WO2011083564A1

WO2011083564A1 - Pon system, subscriber-side device, station-side device, and communications method

Info

Publication number: WO2011083564A1
Application number: PCT/JP2010/050033
Authority: WO
Inventors: 亮宏辻; 浩史杉村
Original assignee: 三菱電機株式会社
Priority date: 2010-01-05
Filing date: 2010-01-05
Publication date: 2011-07-14
Also published as: TW201145859A

Abstract

A PON system comprises an ONU (2) and an OLT (1). The OLT (1) further comprises a buffer (10) for storing downstream data; a transmission timing determination unit (14) that determines a data transmission period of the downstream data on a per band update cycle basis; and a PON control unit (19) that adds the data transmission period to a gate frame and transmits same. The ONU (2) further comprises a light receiving device (27) and a frame division unit (28), which carry out a prescribed reception process upon the downstream data that is received from the OLT (1); and a reception timing instruction unit (29), which transitions the light receiving device (27) and the frame division unit (28) to either a power conservation state or a normal operation state on the basis of the data transmission period included within the gate frame.

Description

PON system, subscriber side device, station side device, and communication method

The present invention relates to a PON (Passive Optical Network) system composed of an OLT (Optical Line Terminal: station side device) and an ONU (Optical Network Unit: subscriber side device).

As an access network for connecting a station and a user's home, a PON system which is one of FTTH (Fiber To The Home) is rapidly spreading due to its high speed and economy. In the PON system, a station side device (OLT) is connected to a plurality of subscriber side devices (ONUs) via an optical splitter that branches signal outputs to a plurality of optical fibers. Further, a TE (Terminal Equipment) is connected to the ONU, for example, via a LAN cable. TE includes HGW (Home Gate Way), VoIP-TA (Voice over Internet Protocol-Terminal Adapter), PC (Personal Computer), etc.

The ONU installed in the user's home always establishes a link with the OLT or TE even during standby when data communication is not performed in order to support services that require real-time performance such as optical telephones. Therefore, there is a problem that the power consumption of the ONU increases.

In order to solve this problem, Non-Patent Document 1 below defines a new protocol and an OAM (Operation Administration and Maintenance) message, and transmits a request to shift from the ONU to the sleep mode, and the OLT returns the ONU based on the request. Is allowed to operate in sleep mode. In this way, in the method described in Non-Patent Document 1 below, the ONU is prevented from consuming unnecessary power when there is no communication.

Also, Patent Document 1 below discloses a method of operating an ONU with power saving in order to ensure a lifeline even when a power failure occurs and the ONU becomes battery-driven in an emergency such as a disaster.

In Patent Document 2 below, a method is disclosed in which the ONU monitors communication in the downstream direction (direction to the user equipment) and reduces power consumption based on the reception status of the user equipment. In Patent Document 3 below, the ONU of the PON system monitors the status of the logical link and the physical link, and controls to shift the mounted circuit to the low power consumption mode when the logical link and the physical link are disconnected. A method is disclosed.

JP 2009-171424 A JP 2009-170986 A JP 2008-113193 A

However, in the method described in Non-Patent Document 1, the ONU defines only the normal mode (transmission / reception enabled state) or the sleep mode, and the upstream communication (direction from the ONU to the OLT) and the downstream are defined. Communication (direction from OLT to ONU) is not distinguished. Therefore, for example, when there is uplink communication, it is necessary to operate the downlink communication circuit, and conversely, when there is downlink communication, it is necessary to operate the uplink communication circuit. Therefore, there is a problem that the power saving efficiency of the ONU is low.

Further, in the method described in Non-Patent Document 1, a dedicated OAM frame for handshaking for performing sleep control between the OLT and the ONU is used. Therefore, there is a problem that an extra communication band is used for sleep control.

Further, in the method described in Patent Document 1, only the processing related to the minimum necessary communication such as a telephone is caused to function, and the bandwidth update period is extended so that the communication for controlling the device is not performed as much as possible. For this reason, no reduction in power consumption during normal communication is disclosed.

In the method disclosed in Patent Document 2, attention is paid to the downlink multicast frame, and the power of the multicast circuit is saved when the multicast frame is not in communication. For this reason, there has been a problem that power cannot be saved in a unicast frame, and low power consumption cannot be achieved if communication of a multicast frame is continued.

Further, in the method of Patent Document 3, since the occurrence of link disconnection is used as a transition trigger to the low power consumption mode, there is a problem that low power consumption cannot be achieved while continuing communication while maintaining the link. there were.

The present invention has been made in view of the above, and an object thereof is to provide a PON system, a subscriber-side device, a station-side device, and a communication method that can improve the efficiency of power saving.

In order to solve the above-described problems and achieve the object, the present invention provides a plurality of subscriber-side devices, a station-side device that allocates an uplink communication band to each subscriber-side device and performs multiplex communication, PON (Passive Optical Network) system, wherein the station side device specifies a part of a period in a subsequent band update cycle as a data transfer period for downlink data, and allocates a band before transferring the downlink data. As a result, PON control means for notifying the subscriber side device is provided, the subscriber side device receiving means for receiving the downlink data transmitted from the station side device, and the data included in the band allocation result And a state control unit that shifts the receiving unit to a power saving state or a normal state based on a transfer period.

