JP5607206B2 - PON system, subscriber-side termination device, station-side termination device, control device, and power saving method - Google Patents

Description

  The present invention relates to a PON (Passive Optical Network) system composed of an OLT (Optical Line Terminal) and a plurality of ONUs (Optical Network Units: subscriber-side terminators).

  In the PON system, communication is performed while synchronizing between the OLT and the ONU so that uplink data transmitted from the ONU does not collide. The OLT plans to give transmission permission to each ONU so that uplink data does not collide. At this time, the delay due to the distance to each ONU is considered. For this reason, the OLT measures the round trip time between each ONU. However, in transmission using an optical fiber, there are fluctuations in the transmission path such as jitter and wander, and therefore it is necessary to perform measurement periodically.

  On the other hand, data communication is not always performed. For example, no data communication is performed at night. However, the round trip time is measured periodically regardless of the presence or absence of data communication as described above. Even when data communication is not performed, it is wasteful to make the ONU always communicable for round trip time measurement. For this reason, a technique for making an ONU transition to a power saving state intermittently by requesting a transition from the ONU to a power saving state has been studied (for example, see Non-Patent Document 1).

ITU-T (International Telecommunication Union Telecommunication standardization sector) SG15Q2 Extended type of document (RC-TD): GR-4, “ONU power-save annex”, PMC-Sierra, April 2008

  According to the technique described in Non-Patent Document 1, the ONU enters a power saving state intermittently. When there is a request for transition from the ONU to the power saving state, the OLT designates a time for continuing the power saving state, and the ONU enters the power saving state for the designated time. Further, when transmission data (downlink data) addressed to the ONU in the power saving state is generated, the downlink data is transmitted after the power saving state ends. Since the ONU cannot know in advance whether or not there is downlink data, even if there is no downlink data from the OLT, the buffer for downlink data is saved when one power saving state is completed (refresh time). It is necessary to return from the power state and enter a state (normal state) where downlink data can be received. Therefore, there is a problem that the ONU consumes unnecessary power when there is no downlink data.

  The present invention has been made in view of the above, and an object thereof is to obtain a PON system and a power saving method capable of reducing the power consumption of an ONU.

In order to solve the above-described problems and achieve the object, the present invention provides a PON system in which a station-side terminator and a subscriber-side terminator are connected using an optical line, and the subscriber-side terminator is An upstream optical transmitter that transmits an upstream optical signal including an upstream control signal to the station-side terminal device; a downstream optical receiver that receives a downstream optical signal including a downstream control signal from the station-side terminal device; and the upstream control A control unit that generates a signal, and controls transition from a normal state to a first power saving state in which both the upstream optical transmitter and the downstream optical receiver are in a power saving state based on the downlink control signal Then, the transition from the first power saving state to the activated state in which both the upstream optical transmitter and the downstream optical receiver are activated and is a partial power saving state is controlled based on a timer. From the state to the first power saving state or communication A first control for controlling a transition to a state, and a downlink control for a transition from a normal state to a second power saving state in which the upstream optical transmitter is in a power saving state and the downstream optical receiver is in an operating state. And controlling the transition from the second power-saving state to the activated state, which is the partial activation of the upstream optical transmitter, based on the timer. A control unit that executes any one of the second control that controls the transition to the power saving state or the normal state, and the station-side terminating device includes the control unit that generates the downlink control signal, A downstream optical transmitter for transmitting a downstream optical signal including the downstream control signal generated by the control unit to the subscriber-side termination device, and an upstream optical for receiving the upstream optical signal including the upstream control signal from the subscriber-side termination device And a receiver. That.

  The PON system, the subscriber-side termination device, the station-side termination device, the control device, and the power saving method according to the present invention have an effect that the power consumption of the subscriber-side termination device can be reduced.

FIG. 1 is a diagram showing a configuration example of a first embodiment of a PON system according to the present invention. FIG. 2 is a sequence diagram illustrating an example of a power saving control procedure according to the first embodiment. FIG. 3 is a sequence diagram illustrating another example of the power saving control procedure according to the first embodiment. FIG. 4 is a diagram illustrating a format of a “Sleep mode change acknowledge” message and a “Sleep” message. FIG. 5 is a diagram illustrating a format of a “Sleep mode change acknowledge” message and a “Sleep” message. FIG. 6 is a diagram illustrating a format of a “Sleep mode change acknowledge” message and a “Sleep” message. FIG. 7 is a diagram showing a format of a “Sleep mode change request” message. FIG. 8 is a diagram illustrating a format of a “Sleep mode change request” message. FIG. 9 is a diagram showing a format of the extended MAC control message. FIG. 10 is a flowchart illustrating an example of an OLT power saving control procedure according to the first embodiment. FIG. 11 is a flowchart illustrating an example of a power saving control procedure performed by the ONU according to the first embodiment. FIG. 12 is a sequence diagram illustrating an example of a power saving control procedure of the PON system according to the second embodiment. FIG. 13 is a sequence diagram illustrating another example of the power saving control procedure according to the second embodiment. FIG. 14 is a flowchart illustrating an example of a power saving control procedure performed by the OLT according to the second embodiment. FIG. 15 is a flowchart illustrating an example of a power saving control procedure performed by the ONU according to the second embodiment.

  Embodiments of a PON system and a power saving method 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 a PON system according to the present invention. As shown in FIG. 1, the PON system according to the present embodiment includes an OLT 1 and ONUs 10-1 to 10-3. The OLT 1 and the ONUs 10-1 to 10-3 are connected by a subscriber line 30 via a splitter 40. The splitter 40 branches the subscriber line 30 connected to the OLT 1 into the number of ONUs 10-1 to 10-3. The ONU 10-1 is connected to the terminals 20-1 and 20-2. In this example, three ONUs are shown, but the number of ONUs is not limited to this, and any number may be used.

