JP2010114830A - Pon optical communication system, station-side apparatus, subscriber-side apparatus and power consumption control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve power consumption reduction by discriminating, from a station-side apparatus OLT, whether or not information addressed to a subscriber-side apparatus ONU is stored. <P>SOLUTION: A PON optical communication system is configured to perform optical communication between a station-side apparatus OLT and a plurality of subscriber-side apparatuses ONUs via a beam splitter, and a transmitter 1 of the station-side apparatus OLT includes a downlink buffer 13 for storing user frames to be sequentially transmitted to the subscriber-side apparatuses ONUs. A power saving mode controller 16 transmits, to a subscriber-side apparatus ONU where user frames to be transmitted in the downlink buffer 13 is empty, a power saving mode-setting frame describing therein a power saving mode time TPS that is shorter than one cycle time from transmission to a certain subscriber-side apparatus ONU through sequential transmission to any other subscriber-side apparatus ONU to re-transmission to the certain subscriber-side apparatus ONU. In the case where a power saving mode setting frame is received, a PON receiver 2 of the subscriber-side apparatus ONU is set to the power saving mode for the power saving mode time TPS described in the power saving mode setting frame. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to power saving of a home device in an optical access network using PON (Passive Optical Network) technology.

Using the optical data communication network between the station side equipment OLT (Optical Line Terminal: optical subscriber line terminal equipment) and a plurality of home side equipment ONU (Optical Network Unit: optical subscriber line termination equipment) Systems that communicate in the direction are known.
In particular, a single star network configuration in which the station-side device OLT and each home-side device ONU are connected radially with a single optical fiber has been put into practical use. This network configuration simplifies the system and equipment configuration, but if one home-side device ONU occupies one optical fiber and there are N home-side device ONUs, it is directly connected from the station-side device OLT. N optical fibers are required, and it is difficult to reduce the cost of the system.

Therefore, a PON (Passive Optical Network) optical communication system in which one optical fiber drawn from the station side device OLT is shared by a plurality of home side devices ONU has been put into practical use. The PON optical communication system is one of low-cost access methods for optical subscribers that have been applied to FTTx such as FTTH (Fiber To The Home) and FTTB (Fiber To The Building).
In the PON optical communication system, one station side is passed through a passive optical branching device (optical coupler) that splits and multiplexes the signal passively from the input signal without the need for external power supply. The device OLT and a plurality of home-side devices ONU are connected by an optical transmission line. The station-side apparatus OLT and the N-station home-side apparatus ONU are based on 1-to-N transmission connected via an optical fiber SMF and an optical coupler OC. Thereby, many home side apparatuses ONU can be allocated with respect to one station side apparatus OLT, and the whole installation cost can be held down.

  In the PON optical communication system, an optical signal transmitted between the station side device OLT and the home side device ONU is usually composed of an FEC (Forward Error Collection) frame including a parity for error correction. . Each of the station side device OLT and the home side device ONU uses the error correction parity included in the received optical signal and performs error correction / decoding of the data of the frame with the error correction code in units of frames with the error correction code. It is carried out.

By the way, the home-side apparatus ONU is usually installed in each subscriber's house, but in recent years, there is an increasing need for low power consumption at the subscriber's house.
For this reason, a technique has been proposed in which when the connection with the station-side apparatus OLT is not established, the home-side apparatus ONU is released from the steady operation state so as not to consume useless power. That is, in the home apparatus ONU, it is determined whether or not an optical signal is input, whether or not a logical link is established with the station apparatus OLT, whether or not there is a connection with a lower computer, and based on the determination result. This is a technique for suppressing the power consumption of some devices of the home-side apparatus ONU.
JP 2000-324101A

  However, the conventional power consumption suppression technology cannot effectively reduce power consumption during normal use of an optical communication system. This is because the optical signal itself is always input and the logical link is established in the home device ONU of the PON optical communication system even when the information addressed to the home device ONU is not transmitted from the station device OLT. The lower computer is in a connected state. Therefore, the opportunity to suppress the power consumption of some devices of the home device ONU is limited.

  Accordingly, the present invention provides a PON optical communication system and station-side apparatus that can realize low power consumption by creating a mechanism for determining whether or not there is information addressed to the home-side apparatus ONU from the station-side apparatus OLT. An object is to provide an OLT, a home-side apparatus ONU, and a power consumption control method.