The PON system according to the present invention has an effect that the efficiency of power saving can be improved.

FIG. 1 is a diagram illustrating a configuration example of the PON system according to the first embodiment. FIG. 2 is a diagram illustrating an example of an operation within the band update period according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of a GATE frame according to the first embodiment. FIG. 4 is a flowchart illustrating an example of the power saving control operation of the PON system according to the first embodiment. FIG. 5 is a diagram illustrating an example of power saving control according to the first embodiment. FIG. 6 is a diagram illustrating an example of contents of a GATE frame according to the first embodiment. FIG. 7 is a diagram illustrating an example of contents of a GATE frame according to the first embodiment. FIG. 8 is a diagram illustrating an example of power saving control when the next operation determination time is set to a time that is one band update cycle or more ahead. FIG. 9 is a diagram illustrating a configuration example of the PON system according to the second embodiment. FIG. 10 is a diagram illustrating an example of an operation within the band update period according to the second embodiment. FIG. 11 is a diagram illustrating a configuration example of a GATE frame according to the second embodiment. FIG. 12 is a flowchart illustrating an example of the power saving control operation of the PON system according to the second embodiment. FIG. 13 is a diagram illustrating an example of power saving control according to the second embodiment. FIG. 14 is a diagram illustrating a content example of a GATE frame according to the second embodiment. FIG. 15 is a diagram illustrating an example of contents of a GATE frame according to the second embodiment. FIG. 16 is a diagram illustrating an example of power saving control according to the second embodiment in the case where a time that is one band update period or more ahead of the ONU is set as the transmission timing of the GATE frame. FIG. 17 is a diagram illustrating a configuration example of the PON system according to the third embodiment. FIG. 18 is a flowchart illustrating an example of the power saving control operation of the PON system according to the third embodiment. FIG. 19 is a diagram illustrating an example of power saving control according to the third embodiment. FIG. 20 is a diagram illustrating a content example of a GATE frame according to the third embodiment. FIG. 21 is a diagram illustrating a content example of a GATE frame according to the third embodiment. FIG. 22 is a diagram illustrating a content example of a GATE frame according to the third embodiment.

Hereinafter, embodiments of a PON system, a subscriber-side device, a station-side device, and a communication method according to the present invention will be described 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 of the present embodiment includes an OLT 1 and an ONU 2 connected to the OLT 1 via a splitter 3. The OLT 1 is connected to the upper apparatus 4, and the ONU 2 is connected to the lower apparatus 5. Although only one ONU 2 is shown in FIG. 1, the number of ONUs 2 connected to the OLT 1 via the splitter 3 may be any number of one or more.

The OLT 1 includes a buffer 10, a write control unit 11, a buffer management unit 12, a read control unit 13, a transmission timing determination unit 14, a frame multiplexing unit 15, an optical transmitter 16, an optical receiver 17, a frame separation unit 18, and a PON control unit. 19.

The buffer 10 is a buffer for temporarily storing downlink data addressed to the ONU 2 received from the host device 4. The write control unit 11 controls the writing of data to the buffer 10, and the read control unit 13 controls the reading of data stored in the buffer 10. The buffer management unit 12 manages the amount of data stored in the buffer 10 based on the write information of the write control unit 11 and the read information of the read control unit 13.

The frame multiplexing unit 15 generates a user frame storing the downlink data read from the buffer 10 by the read control unit 13, and multiplexes the generated user frame and the control frame. The optical transmitter 16 converts the multiplexed frame, which is an electrical signal, into an optical signal and transmits it to the ONU 2 via the splitter 3. Further, the transmission timing determination unit 14 determines the transmission timing of the downlink data based on the data amount (downstream buffer amount) accumulated in the buffer 10 notified from the buffer management unit 12, and performs the PON control on the determined transmission timing. Notification to the unit 19.

The PON controller 19 (PON controller) 19 performs a predetermined process based on the control frame received from the ONU 2 and generates a control frame to be transmitted to the ONU 2, and also transmits an upstream data band (transmission time band) to the ONU 2. Is assigned.

The optical receiver 17 converts the optical signal received from the ONU 2 into an electrical signal and outputs it to the frame separation unit 18. The frame separation unit 18 separates the electrical signal received from the optical receiver 17 into a control frame and a user frame, outputs the control frame to the PON control unit 19, and transmits the user frame to the host device 4.

The ONU 2 includes a buffer 20, a write control unit 21, a buffer management unit 22, a read control unit 23, a frame multiplexing unit 24, an optical transmitter 25, a PON control unit 26, an optical receiver 27, a frame separation unit 28, and a reception timing instruction unit. 29.

The buffer 20 is a buffer that temporarily stores uplink data (data to be transmitted to the OLT 1) received from the lower-level device 5. The write control unit 21 controls the writing of data to the buffer 20, and the read control unit 23 controls the reading of data stored in the buffer 20. The buffer management unit 22 manages the amount of data stored in the buffer 20 based on the write information of the write control unit 21 and the read information of the read control unit 23.