  The OLT 1 includes a PON control unit 2 that performs processing on the OLT side based on the PON protocol, a reception buffer 3 that is a buffer for storing uplink data received from the ONUs 10-1 to 10-3, and ONUs 10-1 to 10-1. 10-3, a transmission buffer 4 that is a buffer for storing downlink data to be transmitted, an optical transmitter / receiver 5 that performs optical signal transmission / reception processing, and a WDM (Wavelength Division Multiplexing) coupler that wavelength-multiplexes upstream data and downstream data. (WDM) 6 and a physical layer processing unit (PHY) 7 that realizes an NNI (Network Node Interface) physical interface function between the network and the network. The optical transceiver 5 includes an optical receiver (Rx: Receiver) 51 that performs reception processing and an optical transmitter (Tx: Transmitter) 52 that performs transmission processing.

  The ONU 10-1 includes a PON control unit 11 that performs processing on the ONU side based on the PON protocol, a transmission buffer (upstream buffer) 12 that is a buffer for storing transmission data (upstream data) to the OLT 1, and an OLT 1 Receive buffer (downlink buffer) 13 that is a buffer for storing received data (downlink data), an optical transmitter / receiver 14, a WDM 15 that wavelength-multiplexes uplink data and downlink data, and terminals 20-1, 20- 2, physical layer processing units (PHYs) 16-1 and 16-2 for realizing a physical interface function of UNI (User Network Interface).

  The optical transceiver 14 includes an optical transmitter (Tx: Transmitter) 141 that performs transmission processing and an optical receiver (Rx: Receiver) 142 that performs reception processing. The PHY 16-1 includes a reception unit (Rx: Receiver) 161-1 that performs reception processing, and a transmission unit (Tx: Transmitter) 162-1 that performs transmission processing, and the PHY 16-2 performs reception processing. It comprises a receiver (Rx: Receiver) 161-2 and a transmitter (Tx: Transmitter) 162-2 that performs transmission processing.

  In addition, although the number of terminals connected to the ONU 10-1 is two, the number of terminals is not limited to this, and any number may be used, and a physical layer processing unit (PHY) corresponding to the number of terminals is provided. Further, in FIG. 1, the configuration example of the ONU 10-1 is shown as a representative, but the ONUs 10-2 and 10-3 have the same configuration as the ONU 10-1.

  In the present embodiment, as in the conventional PON system, the PON control unit 2 of the OLT 1 grants transmission permission to the ONUs 10-1 to 10-3 so that the transmission time zones do not overlap each other. Bandwidth allocation is performed to prevent collision of transmission data of the ONUs 10-1 to 10-3. Any method may be used for this bandwidth allocation. For example, “Su-il Choi and Jae-doo”, “HuhDynamic Bandwidth Allocation Algorithm for Multimedia Services over Ethernet (registered trademark) PONs”, ETRI Journal, Dynamic Bandwidth Allocation Algorithm described in “Volume 24, Number 6, December 2002, p.465 to p.466” can be used.

  Next, the overall operation of the OLT 1 and the ONUs 10-1 to 10-3 according to the present embodiment will be described. The PON control unit 2 stores downlink data (downlink communication data) received from the network via the PHY 7 in the transmission buffer 4. When transmitting data from the OLT 1, the PON control unit 2 reads the downlink data stored in the transmission buffer 4 and outputs it to the optical transceiver 5, and the Tx 52 of the optical transceiver 5 uses the transmission data as an optical signal. Output to the WDM 6, the WDM 6 performs wavelength multiplexing on the optical signal output from the optical transmitter / receiver 5, and outputs it to the ONUs 10-1 to 10-3 via the subscriber line 30. In addition, when the PON control unit 2 transmits a control message such as a transmission permission signal for transmitting a transmission permission instruction, the control message generated by the PON control unit 2 is output to the optical transceiver 5. It transmits to ONU10-1-10-3 like data. In the PON system of FIG. 1, the WDMs 6 and 15 are used for wavelength multiplexing, but the WDMs 6 and 15 are not essential when communicating at a single wavelength.

  In the ONUs 10-1 to 10-3, when receiving a downlink signal from the OLT 1, the WDM 15 separates and outputs the downlink signal to the optical transceiver 14, and the Rx 142 of the optical transceiver 14 converts the downlink signal into downlink data of an electrical signal. And output to the PON control unit 11. The PON control unit 11 stores the downlink data output from the Rx 142 of the optical transceiver 14 in the reception buffer 13. The PON control unit 11 reads the downlink data stored in the reception buffer 13 and outputs it to both or one of the PHYs 16-1 and 16-2 according to the destination of the data. The PHYs 16-1 and 16-2 that have received the downlink data perform predetermined processing on the downlink data and transmit the downlink data to the terminals 20-1 and 20-2 to which the PHYs 16-1 and 16-2 are connected.

  On the other hand, when transmitting upstream data from the ONUs 10-1 to 10-3, the PON control unit 11 transmits upstream data acquired from the terminals 20-1 and 20-2 via the PHYs 16-1 and 16-2. 12. Based on the transmission permission given from the OLT 1, the uplink data stored in the transmission buffer is read and output to the optical transceiver 14. The Tx 141 of the optical transceiver 14 converts the upstream data into an optical signal (upstream signal) and transmits it to the OLT 1 via the WDM 15 and the subscriber line 30.

  The PON control unit 2 of the OLT 1 stores the uplink data received from the ONUs 10-1 to 10-3 via the subscriber line 30, the WDM 6, and the Rx 51 of the optical transceiver 5 in the reception buffer 3. The PON control unit 2 reads the uplink data stored in the reception buffer 3 and outputs it to the network via the PHY 7.

  In addition, the ONUs 10-1 to 10-3 receive control messages from the OLT 1 by the PON control unit 11 via the WDM 15 and the Rx 142 of the optical transceiver 14 and execute an operation based on an instruction of the control message. Generate a response to.

  Next, the power saving control operation of the present embodiment will be described. In the present embodiment, the OLT 1 instructs the ONUs 10-1 to 10-3 in which no downlink data exists to make a transition to the downlink power saving state in which the component that performs the downlink data processing is in the power saving state. The ONUs 10-1 to 10-3 instructed to transition to the downlink power saving state transition to the downlink power saving state.

