot information includes information on the start time and slot length of the streaming data slot, and the non-streaming data slot information includes information on the start time and slot length of the non-streaming data slot. The channel slot information includes information on the start time of each channel slot. However, the information included in the downlink time slot information may be any information as long as the configuration of the streaming data slot and the non-streaming data slot included in one band update period can be grasped. is not. The OLT 1 stores this downlink time slot information in a control frame such as an OAM frame or an extended MAC control frame and transmits it to each ONU.

  When the transmission of the downlink time slot information is completed, the OLT 1 becomes the streaming data slot start time according to the determined time slot configuration (configuration of the streaming data slot and the non-streaming data slot indicated by the downlink time slot information). At that time, the streaming data is transmitted to each ONU.

  On the other hand, according to the downlink time slot information received from the OLT 1, each ONU shifts to an activated state at the start time of the channel slot requested by itself (own ONU), maintains the activated state for the slot length, and A streaming data frame transmitted in a channel slot is received. Also, each ONU ends when the channel slot corresponding to the channel requested for viewing ends, and when the start time of the channel slot different from the one requested for viewing after receiving downlink time slot information , Go to sleep. That is, within one bandwidth update period, each ONU analyzes the received downlink time slot information to identify a period during which the channel slot requested for viewing by itself is transmitted. To move to.

In the example shown in FIG. 3, only the ONU 3 ₂ shifts to the activated state in the channel slot that is transmitting the streaming data (ch1) in the bandwidth update period in which the downlink time slot information notification (A) is transmitted from the OLT 1. , ONUs 3 ₁ and 3 _n are in the sleep state. Similarly, in the channel slot in transmitting streaming data (ch2), the process proceeds to active state only ONU 3 _1, ONU 3 ₂ and 3 _n is in the sleep state, the channel slot in transmitting streaming data (ch4), ONU 3 _n Only the ONUs 3 ₁ and 3 ₂ enter the sleep state.

  The OLT 1 transmits non-streaming data to each ONU when the non-streaming data slot start time comes. Each ONU shifts to an activated state when the non-streaming data slot start time is reached, receives a non-streaming data frame, and transmits only a frame addressed to itself included in the non-streaming data frame to a lower level device (such as a PC) To do.

  The above is the operation sequence of the OLT 1 and each ONU in one band update cycle, and the OLT 1 and each ONU communicate downlink signals by repeating the operation within this band update cycle. Although FIG. 3 shows an example in which the OLT 1 collects channel viewing requests from each ONU every several bandwidth update cycles, the actual operation is not limited to this.

In FIG. 3, the OLT 1 collects the A-th viewing request immediately before the bandwidth update period N, and as a result, it detects that the ONU 3 ₁ is making a viewing request for ch2, the ONU3 ₂ is a ch1, and the ONU3 _n is making a viewing request for a ch4. Then, in the downlink time slot information notification (A) after the band update period N, downlink time slot information (see FIG. 4) storing the start time and slot length of each channel slot of ch1, ch2, and ch4 is sent to each ONU. Notice. Thereafter, the OLT 1 collects the B-th viewing request immediately before the bandwidth update cycle M, and as a result, detects that the viewing channel of the ONU 3 _n has been changed from ch4 to ch5, and downloads after the bandwidth update cycle M. In the time slot information notification (B), downlink time slot information (see FIG. 5) storing the start time and slot length of each channel slot of ch1, ch2, and ch5 is notified to each ONU. The operation sequence example in such a case is shown.

Next, the configuration of the OLT 1 will be described with reference to FIG. FIG. 6 is a diagram illustrating a configuration example of the OLT 1. As shown in FIG. 6, the OLT 1 includes a line termination unit 11, a frame determination unit 12, a streaming data buffer 13, a non-streaming data buffer 14, a buffer selector 15, a downlink time slot control unit 16, a PON processing unit 17, and an optical IF. The unit 18 is provided. The streaming data buffer 13 includes an input side selector 131, queues 132 _{1 to} 132 _T, and an output side selector 133. In FIG. 6, arrows whose contents are not clearly shown indicate connection of main signals. In FIG. 6, the streaming data buffer 13, the non-streaming data buffer 14, the buffer selector 15, the downlink time slot control unit 16, and the PON processing unit 17 constitute a downlink signal transmission unit.

  In the OLT 1 configured as described above, the line termination unit 11 is used for connection with the higher-level device, and forwards the downlink signal input from the higher-level device to the frame determination unit 12. Also, the upstream signal input from the PON processing unit 17 is transferred to the host device.

  The frame determination unit 12 determines a streaming data frame and a non-streaming data frame in the downlink signal received from the line termination unit 11. As for a streaming data frame, the channel to which the frame belongs is determined by an identifier (for example, VLANID) stored in the frame. The frame determined to be a streaming data frame is transferred to the streaming data buffer 13, and the frame determined to be a non-streaming data frame is transferred to the non-streaming data buffer 14. At the same time, a channel queue input instruction is output to the streaming data buffer 13 for distribution to a queue within the buffer, and non-streaming data for capturing a frame to the non-streaming data buffer 14 Output input instructions.

  As shown in the figure, the streaming data buffer 13 has a queue corresponding to each channel in order to hold the input frames for each channel to which they belong. When a streaming data frame and a channel queue input instruction are input from the frame determination unit 12, the input side selector 131 is switched by the channel queue input instruction, and the queue is associated with the channel to which the frame belongs. Store. When the streaming data buffer 13 receives a channel queue output instruction from the downlink time slot control unit 16, the streaming data buffer 13 switches the output side selector 133 in accordance with the instruction content, extracts the streaming data frame from the queue indicated by the instruction content, and extracts the streaming data frame 15. Output to.

  When a non-streaming data frame and a non-streaming data input instruction are input from the frame determination unit 12, the non-streaming data buffer 14 stores the received non-streaming data frame. Further, upon receiving a non-streaming data output instruction from the downstream time slot control unit 16, the non-streaming data buffer 14 outputs the held non-streaming data frame to the buffer selector 15. When a plurality of non-streaming data frames are held, the oldest frame (the frame received first) is output. However, the implementation of the output method from the buffer is not limited to this.

  In accordance with the buffer output switching instruction from the downlink time slot control unit 16, the buffer selector 15 selects either the input signal (streaming data frame) from the streaming data buffer 13 or the input signal (non-streaming data frame) from the non-streaming data buffer 14. Either one is selected and output to the PON processing unit 17.

  When the downlink time slot control unit 16 receives a channel viewing request from the ONU via the PON processing unit 17, the downlink time slot control unit 16 determines the channel indicated by the received channel viewing request within the downlink bandwidth update period set by the operator or the like. From the rate and the bandwidth update period, the start time and slot length of each channel slot are determined, and further, the time allocation of streaming data slots and non-streaming data slots is determined. Then, downlink time slot information indicating the determination content is generated and output to the PON processing unit 17. Further, in order to control the timing of outputting the streaming data frame from the streaming data buffer 13 and the timing of outputting the non-streaming data frame as described above, a buffer output switching instruction is output to the buffer selector 15; Further, a channel queue output instruction is output to the output side selector 133, and a non-streaming data output instruction is output to the non-streaming data buffer 14. In particular, the channel queue output instruction controls the output timing of the streaming data frame of each channel according to the start time of each channel slot in the streaming data slot.

  The PON processing unit 17 processes a control frame for controlling the upstream communication of each ONU. This control frame includes a channel viewing request. Further, the downlink time slot information input from the downlink time slot control unit 16 is included in the frame, multiplexed into the downlink signal, and transferred to the optical IF. As described above, the downlink time slot information is transmitted by being included in a control frame such as an OAM frame or an extended MAC control frame. Also, the data frame (streaming data frame, non-streaming data frame) input via the buffer selector 15 is output to the optical IF unit 18.

  When receiving the upstream optical signal via the connected optical fiber, the optical IF unit 18 converts it into an upstream electrical signal and transfers it to the PON processing unit 17. When a downstream electrical signal is received from the PON processing unit 17, it is converted into a downstream optical signal and transmitted to the ONU via an optical fiber.