In this section, numbers and the like in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.
The PON optical communication system of the present invention performs optical communication between a station side device OLT and a plurality of home side devices ONU via an optical branching unit, and the transmission unit 1 of the station side device OLT A downlink buffer unit 13 that accumulates user frames to be sequentially transmitted to the home apparatus ONU and a power saving mode control unit 16 are provided. The power saving mode control unit 16 determines whether user frames to be transmitted in the downlink buffer unit 13 are transmitted. For an empty home-side device ONU, an uplink bandwidth allocation control frame is transmitted to the home-side device ONU, and then sequentially transmitted to other home-side devices ONU, and an upstream bandwidth allocation control frame is transmitted to the home-side device ONU. The power-saving mode setting frame describing the power-saving mode time TPS, which is shorter than the round-trip time until another time is transmitted, is transmitted, and the PON receiving unit 2 of the home-side apparatus ONU receives from the station-side apparatus OLT. A frame analysis unit that analyzes the frame addressed to the local station, and when the frame analysis unit receives the power saving mode setting frame, the frame analysis unit covers the power saving mode time TPS described in the power saving mode setting frame. In this system, the PON receiving unit 2 is set to a power saving mode.

  In this configuration, the station side device OLT transmits a power saving mode setting frame describing the power saving mode time TPS to the home side device ONU having no data to be transmitted. The home-side apparatus ONU that has received the power-saving mode setting frame addressed to the own station sets the PON receiving unit 2 of the own station to the power-saving mode over the designated power-saving mode time TPS. Since the power saving mode time TPS is shorter than one round time, the power saving mode time TPS ends before the communication start frame comes from the station side device OLT. Therefore, when a communication start frame comes from the station side device OLT next time, the communication start frame and subsequent frames can be received and analyzed.

In the present invention, a frame with an error correction code is optically transmitted from the station side device OLT to the home side device ONU, and a frame analysis unit of the home side device ONU corrects an error of the frame with the error correction code. If the error correction frame decoding unit 24 is stopped, the power saving effect is great.
Further, it is preferable that the frame analysis unit of the home-side apparatus ONU does not stop the clock recovery unit 21 that recovers a clock for performing uplink burst transmission based on the received frame even during the power saving mode period. This is because the home apparatus ONU that is network-synchronized with the station apparatus OLT needs to transmit the uplink burst signal using the clock extracted from the downlink data signal even during the power saving mode period.

  Further, it is preferable that the frame analysis unit of the home device ONU normally operates the error correction frame synchronization unit 23 for PON reception even during the power saving mode period. When the error correction frame synchronization unit 23 is operating, the synchronization of the downlink signal from the station side apparatus OLT is maintained even during the power saving mode period, so that the station side apparatus received after the power saving mode period ends. There is no need to synchronize the downstream signal from the OLT again. Therefore, even if the power consumption is slightly increased, it becomes possible to receive the signal immediately and the frame analysis of the downlink signal can be started.

  Further, the power saving mode control unit 16 may transmit the power saving mode setting frame a plurality of times in one round time. The transmitting unit 1 of the station-side device OLT stores any data to be transmitted to the home-side device ONU received from the higher layer in the downstream buffer unit 13 while a certain home-side device ONU is in the power saving mode. is doing. If there is data to be transmitted to the home device ONU at the time when one power saving mode time TPS is completed, the power saving mode control unit 16 does not end the round-trip time, and the subsequent power saving mode setting frame Transmission can be stopped and a frame addressed to the home device ONU can be transmitted.

  Further, the transmission unit 1 of the station side device OLT used in the PON (Passive Optical Network) optical communication system of the present invention includes a downlink buffer unit 13 for storing user frames to be sequentially transmitted to each home side device ONU, and a power saving mode. The power saving mode control unit 16 has a power saving mode setting in which the power saving mode time TPS is described for the home device ONU in which the user frame to be transmitted in the downlink buffer unit 13 is empty. A frame is transmitted.