  FIG. 2 is a sequence diagram illustrating an example of a power saving control procedure according to the present embodiment. In the following description, the ONUs 10-1 to 10-3 connected to the OLT 1 are generalized and expressed as ONU # i (i = 1, 2,..., N: N is the number of ONUs). The configuration of ONU # i is the same as the configuration of ONU 10-1 shown in FIG.

  First, when the PON control unit 2 of the OLT 1 detects that there is no downlink data for the ONU #i with reference to the transmission buffer 4 (step S1), the transmission of the downlink signal addressed to the ONU #i is stopped (step S1). S2). This means that the data addressed to ONU # i received from the network via PHY 7 is stored in the transmission buffer 4 thereafter. Then, the PON control unit 2 of the OLT 1 transmits a downlink power saving state transition request (permission) that requests (or permits) a transition to the downlink power saving state (first sleep mode) to the ONU # i ( Step S3). The PON control unit 2 transmits the downlink power saving state transition request including a sleep time (sleep time) t for continuing the downlink power saving state.

  After transmitting the downlink power saving state transition request, the PON control unit 2 of the OLT 1 transmits a transmission permission signal that is a control message for giving transmission permission to the ONU #i (step S4). This transmission permission signal is given for ONU # i to transmit a response to the downlink power saving state transition request.

  In the ONU # i that has received the downlink power saving state transition request, the PON control unit 11 transmits to the OLT 1 a downlink power saving state transition response that is a response indicating that the request has been accepted for the power saving state transition request ( Step S5).

  In the OLT 1 that has received the downlink power saving state transition response, the PON control unit 2 sets a timer for measuring the sleep time t (step S6), and stops issuing a transmission permission signal to the ONU #i (step S6). S7). Then, when the timer expires (time elapses by t) (step S8), the transmission buffer 4 is referred to detect the presence / absence of downlink data for the ONU # i, and when there is no downlink data (step S9), Transmission of the downlink signal addressed to ONU # i is stopped (step S10). Then, the PON control unit 2 transmits a downlink power saving state transition request again (step S11), and transmits a transmission permission signal (step S12).

  On the other hand, when the ONU # i receiving the downlink power saving state transition request transmits a downlink power saving state transition response, it sets a timer for measuring the sleep time t included in the downlink power saving state transition request (step S13). ). Then, the reception buffer 13 is shifted to the power saving state (step S14). Further, the downlink control message reception processing unit (Rx 142 of the optical transmitter / receiver 14, the downlink control message processing function part of the PON control unit 11, etc.) is shifted to the power saving state (downstream power saving state) (step S15). The downlink power saving state set in step S14 and step S15 will be described later.

  In ONU # i, when the timer set in step S13 expires (time elapses) (step S16), the downlink control message reception processing unit that has been shifted to the power saving state in step S15 is changed from the power saving state to the normal state. (Step S17). Here, although the downlink control message reception processing unit can receive the control message, some devices that do not need to be operating when receiving the control message such as the reception buffer 14 continue the power saving state. , ONU # i has entered a partial power saving state (second sleep mode). When the ONU #i receives the downlink power saving state transition request transmitted in step S11, the ONU #i transmits a downlink power saving state transition response to the OLT 1 (step S18).

  The process from step S13 to step S18 is set as process A, and process A is repeated while OLT 1 does not detect (receive) the downlink data addressed to ONU # i. While the processing A is repeated, the downlink control message reception processing unit temporarily returns to the normal state every sleep time t, but the reception buffer 14 can be continuously put into the power saving state.

  Here, the downstream power saving state of ONU # i will be described. In step S14, the reception buffer 13 is changed to the power saving state, and in step S15, the downlink control message reception processing unit is changed to the power saving state. However, the power saving state set in these two steps is changed to ONU # i downlink saving. This is called the power state. The reception buffer 13 and the downlink control message reception processing unit can be considered as downlink signal processing means, and the downlink power saving state can be considered as a state in which the downlink signal processing means is transitioning to the power saving state.

  In step S14, the reception buffer 13 is changed to the power saving state, and in step S15, the downlink control message reception processing unit is changed. The downlink control message reception processing unit to be shifted to the power saving state in step S15 is a component related to processing of control messages transmitted from the OLT 1, such as the Rx 142 of the optical transceiver 14 and the control message processing function part of the PON control unit 11. is there. As described above, even when the state in which the OLT 1 does not detect the downlink data addressed to the ONU #i continues for the sleep time t or longer, the OLT 1 transmits the next downlink power saving state transition request as a control message in step S11. In this case, the transition to the power saving state is performed separately for the part related to the processing of the control message and the part not related.

  In the example of FIG. 2, the transition to the power saving state is performed in steps S <b> 14 and S <b> 15, but the transition may be performed simultaneously without dividing the steps. However, also in that case, the downlink control message reception processing unit is shifted to the normal state after the timer expires.

  In step S14, not only the reception buffer 13 but also Tx 162-1 of PHY 16-1 and Tx 162-2 of PHY 16-2 may be shifted to the power saving state. Furthermore, the device (signal processing means) to be in the power saving state in the second sleep mode is not limited to these, and any device can be selected as long as it is unnecessary for the reception processing of some or all of the control messages. The power saving state may be shifted.

  Specific examples of the transition method to the downlink power saving state include the following methods. For example, when the reception buffer 13 is composed of a DDR (Double Data Rate) memory, the PON control unit 11 disables the DDR memory by inputting a command to the memory controller. Further, the PON control unit 11 sets the Rx 142 in a power saving state by transmitting an instruction such as power down or shutdown to the Rx 142 of the optical transceiver 14. For PHY16-1 Tx162-1, PHY16-2 Tx162-2, when PHY16-1 and PHY16-2 support the power save mode specified in IEEE802.3az, for example, , To shift to the “Low Power Idle” state.