  Here, each block in FIG. 6 is shown as an example of a functional block, and is not limited to this when actually mounted.

  FIG. 7 is a flowchart illustrating an operation example of the OLT 1, and is a flowchart when the operation as illustrated in FIG. 3 is performed. Hereinafter, an operation when the OLT 1 transmits a downlink signal will be described with reference to FIGS. 3, 6, and 7.

  In transmitting the downlink signal, the OLT 1 first acquires information on the band update period (step S11). In this step S11, for example, when the setting operation of the band update period in the downlink signal is performed by an operator or the like, the downlink time slot control unit 16 acquires the setting content. When the bandwidth update period is acquired, the downlink time slot control unit 16 then starts monitoring the channel viewing request from each ONU and confirms whether there has been a change in the channel viewing request (step S12). More specifically, every time the bandwidth update period ends (strictly, at the timing of generating downlink time slot information to be transmitted in the next bandwidth update period), a channel viewing request is issued after confirming whether there has been a previous change. It is confirmed whether or not the channel viewing request received this time is different from the content of the channel viewing request previously received from the transmission source ONU. For example, when an A-th channel viewing request is received from each ONU and then an A + 1-th channel viewing request is received, it is confirmed whether there is a change in the channel viewing request received from the same ONU. If there is a change in the above channel viewing request, it is determined that there is a change.

  If there is a change in the channel viewing request (step S12-Yes), the distribution of the streaming data slot and the non-streaming data slot is determined based on the channel viewing request from each ONU (step S13). The indicated downlink time slot information is notified to each ONU (step S14). In these steps S13 and S14, as already described with reference to FIG. 2, distribution is determined for the purpose of collecting and transmitting each frame of streaming data by type. Specifically, the streaming data slot start time and slot length, and the start time of each channel slot are determined so that streaming data frames of the same channel are continuously transmitted (FIGS. 2, 4, and 4). 5).

  When there is no change in the channel viewing request (step S12-No), the same downlink time slot information as the previously notified downlink time slot information is notified to each ONU (step S14). In the example shown in FIG. 3, the downlink time slot information is always transmitted in each band update period regardless of whether or not the channel viewing request has changed, but only when there is a change, the downlink time slot is transmitted. Information may be transmitted. In other words, the OLT 1 may execute step S14 and subsequent steps only when it is determined “Yes” in step S12. In this case, each ONU operates by determining that the bandwidth has not been updated unless receiving notification of downlink time slot information.

  After notifying the downlink timing slot information in step S14, the OLT 1 transmits streaming data when the start time of the streaming data slot comes (step S15). Specifically, the downlink time slot control unit 16 outputs a buffer switching instruction and a channel queue output instruction, and generates a streaming data slot having the same configuration as that indicated by the downlink timing slot information notified in step S14. As described above, the buffer selector 15 and the streaming data buffer 13 are controlled, and the PON processing unit 17 transmits the signal (frame) output from the buffer selector 15 to each ONU via the optical IF unit 18.

  Further, the OLT 1 transmits non-streaming data when the start time of the non-streaming data slot comes (step S16). Specifically, the downlink time slot control unit 16 outputs a buffer switching instruction and a non-streaming data output instruction, and a non-streaming data slot having the same configuration as the configuration indicated by the downlink timing slot information notified in step S14 above. The PON processing unit 17 transmits a signal (frame) output from the buffer selector 15 to each ONU via the optical IF unit 18 so that the buffer selector 15 and the non-streaming data buffer 14 are controlled. .

  OLT1 returns to step S12 after performing said step S16, and repeats the process of step S12-step S16.

Next, the configuration of the ONUs 3 _{1 to} 3 _n will be described with reference to FIG. FIG. 8 is a diagram illustrating a configuration example of the ONUs 3 _{1 to} 3 _n . As shown in FIG. 8, the ONUs 3 _{1 to} 3 _n have the same configuration, and the optical IF unit 31, the PON processing unit 32, the downstream time slot processing unit 33, the upstream buffer 34, the downstream buffer 35, and the line termination, respectively. Part 36 is provided. In FIG. 8, arrows whose contents are not clearly shown indicate connection of main signals.

  In each ONU configured as described above, the line termination unit 36 is used for connection with a lower-level device (such as HGW) and transfers an upstream signal input from the lower-level device to the upstream buffer 34. In addition, the downlink signal input from the downlink buffer 35 is transferred to the lower-level device.

  The upstream buffer 34 accumulates upstream signals to be transmitted to the OLT 1, and transfers the accumulated upstream signals to the PON processing unit 32 according to the control of the PON processing unit 32. On the other hand, the downlink buffer 35 accumulates downlink signals to be transmitted to the lower order devices.

  The PON processing unit 32 processes each frame received from the OLT 1, controls the output timing of the frame from the upstream buffer 34 according to the processing result of the control frame for controlling the upstream communication, and also transmits the downstream signal addressed to the own ONU. Extract and transfer to the downstream buffer 35. Further, if the received frame includes downlink time slot information, it is extracted and transferred to the downlink time slot processing unit 33.

  When the downlink time slot processing unit 33 receives the downlink time slot information received from the OLT 1 via the PON processing unit 32, the start / end time of the own ONU viewing request channel slot and the start / end time of the non-streaming data slot in the information are received. The end time is confirmed, and a sleep / wake-up instruction is issued to the optical IF unit 31, the PON processing unit 32, and the down buffer 35 according to the confirmation result.

  When receiving the downstream optical signal from the OLT 1 via the connected optical fiber, the optical IF unit 31 converts it into a downstream electrical signal and transfers it to the PON processing unit 32. When an upstream electrical signal is received from the PON processing unit 32, it is converted into an upstream optical signal and output to the OLT 1 via an optical fiber.

  Here, each block in FIG. 8 is shown as an example of a functional block, and is not limited to this when actually mounted.

FIG. 9 is a flowchart showing an operation example of the ONUs 3 _{1 to} 3 _n , and is a flowchart when the operation as shown in FIG. 3 is performed. Hereinafter, the operation when the ONUs 3 _{1 to} 3 _n receive downlink signals will be described with reference to FIGS. 3, 8, and 9.

  Each ONU first receives downlink time slot information in the downlink signal reception operation (step S31). More specifically, the downlink time slot processing unit 33 receives the downlink time slot information (see FIGS. 4 and 5) from the OLT 1 via the PON processing unit 32, and the own ONU viewing request channel slot (self Confirms the start / end time of the channel slot corresponding to the channel requested to view and the start / end time of the non-streaming data slot.

  Then, after confirming the start / end times of the own ONU viewing request channel slot and the non-streaming data slot, the downstream time slot processing unit 33 of each ONU performs the own viewing request channel slot (streaming of the channel for which the viewing request has been made). It is monitored whether or not the start time of the streaming data slot in which the data frame is distributed (step S32). If it is not the start time (step S32-No), the process shifts to the sleep state (step S33). Specifically, the downlink time slot processing unit 33 outputs a sleep instruction to the optical IF unit 31, the PON processing unit 32, and the downlink buffer 35. Thereafter, the sleep state is continued until the start time of the own viewing request channel slot. However, if the own viewing channel does not exist (no channel viewing is requested) in step S32, the process proceeds to step S37.

  On the other hand, when the start time is reached (step S32—Yes), the ONU shifts to the activated state (step S34). Specifically, the downlink time slot processing unit 33 outputs an activation instruction to the optical IF unit 31, the PON processing unit 32, and the downlink buffer 35. Then, the ONU receives the streaming data frame of the own viewing channel (the channel that requested the viewing request) in the activated state (step S35), and further monitors whether the end time of the own viewing request channel slot has been reached (step S35). Step S36). If it is not the end time (step S36-No), reception of the streaming data frame of the own viewing channel and confirmation of whether or not the own viewing request channel slot is finished are continued until the own viewing request channel slot is finished.