According to this station side device OLT, after the logical link addressed to the home device ONU is established, the time during which the frame addressed to the home device ONU is not transmitted is set in the power saving mode setting frame and transmitted to the home device ONU. be able to.
The PON receiving unit 2 of the home-side apparatus ONU used in the optical communication system of the present invention has a frame analyzing unit that analyzes a frame addressed to the own station received from the station-side apparatus OLT. When the power mode setting frame is received, the PON receiving unit 2 is set to the power saving mode over the power saving mode time TPS described in the power saving mode setting frame.

According to this home-side apparatus ONU, when the power-saving mode setting frame is received from the station-side apparatus OLT, the power consumption of the own station can be reduced.
The power consumption control method in optical communication according to the present invention is a method according to the invention substantially the same as the invention in the PON optical communication system.

  As described above, according to the present invention, when a logical link on the PON is established and the home side device ONU and the lower network side device are connected, there is no data to be transmitted to the home side device ONU. In addition, since the home device ONU can be set in the power saving mode, power consumption can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram illustrating a configuration example of a PON optical communication system.
In the PON optical communication system, a station side device OLT provided in a station building and a home side device ONU provided in a plurality of subscribers are connected via an optical fiber SMF and an optical coupler OC.
The home-side apparatus ONU includes a network interface for connecting a terminal for enjoying an optical network service such as a personal computer installed in the subscriber's home.

The optical coupler OC is composed of a star coupler that passively branches and multiplexes a signal from an input signal without requiring an external power supply.
The optical fibers connected to the station-side device OLT, the optical coupler OC, the optical coupler OC, and the home-side device ONU are single mode fibers each composed of one optical fiber SMF. That is, one station side device OLT is connected to one optical coupler OC through one trunk optical fiber SMF. If necessary, one optical coupler OC is connected to M second optical couplers OC (M is 1 in this example) by an optical fiber SMF. The second optical coupler OC is connected to L units (L is a number of 32 or less in this example) of home-side devices ONU via branch optical fibers SMF. Therefore, a signal transmitted / received by one station-side apparatus OLT is distributed to a plurality of home-side apparatuses ONU by a two-stage optical coupler OC. The numbers of optical couplers OC and home-side devices ONU are merely examples.

An optical communication system according to an embodiment of the present invention incorporates Ethernet (Ethernet is a registered trademark) technology into the PON optical communication system, and performs optical fiber access section communication at a baseband speed of Gbps. A GE-PON (Gigabit Ethernet-Passive Optical Network) method or a 10G-EPON method is employed.
According to the GE-PON system or 10G-EPON system, communication between the station side apparatus OLT and the home side apparatus ONU is performed in units of variable length frames.

  First, a downlink frame that enters each station-side apparatus OLT in a broadcast form from a higher-level network is subjected to predetermined processing in the station-side apparatus OLT, and a logical link (MPCP link) to be relayed is specified. Then, it is transmitted to the optical fiber SMF as an optical signal through the station side device OLT. The optical signal transmitted to the optical fiber SMF is branched by the optical coupler OC and transmitted to the home-side device ONU connected to the optical coupler OC. However, only the home-side device ONU constituting the MPCP link transmits a predetermined downlink frame. Capture and relay frame to home network interface.

  On the other hand, the upstream optical signal includes an upstream frame from each home-side apparatus ONU. The upstream optical signal needs to be transmitted so that the optical signals from the respective home devices ONU do not compete with each other in time. For this purpose, the station-side apparatus OLT allocates a window (hereinafter simply referred to as a window) during which an upstream optical signal may be transmitted to each home-side apparatus ONU and notifies it as an uplink bandwidth allocation control frame. The home-side apparatus ONU to which the window is assigned transmits an upstream optical signal during the assigned window period. This upstream optical signal is referred to as a “burst optical signal”. The burst optical signal is a finite-time optical signal sequence which is transmitted from each home-side apparatus ONU and whose light emission state is changed by the baseband signal.

Therefore, the competition of the upstream optical signal between each home-side apparatus ONU is avoided. Each home-side apparatus ONU, when given a certain window, may transmit frames continuously as long as it fits in that window. The station apparatus OLT can receive a burst optical signal including a series of frame signals from each home apparatus ONU.
FIG. 2 is a block diagram showing an internal configuration of the station side apparatus OLT, and only the transmission unit 1 from the station side apparatus OLT to the home side apparatus ONU is illustrated.