  FIG. 3 is a sequence diagram illustrating another example of the power saving control procedure of the present embodiment. Steps S1 to S7 are the same as Steps S1 to S7 in the example of FIG. 2. However, in the example of FIG. Downlink data) is received and stored in the transmission buffer 4 (step S21). That is, ONU # i is in an upstream power saving state, and even if OLT1 transmits downlink data addressed to ONU # i, it is not in a state where ONU # i can be received. Ing. Then, when the measurement of the timer set in step S6 has expired (time has elapsed by t) (step S8), the PON control unit 2 sends a downlink power saving state end request for instructing the end of the downlink power saving state to ONU #. It transmits to i (step S22). Further, the PON control unit 2 transmits a transmission permission signal to the ONU #i (step S23).

  On the other hand, in ONU # i, after step S5, the process of step S13-step S17 is implemented similarly to FIG. When the PON control unit 11 of the ONU #i receives the downlink power saving state end request transmitted in step S22, it instructs the reception buffer 13 to return to the normal state, thereby saving the reception buffer 13. The power state is changed to the normal state (step S24). Here, an example is shown in which the reception buffer 13 is set in a power saving state. However, when the Tx 162-1 of the PHY 16-1 and the TX 162-2 of the PHY 16-2 are also in the power saving state as described above, These are also transitioned to the normal state.

  Then, the PON control unit 11 of the ONU #i transmits a downlink power saving state end response, which is a response to the downlink power saving state end request, to the OLT 1 (step S25). In the OLT 1 that has received the downlink power saving state end response, the PON control unit 2 reads the downlink data addressed to the ONU #i stored in the transmission buffer 4 (step S26), and transmits the read downlink data to the ONU #i. (Step S27). Thereafter, communication in a normal state (normal mode) is performed.

  The ONU # i downstream power saving state is set and canceled by the sequence as described above. The format of the control message used between the OLT 1 and the ONU # i will be supplementarily described below.

  FIGS. 4 to 6 show three PLOAM (Physical Layer Operation and Maintenance) messages for controlling the sleep mode. Two of these PLOAM messages are messages transmitted from the OLT to the ONU, and are a “Sleep mode change acknowledge” message and a “Sleep” message. The remaining one is a “Sleep mode change request” message transmitted from the ONU to the OLT.

  4 to 6 are diagrams showing formats of a “Sleep mode change acknowledge” message and a “Sleep” message. 7 and 8 are diagrams showing the format of the “Sleep mode change request” message.

  The ONU sends a “Sleep mode change request” message to the OLT requesting the transition to its power saving state (sleep mode). When receiving the “Sleep mode change request” message, the OLT transmits a “Sleep mode change acknowledge” message as a response. As shown in FIG. 8, this “Sleep mode change acknowledge” message includes the SuperFrame counter value until FrameCounter1 and FrameCounter4 return from sleep mode (that is, the time until return from sleep mode). Yes.

  4 to 8 show examples in which the PLOAM message is used as means for synchronizing between the OLT and the ONU, but the same power saving method can also be applied to the IEEE standard PON system. IEEE 802.3av defines an extended MAC control message corresponding to a PLOAM message. FIG. 9 shows an example of a message format when using the extended MAC control message. As messages requested from the OLT, a downlink power saving state transition request and a downlink power saving state end request are defined. For these messages, the ONU transmits a response message with the most significant bit of the message type field as “1”. A power saving state request is defined as a message requested from the ONU. Define only upstream, downstream only, and bidirectional as request message parameters. In response to this message, the OLT sets the most significant bit of the message type field to “1” as a response message, and specifies the sleep time as a parameter.

  In this embodiment, in addition to the procedure for requesting the transition from the ONU to the sleep mode, the OLT 1 instructs the ONU #i to transition to the power saving state. For this reason, it is possible to continuously save power in the downstream receiving device (for example, the reception buffer 13) and to further reduce power consumption, compared to the procedure of the sleep mode for upstream data.

  On the other hand, as the format of the control message used in the sequences shown in FIGS. 2 and 3, the message formats shown in FIGS. 4 to 9 may be used. For example, the format of the “Sleep mode change acknowledge” message shown in FIGS. 4 to 6 or a format according to this is used as the control message for the downlink power saving state transition request and the downlink power saving state end request transmitted by the OLT 1. Also good. For example, in the case of a downlink power saving state transition request, 7 Octet P is set to “1”, and in the case of a downlink power saving state end request, P of 7 Octet is set to “0”. Here, in the following description, an example using the message format shown in FIG. 9 is shown.

  Next, a detailed procedure of power saving control of the OLT 1 will be described. FIG. 10 is a flowchart illustrating an example of a power saving control procedure performed by the OLT 1 of the present embodiment.

  As shown in FIG. 10, the PON control unit 2 refers to the transmission buffer 4 to determine whether or not no downlink data addressed to ONU # i is detected (step S31), and in step S31, addressed to ONU # i. If it is determined that no downstream data is detected (No in step S31), the process returns to step S31.

  If it is determined in step S31 that the downlink data addressed to ONU # i has detected no data (Yes in step S31), the PON control unit 2 stops the transmission of the downlink signal to ONU # i (step S32). A downlink power saving state transition request is transmitted to ONU # i (step S33). Next, a transmission permission signal is transmitted to ONU # i (step S34), and it is determined whether or not a downlink power saving state transition response is received from ONU # i (step S35). If it is determined in step S35 that the downlink power saving state transition response has not been received (No in step S35), the process returns to step 31. If the downlink power saving state transition response has been received (step S35 Yes), the downlink saving A timer for measuring the sleep time t specified by the power state transition request is set (step S36), and issuance of a transmission permission signal to the ONU # i is stopped (step 37).

  The PON control unit 2 determines whether or not the timer set in step S36 has expired (time has elapsed by t) (step S38), and if it is determined that the timer has not expired (step S38 No), Step S38 is performed again.

  If it is determined that the timer has expired (Yes in step S38), the PON control unit 2 refers to the transmission buffer 4 and determines whether or not no downlink data addressed to ONU # i has been detected (step S39). . The method of referring to the data on the transmission buffer 4 when determining whether there is downlink data addressed to ONU # i is an example of this determination method, and other methods (for example, a data transmission request, It may be determined by notification from the network side).