  If it is the end time of the own viewing request channel slot (step S36-Yes), it is determined whether it is the start time of the non-streaming data slot (step S37), and if it is not the start time (step S37-No), Transition to the sleep state (step S38). Thereafter, the sleep state is continued until the start time of the non-streaming data slot.

  On the other hand, when the start time of the non-streaming data slot is reached (step S37—Yes), the ONU shifts to an activated state (step S39) and receives non-streaming data (step S40). Then, it is monitored whether or not the end time of the non-streaming data slot is reached (step S41). If it is not the end time (step S41-No), reception of non-streaming data and confirmation of whether or not the non-streaming data slot is ended Continue until the end of the non-streaming data slot. If it is determined that the non-streaming data slot has ended (step S41—Yes), the process returns to step S31, and the processes of steps S31 to S41 are repeated.

  By operating the OLT and the ONU as described above, the ONU that has been always activated at the time of streaming data distribution can be put to sleep at the time of unviewed channel distribution. In particular, the downlink buffer related to the downstream signal processing of the ONU 35. By making the downstream signal processing related block in the PON processing unit 32 and the optical receiver in the optical IF unit 31 sleep, low power consumption can be realized.

  Further, when this embodiment is applied, streaming data frames and non-streaming data frames are aggregated in each slot (streaming data slot, non-streaming data slot), and further, streaming data frames are aggregated for each channel. Even when control is performed such that a sleep request is made from the ONU to the OLT as described in Non-Patent Document 1 above, a reduction in bandwidth efficiency due to control frame transmission / reception operation is prevented, and simple Control can be simplified by exchanging control frames.

Here, FIG. 10 is a diagram comparing the power saving control operation in the system of the present embodiment and the power saving control operation in the conventional system. As an example, ONU 1 views ch 2 and ONU 2 views ch 1. Shows the behavior of the case. When the frames ch1 and ch2 are mixed, each ONU (ONU3 ₁ , ONU3 ₂ ) has four rises / rises when the channel slot is not applied (corresponding to the conventional system) as shown in the upper row. Although down time is required, when a channel slot is applied (corresponding to the system of the present embodiment), only one rise / fall time is required. The accumulated value of time becomes smaller. When the channel slot is not applied, the transmission interval of each frame must be increased by the rise / fall time. When the channel slot is applied, the rise / fall time is considered when determining the transmission interval of each frame. There is no need.

  Therefore, by integrating channel slots into the slots by applying channel slots, the integrated values of rise time and fall time at the time of state transition are made smaller than when ONU activation / sleep is performed in units of frames. Therefore, power consumption can be reduced efficiently.

  As described above, in the optical communication system according to the present embodiment, the OLT performs each streaming data frame and each non-streaming data frame to be transmitted within the subsequent bandwidth update period based on the channel viewing request received from each subordinate ONU. Are scheduled so that each data frame is arranged so that streaming data frames of the same channel (that is, streaming data frames addressed to the same ONU) are continuously transmitted. As a result, the ONU can collectively receive the streaming data frames of the channel for which it has requested viewing, and can enter the sleep state during the period in which the streaming data frames addressed to other ONUs are distributed. Low power consumption can be realized.

  In the present embodiment, an example in which the streaming data slot is arranged to precede the band update cycle has been described. However, the non-streaming data slot may be arranged to precede.

Embodiment 2. FIG.
Next, the optical communication system according to the second embodiment will be described. In the first embodiment, the optical communication system in which the ONU shifts to the sleep state during the reception operation in the streaming data slot to reduce power consumption has been described. However, in the present embodiment, the reception operation in the non-streaming data slot is further performed. An optical communication system that shifts to the sleep state to reduce power consumption will be described. Note that the configuration of the optical communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1). However, in the present embodiment, it is assumed that PCs 5 ₁ and 5 ₂ are activated and PC 5 _n is in a stopped state. As for the viewing request, as in the example of the first embodiment, ONU 3 ₁ requests viewing of ch ₂ , ONU 3 ₂ requests viewing of ch 1, and ONU 3 _n requests viewing of ch 4. Suppose. However, these are examples for explanation and are not limited to this.

First, the overall operation of the optical communication system according to the present embodiment will be described. FIG. 11 is a diagram showing a downlink signal transmission / reception sequence in the OLT (referred to as OLT 1a) and the ONUs 3 _{1 to} 3 _n of the optical communication system according to the present embodiment. The difference between the sequence shown in FIG. 11 and the sequence (see FIG. 3) in the optical communication system shown in the first embodiment is that each ONU is in a sleep state in a non-streaming data slot in which a data frame addressed to itself is not distributed. It is a point that has shifted to. In order to realize such an operation, the OLT 1a of the present embodiment notifies each ONU of downlink time slot information having a configuration different from that of the first embodiment, and each ONU notifies the notified downlink time slot. When an instruction is received from the information, the sleep state is entered in the non-streaming data slot.

  12 and 13 are diagrams showing a configuration example of the downlink time slot information notified to each ONU by the OLT according to the present embodiment. FIG. 12 shows the “downlink time slot information notification (A ')' Shows an example of downlink time slot information transmitted. Similarly, FIG. 13 shows an example of downlink time slot information transmitted by the “downlink time slot information notification (B ′)” shown in FIG. As illustrated, the downlink time slot information transmitted by the OLT of the present embodiment is non-streaming data compared to the downlink time slot information (see FIGS. 4 and 5) transmitted by the OLT of the first embodiment. Information of an ONU that sleeps at the time of a slot (an ONU that does not need to receive a non-streaming data frame) is added.

  Since the operation in the section in which streaming data is distributed (streaming data slot) is the same as that in Embodiment 1, the operation in the section in which non-streaming data is distributed (non-streaming data slot) will be described here.

  When the OLT receives the non-streaming data frame from the host device until the start of the update cycle, the OLT monitors the destination, and when the ONU sleep condition in the non-streaming data slot is met, the sleep instruction for the corresponding ONU is shown in FIG. It is included in the downlink time slot information having the configuration shown in FIG. 13 and transmitted to all ONUs. Specifically, the OLT is set to an ONU that does not correspond to any destination of the non-streaming data frame received during the monitoring period, that is, any destination of the non-streaming data frame input from the upper station during the monitoring period. If there is an ONU that has not been set, it is determined that the ONU has met the ONU sleep condition, and the sleep instruction for the ONU is included in the downlink time slot information. On the other hand, when each ONU receives the downlink time slot information, it determines whether the ONU sleep instruction at the time of the non-streaming data slot stored therein corresponds to its own ONU. Transition to sleep mode.

In Figure 11, only PC 5 _n at the beginning of the bandwidth update cycle N are in stopped state, no non-streaming data frame addressed to ONU 3 _n, because the sleep conditions are true for the ONU 3 _n, OLT, the bandwidth update cycle N after is as shown in FIG. 12, and notifies the downlink time slot information stored sleep instruction in non-streaming data slots to all ONU for ONU 3 _n, ONU 3 _n sleeps in a non-streaming data slots in accordance with the instruction, also, only PC 5 ₁ at the beginning of the bandwidth update cycle M is in the stopped state, there is no non-streaming data frame addressed to ONU 3 _1, because the sleep conditions are true for the ONU 3 _1, OLT, the bandwidth updating period M after in FIG. 13 indicated as Sri in non-streaming data slots for ONU 3 ₁ The downlink time slot information stored up instruction notified to all ONU, ONU 3 ₁ shows an operation sequence example in the case such that, sleeps nonstreaming data slots in accordance with their instructions.

  Next, the configuration of the OLT 1a will be described with reference to FIG. FIG. 14 is a diagram illustrating a configuration example of the OLT 1a. As shown in FIG. 14, the OLT 1a replaces the frame determination unit 12 and the downlink time slot control unit 16 of the OLT 1 (see FIG. 6) described in Embodiment 1 with the frame determination unit 12a and the downlink time slot control unit 16a. It is a replacement. In the present embodiment, only parts different from the OLT 1 described in the first embodiment will be described.