The frame multiplexing unit 24 generates a user frame storing the uplink data read from the buffer 20 by the read control unit 23, and multiplexes the generated user frame and the control frame. The optical transmitter 25 converts the multiplexed frame, which is an electrical signal, into an optical signal and transmits it to the OLT 1 via the splitter 3.

The optical receiver 27 converts the optical signal received from the OLT 1 into an electrical signal and outputs it to the frame separation unit 28. The frame separation unit 28 separates the electrical signal received from the optical receiver 27 into a control frame and a user frame, outputs the control frame to the PON control unit 26, and transmits the user frame to the lower apparatus 5. The frame separation unit 28 also outputs a GATE frame, which is a control frame for notifying the band allocation result transmitted from the OLT 1, to the reception timing instruction unit 29. In this embodiment, as described later, in the GATE frame, downlink data is transmitted from OLT 1 to ONU 2 as downlink transmission information as well as a bandwidth allocation result for transmission of uplink data from ONU 2 as in the conventional case. The information of the time zone to be used is stored.

The PON control unit 26 performs a predetermined process based on the control frame received from the OLT 1 and generates a control frame to be transmitted to the OLT 1. The PON control unit 26 is a control frame that notifies the upstream buffer amount and requests bandwidth allocation based on the data amount (upstream buffer amount) accumulated in the buffer 20 notified from the buffer management unit 22. A Report frame is generated.

In addition, the reception timing instruction unit (state control means) 29 obtains a reception time zone in which the device receives an optical signal from the OLT 1 based on the GATE frame transmitted from the OLT 1 and can receive in the obtained reception time zone. The optical receiver 27 and the frame separation unit 28 are activated so as to achieve a proper state. In general, since a predetermined preparation period is required from when the optical receiver 27 and the like are activated until the optical receiver 27 and the like can actually be received, the reception timing instruction unit 29 sets the optical receiver 27 and the like to the start time of the reception time zone. Is activated by a predetermined preparation time. In addition, when the reception time period ends, the reception timing instruction unit 29 shifts the optical receiver 27 and the frame separation unit 28 to a power saving mode that is in a state of saving power (downlink power saving). Any method may be used as a power saving method for the optical receiver 27 and the frame separation unit 28, but power saving is performed using a technique such as power gating and clock gating.

Further, the PON control unit 26, based on the allocation result (for uplink data transmission) notified in the GATE frame, is a constituent unit (optical transmitter 25, frame multiplexing unit) necessary for uplink transmission in a time zone in which no uplink transmission is performed. 24, the read control unit 23, and the like) are power-saving (up-direction power saving). In the present embodiment, both the power saving in the upstream direction and the power saving in the downstream direction (power saving of the optical receiver 27 and the frame separation unit 28) are performed. Only power saving may be performed. In addition, the power saving components may not be all of the above-described components, but may be one or more of the above-described components, and other related components may be power-saving. Also good.

In the OLT 1 as well, the PON control unit 19 saves power in the frame multiplexing unit 15 and the optical transmitter 16 in a time zone that is not allocated to the ONU 2 as an upstream data transmission time zone. Further, in a time zone during which no optical signal is transmitted to the ONU 2, the transmission timing determination unit 14 saves power in the optical transmitter 16, the frame multiplexing unit 15, and the readout control unit 13. The transmission timing determination unit 14 may control the power saving of the optical transmitter 16, the frame multiplexing unit 15, and the readout control unit 13 by the PON control unit 19. In addition, although power saving of such OLT1 was performed here, power saving of OLT1 does not need to be implemented, and power saving of only one of the down direction or the up direction is performed. You may make it implement. In addition, the power saving components may not be all of the above-described components, but may be one or more of the above-described components, and other related components may be power-saving. Also good.

Next, the operation of this embodiment will be described. FIG. 2 is a diagram illustrating an example of the operation within the band update period according to the present embodiment. In the PON system, bandwidth allocation is performed in units of a predetermined bandwidth update period. As shown in FIG. 2, the bandwidth update period can be divided into a data transfer period and a next period operation determination period. In the next cycle operation determination period, the OLT 1 transmits a GATE frame in which the uplink data transmission start time and the transmission duration time (= transmission data amount) are stored in the next bandwidth update cycle assigned to each ONU 2.

In the bandwidth update cycle, the ONU 2 receives the GATE frame for the own device received from the OLT 1 and transmits a Report frame storing the uplink buffer amount of the own device to the OLT 1. As the transmission start time, for example, a time called a time stamp using a PON clock used for synchronization between the OLT 1 and the ONU 2 defined by MPCP (Multi Point Control Protocol) is used. The transmission duration uses, for example, TQ (Time Quanta), which is an MPCP processing unit. Although the transmission duration is stored as a transmission data amount, the transmission data amount can be converted into a transmission duration based on the line speed.

The OLT 1 allocates bandwidth to each ONU (transmission start time and transmission continuation) within the data transfer period of the next bandwidth update cycle based on the uplink buffer amount included in the Report frame received in the previous bandwidth update cycle. Time allocation) and the transmission time of downlink data from the own apparatus to each ONU within the data transfer period of the next bandwidth update cycle. Then, the bandwidth allocation result is notified to each ONU using the GATE frame in the next cycle operation determination period.