  If no downlink data addressed to ONU # i is detected in step S39 (No in step S39), a downlink power saving state end request is transmitted to ONU # i (step S40), and a transmission permission signal is transmitted to ONU # i. (Step S41), it is determined whether or not a downstream power saving state end response is received from ONU #i (Step S42). If it is determined in step S42 that a downlink power saving state end response has been received (step S42 Yes), transmission of a downlink signal (a signal including downlink data) to ONU # i is resumed (step S43). On the other hand, when it is determined in step S42 that the downstream power saving state end response has not been received (No in step S42), the process returns to step S41. If it is detected in step S39 that there is no downlink data addressed to ONU # i (step S39 Yes), the process returns to step S32.

  Next, a detailed procedure of the power saving control of ONU # i will be described. FIG. 11 is a flowchart illustrating an example of a power saving control procedure performed by the ONU # i according to the present embodiment. In ONU # i, the PON control unit 11 determines whether or not a downlink power saving state transition request has been received from the OLT 1 (step S51).

  If it is determined in step S51 that a downlink power saving state transition request has been received from the OLT 1 (step S51 Yes), the PON control unit 11 determines whether a transmission permission signal has been received (step S52). If it is determined in step S51 that the downlink power saving state transition request has not been received from the OLT 1 (No in step S51), step S51 is performed again.

  If it is determined in step S52 that the transmission permission signal has been received (step S52 Yes), the PON control unit 11 transmits a downlink power saving state transition response to the OLT 1 (step S53), and is designated by the downlink power saving state transition request. A timer for measuring the sleep time t is set (step S54).

  Then, the PON control unit 11 causes the reception buffer 13 to transition to the power saving state (step S55), and causes the downlink control message reception processing unit to transition to the power saving state (step S56). In step S55, similarly to step S14 described above, Tx 162-1 of PHY 16-1 and Tx 162-2 of PHY 16-2 may be shifted to the power saving state.

  Next, the PON control unit 11 determines whether or not the timer has expired (step S57). If it is determined that the timer has not expired (No in step S57), step S57 is performed again. If it is determined that the timer has expired (step S57 Yes), the downlink control message reception processing unit is shifted to the normal state (step S58).

  Then, the PON control unit 11 determines whether or not a downlink power saving state end request has been received from the OLT 1 (step S59). If it is determined that the request has not been received (step S59 No), step S59 is performed again. .

  If it is determined in step S59 that the downlink power saving state end request has been received from the OLT 1 (step S59 Yes), the PON control unit 11 changes the reception buffer 13 to the normal state (step S60), and causes the OLT 1 to enter the downlink power saving state. An end response is transmitted (step S61), and the process returns to step S51.

  In this embodiment, the PON control unit 11 causes the reception buffer 13 and the downlink control message reception processing unit to transition to the power saving state (instructs to shift to the power saving state) and the function to return to the normal state. That is, although it has a function as a downlink power saving control means, it is provided with a downlink power saving control means (controller) separately from the PON control unit 11, and the downlink power saving control means is a PON control of the above-described power saving control. You may make it implement one part or all part of the process which the part 11 implemented.

  As described above, in the present embodiment, when there is no downlink data to ONU #i, OLT 1 transmits a downlink power saving state transition request to ONU #i and receives the downlink power saving state transition request. i is shifted to the downstream power saving state. Therefore, during a period when there is no downlink data from the OLT 1 to the ONU #i, the ONU #i can save the power consumption of components necessary for the downlink data processing such as the reception buffer 13, and the consumption of the ONU #i compared to the conventional case. Electric power can be reduced.

  Further, the PON system of this embodiment includes a first sleep mode in which reception of control messages and downlink data is suspended, and a second sleep mode in which control messages are waited to be received and downlink data reception processing is not performed. Can be used as needed. Therefore, even when ONU # i is in the power saving state, even when it is necessary to intermittently enter the reception state, power saving in this reception state can be realized.

Embodiment 2. FIG.
FIG. 12 is a sequence diagram showing an example of a power saving control procedure of the second embodiment of the PON system according to the present invention. The configuration of the PON system of the present embodiment is the same as the configuration of the PON system of the first embodiment. The configurations of the OLT and ONU of the present embodiment are the same as those of the OLT 1 and ONU 10-1 to ONU 10-3 of the first embodiment. Hereinafter, differences from the first embodiment will be described.

  In the first embodiment, the OLT 1 transmits the downlink power saving state transition request to the ONU # i when there is no downlink data addressed to the ONU # i. However, in this embodiment, the ONT # i further Is transmitted to the OLT 1 when a predetermined condition is satisfied.

  In the first embodiment, the request for switching from the ONU to the sleep mode, that is, the sleep mode related to the uplink communication has been described. However, in the first embodiment, the request for switching to the sleep mode when the ONU is used. , I.e., the trigger for transmitting the sleep mode transition request was not specified. In the present embodiment, this opportunity will be described in detail, and an ONU sleep mode transition request procedure will be realized.

  In the present embodiment, ONU # i determines whether there is uplink data, and transmits an uplink power saving state transition request when determining that there is no uplink data. As a determination condition for determining that there is no uplink data, for example, all of the terminals connected to the terminal (here, terminals 20-1 and 20-2) have entered the power saving state, for example, IEEE802. When it is detected by a method such as LPI reception specified in 3az, or when it is detected that all power sources of terminals connected to itself are turned off (not operating), or a terminal connected to itself If no uplink data is received for a certain period of time, etc. can be set. In the present embodiment, the PHYs 16-1 and 16-2 make these determinations and notify the PON control unit 11 of the determination results. That is, in this embodiment, PHYs 16-1 and 16-2 have a function as uplink data detection means for detecting the presence or absence of uplink data from terminals 20-1 and 20-2.