  In addition to the operation performed by the frame determination unit 12 described in the first embodiment, the frame determination unit 12a monitors the destination of the non-streaming data frame until the start of the update cycle, and determines the sleep of the non-streaming data slot. When there is an ONU corresponding to the condition, an operation of outputting the information as corresponding ONU sleep information to the downlink time slot control unit 16a is executed. When the downlink time slot control unit 16a receives ONU sleep information in addition to the operation performed by the downlink time slot control unit 16 described in the first embodiment, the downlink time slot control unit 16a receives the downlink time slot information (FIG. 12, FIG. 12). The operation of storing in FIG. 13) and outputting to the PON processing unit 17 is executed. Here, the sleep determination condition of the non-streaming data slot may be, for example, a condition that there is no non-streaming data frame addressed to the ONU for a certain period of time, but is not limited to this.

  FIG. 15 is a flowchart showing an operation example of the OLT 1a, and is a flowchart in the case of performing the operation as shown in FIG. FIG. 15 is obtained by adding step S21 to the flowchart (see FIG. 7) showing the operation example of the OLT 1 of the first embodiment. The operation when the OLT 1a transmits a downlink signal will be described below with reference to FIG. Here, only the newly added step S21 will be described.

  In the downlink signal transmission operation, the OLT 1a executes step S13 to determine the allocation of the streaming data slot and the non-streaming data slot, or determines that the channel viewing request has not changed in step S12, and then performs non-streaming. The ONU to sleep in the data slot is determined (step S21). In order to execute this processing, the OLT 1a monitors the destination of the non-streaming data frame received from the higher-level device as described above. Then, based on the monitoring result, the ONU to sleep in the non-streaming data slot is determined in step S21. The determination result at step S21 is included in the downlink time slot information and notified to each ONU at step S14.

  Next, the ONU of this embodiment will be described. The configuration of the ONU of this embodiment is the same as that of the ONU of the first embodiment (see FIG. 8). In addition to the function that the ONU of Embodiment 1 had, the operation has a function to shift to a sleep state in a non-streaming data slot when instructed by the downlink time slot information received from the OLT 1a. The point is different. Specifically, the downstream time slot processing unit 33 provided in the ONU of the present embodiment performs non-deletion from the downstream time slot information transferred from the PON processing unit 32 in addition to the operation described in the first embodiment. The ONU sleep instruction in the streaming data slot is extracted, it is determined whether or not the own ONU needs to sleep in the non-streaming data slot, and if it is necessary to sleep, the optical IF unit 31, the PON processing unit 32, and the downstream buffer 35 is different in that a sleep instruction is issued at the start time of the non-streaming data slot and an activation instruction is issued at the end time.

  FIG. 16 is a flowchart illustrating an example of the ONU operation according to the present embodiment. Steps S51 to S54 are added to the flowchart illustrating the example of the ONU operation according to the first embodiment (see FIG. 9). It is. Hereinafter, the operation when the ONU according to the present embodiment receives a downlink signal will be described with reference to FIG. Here, only the newly added steps S51 to S54 will be described.

  When the ONU of the present embodiment detects that it is the start time of the non-streaming data slot in the downlink signal reception operation in step S37, the ONU next confirms the downlink time slot information received in step S31, and starts from the OLT. It is determined whether or not there is an instruction to sleep at the non-streaming data slot (step S51). And when it determines with there being no instruction | indication (step S51-No), it changes to step S39. On the other hand, if it is determined that there is an instruction (step S51-Yes), the process shifts to the sleep state (step S52). Thereafter, it is monitored whether or not the end time of the non-streaming data slot is reached (step S53). If it is not the end time (step S53-No), the sleep state is continued until it is detected that the end time has been reached. If it is detected that the end time has been reached (step S53-Yes), the process shifts to an activated state (step S54). The determination process shown in steps S51 and S53 is executed by the downstream time slot processing unit 33 of the ONU. In Steps S52 and S54, the downstream time slot processing unit 33 controls the optical IF unit 31, the PON processing unit 32, and the downstream buffer 35 to perform transition to the sleep state and transition to the startup state.

  As described above, in the optical communication system according to the present embodiment, the OLT performs the operation described in the first embodiment, and whether there is an ONU that does not need to receive a non-streaming data frame within the bandwidth update period. Is monitored by monitoring the destination of each non-streaming data frame, and an ONU that does not need to receive the non-streaming data frame is instructed to sleep in the non-streaming data slot that distributes the non-streaming data frame. It was decided. As a result, the ONU can shift to the sleep state in a section where streaming data frames addressed to other ONUs are distributed and in non-streaming data slots where non-streaming data frames addressed to itself are not distributed. Further reduction.

Embodiment 3 FIG.
Next, the optical communication system according to the third embodiment will be described. In the first and second embodiments, the optical communication system that distributes only streaming data of a channel for which viewing is requested has been described. In the present embodiment, an optical communication system that distributes streaming data of all channels will be described. . Note that the configuration of the optical communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1).

  FIG. 17 is a diagram illustrating an example of a timing chart of a downlink signal in the optical communication system according to the present embodiment. When the total number of channels is T, channel slots from ch1 to chT in the streaming data slot The example in the case of arranging is shown.

FIG. 18 is a diagram illustrating an example of a downlink signal transmission / reception sequence in the OLT 1 and the ONUs 3 _{1 to} 3 _n of the optical communication system according to the present embodiment. In FIG. 18, as in Embodiment 2, PCs 5 ₁ and 5 ₂ are activated, PC 5 _n is in a stopped state, ONU 3 ₁ requests viewing of ch ₂ , and ONU 3 ₂ views viewing of ch 1. In this example, ONU3 _n requests viewing of ch4.

  The overall operation of the optical communication system according to the present embodiment is the same as the overall operation of the optical communication system described in Embodiment 2, except that the OLT also transmits streaming data of channels that are not requested to be viewed from the ONU. And basically the same. That is, the OLT transmits a downlink signal by arranging a channel slot in the streaming data slot so that all streaming data is distributed, and each ONU receives the streaming data by starting in the own viewing request channel slot. In other channel slots, the sleep state is entered. In addition, even in a non-streaming data slot to which data addressed to itself is not distributed, a transition is made to the sleep state.

  FIG. 19 is a flowchart showing an operation example of the OLT according to the present embodiment. This flowchart is obtained by deleting the process of step S12 from the flowchart (FIG. 15) showing the operation of the OLT 1a according to the second embodiment. is there. However, in step S13, channel slots for all channels are arranged in the streaming data slot. The operation in each step other than this is as described in the second embodiment.

  The operation of the ONU in the present embodiment is the same as that of the ONU in the second embodiment. Further, the configurations of the OLT and ONU of the present embodiment are the same as those of the OLT and ONU of the second embodiment.

  As described above, in the optical communication system according to the present embodiment, the OLT also distributes streaming data of a channel that has not received a viewing request to the ONU, and starts distributing data within the bandwidth update period. Previously, the downlink time slot information including the start time and slot length of the streaming data slot and the non-streaming data slot, the start time of each channel slot, and the information of the ONU to sleep in the non-streaming data slot is transmitted to each ONU. In accordance with the downlink time slot information received from the OLT, the ONU is a section (channel slot) in which streaming data frames addressed to other ONUs are distributed, and a non-streaming data slot in which non-streaming data frames addressed to itself are not distributed. In, it was decided to shift to a sleep state. Thereby, the same effect as the optical communication system of Embodiment 2 is acquired. Further, since the slot position of the channel is fixed, the mounting is simplified and the cost can be reduced.

  In the present embodiment, as in the second embodiment, an example in which the ONU is configured to sleep even in a non-streaming data slot has been described. However, as in the first embodiment, the sleep is performed only in the streaming data slot. It is also possible to shift to a state. In this case, since the configuration of the streaming data slot, the non-streaming data slot, and each channel slot is fixed, the OLT does not transmit the downlink time slot information at each band update period, but when the ONU newly links up Only the downlink time slot information can be notified, and the implementation can be simplified.

  The control operation shown in the present embodiment can be applied not only to the PON connection configuration shown in FIG. 1 but also to the one-to-one connection configuration as shown in FIG.