  The transmission unit 1 stores a downlink input unit 11 that inputs a downlink frame from an upper network such as the Internet, and a FIFO (First In First Out) of the downlink buffer unit 13 that stores the frame acquired by the downlink input unit 11. It has a frame distribution processing unit 12 that performs distribution, and a downlink buffer unit 13 that accumulates the frames distributed by the frame distribution processing unit 12.

  In this embodiment, the downlink buffer unit 13 has one control frame FIFO common to each home-side apparatus ONU and a user frame FIFO addressed to each home-side apparatus ONU. In FIG. 2, for example, a user frame FIFO addressed to the home apparatus ONU1 is displayed as “ONU1 FIFO”. The number of user frame FIFOs is equal to or greater than the number N of home-side devices ONUs that can be connected to the system.

The transmission unit 1 further includes an MPCP (multi-point control protocol) control unit 14, a scheduling processing unit 15, a power saving mode control unit 16, a power saving timer 27 b unit 17, and a downlink transmission unit 18.
The MPCP control unit 14 controls the MPCP link between the station side device OLT and the home side device ONU. That is, the MPCP control unit 14 generates an MPCP Gate frame for teaching the timing of transmitting an uplink signal to a specific home-side apparatus ONU (denoted ONUi), and the MPCP Gate frame is used as a power saving mode control unit. 16 to the downlink. Normally, an MPCP Gate frame is periodically transmitted every several ms (this time interval is referred to as an MPCP GATE transmission time cycle TNG). In IEEE EPON, the transmission interval of MPCP Gate frames is 50 ms at maximum.

A specific home-side device ONUi receives and decodes the MPCP Gate frame, and an MPCP Report frame is sent from the home-side device ONUi to the station-side device OLT to notify the upstream buffer storage amount of the home-side device ONUi. The MPCP link is established.
The scheduling processing unit 15 manages transmission scheduling of each FIFO in the downlink buffer unit 13. That is, the FIFO length (capacity currently stored in the FIFO) for each home-side apparatus ONU is read from the downlink buffer unit 13 and sent to the power saving mode control unit 16.

Based on this FIFO length, the power saving mode control unit 16 determines the transmission schedule ON / OFF for each home-side apparatus ONU and sends it to the scheduling processing unit 15. The FIFO transmission schedule ON is set for a FIFO whose FIFO length is not 0, and the FIFO transmission schedule is set OFF for a FIFO whose FIFO length is 0.
The scheduling processing unit 15 supplies the “transmission FIFO instruction” for instructing the FIFO to transmit the frame next to the downlink buffer unit 13. This instruction is given only to the home device ONU of the transmission schedule ON.

  On the other hand, when the FIFO length of the user frame FIFO in the downlink buffer unit 13 is 0, the power saving mode control unit 16 interrupts during the MPCP Gate frame transmission to the home side device ONUi, and the home side device ONUi Control for transmitting a power saving mode setting frame to the destination is performed. For this reason, the power saving mode control unit 16 sends the MPCP Gate frame addressed to the home device ONUi and the time interval parameter for sending the MPCP Gate frame (one round time; called MPCP GATE transmission time cycle TNG) from the MPCP control unit 14. If it is received, until the next MPCP Gate frame is transmitted, a power saving mode setting frame for the home apparatus ONUi is created based on the power saving mode time TPS set in advance by the power saving timer 27b unit 17, Transmit to the home device ONUi. Here, the “power saving mode time TPS” is a time interval for transmitting a power saving mode setting frame. The power saving mode time TPS is set to a time not longer than the MPCP GATE transmission time cycle TNG addressed to the home device ONU.

  In addition, the power saving mode control unit 16 transmits a power saving mode setting frame for the home-side device ONUi, and at the same time, the scheduling processing unit 15 responds to the user frame FIFO to be set to the power saving mode as described above. By turning off all scheduling, the home device ONUi that is set to the power saving mode is prevented from transmitting a frame destined for the home device ONUi.

The power saving timer 27b unit 17 sets and measures the power saving mode time TPS in the station side device OLT, and determines the number of repetitions of the power saving mode time TPS between transmissions of the MPCP Gate frame.
The downlink transmission unit 18 includes an MPCP Gate frame addressed to the home device ONUi, a FIFO length of 0, that is, a power saving mode setting frame for the home device ONUi having no information to transmit, and a downlink information frame including the contents accumulated in the FIFO Are transmitted in broadcast form.