  The power saving control procedure of this embodiment will be described with reference to FIG. First, in ONU # i, PHYs 16-1 and 16-2 determine that there is no uplink data based on the above-described determination conditions, and notify the PON control unit 11 of the determination result (step S71). The PON control unit 11 causes the transmission buffer 12 to transition to the power saving state (step S72).

  Next, when receiving the transmission permission signal from the OLT 1 (Step S73), the PON control unit 11 of the ONU #i transmits an upstream power saving state transition request to the OLT 1 (Step S74).

  The PON control unit 2 of the OLT 1 that has received the uplink power saving state transition request transmits an uplink power saving transition response including the sleep time T (duration of the uplink power saving state) to the ONU #i (step S75). Then, the PON control unit 2 sets a timer for measuring the sleep time T (step S76), and stops issuing a transmission permission signal to the ONU # i (step S77). Thereafter, when the timer expires (time elapses by T) (step S78), the PON control unit 2 transmits a transmission permission signal to the ONU #i (step S79).

  On the other hand, in the ONU # i that has received the uplink power saving transition response, the PON control unit 11 sets a timer for measuring the sleep time T included in the uplink power saving transition response (step S80). Then, the PON control unit 11 causes the uplink control message transmission processing unit (such as Tx 141 of the optical transceiver 14 and the uplink control message processing function part of the PON control unit 11) to transition to the power saving state (step S81).

  The uplink control message transmission processing unit is configured with components necessary for ONU # i to transmit a control message to the OLT 1, such as the Tx 141 of the optical transceiver 14 and the uplink control message processing function part of the PON control unit 11. The The state in which the transmission buffer 12 and the uplink control message transmission processing unit are in the power saving state is referred to as the uplink power saving state. Further, the transmission buffer 12 and the uplink control message transmission processing unit can be considered as uplink signal processing means, and the uplink power saving state can be considered as the state in which the uplink signal processing means is transitioning to the power saving state.

  Thereafter, the PON control unit 11 expires the timer (time elapses by T) (step S82), changes the uplink control message transmission processing unit to the normal state (step S83), and transmits the transmission permission transmitted in step S79. When the signal is received, an upstream power saving state transition request is transmitted to the OLT 1 (step S84).

  The above steps S75 to S84 are set as the process B, and the process B is repeatedly performed while the ONU #i determines that there is no uplink data. While this process B is repeated, the uplink control message transmission processing unit temporarily returns to the normal state every sleep time T, but the uplink transmission buffer 12 can continue the power saving state.

  FIG. 13 is a sequence diagram illustrating another example of the power saving control procedure according to the present embodiment. First, steps S71 to S81 are performed in the same manner as steps S71 to S81 described with reference to FIG.

  In the example of FIG. 13, in ONU # i, after step S81, uplink traffic occurs, PHYs 16-1 and 16-2 determine that there is uplink data, and notify the PON control unit 11 of the determination result ( Step S91). The PON control unit 11 changes the transmission buffer 12 to the normal state, and stores the uplink data received from the terminals 20-1 and 20-2 in the transmission buffer 12 (step S92).

  When the timer expires (time elapses by T) (step S82) and the transmission permission signal transmitted in step S79 is received, the PON control unit 11 reads the uplink data stored in the transmission buffer 12. It transmits to OLT1 (step S93). Thereafter, normal communication is performed.

  Note that the above-described uplink power-saving state transition request and uplink power-saving transition response control messages are not limited to those shown in FIG. 9, but are “Sleep mode change request” messages shown in FIG. 7 and FIG. The “Sleep mode change acknowledge” message shown in FIG. 6 may be used. However, when these messages are also used in the control of the downlink power saving state according to the first embodiment, information for identifying whether the message is related to the uplink power saving state or the downlink power saving state. It should be included in the format.

  Next, a detailed procedure of power saving control of the OLT 1 will be described. FIG. 14 is a flowchart illustrating an example of a power saving control procedure performed by the OLT 1 of the present embodiment. As shown in FIG. 14, the PON control unit 2 of the OLT 1 plans a time for granting transmission permission to each ONU as in the conventional PON control, and transmits a transmission permission signal to the ONU #i (step S101). Next, the PON control unit 2 determines whether or not an upstream power saving state request has been received from the ONU #i (step S102).

  If it is determined in step S102 that an upstream power saving state request has not been received from ONU # i (No in step S102), the process returns to step S101. If it is determined in step S102 that an upstream power saving state request has been received from the ONU #i (Yes in step S102), the PON control unit 2 stops issuing a transmission permission signal to the ONU #i (step S103). Then, the PON control unit 2 transmits a power saving state transition response including the sleep time T to the ONU #i (step S104), and sets a timer for measuring T (step S105).

  Next, the PON control unit 2 determines whether or not the timer has expired (time has elapsed by T) (step S106). If it is determined that the timer has expired (step S106 Yes), the process returns to step S101. . If it is determined that the timer has not expired (No in step S106), step S106 is performed again.

  Next, a detailed procedure of the power saving control of ONU # i will be described. FIG. 15 is a flowchart illustrating an example of a power saving control procedure performed by the ONU # i according to the present embodiment. In the ONU # i, the PHYs 16-1 and 16-2 determine whether there is no uplink data based on the above-described determination condition of the presence of uplink data, and notify the PON control unit 11 of the determination result (step S111). ). When the determination result is a determination result indicating that there is uplink data (No at Step S111), the PON control unit 11 changes the transmission buffer 12 to the normal state (Step S114).

  When it is determined that the transmission buffer 12 is in the power saving state (step S112 Yes), the PON control unit 11 changes the transmission buffer 12 to the normal state (step S113).

  On the other hand, when no uplink data is detected in step S111 (step S111 Yes), the PON control unit 11 determines whether or not the transmission buffer 12 is in a power saving state (step S112). When it is determined that the transmission buffer 12 is not in the power saving state (No in step S112), the PON control unit 11 changes the transmission buffer 12 to the power saving state (step S113), and proceeds to step S115.

  If the timer for measuring the sleep time T in the upstream power saving state is not set in step S117, or if the timer has expired (No in step S117), the process returns to step S111.