In the data transfer period, the ONU 2 transmits uplink data to the OLT 1 based on the transmission start time and the transmission duration specified by the GATE frame received in the previous band update cycle. Further, the OLT 1 transmits the downlink data from the own apparatus to each ONU based on the downlink data transmission time allocated in the previous band update period in the data transfer period. The operation in each band update cycle so far is the same as that of a normal PON system.

In the present embodiment, a transfer period (transmission start time and transmission duration) during which OLT 1 transmits a downlink frame (user frame of downlink data) is added to a GATE frame that notifies the transmission start time and transmission duration of uplink data. To do. In the present embodiment, the transmission duration is from the transmission of the first downlink frame to the transmission of the last downlink frame within one band update period (data transfer period). Since the transmission continuation time is notified by the data amount, the total data amount transmitted in one bandwidth update cycle is notified. Further, a time at which the OLT 1 transmits the GATE frame next time is added to the GATE frame.

FIG. 3 is a diagram illustrating a configuration example of a GATE frame according to the present embodiment. As shown in FIG. 3, the GATE frame according to the present embodiment includes header information including a destination, a frame type, time, and the like, uplink transmission information, and downlink transmission information. The uplink transmission information includes the transmission start time and the transmission duration time of the uplink data assigned by the OLT 1 to the ONU 2 as in the conventional case. The downlink transmission information is divided into two types: data transfer period information and operation determination period information. The data transfer period information includes a transmission start time and a transmission continuation time when the OLT 1 transmits downlink data to the ONU 2 in the next bandwidth update cycle. The operation determination period information is information related to a time zone in which the OLT 1 next transmits a GATE frame (performs band allocation), and the transmission start time and transmission duration time of the GATE frame (the length of the GATE frame: GATE length). )including.

When the ONU 2 receives the GATE frame illustrated in FIG. 3, it can grasp the time zone in which the downlink data should be received. Therefore, as described above, the reception timing instruction unit 29 determines the reception time zone based on the data transfer period information of the downlink transmission information stored in the GATE frame so that reception is possible in the reception time zone. Each unit related to downlink reception (optical receiver 27 and frame separation unit 28: hereinafter referred to as downlink reception unit) can be power-saving or activated.

Also, the ONU 2 needs to activate the downlink receiving unit in order to receive the GATE frame. In this embodiment, the OLT 1 performs burst transmission of downlink data within a predetermined transmission period. Then, the OLT 1 notifies the time when the burst transmission of the downlink data is performed as the operation determination period information of the downlink transmission information, whereby the ONU 2 can grasp the time when the GATE frame should be received next. Therefore, the ONU 2 can save power in the downlink receiving unit in a time zone other than the time zone stored in the data transfer period information of the downlink transmission information and in a time zone other than the time when the GATE frame should be received. . Similarly, in the OLT 1, in a time zone in which no downlink data is transmitted and no GATE frame is transmitted, each unit (optical transmitter 16, frame multiplexing unit 15, readout control unit 13, etc.) related to downlink data transmission saves power. Can be

As for uplink data, burst transmission is conventionally performed in the PON system, and in the ONU 2, each unit related to uplink transmission (the optical transmitter 25, the frame multiplexing unit 24, and the readout) is read based on the uplink transmission information included in the GATE frame. It is possible to save power in the control unit 23 and the like.

Next, the detailed operation of the present embodiment will be described. FIG. 4 is a flowchart illustrating an example of the power saving control operation of the PON system according to the present embodiment. First, the operation of the OLT 1 will be described with reference to FIG. In OLT1, the transmission timing determination unit 14 determines whether or not the current time is the operation determination time (step S1), and if it is not the operation determination time (No in step S1), repeats step S1.

The operation determination time is the time when the operation is determined next, and is determined by the PON control unit 19 at the time of transmitting the GATE frame and notified to the transmission timing determination unit 14. In addition, for example, when a GATE frame is transmitted for each band update period, the operation determination time is set for each band update period. As illustrated in FIG. 3, the OLT 1 transmits the operation determination period information as downlink transmission information in the GATE frame, and the operation determination time is the GATE frame in which the transmission start time and the transmission duration time are notified by the operation determination period information. This is the time at which the processing for obtaining the information stored in (band update processing) is started. The transmission start time of the operation determination period information is set as a time after a minute considering the processing time of the band update process from the operation determination time.

When the current time is the operation determination time (step S1, Yes), the transmission timing determination unit 14 receives the downlink buffer amount (the total frame accumulation amount accumulated in the buffer 10) from the buffer management unit 12 ( Step S2). Then, the transmission timing determination unit 14 determines the transmission start time and the transmission data amount (corresponding to the transmission continuation time) of downlink data for the ONU 2 based on the downlink buffer amount (step S3). The determined downlink data transmission start time and transmission data amount are retained.

Next, the transmission timing determination unit 14 determines whether or not the operation determination period transmission time (transmission start time of the operation determination period information of the GATE frame transmitted to the ONU 2) has been reached (step S4), and the operation determination period transmission time If not (step S4, No), repeat step S4.