FIG. 3 is a schematic diagram illustrating an example of a power saving mode setting frame. The power saving mode setting frame includes a destination address, a source address, a length / type, an operation code, a power saving mode time TPS, padding, and an FCS (Frequency Check Sequence).
The destination address is the address of the home device ONUi that is the target of the power saving mode setting. If this address is its own address, the home-side apparatus ONUi that has received the power saving mode setting frame knows that its own station should be set in the power saving mode. If the address of the home device ONU that has received the power saving mode setting frame is different from this address, the power saving mode setting frame is ignored.

The source address is the address of the station side device OLT. The power saving mode time TPS is the time set by the power saving timer 27b unit 17 described above, and the home device ONU sets the PON receiving unit 2 in the power saving mode over the power saving mode time TPS.
Next, processing of the power saving mode control unit 16 of the station side apparatus OLT will be described. First, the power saving mode control unit 16 receives from the MPCP control unit 14 an MPCP Gate frame addressed to the home device ONUi, and also receives information on the MPCP GATE transmission time cycle TNG addressed to the home device ONUi.

If the user frame FIFO of the home side apparatus ONUi in the downlink buffer unit 13 is empty, the power saving mode control unit 16 sets the home side apparatus ONUi to the power saving mode. For this reason, the following processing is performed.
FIG. 4 is a flowchart showing processing of the power saving mode control unit 16.
The power saving mode control unit 16 confirms that the MPCP GATE transmission time cycle TNG is longer than the power saving mode time TPS (steps S1 and S2), and if so, sets the home device ONUi to the power saving mode. Therefore (step S3), the power saving mode setting frame is transmitted to the home device ONUi (step S4), and the power saving timer 27b unit 17 starts counting down the power saving mode time TPS (step S5). That is, the unit time (for example, 1 msec) is subtracted until the power saving mode counter Tpsc of the home-side apparatus ONUi reaches 0 (steps S6 and S7).

  During this power saving mode, the power saving mode control unit 16 prevents the scheduling of downlink transmission from being performed for the user frame FIFO of the home-side apparatus ONUi that sends the power saving mode setting frame. Notify This is to prevent a frame from being transmitted to the home device ONUi during the power saving mode (even if transmitted, the home device ONUi cannot be received because it is in the power saving mode).

The data to be transmitted to the home device ONUi received from the downlink input unit 11 during the power save mode time TPS set in the power save mode setting frame is the ONU addressed to the home device ONUi within the station side device OLT. Buffer in the frame.
If the power saving mode counter Tpsc becomes 0, the process proceeds to step S8, where it is confirmed whether the user frame FIFO of the home side apparatus ONUi of the downlink buffer unit 13 is still empty.

  If it is empty, the power saving mode time TPS is subtracted from the power saving mode counter Tpsc of the home device ONUi (step S9), and it is determined whether or not the power saving mode counter Tpsc is greater than 0 (step S10). If it is greater than 0, there is room to repeat the power saving mode time TPS until the time of sending the next MPCP Gate. Therefore, the process returns to step S4 to transmit the power saving mode setting frame to the home device ONUi again and save the power. Starts counting down the power mode counter Tpsc.

  If it is determined that the power saving mode counter Tpsc is 0 or less, that is, the power saving mode time TPS does not enter the remaining time of the MPCP GATE transmission time cycle TNGc (i), An instruction to stop the power saving mode of the home side apparatus ONUi, resume the FIFO transmission scheduling of the home side apparatus ONUi (set the transmission schedule to ON) is issued (step S11), and this process is terminated.

  Also, if the FIFO of the home device ONUi in the downlink buffer unit 13 is not empty in step S8 (that is, data to be transmitted to the home device ONUi is accumulated during the power saving mode time TPS), MPCP GATE Without waiting for the transmission time cycle TNG to elapse, an instruction to resume the FIFO transmission scheduling of the home device ONUi is issued (step S11), and this process is terminated.