Embodiment 4 FIG.
Next, the optical communication system according to the fourth embodiment will be described. In the first to third embodiments, the optical communication system in which the bandwidth update period is divided and the streaming data slot and the non-streaming data slot are arranged has been described. However, in this embodiment, the bandwidth update is performed with the non-streaming data slot width being constant. An optical communication system will be described that is arranged within a period and that a streaming data slot is arranged to interrupt during a band update period and transmits a downlink signal. Note that the configuration of the optical communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1).

  FIG. 21 is a diagram illustrating an example of a timing chart of a downlink signal in the optical communication system according to the present embodiment. As described above, the streaming data slot is arranged so as to be interrupted during the band update period. An example is shown.

  In the optical communication system of the present embodiment, a downlink signal having the configuration shown in FIG. 21 is transmitted from the OLT to each ONU. That is, the OLT transmits a non-streaming data frame within a band update period (non-streaming data slot), and transmits a streaming data frame in a streaming data slot inserted during the band update period.

  For this reason, the OLT according to the present embodiment generates downlink time slot information and ONU sleep information in non-streaming data slots as separate information, and the downlink time slot information is transmitted at the beginning of the streaming data slot. The ONU sleep information in the non-streaming data slot is transmitted at the beginning of the non-streaming data slot. The structure of the downlink time slot information is the same as that shown in FIGS. The ONU sleep information in the non-streaming data slot is the same information as the “ONU sleeping in the non-streaming data slot” included in the downlink time slot information shown in FIGS.

  On the other hand, when the ONU of the present embodiment receives the downlink time slot information, the ONU determines that the slot is a streaming data slot, activates in the own viewing channel slot, receives a streaming data frame, and other channels. The slot shifts to the sleep state. If ONU sleep information is received, it is determined that the slot is a non-streaming data slot. If the ONU sleep information includes a sleep instruction for the own ONU, the sleep state is shifted to the end time of the non-streaming data slot. . When the sleep instruction for the own ONU is not included, the non-streaming data frame addressed to the own ONU is received in the activated state.

  Next, the OLT of the present embodiment will be described in detail. Note that the configuration of the OLT of the present embodiment is the same as that of the OLT of the second embodiment (see FIG. 14). First, the operation of each part of the OLT will be described with reference to FIG. In the OLT, the downlink time slot control unit 16a sets a band update cycle and determines a cycle for inserting a streaming data slot. In the optical communication system according to the present embodiment, the normal bandwidth update cycle is a non-streaming data slot. Therefore, when receiving the ONU sleep information from the frame determination unit 12a, the downlink time slot control unit 16a converts the ONU sleep information into the downlink time. The data is transferred to the PON processing unit 17 through the same route as the slot information. Then, an output instruction (non-streaming data output instruction) is issued to the non-streaming data buffer 14 until the end time of the determined non-streaming data slot. Also, when inserting a streaming data slot, the PON processing unit determines the arrangement of the channel slot in the streaming data slot based on the viewing channel information in the channel viewing request received from each ONU, and uses the determined result as downlink time slot information. 17 to transfer. Thereafter, an output instruction (channel queue output instruction) is issued to the streaming data buffer 13 according to the determined channel slot arrangement until the end time of the streaming data slot. The downlink time slot control unit 16a switches the setting of the buffer selector 15 at the timing when the non-streaming data slot and the streaming data slot are switched. Further, the operations of the constituent elements other than the downlink time slot control unit 16a are the same as those of the OLT of the second embodiment.

  FIG. 22 is a flowchart illustrating an operation example of the OLT according to the present embodiment. The operation when the OLT according to the present embodiment transmits a downlink signal will be described below with reference to FIG. In FIG. 22, the same processes as those described in the previous embodiment are the steps used in the flowcharts (FIGS. 7, 15, and 19) showing the operation of the previous embodiment. The same step number as the number is attached. For this reason, in the present embodiment, detailed description of the process having the same step number as the process already described is omitted.

  In the downlink signal transmission operation, when the OLT executes step S11 to acquire information on the band update period, it next determines whether or not to insert a streaming data slot based on the streaming data viewing status of the ONU (step S11). S22). For example, when there is an ONU requesting delivery of streaming data, or when there is an ONU that is viewing streaming data, it is determined to “insert”. However, it is considered that the streaming data slots are not continuous. Therefore, it is determined that “not inserted” immediately after transmission of the streaming data slot.

  If it is determined in step S22 that a streaming data slot is not inserted (step S22-No), step S21 is executed to determine an ONU to be sloped in a non-streaming data slot, and ONU sleep information indicating the determination result is determined. Each ONU is notified (step S23). Further, step S16 is executed to transmit non-streaming data.

  On the other hand, if it is determined that a streaming data slot is to be inserted (step S22-Yes), step S12 is executed, and if there is a change in the viewing request channel (step S12-Yes), the arrangement of the channel slot in the streaming data slot Is determined (step S24), and downlink time slot information indicating the determination result is notified to each ONU (step S14). When it is determined in step S12 that there is no change in the viewing request channel (step S12-No), the same information as the previously transmitted downlink time slot information is notified to each ONU (step S14).

  Next, the ONU of this embodiment will be described in detail. Note that the configuration of the OLT of the present embodiment is the same as that of the ONU of the first embodiment (see FIG. 8). However, as described above, the OLT according to the present embodiment transmits the downlink time slot information and the ONU sleep information separately, so that the ONU performs an operation corresponding to the information. Specifically, in the ONU, when the PON processing unit 32 receives downlink time slot information or ONU sleep information from the OLT, the PON processing unit 32 outputs the received information to the downlink time slot processing unit 33. Also, when the downlink time slot processing unit 33 receives the downlink time slot information from the PON processing unit 32, the downlink time slot processing unit 33 determines that the next slot is a streaming data slot, and starts / starts the own viewing channel slot based on the downlink time slot information. Specify the end time. Then, a sleep / wake-up instruction is issued to the optical IF unit 31, the PON processing unit 32, and the down buffer 35 so that the self-viewing channel slot is activated and the other channel slots are shifted to the sleep state. Further, when ONU sleep information is received from the PON processing unit 32, it is determined that the next slot is a non-streaming data slot. Further, when the ONU sleep information includes a sleep instruction for the own ONU, non-streaming data is determined. A sleep / activation instruction is issued to the optical IF unit 31, the PON processing unit 32, and the down buffer 35 so that the sleep state is maintained until the slot end time.

  FIG. 23 is a flowchart illustrating an operation example of the ONU according to the present embodiment. The operation when the ONU according to the present embodiment receives a downlink signal will be described below with reference to FIG. In FIG. 23, the same processes as those described in the previous embodiment are the same as the step numbers used in the flowcharts (FIGS. 9 and 16) showing the operation of the previous embodiment. A step number is attached. For this reason, in the present embodiment, detailed description of the process having the same step number as the process already described is omitted.

  In the downlink signal reception operation, when receiving the downlink time slot information or ONU sleep information, the ONU determines from the received information whether the next slot is a streaming data slot or a non-streaming data slot (step S61). , S62). As described above, when downlink time slot information is received, it is determined that the next slot is a streaming data slot, and when ONU sleep information is received, the next slot is a non-streaming data slot. to decide.

  If it is determined in step S62 that the next slot is a non-streaming data slot, it is further determined whether or not a transition to the sleep state is instructed in the non-streaming data slot (step S51). The operation after step S51 is the same as that of the ONU of the second embodiment (see FIG. 16).

  If it is determined in step S62 that the next slot is a streaming data slot, steps S32 to S36 are executed to perform the streaming data receiving operation requested by the user himself / herself. It is confirmed whether it is the end time of the slot (step S63). If it is not the end time of the streaming data slot (step S63-No), the process shifts to the sleep state until the end time of the streaming data slot is reached (step S64). On the other hand, when it is detected that the end time of the streaming data slot is reached (step S63—Yes), the process returns to step S61 and the above-described processes are repeated.