  In step S115, the PON control unit 11 determines whether a transmission permission signal is received from the OLT 1 (step S115). When it is determined that the transmission permission signal has not been received (No at Step S115), the process returns to Step S111.

  If it is determined in step S115 that a transmission permission signal has been received (step S115 Yes), the PON control unit 11 determines whether or not the transmission buffer 12 is in a power saving state (step S116). When it is determined that the transmission buffer 12 is not in the power saving state (No in step S116), the PON control unit 11 determines whether data is stored in the transmission buffer 12 (step S123).

  If it is determined in step S123 that data is stored in the transmission buffer 12 (step S123 Yes), the PON control unit 11 transmits the uplink data stored in the transmission buffer 12 to the OLT 1 (step S124). If it is determined in step S123 that no data is stored in the transmission buffer 12 (No in step S123), the process returns to step S111.

  If it is determined in step S116 that the transmission buffer 12 is in the power saving state (step S116 Yes), the PON control unit 11 transmits an upstream power saving state transition request to the OLT 1 (step S117). Then, the PON control unit 11 determines whether or not the upstream power saving state transition permission has been received from the OLT 1 (step S118), and when determining that it has not been received (No in step S118), the process returns to step S111.

  If it is determined in step S118 that the uplink power saving state transition permission has been received from the OLT 1 (Yes in step S118), the PON control unit 11 causes the uplink control message transmission processing unit to transition to the power saving state (step S119). A timer for measuring the sleep time T included in the power state transition response is set (step S120), the process proceeds to step S121, and the PON control unit 11 expires the timer for measuring the sleep time T in the upstream power saving state. It is determined whether or not it has been done (step S121). If the timer for measuring the sleep time T in the uplink power saving state has not expired in step S121 (No in step S121), the process returns to step 121. When the timer for measuring the sleep time T in the uplink power saving state expires in step S121 (step S121 Yes), the PON control unit 11 causes the uplink control message transmission processing unit to transition to the normal state (step S122).

  In the above description, since the trigger for the uplink power saving state transition and the trigger for the downlink power saving state transition are different, the control of the downlink power saving state transition of the first embodiment and the uplink power saving state transition of the present embodiment are different. Although an example in which control is performed independently has been described, for example, when all terminals connected to the ONU # i are turned off due to a failure or the like, it is also possible to simultaneously perform power saving state transition in both directions. In such a case, the upstream power saving state transition request is transmitted from the ONU, and the downstream power saving state transition request is transmitted, and thereafter, the transition to the downstream power saving state is performed in the same procedure as in the first embodiment. . Note that the ONU may transmit the upstream power saving state transition request and the downstream power saving state transition request independently without transmitting them simultaneously.

  Further, the downlink data addressed to the ONU #i that has arrived at the OLT 1 while the ONU #i is in the downlink power saving state may be discarded without being stored in the transmission buffer 4. In this case, for example, information indicating whether or not the downlink data can be discarded is included in the downlink power saving state transition request transmitted from the ONU, and the OLT 1 determines whether to discard or store based on the information. To do.

  In the above description, both the downlink power saving state transition control according to the first embodiment and the uplink power saving state transition control according to the present embodiment are performed. However, the uplink power saving state transition described in the present embodiment is performed. Only power state transition control may be performed.

  In this embodiment, the PON control unit 11 causes the transmission buffer 12 and the uplink control message reception processing unit to transition to the power saving state (instructs to shift to the power saving state) and the function to return to the normal state. That is, although it has a function as an upstream power saving control means, it is provided with an upstream power saving control means separately from the PON control section 11, and the upstream power saving control means has the above-described power saving control PON control section 11. Part or all of the performed processing may be performed.

  As described above, in this embodiment, when the PHYs 16-1 and 16-2 of the ONU #i determine that there is no uplink data transmitted from the terminal, the transmission buffer 12 is shifted to the power saving state, and the OLT 1 is performed. The upstream power saving state transition request is transmitted, and the upstream power saving state transition response that permits the OLT 1 to transition ONU # i to the upstream power saving state is transmitted. On receiving the power saving state transition response, ONU # i causes the uplink control message transmission unit to transition to the power saving state. Therefore, ONU # i can realize the effect of the first embodiment, and can further reduce the power consumption for uplink communication.

  As described above, the PON system and the power saving method according to the present invention are useful for a PON system for measuring power saving, and particularly suitable for a PON system in which a state in which no communication data exists may last for a long time. ing.

  1 OLT, 2 PON control unit, 3, 13 reception buffer, 4,12 transmission buffer, 5,14 optical transceiver, 6 WDM, 7 PHY, 10-1 to 10-3 ONU, 11 PON control unit, 20-1 , 20-2 terminal, 30 subscriber line, 40 splitter, 51, 142, 161-1, 161-2 Rx, 52, 141, 162-1, 162-2 Tx.

Claims (14)