  In this way, the station side device OLT, for example, transmits the first power saving mode setting frame, and then when the user frame addressed to the home side device ONUi comes from the upper network, the second power saving mode setting frame is transmitted. It is possible to return to the normal mode without transmitting the power mode setting frame. Since the station side device OLT can shorten the time for holding the ONU frame inside the station side device OLT rather than waiting until the MPCP cycle ends, the frame buffer for ONU in the station side device OLT Small capacity is required.

  FIG. 5 is a time flow chart showing the flow of transmission of the MPCP Gate frame and the power saving mode setting frame. After transmitting the MPCP Gate frame addressed to the home device ONUi, if there is no data in the ONU frame addressed to the home device ONUi, the power save mode setting frame for the home device ONUi at the head of each power save mode time TPS Is sending. If the power saving mode time TPS elapses and the FIFO of the home device ONUi of the downlink buffer unit 13 is still empty, the power saving mode setting frame is continuously transmitted. In this manner, the power saving mode setting frame is continuously transmitted as long as necessary in the MPCP GATE transmission time cycle TNGc (i). When the MPCP GATE transmission time cycle TNGc (i) elapses, the next MPCP Gate frame is transmitted to the home device ONUi, and the above procedure is repeated.

In the case of FIG. 5, the MPCP Gate to be sent to another home-side device ONUi + 1 or the like is executed independently of the schedule for the home-side device ONUi. For example, after sending the MPCP Gate and sending the power saving mode setting frame, the MPCP Gate is also sent to other home side devices ONUi + 1 and the like until the power saving mode time TPS elapses.
As a specific design example of time, the time of the MPCP Gate and the power saving mode setting frame is 50 nanoseconds, the power saving mode time TPS is 300 μsec, and the MPCP GATE transmission time cycle TNG is about 1 ms. For this reason, the number of MPCP Gate frames, power saving mode setting frames, and user frames that can be sent to the home apparatus ONU during one power saving mode time TPS is several thousand. Therefore, the power saving mode control unit 16 can individually execute the power saving mode setting schedule for each of the home-side devices ONU for each of the home-side devices ONU.

  In FIG. 5, when the power saving mode time TPS is shorter than the MPCP GATE transmission time cycle TNG, for example, the MPCP GATE transmission time cycle TNG shows an example in which the power saving mode time TPS of the home device ONUi enters three times. Even when the power saving mode time TPS is the same length as the MPCP GATE transmission time cycle TNG, the power saving mode setting schedule can be executed. In this case, step S10 in FIG. 4 is always determined as “NO”, but only the procedure in FIG. 4 is different. In the operation example of FIG. 5, since the number of times of sending the power saving mode setting frame in the MPCP GATE transmission time cycle TNG is one time minimum, the time for sending the frame addressed to the downstream ONU lives without being reduced, and the bandwidth is effectively used. Can do.

  FIG. 6 shows a flow of frame transmission when the power saving mode time TPS of the home side apparatus ONUi enters once during the MPCP Gate frame transmission interval time TNG for the home side apparatus ONUi. In this case, the power saving mode time TPS needs to be somewhat shorter than the MPCP GATE transmission time cycle TNG. This is because when the home device ONU returns from the power saving mode to the normal mode, it takes time to be able to receive a frame normally. The required time depends on the circuit type of the home-side apparatus ONU that stops the operation during the power saving mode.

As described above, by sending a power saving mode setting frame to the home device ONUi at the beginning of each power saving mode time TPS, a part of the PON receiving unit 2 of the home device ONUi stops the frame receiving process. . Since the home device ONUi is in the power saving mode, the power consumption of the home device ONUi can be reduced.
Next, the configuration on the home device ONU side in which the power saving mode is set will be described.

FIG. 7 is a block diagram of the PON receiver 2 of the home device ONU.
The PON receiving unit 2 includes an O / E conversion unit 20, a clock recovery unit 21 (CDR) unit 21 that reproduces clock data, a deserializer (DES) unit 22 that converts a serial signal into a parallel signal, and a frame boundary. Error correction frame synchronization unit 23, error correction frame decoding unit 24 for correcting errors of frames with error correction codes arranged in parallel with each other, descrambling unit 25 for decrypting code, 64B / 66B decoder unit 26, and frame analysis A MACPON receiving unit 27 is provided.