  As described above, in the optical communication system according to the present embodiment, the non-streaming data slot is a fixed length slot, and the streaming data slot is inserted between the non-streaming data slots for transmission. As a result, even when the viewing request channel of the ONU is changed, it is not necessary to determine the distribution of the streaming data slot and the non-streaming data slot again, so that the implementation can be simplified. Also with such a configuration, the same low power consumption effect as in the first to third embodiments can be obtained.

Embodiment 5 FIG.
Next, the optical communication system according to the fifth embodiment will be described. In the first to fourth embodiments, the optical communication system that distributes without considering the class of streaming data (considering distribution as the same class) has been described. However, in this embodiment, the bandwidth of the channel to be distributed is high. Multiple classes of channels, such as high-rate channels such as high-definition video and low-rate channels such as low-definition video such as teletext, or differences in allowable delay time, etc. An optical communication system that distributes different classes of streaming data in a mixed manner will be described. Note that the configuration of the optical communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1).

  FIG. 24 is a diagram showing an example of a timing chart of a downlink signal in the optical communication system according to the present embodiment. More specifically, each streaming data frame is classified into two classes, high and low, and streaming data slots It is the figure which showed the timing chart of the downlink signal which determined and arrange | positioned the insertion position of based on a class. In this example, the case of classifying into two classes is shown, but in reality, this is not restrictive, and the class may be classified into three or more classes.

  In the example shown in FIG. 24, the high-class (high priority class) streaming data slot is inserted in the band update period N, N + 3, N + 6, and the low-class streaming data slot is in the band update period N + 2. The other band update period is a downlink signal having a configuration in which only non-streaming data slots are inserted. That is, the streaming data slot of each class is inserted with high frequency in the high class and with low frequency in the low class. The streaming data slot insertion interval for each class is determined by snooping the contents of the frame stored in the streaming data buffer, extracting information such as the rate and allowable delay time, and the optimal streaming data slot for the one corresponding to the channel class A time slot of the downlink signal is determined by applying the insertion interval. The ONU controls its sleep state and activation state according to the downlink time slot information from the OLT.

  Next, the OLT of the present embodiment will be described in detail. FIG. 25 is a diagram illustrating a configuration example of the OLT (referred to as OLT 1b) of the present embodiment. As shown in FIG. 25, the OLT 1b replaces the streaming data buffer 13 and the downlink time slot controller 16a of the OLT 1a (see FIG. 14) described in Embodiment 2 with the streaming data buffer 13b and the downlink time slot controller 16b. It is a replacement. In the present embodiment, only portions different from the OLT 1a described in the second embodiment will be described.

In the OLT 1b according to the present embodiment, the streaming data buffer 13b includes, in addition to the operations performed by the streaming data buffer 13 according to the second embodiment, the streaming data frames stored in the respective queues (queues 132 _{1 to} 132 _T ). The contents are snooped, the rate, allowable delay time, etc. are confirmed, the class of the frame is determined, and the determination result is output to the downlink time slot control unit 16b as channel queue class information. When the downlink time slot control unit 16b receives the channel queue class information, the downlink time slot control unit 16b first determines an interval (transmission frequency) for transmitting the data streaming slot of each class based on the channel queue class information. Based on the determined interval and information on the streaming data frames classified by class (how much streaming data frames are classified into which class, corresponding to the data transmission amount for each class) The time allocation of the streaming data slot and the channel slot to be arranged in the streaming data slot are determined. Next, the downlink time slot control unit 16b stores information indicating the determination result in the downlink time slot information and outputs the information to the PON processing unit 17 so as to notify each ONU from the PON processing unit 17, and the downlink time slot. The output timing of the streaming data frame and the non-streaming data frame is controlled according to the information stored in the information.

  FIG. 26 is a flowchart showing an operation example of the OLT of the present embodiment. Step S13 is deleted from the flowchart (see FIG. 15) showing the operation example of the OLT 1a of the second embodiment. S26 is added. The operation when the OLT according to the present embodiment transmits a downlink signal will be described below with reference to FIG. In the present embodiment, only the newly added steps S25 and S25 will be described.

In the downlink signal transmission operation, the OLT 1b executes step S12 to check whether or not there is a change in the channel viewing request. If there is a change (step S12—Yes), each ONU requests viewing. Collect class information for the channels (confirm the class of each requested channel). The class information is collected by snooping the contents of the streaming data frame stored in the queue corresponding to the channel for which viewing is requested among the queues 132 _{1 to} 132 _T in the streaming data buffer 13b. Then, based on the collected class information, a slot insertion interval for each class and a channel slot to be arranged in the streaming data slot for each class are determined (step S25). Further, the class of the streaming data slot to be inserted in the next band update period and the distribution of the streaming data slot and the non-streaming data slot are determined (step S26).

  On the other hand, as a result of the confirmation in step S12, when it is determined that there is no change in the channel viewing request (step S12-No), step S26 is executed without executing step S25.

  The configuration and operation of the ONU of the present embodiment are the same as those of the ONU of the second embodiment.

  In the present embodiment, the case where the transmission operation considering the class of streaming data is applied to the optical communication system of the second embodiment has been described. However, the transmission operation considering this class is described in the first embodiment. It can also be applied to 3 or 4 optical communication systems.

  As described above, in the optical communication system according to the present embodiment, the OLT classifies each streaming data to be distributed to the ONU into a plurality of classes and transmits the data at different frequencies for each class. As a result, there is a problem when processing all streaming data as the same class, that is, if all the streaming data of different classes are inserted into the streaming data slot of the same period, the low-class streaming data cannot be sufficiently aggregated. The problem that a sufficient channel slot length cannot be secured is improved. Specifically, by setting the optimum streaming data slot insertion interval according to the class of streaming data, a sufficient channel slot length can be ensured and the power consumption can be efficiently reduced. Even for streaming data that requires low delay, setting a high-class streaming data slot and inserting the slot at a high frequency can shorten the delay time while obtaining a low power consumption effect. it can.

Embodiment 6 FIG.
Next, the optical communication system according to the sixth embodiment will be described. In the fifth embodiment, the optical communication system that dynamically changes the insertion interval of the streaming data slot based on the class of the streaming data has been described. However, in the present embodiment, the traffic situation of the non-streaming data frame and the streaming data frame , And monitoring the buffer accumulation amount, and the streaming data slot insertion position for each bandwidth update period according to the traffic fluctuation and buffer usage of non-streaming data and streaming data (time allocation between streaming data slot and non-streaming data slot) An optical communication system that dynamically changes the above will be described. Note that the configuration of the optical communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1).

  FIG. 27 is a diagram illustrating an example of a timing chart of a downlink signal in the optical communication system according to the present embodiment. More specifically, the traffic status of the non-streaming data frame and the streaming data frame, and the buffer accumulation amount are monitored. It is the figure which showed the timing chart in the case of changing dynamically the time allocation of a streaming data slot and a non-streaming data slot based on a result.

  In the optical communication system of the present embodiment, the OLT sets a monitoring cycle for monitoring traffic fluctuations and buffer usage, as shown in FIG. In the example of FIG. 27, in the monitoring period F, the time distribution of the streaming data slot and the non-streaming data slot within the band update period is set to 1: 1. Then, when the OLT determines that the traffic status of the non-streaming data frame becomes a high rate within the monitoring period F, for example, in the next monitoring period F + 1, the streaming data slot and the non-streaming data slot within the bandwidth update period are displayed. Set the time distribution to 1: 2 to increase the distribution of non-streaming data. In addition, if it is determined that, for example, a new high-rate channel is requested for viewing within the monitoring period F + 1 and the non-streaming data traffic has become a low rate, the next monitoring period F + 2 Streaming data slot allocation is set to 2: 1 to increase the allocation of streaming data. As described above, in the optical communication system according to the present embodiment, the optimal time distribution between the streaming data slot and the non-streaming data slot is set according to the traffic fluctuation and the buffer usage.