A PON system in which a station-side terminal device and a subscriber-side terminal device are connected using an optical line,
The subscriber-side termination device is:
An upstream optical transmitter for transmitting an upstream optical signal including an upstream control signal to the station-side terminal device;
A downstream optical receiver for receiving a downstream optical signal including a downstream control signal from the station-side terminal device;
A control unit that generates the uplink control signal, wherein a transition from a normal state to a first power saving state in which both the upstream optical transmitter and the downstream optical receiver are in a power saving state is used as the downlink control signal. Based on the timer, the transition from the first power saving state to the activated state where both the upstream optical transmitter and the downstream optical receiver are activated and is a partial power saving state is controlled. First control for controlling a transition from the activated state to the first power saving state or the normal state, and the upstream optical transmitter from the normal state to the power saving state and the downstream optical receiver to the operating state. Transition to the second power saving state is controlled based on the downlink control signal, and the transition from the second power saving state to the activated state in which the upstream optical transmitter is activated and is a partial power saving state Control based on a timer. And a control unit for executing any of the state of the second control for controlling the transition to the second power-saving state or a normal state, a,
The station side termination device is:
A control unit for generating the downlink control signal;
A downstream optical transmitter for transmitting a downstream optical signal including the downstream control signal generated by the control unit to the subscriber-side terminating device;
An upstream optical receiver for receiving an upstream optical signal including the upstream control signal from the subscriber-side termination device,
PON system characterized by that. The control unit of the subscriber-side terminal device controls transition from the activated state to the normal state based on the downlink control signal.
The PON system according to claim 1 . The PON system according to claim 1 or 2 , wherein a timer of a control unit of the subscriber-side terminal device measures a sleep time included in the downlink control signal. The activated state is a third power saving state in which a part or all of a configuration unnecessary for processing the uplink control signal and a part unnecessary for processing the downlink control signal are in a power saving state. The PON system according to claim 1 , 2 or 3 . A subscriber-side terminator that can be connected to a station-side terminator via an optical line,
An upstream optical transmitter for transmitting an upstream optical signal including an upstream control signal to the station-side terminal device;
A downstream optical receiver for receiving a downstream optical signal including a downstream control signal from the station-side terminal device;
A control unit that generates the uplink control signal, wherein a transition from a normal state to a first power saving state in which both the upstream optical transmitter and the downstream optical receiver are in a power saving state is used as the downlink control signal. Based on the timer, the transition from the first power saving state to the activated state where both the upstream optical transmitter and the downstream optical receiver are activated and is a partial power saving state is controlled. First control for controlling a transition from the activated state to the first power saving state or the normal state, and the upstream optical transmitter from the normal state to the power saving state and the downstream optical receiver to the operating state. Transition to the second power saving state is controlled based on the downlink control signal, and the transition from the second power saving state to the activated state in which the upstream optical transmitter is activated and is a partial power saving state Control based on a timer. A control unit for executing any of the state of the second control for controlling the transition to the second power-saving state or a normal state,
A subscriber-side terminating device comprising: 6. The subscriber-side termination device according to claim 5 , wherein the control unit controls transition from an activated state to a normal state based on the downlink control signal. The subscriber-side terminating device according to claim 5 or 6 , wherein the timer of the control unit measures a sleep time included in the downlink control signal. The activated state is a third power saving state in which a part or all of a configuration unnecessary for processing the uplink control signal and a part unnecessary for processing the downlink control signal are in a power saving state. The subscriber-side terminating device according to claim 5, 6 or 7 . A station-side termination device connectable to the subscriber-side termination device according to any one of claims 5 to 8 via an optical line,
A control unit for generating the downlink control signal;
A downstream optical transmitter for transmitting a downstream optical signal including the downstream control signal generated by the control unit to the subscriber-side terminating device;
An upstream optical receiver for receiving an upstream optical signal including the upstream control signal from the subscriber-side termination device;
A station-side terminating device comprising: Use an optical line to connect the station-side terminator and subscriber-side terminator,
The subscriber-side termination device is:
An upstream optical transmitter for transmitting an upstream optical signal including an upstream control signal to the station-side terminal device;
A downstream optical receiver for receiving a downstream optical signal including a downstream control signal from the station-side terminal device;
A PON system control device comprising:
The transition from the normal state to the first power saving state in which both the upstream optical transmitter and the downstream optical receiver are in the power saving state is controlled based on the downlink control signal, and from the first power saving state, The upstream optical transmitter and the downstream optical receiver are both activated and controlled based on a timer to transition to an activated state, which is a partial power saving state. From the activated state to the first power saving state or normal A first control for controlling a transition to a state, and a downlink control for a transition from a normal state to a second power saving state in which the upstream optical transmitter is in a power saving state and the downstream optical receiver is in an operating state. And controlling the transition from the second power-saving state to the activated state, which is the partial activation of the upstream optical transmitter, based on the timer. 2 Power saving state or normal state Perform one of the second control for controlling the transition,
A control device characterized by that. A power saving method in a PON system in which a station-side terminal device is connected to a subscriber-side terminal device by an optical line,
A first step of receiving, by a downstream optical receiver, a downstream optical signal including a downstream control signal from the station-side terminal device;
A second step of transmitting an upstream optical signal including an upstream control signal to the station side terminal device by an upstream optical transmitter, and a power saving method comprising:
A third step of controlling a transition from a normal state to a first power saving state in which both the upstream optical transmitter and the downstream optical receiver are in a power saving state based on the downlink control signal;
A fourth step of controlling, based on a timer, a transition from the first power saving state to the activated state in which both the upstream optical transmitter and the downstream optical receiver are activated and are partially in the power saving state ; ,
A first step including a fifth step of controlling a transition from the activated state to the first power saving state or the normal state, and
A sixth step of controlling, based on the downlink control signal, a transition from a normal state to a second power saving state in which the upstream optical transmitter is in a power saving state and the downstream optical receiver is in an operating state;
A seventh step of controlling a transition from the second power saving state to the activated state in which the upstream optical transmitter is activated and is a partial power saving state based on a timer;
An eighth step of controlling the transition from the activated state to the second power saving state or the normal state;
Executing one of the second controls including:
A power saving method characterized by that. Ninth steps of receiving by the fourth of the downstream optical receiver downstream optical signal including the downlink control signal from the station side terminating device after step, wherein the
In the fifth step, the transition from the activated state to the normal state is controlled based on the downlink control signal in the ninth step, or
Tenth steps of receiving by the seventh said downlink optical receiver downstream optical signal including the downlink control signal from the station side terminating device after step, wherein the
In the eighth step, the transition from the activated state to the normal state is controlled based on the downlink control signal in the tenth step.
Power saving method of claim 1 1, wherein the. The power save method according to claim 11 or 12 , wherein the timer in the fourth step or the seventh step measures a sleep time included in the downlink control signal in the first step. The activation state of the fourth step or the seventh step is a third power saving state in which part or all of the configuration unnecessary for processing of the uplink control signal and the configuration unnecessary for processing of the downlink control signal are set in the power saving state. power saving method of claim 1 1, 12 or 13, which is a state.

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