When receiving the power saving mode setting frame addressed to the own station from the station side device OLT, the MACPON receiving unit 27 sets the power saving mode signal to “1” (power saving mode) and notifies the other blocks to that effect.
The MACPON receiving unit 27 reads the power saving mode time TPS described in the frame, and sets the power saving mode time TPS in the power saving timer 27 b of the MACPON receiving unit 27. The power saving timer 27b is decremented at regular intervals, and if the timer value is not 0, the power saving mode is continued. When the power saving mode timer reaches 0, the decrement is stopped and the power saving mode signal is set to “0” (normal mode).

In the embodiment of the present invention, the power saving mode signal is input to each block of the error correction frame decoding unit 24, the descrambling unit 25, and the 64B / 66B decoder unit 26 of the PON receiving unit 2.
Each block stops the circuit operation of the internal block while the power saving mode signal is “1”, thereby reducing the power consumption of the circuit.
Here, “stopping the circuit operation of the internal block” may be (1) stopping the supply of power to the main components in the own block, or (2) to the main components in the own block. The clock input to the flip-flop may be stopped.

Since the state transition is interrupted by stopping the input clock, the power required for the logical operation can be made extremely small.
When the power supply or clock input to the error correction frame decoding unit 24 as “main part” is stopped, the error correction operation is stopped. In the PON receiving unit 2, since the power consumption of the error correction frame decoding unit 24 is large, the effect of reducing the power consumption by setting the error correction frame decoding unit 24 in the power saving mode is great.

However, the clock recovery unit 21 of the PON reception unit 2 needs to continue the clock recovery included in the reception data from the station side device OLT and distribute it to the PON transmission unit 1 in order to transmit the upstream frame data. Do not enter power saving mode.
In order to further reduce power consumption, a power saving mode signal is input to the deserializer unit 22 and the error correction frame synchronization unit 23, and the circuit operations of the deserializer unit 22 and the error correction frame synchronization unit 23 are also stopped. It is also possible to switch to a mode.

  However, the error correction frame synchronization unit 23 is a block for establishing synchronization of a frame with an error correction code, and if a power saving mode signal is input, the operation for synchronizing the operation is stopped. In this case, since it takes time to search for the boundary of the frame with the error correction code when restarted next time, it is preferable to operate the error correction frame synchronization unit 23 even during the power saving mode period.

  However, the operation of the error correction frame synchronization unit 23 can be stopped. This is because even if the operation for obtaining the synchronization is stopped, if the operation is resumed when returning to the normal mode, there is no problem even if the operation of the error correction frame synchronization unit 23 is stopped. In this case, the station side device OLT considers the power saving mode time TPS in the power saving mode setting frame in consideration of the longest time expected for the error correction frame synchronization unit 23 to synchronize the frame with the error correction code. It is desirable to set it. For example, as shown in FIG. 6, when the power saving mode time TPS of the home side apparatus ONUi enters once during the MPCP Gate frame transmission interval time TNG for the home side apparatus ONUi, the power saving mode time TPS is set to MPCP GATE. It is desirable to make it shorter than the transmission time cycle TNG by the “longest time expected for the error correction frame synchronization unit 23 to synchronize the frame with the error correction code”.

  If the error correction frame synchronization unit 23 continues normal operation, the deserializer unit 22 does not enter the power saving mode in order to continue supplying the received data to the error correction frame synchronization unit 23. It is necessary to continue normal operation. However, if the error correction frame synchronization unit 23 is set to the power saving mode, the deserializer unit 22 can also be set to the power saving mode.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

It is the schematic which shows the structural example of the PON optical communication system which connected between the station side apparatus OLT and several home side apparatus ONU with the optical fiber via the optical coupler. It is a block diagram which shows the internal structure of the station side apparatus OLT. It is a figure which shows an example of a power saving mode setting frame. 4 is a flowchart showing processing of a power saving mode control unit 16. It is a figure which shows the flow of transmission of the MPCP Gate frame and power saving mode setting frame from the station side device OLT, and the power saving mode time of the home side device ONUi during the MPCP Gate frame transmission interval time TNG for the home side device ONUi TPS is repeated a plurality of times. It is a figure which shows the flow of the transmission of the flame | frame when the power saving mode time TPS of the home side apparatus ONUi enters once during the MPCP Gate frame transmission interval time TNG with respect to the home side apparatus ONUi. It is a block diagram of the PON receiving part 2 of the home side apparatus ONU.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission part 2 PON receiving part 11 Downlink input part 12 Frame distribution process part 13 Downstream buffer part 14 MPCP control part 15 Scheduling process part 16 Power saving mode control part 17 Power saving timer 27b part 18 Downstream transmission part 20 O / E conversion part 21 Clock recovery (CDR) unit 22 Deserializer (DES) unit 23 Error correction frame synchronization unit 24 Error correction frame decoding unit 25 Descramble unit 26 64B / 66B decoder unit 27 MAC reception unit 27a Frame analysis unit 27b Power saving timer 27c Frame error check section