  Next, the OLT of the present embodiment will be described in detail. FIG. 28 is a diagram illustrating a configuration example of the OLT (referred to as OLT 1c) of the present embodiment. The OLT 1c shown in FIG. 28 includes the frame determination unit 12a, the streaming data buffer 13, the non-streaming data buffer 14, and the downlink time slot control unit 16a of the OLT 1a (see FIG. 14) described in the second embodiment. The streaming data buffer 13c, the non-streaming data buffer 14c, and the downlink time slot control unit 16c are replaced. In the present embodiment, only portions different from the OLT 1a described in the second embodiment will be described.

In the OLT 1c according to the present embodiment, the frame determination unit 12c monitors the traffic conditions such as the average rate by monitoring the downlink signal in addition to the operation performed by the frame determination unit 12a according to the second embodiment. Is output as a traffic situation to the downlink time slot control unit. In addition to the operations performed by the streaming data buffer 13 of the second embodiment, the streaming data buffer 13c uses the accumulated information (streaming data buffer accumulated information) of each queue (queues 132 _{1 to} 132 _n ) as a downlink time slot control unit. The operation of outputting to 16c is executed. Similarly, the non-streaming data buffer 14c outputs buffer accumulation information (non-streaming data buffer accumulation information) to the downlink time slot control unit 16c in addition to the operations performed by the non-streaming data buffer 14 of the second embodiment. Perform the action to be performed.

  Further, the downlink time slot control unit 16c sets a monitoring cycle in which a plurality of band update cycles are collected, and in the set monitoring cycle, the traffic situation output from the frame determination unit 12c and the streaming output from the streaming data buffer 13c. Data buffer accumulation information and non-streaming data buffer accumulation information output from the non-streaming data buffer 14c are collected. Further, based on each collected information, distribution of streaming data slots and non-streaming data slots and channel slot arrangement in the streaming data slot are dynamically controlled. For example, when a change in traffic situation is detected and it is determined that the non-streaming data slot has changed to a high rate, the downlink time slot control unit 16c performs control to increase the time distribution of the non-streaming data slot. Also, when it is detected that the accumulated amount of a certain queue in the streaming data buffer 13c exceeds a predetermined threshold, control is performed to increase the time distribution of streaming data slots. However, these controls and the slot time allocation shown in FIG. 27 show examples of the time allocation between the streaming data slot and the non-streaming data slot. Further, the time distribution may be controlled based on only one of the traffic status and the queue accumulation amount. Further, the downlink time slot control unit 16c stores the determined time distribution of the streaming data slot and the non-streaming data slot and information on the arrangement result of the channel slot in the streaming data slot in the downlink time slot information to perform the PON processing. The PON processing unit 17 notifies each ONU by outputting to the unit 17 and controls the output timing of the streaming data frame and the non-streaming data frame according to the information stored in the time slot information.

  FIG. 29 is a flowchart illustrating an operation example of the OLT according to the present embodiment. The operation when the OLT according to the present embodiment transmits a downlink signal will be described below with reference to FIG. In FIG. 29, the same processing as that described in the previous embodiment is the same as the step number used in the flowchart (FIGS. 7 and 15) showing the operation of the previous embodiment. A step number is attached. For this reason, in the present embodiment, detailed description of the process having the same step number as the process already described is omitted.

  In the downlink signal transmission operation, the OLT 1c first acquires information on the monitoring period and information on the band update period (step S27). In step S27, for example, when an operator or the like performs an operation for setting a monitoring period and a band update period in the downlink signal, the downlink time slot control unit 16c acquires the setting contents. When the process of step S27 is completed, the OLT 1c then starts monitoring the channel viewing request from each ONU and monitoring the traffic state, whether the request has changed to the channel viewing request, and whether the current monitoring cycle has ended. Whether or not each time the bandwidth update cycle ends (strictly, at the timing of generating downlink time slot information to be transmitted in the next bandwidth update cycle) is checked (step S28).

  If the channel viewing request has changed or the monitoring cycle has ended (step S28-Yes), the traffic status and the accumulated information of each buffer (streaming data buffer accumulated information, non-streaming data buffer accumulated information) are collected. (Step S29) Based on the collected traffic status and the accumulated information of each buffer, the distribution of the streaming data slot and the non-streaming data slot in the next monitoring period is determined (Step S30). Further, the ONU to be put to sleep in the non-streaming data slot within the next band update cycle is determined (step S21).

  If it is determined in step S28 that the channel viewing request has not changed and the current monitoring cycle has not ended (step S28-No), step S21 is executed without executing steps S29 and S30. To do. The processing after step S21 is as described in the previous embodiment.

  As described above, in the optical communication system according to the present embodiment, the time allocation between the streaming data slot and the non-streaming data slot within the bandwidth update period is dynamically changed based on the traffic situation and the buffer accumulation amount. . Thereby, efficient low power consumption can be realized.

  In the present embodiment, the case where the information acquired from the streaming data buffer 13c is only the accumulation amount has been described. However, the class information shown in the fifth embodiment is also acquired, and this class information is also taken into consideration. The insertion interval of the streaming data slot and the time distribution of the streaming data slot and the non-streaming data slot within the band update period may be determined.

Embodiment 7 FIG.
Next, the optical communication system according to the seventh embodiment will be described. In the first to sixth embodiments, the optical communication system that does not specify the transfer rule of the non-streaming data frame has been described. However, in this embodiment, a queue is provided in the buffer even in the non-streaming data frame, and the identifier ( For example, an optical communication system that determines which queue in the non-streaming data buffer is to be stored based on, for example, the priority indicated by the CoS value of the VLAN will be described.

FIG. 30 is a diagram illustrating a configuration example of the OLT (referred to as OLT 1d) of the present embodiment. As illustrated, the OLT 1d of the present embodiment includes the frame determination unit 12, the non-streaming data buffer 14, and the downlink time slot control unit 16 of the OLT 1 (see FIG. 6) described in the first embodiment. The non-streaming data buffer 14d and the downlink time slot control unit 16d are replaced. The non-streaming data buffer 14d includes an input side selector 141, queues 142 _{1 to} 142 _M, and an output side selector 143. In the present embodiment, only parts different from the OLT 1 described in the first embodiment will be described.

  In the OLT 1d according to the present embodiment, the frame determination unit 12d stores the non-streaming data frame received from the host device in addition to the operation performed by the frame determination unit 12 according to the first embodiment. The priority information is extracted, a queue in the non-streaming data buffer 14d is determined according to a preset transfer rule, and a non-streaming data frame and queue input instruction are further given to the non-streaming data buffer 14d. The operation to output is executed.

The non-streaming data buffer 14d has queues 142 _{1 to} 142 _M , and stores non-streaming data frames in the queue according to a queue input instruction from the frame determination unit 12d. Further, according to the queue output instruction from the downlink time slot control unit 16d, the non-streaming data frame is output from the instructed queue. The number of queues is not limited because it depends on the implementation and settings.

  The downlink time slot control unit 16d controls the output timing of the non-streaming data frame in the non-streaming data slot according to the set transfer rule in addition to the operation performed by the downlink time slot control unit 16 of the first embodiment. Execute the operation to output the queue output instruction.

  Although the case where the non-streaming data buffer 14d is applied to the optical communication system according to the first embodiment has been described, the non-streaming data buffer 14d may be applied to the optical communication system according to the second to sixth embodiments. Is possible.

  As described above, in the optical communication system according to the present embodiment, the OLT includes a buffer having a configuration including a plurality of corresponding queues having different priorities as the non-streaming data buffer. Thereby, priority control of a non-streaming data frame can be performed while realizing low power consumption similar to that of the optical communication system described in the first to sixth embodiments.

  As described above, the optical communication system according to the present invention is useful when distributing downstream signals in which streaming data and non-streaming data are mixed, and in particular, it is possible to reduce power consumption in the subscriber side device. It is suitable for an optical communication system.