When the operation determination period transmission time comes, the transmission timing determination unit 14 activates the transmission block (downlink transmission unit) and shifts to a state in which downlink transmission is possible (step S5). Then, the PON control unit 19 is notified of the downlink data transmission start time and transmission data amount determined in step S3 to the PON control unit 19, and the PON control unit 19 stores the ONU allocation result for uplink transmission. The notified transmission start time and transmission data amount are added to the frame as data transfer period information of downlink transmission information. At this time, the PON control unit 19 also determines the next operation determination time, obtains the operation determination period information corresponding to the operation determination time, adds it to the GATE frame, and adds the data transfer period information and the operation determination period information. The added GATE frame is transmitted to the ONU 2 via the frame multiplexing unit 15 and the optical transmitter 16 (step S6).

When the transmission of the GATE frame in step S6 is completed, the PON control unit 19 instructs the transmission timing determination unit 14 to save the transmission block. Upon receiving the notification, the transmission timing determination unit 14 saves the transmission block. (Step S7).

Next, the transmission timing determination unit 14 determines whether there is downlink data (user data) to be transmitted within the data transfer period of the current bandwidth update cycle (step S8), and when there is no user data (step S8). In S8 No), the process returns to Step S1.

If there is downlink data (user data) to be transmitted within the data transfer period of the current bandwidth update cycle (Yes in step S8), whether or not the transmission start time (downlink data transmission start time) of the data transfer period has come Is determined (step S9), and if the transmission start time of downlink data is not reached (No in step S9), step S9 is repeated.

When the downlink data transmission start time is reached (Yes in step S9), the transmission block is activated to shift to a state in which downlink transmission is possible (step S10). Then, the transmission timing determination unit 14 instructs the read control unit 13 to read data based on the transmission start time and the data amount of the downlink data, and the read control unit 13 sends the data from the buffer 10 based on the instruction. Read and output to the frame multiplexing unit 15 (step S11).

The frame multiplexing unit 15 generates a user frame storing the data received from the read control unit 13, and transmits it to the ONU 2 via the optical transmitter 16 (step S12). When there is a control frame output from the PON control unit 19, the frame multiplexing unit 15 multiplexes the control frame and the user frame and transmits the multiplexed frame to the ONU 2.

The transmission timing determination unit 14 determines whether or not downlink data transmission is scheduled to continue in the band update period based on the transmission start time and data amount of the downlink data that is held (step S13). If there is a transmission schedule (step S13, Yes), the process returns to step S11. When there is no transmission plan (No in step S13), power saving is performed on the transmission block (step S14), and the process returns to step S1.

Next, the detailed operation of ONU2 will be described. In the ONU 2, the reception timing instruction unit 29 determines whether or not the reception time of the GATE frame obtained based on the transmission start time of the operation cycle determination period information notified from the OLT 1 by the GATE frame is reached (step S21). When the operation determination period reception time comes (step S21: Yes), the reception block (downlink reception unit) is activated to receive the GATE frame (step S22). If it is not the operation determination period reception time (No at Step S21), Step S21 is repeated.

After step S22, when receiving the GATE frame from the OLT 1 (step S23), the reception timing instruction unit 29 saves power in the reception block (step S24). Then, it is determined whether or not there is information (information for which transmission duration is not 0) indicating that downlink data is transmitted in the data (user data) transfer period stored in the received GATE frame (step S25). If there is no information indicating that there is downlink data transmission (No in step S25), the process returns to step S21.

When there is information indicating that there is downlink data transmission in the GATE frame (step S25, Yes), the reception timing instruction unit 29 receives the downlink frame reception time obtained based on the transmission start time of the data transfer period information of the GATE frame. Is determined (step S26), and if it is not the transmission start time of the data transfer period information (No in step S26), step S26 is repeated.

When the transmission start time of the data transfer period information comes (step S26 Yes), the reception timing instruction unit 29 activates the reception block (step S27). The ONU 2 receives the user frame (downlink data) from the OLT 1 (step S28), ends the reception (after the transmission duration time has elapsed), saves power in the reception block (step S29), and returns to step S21.

Note that the activation of the reception block in step S22 and step S27 is activated before the scheduled reception time if preparation time is required from when the activation instruction is issued until it becomes ready for reception. To give instructions.

FIG. 5 is a diagram illustrating an example of power saving control according to the present embodiment. In the example of FIG. 5, it is assumed that ONUs # 1 to # 3 having the same configuration as the ONU 2 are connected to the OLT 1. The OLT 1 receives the downlink data addressed to the ONU # 1 to ONU # 3 from the upper apparatus 4. As described above, the OLT 1 determines the transmission start time and the transmission continuation time for transmitting the user frame storing the downlink data based on the downlink buffer amount, and sets the GATE frame storing the determined information as the ONU # 1 to ONU #. 3 to send. Also, in this GATE frame, the transmission start time and the GATE length of the next GATE frame are stored as operation determination period information and transmitted. Then, the OLT 1 transmits the GATE frame 71 addressed to the ONU # 1, the GATE frame 72 addressed to the ONU2 in the next period operation determination period.