Claims (8)

In a PON (Passive Optical Network) optical communication system that performs optical communication between a station side device and a plurality of home side devices via an optical splitter,
The transmission unit of the station side device includes a downlink buffer unit that accumulates user frames to be sequentially transmitted to each home side device, and a power saving mode control unit, and the power saving mode control unit includes: For the home device with an empty user frame to be transmitted, an upstream bandwidth allocation control frame is transmitted to the home device and then sequentially transmitted to other home devices to allocate upstream bandwidth to the home device. A power saving mode setting frame describing a power saving mode time set to a time shorter than a round time until a control frame is transmitted,
The PON receiving unit of the home side device has a frame analyzing unit that analyzes a frame addressed to the local station received from the station side device, and the frame analyzing unit receives the power saving mode setting frame A PON optical communication system, wherein the PON receiving unit is set in a power saving mode over a power saving mode time described in the power saving mode setting frame. The optical communication system is a system in which a frame with an error correction code is optically transmitted from the station side device to the home side device,
The PON receiving unit of the home side device has an error correction frame decoding unit that corrects an error of the frame with the error correction code, and when the frame analysis unit receives the power saving mode setting frame, at least The PON optical communication system according to claim 1, wherein the error correction frame decoding unit is stopped.   2. The PON receiving unit of the home side apparatus has a clock recovery unit that recovers a clock for performing uplink burst transmission, and the frame analysis unit does not stop the clock recovery unit even during a power saving mode period. Alternatively, the PON optical communication system according to claim 2.   The PON receiving unit of the home-side apparatus has an error correction frame synchronization unit that synchronizes the frame with the error correction code, and the frame analysis unit operates the error correction frame synchronization unit even during the power saving mode period. The PON optical communication system according to claim 1.   The PON optical communication system according to claim 1, wherein the power saving mode control unit of the station side device transmits the power saving mode setting frame a plurality of times in the round trip time. A station-side device used in a PON (Passive Optical Network) optical communication system that performs optical communication via an optical branching device between a station-side device and a plurality of home-side devices,
The transmission unit of the station side device includes a downlink buffer unit that accumulates user frames to be sequentially transmitted to each home side device, and a power saving mode control unit,
The power saving mode control unit transmits to the home side device that the user frame to be transmitted in the downlink buffer unit is empty, and then sequentially transmits the home frame to another home side device. A station-side device that transmits a power-saving mode setting frame that describes a power-saving mode time that is set to a time shorter than a round time until transmission to the side device. A home-side device used in a PON (Passive Optical Network) optical communication system that performs optical communication between a station-side device and a plurality of home-side devices via an optical splitter,
The PON receiver of the home side device has a frame analysis unit for analyzing a frame addressed to the local station received from the station side device,
When the frame analysis unit receives the power saving mode setting frame, the frame analysis unit sets the PON receiving unit to a power saving mode for a power saving mode time described in the power saving mode setting frame. A home-side device. A power consumption control method in optical communication performed via an optical branching unit between a station side device and a plurality of home side devices,
When sequentially transmitting user frames from the station-side device to each home-side device, to the home-side device that does not have a user frame to be transmitted, it is sent to the home-side device and then sequentially sent to other home-side devices. Then, a power saving mode setting frame describing a power saving mode time set to a time shorter than one round time until transmission to the home side device is transmitted,
The home-side device that has received the power-saving mode setting frame sets the PON receiving unit of the home-side device in the power-saving mode over the power-saving mode time described in the power-saving mode setting frame. Power control method in optical communication.

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