1, 1a, 1b, 1c, 1d, 10 OLT (station side device)
2 Optical splitter 3 _{1 to} 3 _n ONU (subscriber side equipment)
4 ₁ to 4 _n HGW
5 _{1 to} 5 _n PC
6 _{1 to} 6 _n STB
7 ₁ ~7 _n TV
11, 36 Line termination unit 12, 12a, 12c, 12d Frame determination unit 13, 13b, 13c Streaming data buffer 14, 14c, 14d Non-streaming data buffer 15 Buffer selector 16, 16a, 16b, 16c, 16d Downstream time slot control unit 17, 32 PON processing unit 18, 31 Optical IF unit 33 Downstream time slot processing unit 34 Upstream buffer 35 Downstream buffer 131, 141 Input side selector 132 _{1 to} 132 _T , 142 _{1 to} 142 _M queue 133, 143 Output side selector

Claims (27)

An optical communication system comprising a station side device and one or more subscriber side devices connected to the station side device via an optical fiber,
The station side device
Frame determination means for classifying a frame broadcast from each higher-level device and broadcast to each connected subscriber-side device into a streaming data frame and a non-streaming data frame;
A downstream signal transmission unit that arranges the streaming data frames in the first section so as to be continuous, and arranges the non-streaming data frames in the second section and transmits them to each subscriber side device;
With
The subscriber side device is:
An optical communication system, wherein a transition to a sleep state is made during a time period when a streaming data frame of a type different from a streaming data frame for which a viewing request is made is transmitted. The frame determination means classifies the frame into a streaming data frame and a non-streaming data frame, and further classifies the streaming data frame into a group of the same channel,
  The downlink signal transmission means is arranged in the first section so that streaming data frames of the same channel are continuous.
  The optical communication system according to claim 1. The downlink signal transmitting means notifies each subscriber apparatus of the arrangement of each type of streaming data frame in the first section before starting the transmission process in the first section. The optical communication system according to claim 1 or 2 . The frame determination means monitors the destination of the non-streaming data frame input from the host device,
The downlink signal transmission unit specifies a subscriber side device that does not correspond to any destination of the non-streaming data frame arranged in the second section based on a destination monitoring result by the frame determination unit, and Before starting the transmission process in the second section, notify each subscriber side of the specific result,
The said subscriber side apparatus shifts to a sleep state in the said 2nd area, when itself corresponds to the subscriber side apparatus specified by the said downlink signal transmission means. The 1st , 2 or 3 characterized by the above-mentioned. The optical communication system described. 5. The optical communication system according to claim 4 , wherein the downlink signal transmitting unit transmits the arrangement of the streaming data frame for each type in the first section and the specific result in the same control frame. . The downlink signal transmission means arranges and transmits the streaming data frame of the type requested by the subscriber side apparatus in the first section among the streaming data frames input from the host apparatus. The optical communication system as described in any one of Claims 1-5 . The light according to any one of claims 1 to 5 , wherein the downlink signal transmission means arranges and transmits all streaming data frames input from the host device in the first section. Communications system. The second section is a fixed length,
The downlink signal transmitting means, an optical communication system according to claim 1, 2 or 3, characterized by transmitting inserted between said one of the first section or two or more consecutive second section . 9. The optical communication system according to claim 8 , wherein the downlink signal transmission means determines the insertion timing of the first section based on streaming data viewing status of each subscriber side device. The frame determination means monitors the destination of the non-streaming data frame input from the host device,
The downlink signal transmission unit specifies a subscriber side device that does not correspond to any destination of the non-streaming data frame arranged in the second section based on a destination monitoring result by the frame determination unit, and Before starting the transmission process in the second section, notify the specified subscriber side device to each subscriber side device,
The said subscriber side apparatus shifts to a sleep state in the said 2nd area, when itself corresponds to the subscriber side apparatus specified by the said downlink signal transmission means. The Claim 8 or 9 characterized by the above-mentioned. Optical communication system. The downlink signal transmitting means, an optical communication system according to any one of claims 1-4 which check the class of each streaming data frame, and transmits the streaming data frame at different intervals for each class . The downlink signal transmitting means may determine the length of the first section and the length of the second section based on at least one of a traffic situation and a queue accumulation situation in a buffer for accumulating streaming data frames. The optical communication system according to any one of claims 1 to 4, wherein the ratio is periodically updated. The downlink signal transmission means includes a buffer configured by a plurality of queues having different priorities as a buffer for storing non-streaming data frames, and each of the non-streaming data frames input from the host device has a corresponding priority queue. optical communication system according to any one of claims 1 to 1 2, characterized in that performing the priority control by storing the. A station-side device that constitutes an optical communication system together with one or more subscriber-side devices connected via an optical fiber,
Frame determination means for classifying a frame broadcast from each higher-level device and broadcast to each connected subscriber-side device into a streaming data frame and a non-streaming data frame;
A downstream signal transmission unit that arranges the streaming data frames in the first section so as to be continuous, and arranges the non-streaming data frames in the second section and transmits them to each subscriber side device;
A station-side device comprising: The downlink signal transmitting means notifies each subscriber apparatus of the arrangement of each type of streaming data frame in the first section before starting the transmission process in the first section. line terminal according to claim 1 4. The frame determination means monitors the destination of the non-streaming data frame input from the host device,
The downlink signal transmission unit specifies a subscriber side device that does not correspond to any destination of the non-streaming data frame arranged in the second section based on a destination monitoring result by the frame determination unit, and before starting the transmission processing in the second interval, the station side device according to claim 1 4 or 1 5, wherein the notifying the specific result to the subscriber unit. 17. The station side according to claim 16 , wherein the downlink signal transmission unit transmits the arrangement of the streaming data frame for each type in the first section and the specific result in the same control frame. apparatus. The downlink signal transmission means arranges and transmits the streaming data frame of the type requested by the subscriber side apparatus in the first section among the streaming data frames input from the host apparatus. line terminal according to any one of claims 1 4 to 1 7. The downlink signal transmitting unit according to any one of claims 1 4 to 1 7, characterized in that to transmit all of the streaming data frame input from the host system by placing in said first section Station side equipment. The second section is a fixed length,
The downlink signal transmission unit, the optical line terminal according to claim 1 4 or 1 5, characterized in that the transmission is inserted between said one of the first section or two or more consecutive second section . 21. The station side apparatus according to claim 20 , wherein the downlink signal transmission means determines the insertion timing of the first section based on streaming data viewing status of each subscriber side apparatus. The frame determination means monitors the destination of the non-streaming data frame input from the host device,
The downlink signal transmission unit specifies a subscriber side device that does not correspond to any destination of the non-streaming data frame arranged in the second section based on a destination monitoring result by the frame determination unit, and Before starting the transmission process in the second section, notify the specified subscriber side device to each subscriber side device,
The subscriber-side apparatus, when itself corresponds to the subscriber unit identified by the downlink signal transmission unit, according to claim 20 or 2 1, characterized in that the transition to the sleep state to the second section Station side equipment. The downlink signal transmitter checks the class of each streaming data frame, the station side device according to claim 1 4, 1 5 or 1 6, characterized in that to transmit the streaming data frame at different intervals for each class . The downlink signal transmitting means may determine the length of the first section and the length of the second section based on at least one of a traffic situation and a queue accumulation situation in a buffer for accumulating streaming data frames. line terminal according to claim 1 4, 1 5 or 1 6, characterized in that periodically updating the ratio. The downlink signal transmission means includes a buffer configured by a plurality of queues having different priorities as a buffer for storing non-streaming data frames, and each of the non-streaming data frames input from the host device has a corresponding priority queue. line terminal according to any one of claims 1 4 21 to 24, characterized in that performing the priority control by storing the. A subscriber-side device that constitutes an optical communication system together with a station-side device connected via an optical fiber,
A section in which a streaming data frame, which is a frame broadcast to each subscriber-side apparatus connected to the station-side apparatus, is transmitted, and a streaming data frame for which a viewing request is made within the section is transmitted. When receiving notification of the coming time zone from the station side device, the subscriber shifts to the sleep state in the interval other than the transmission time zone of the streaming data frame for which he / she requested viewing Side device. 27. The subscription according to claim 26 , wherein, in addition to the notification of the time period, when receiving a notification of a section in which a non-streaming data frame addressed to itself is not notified, transition to a sleep state is also performed in the section. Person side device.

Images