FIG. 6 is a diagram illustrating an example of the content of a GATE frame 71 transmitted to ONU # 1, and FIG. 7 is a diagram illustrating an example of the content of a GATE frame 72 transmitted to ONU # 2. As shown in FIG. 6, in the GATE frame 71 transmitted to the ONU # 1, the start time # 1 is stored at the transmission start time and the duration # 1 is stored as the transmission duration as data transfer period information. And In the GATE frame 71, it is assumed that the start time # 2 is stored at the transmission start time and the GATE length is stored at the transmission continuation time as the operation determination period information. In the GATE frame 72 transmitted to the ONU # 2, it is assumed that the start time # 1 is stored at the transmission start time and the duration # 1 is stored as the transmission continuation time as data transfer period information. In the GATE frame 72, it is assumed that the start time # 3 is stored at the transmission start time and the GATE length is stored at the transmission continuation time as the operation determination period information. The data transfer period information is the same information in the GATE frame 71 and the GATE frame 72 because the total period for transmitting the downlink frame within one band update cycle is stored. On the other hand, the operation determination period information is different in the GATE frame 71 and the GATE frame 72 because the transmission time zone is different for each ONU.

In the ONU # 1 to ONU # 3, as described above, when no GATE frame is received and no downstream frame is received, the reception block is in a power saving state. Then, the reception block is activated only before the overhead 61 corresponding to the preparation period for starting the reception block from the reception time of the GATE frame or the reception time of the downstream frame. Further, the reception block is shifted to the power saving state at the reception end time (the reception end time obtained based on the transmission start time and the transmission continuation time). At this time, it is assumed that a period of overhead 62 is required from when the power saving instruction is issued until the power saving state is actually entered.

In FIG. 5, ONU # 1 to ONU # 3 activate the reception block just before the overhead time 61 shown in FIG. 6 by the overhead 61, and after the continuation time # 1 has elapsed from the start time # 1, Save power. The ONU # 1 activates the reception block just before the overhead 61 in the preparation period from the start time # 2 shown in FIG. 6, and saves power after the continuation time # 2 has elapsed from the start time # 2. . On the ONU # 2, the reception block is activated only by the preparation period 61 before the start time # 3 shown in FIG. 7, and power is saved after the continuation time # 3 has elapsed from the start time # 3.

In the example of FIG. 5, an example is shown in which the OLT 1 transmits a GATE frame at each band update period. However, there is no data transmitted from the ONU # 1 to ONU # 3 and no data transmitted from the OLT1. The next operation determination time may be a time that is one band update cycle or more ahead. FIG. 8 is a diagram illustrating an example of power saving control when the next operation determination time is set to a time that is one band update cycle or more ahead.

8, it is assumed that the GATE frames 71 and 72 shown in FIG. 6 and FIG. 7 are transmitted in the same manner as in FIG. 5, but in the example of FIG. 8, the start time # 2 and the start time # 2 are GATE frames. The time is one band update cycle or more ahead of the time at which 71 and 72 are transmitted. Therefore, as shown in FIG. 8, the power saving state can be continued for a long time, and the number of

overheads

61 and 62 can be reduced. Bandwidth allocation for this GATE frame can be performed individually according to the individual data transmission / reception states of the ONU # 1 to ONU # 3. That is, it is possible to allocate a bandwidth for some ONUs in the next bandwidth update cycle and to allocate a bandwidth for different or all ONUs in subsequent bandwidth update cycles.

As described above, in this embodiment, the OLT 1 determines the transmission start time and transmission duration of the downlink user frame, the transmission start time and transmission duration of the next GATE frame, and the upstream band for the ONU 2 The determined two types of transmission start time and transmission duration are stored in the GATE frame that notifies the allocation of the transmission. Since both the downlink user frame and the GATE frame are downlink communications from the OLT 1, both of these two types of transmission start times and transmission continuation times can be considered as downlink communication times. In the ONU 2, power saving of the uplink transmission unit and power saving of the downlink reception unit are performed independently, and the downlink reception unit is set in the power saving state in a time zone other than the downlink communication time based on the GATE frame. Therefore, it is possible to efficiently save power while continuing normal communication. In addition, since no special frame transmission is required, power can be saved without wasting bandwidth.

In addition, even if there are components with large overhead when shifting to power saving and activation, frames are transmitted in bursts, so the number of times of shifting to power saving / activation is reduced and the total is reduced. Therefore, the power saving efficiency can be further improved. Further, since the downlink data received by the OLT 1 when the downlink receiving unit of the ONU 2 is in the power saving state is accumulated in the buffer 10 and transmitted when the downlink communication is resumed, there is an effect that no frame loss occurs.

In the conventional PON system, the ONU transmits a request for the sleep mode to the OLT based on the uplink communication status known by the ONU, and shifts to the sleep mode after receiving the permission from the OLT. For this reason, it takes time until the ONU can enter the sleep mode until it actually enters the sleep mode, which consumes extra power. On the other hand, in this embodiment, the ONU 2 can shift to the power saving state based on the transmission start time and the transmission duration time of the uplink communication notified by the GATE frame. Can be further enhanced.

Further, in the conventional PON system, when data to be transmitted to the ONU in the sleep mode occurs, the OLT cannot immediately transmit the data, and there is a possibility that the downlink communication is unnecessarily delayed. On the other hand, in the present embodiment, since power saving is performed independently for downlink communication and uplink communication, downlink data can be transmitted from the OLT 1 to the ONU 2 in a state where the uplink transmission unit saves power. Can be reduced.

Further, in the conventional PON system, the OLT did not determine the time frame for transmitting the downlink frame in advance and transmitted it in an arbitrary time zone within the data transfer period. However, in this embodiment, the OLT transmits the downlink frame. Since the transmission time zone to be transmitted is determined in advance, it is possible to activate the downlink transmission unit in the transmission time zone and save power in the downlink transmission unit in a data transfer period other than the transmission time zone. Therefore, the OLT 1 can save power compared to the conventional case.

In the above description, the transmission continuation time is notified by the data amount, but may be notified by other information (time, the number of clocks, etc.) without using the data amount. Further, in FIG. 3 and the like, the downlink communication information is added after the uplink transmission information, but the downlink transmission information can be transmitted separately from the uplink transmission information.

Embodiment 2. FIG.
FIG. 9 is a diagram showing a configuration example of the second embodiment of the PON system according to the present invention. The PON system of the present embodiment is the same as the PON system of the first embodiment, except that the OLT 1 of the PON system of the first embodiment is replaced with an OLT 1a. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

The OLT 1a includes the buffer 10, the write control unit 11, the buffer management unit 12, the read control unit 13, and the transmission timing determination unit 14 of the OLT 1 according to the first embodiment. The buffer 10a, the write control unit 11a, the buffer management unit 12a, and the read control, respectively. It is the same as that of the OLT 1 in the embodiment except that the unit 13a and the transmission timing determination unit 14a are used.

In the present embodiment, it is assumed that the buffer 10a is divided into areas for storing data for each ONU, and the write control unit 11a corresponds the downlink data received from the host device 4 to the ONU that is the destination of the downlink data in the buffer 10a. Store in the area to be used. That is, the write control unit 11a has a function as a destination classification unit that classifies the downlink data for each destination ONU. The buffer 10a also includes a broadcast area in addition to the area for each ONU, and the write control unit 11a stores downlink data to be transmitted by broadcast in that area. The buffer management unit 12a manages the buffer accumulation amount for each region, and the read control unit 13a reads data from the buffer 11a for each region.

Then, the transmission timing determination unit 14a of the OLT 1a determines a period (transmission start time and transmission duration) for transmitting a downlink frame for each ONU, and notifies the corresponding ONU of the determined period. In the first embodiment, the transmission period to be transmitted to all ONUs within one bandwidth update period is collectively determined and notified to all ONUs. However, in this embodiment, each ONU has a downlink frame addressed to that ONU. Will be notified of the time to send.

Next, the operation of this embodiment will be described. FIG. 10 is a diagram illustrating an example of an operation within the band update period according to the present embodiment. As shown in FIG. 10, in this embodiment, the data transfer period within the bandwidth update period is divided into a broadcast / multicast transfer period and other periods (period in which frames are unicasted to each ONU). Other than the above, the second embodiment is the same as the first embodiment.

In the next periodic operation determination period, as in the first embodiment, a GATE frame for notifying the ONU 2 of the uplink transmission bandwidth allocation result is transmitted, and as a response, the ONU 2 transmits a report frame storing the uplink buffer amount. .

In this embodiment, the OLT 1a transmits a broadcast frame and a multicast frame during the broadcast / multicast transfer period shown in FIG. A user frame transmitted by unicast to each ONU is transmitted in a data transfer period other than the broadcast multicast transfer period.

FIG. 11 is a diagram illustrating a configuration example of a GATE frame according to the present embodiment. As shown in FIG. 11, the GATE frame of the present embodiment has a configuration in which broadcast / multicast transfer period information is added to the GATE frame of the first embodiment. The broadcast / multicast transfer period information is composed of the transmission start time and the transmission continuation time of the broadcast / multicast transfer period shown in FIG. However, in the present embodiment, the data transfer period information stores different information for each ONU.

The ONU 2 activates the downlink receiving unit in the time zone corresponding to the broadcast / multicast transfer period information and the data transfer period information (addressed to its own device) based on such a GATE frame, and receives the downlink in other time zones. To save power.

FIG. 12 is a flowchart showing an example of the power saving control operation of the PON system of the present embodiment. Based on FIG. 12, the operation of the OLT 1a will be described. Step S1 is the same as step S1 of the first embodiment. When the operation determination time comes (step S1, Yes), the transmission timing determination unit 14a acquires the buffer accumulation amount for each ONU from the buffer management unit 12a (step S3a), and for each ONU based on the buffer accumulation amount for each ONU. Next, the transmission start time and transmission data amount (transmission continuation time) of the downlink frame are determined (step S3a). Here, the broadcast / multicast transfer period is determined as a predetermined period from the beginning of the data transfer period, and the broadcast / multicast transfer period is not determined based on the data amount. However, the broadcast / multicast transfer period may be determined based on the accumulation amount of data transmitted by broadcast / multicast.

Step S4 and subsequent steps are the same as those in the first embodiment except that steps S9a and S11a are performed instead of steps S9 and S11, respectively. In step S9a, it is determined whether it is the transmission start time of the data transfer period for each ONU. In step S11a, data is read from the corresponding area of the buffer 10a for each ONU.

Further, the operation of the ONU 2 is the same as that of the first embodiment. However, the reception timing control unit 29 refers to the broadcast / multicast transfer period information of the GATE frame and activates the downlink transmission unit even in the broadcast / multicast transfer period. The operations of the present embodiment other than those described above are the same as those of the first embodiment.

FIG. 13 is a diagram illustrating an example of power saving control according to the present embodiment. In the example of FIG. 13, it is assumed that ONUs # 1 to # 3 having the same configuration as the ONU 2 are connected to the OLT 1a. The OLT 1a receives downlink data addressed to the ONU # 1 to ONU # 3 from the upper apparatus 4. Then, the OLT 1a transmits the downstream frame to the ONU # 1 to ONU # 3, and transmits the GATE frame 73 addressed to the ONU # 1, the GATE frame 74 addressed to the ONU # 2 in the next period operation determination period.

FIG. 14 is a diagram illustrating an example of contents of a GATE frame 73 transmitted to ONU # 1, and FIG. 15 is a diagram illustrating an example of contents of a GATE frame 74 transmitted to ONU # 2. As shown in FIG. 14, the GATE frame 73 transmitted to the ONU # 1 stores the start time # 4 at the transmission start time as the operation determination period information, and the start time # at the transmission start time as the data transfer period information. 2 is stored, the duration # 2 is stored in the transmission duration, the start time # 1 is stored in the transmission start time, and the duration # 1 is stored in the transmission duration as broadcast / multicast transfer period information. And As shown in FIG. 15, the GATE frame 74 stores the start time # 5 at the transmission start time as the operation determination period information, and stores the start time # 3 at the transmission start time as the data transfer period information. Assume that the duration # 3 is stored in the transmission duration, the start time # 1 is stored in the transmission start time, and the duration # 1 is stored in the transmission duration as broadcast / multicast transfer period information.

As shown in FIG. 13, in the present embodiment, ONU # 1 to ONU # 3 receive the downlink only during the period in which the downlink frame addressed to itself is transmitted in the data transfer period (except for the broadcast / multicast transfer period). It is possible to save the power of the downlink receiving unit.

In the example of FIG. 13, the GATE frame is transmitted to all ONUs every band update period. However, for ONUs that have no data to be transmitted / received, the transmission timing of the GATE frame may be one band update period or more ahead. . FIG. 16 is a diagram illustrating an example of power saving control according to the present embodiment in the case where a time that is one band update period or more ahead of the ONU 2 is set as the transmission timing of the GATE frame. FIG. 16 illustrates an example in which the start time # 5 (transmission start time of the operation determination period information) notified by the GATE frame 74 is after the period illustrated in FIG.

As shown in FIG. 16, in ONU # 2, the downlink receiving unit can be continuously put into the power saving state including the reception period of the GATE frame, so that the power saving efficiency can be further improved. .

Thus, in the present embodiment, the transmission timing determination unit 14a of the OLT 1a determines the transmission time zone of the downlink frame based on the downlink buffer amount for each ONU, and corresponds to the transmission time zone determined for each ONU. The ONU was notified. Therefore, the same effect as that of the first embodiment can be obtained, and the power saving state period can be further ensured longer than that of the first embodiment.

Embodiment 3 FIG.
FIG. 17 is a diagram illustrating a configuration example of the third embodiment of the PON system according to the present invention. The PON system of the present embodiment is the same as the PON system of the first embodiment, except that the OLT 1 of the PON system of the first embodiment is replaced with an OLT 1b. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

The OLT 1b includes the buffer 10, the write control unit 11, the buffer management unit 12, the read control unit 13, and the transmission timing determination unit 14 of the OLT 1 according to the first embodiment, and the buffer control unit 10b, the write control unit 11b, the buffer management unit 12b, and the read control, respectively. This is the same as the OLT 1 in the embodiment except that the unit 13b and the transmission timing determination unit 14b are replaced.

In the first embodiment, the OLT 1a determines the transmission time zone of the downlink frame based on the downlink buffer amount for each ONU. However, in this embodiment, the transmission time zone is determined based on the data delay class.

In the present embodiment, the write control unit 11b uses, as the downlink data received from the host device 4, low delay data that is data of a class that requires low delay based on the delay class, and delay that does not require low delay. It is classified into non-low-latency data that is class data. That is, the write control unit 11b has a function as a destination classifying unit that classifies downlink data for each destination ONU and a function of a delay class classification unit that classifies downlink data for each delay class. The buffer 10b is divided into areas for low delay and non-low delay, and further divided into areas for each ONU. It is also assumed that a broadcast data area is provided as in the second embodiment. Here, as shown in FIG. 17, the buffer 10b has a low delay for ONU # 1, a low delay for ONU # 2,..., A non-low delay for ONU # 1, a non-low delay for ONU # 2,. It is assumed that it is divided into areas. Here, it is assumed that the data addressed to the broadcast has non-low delay and one area for broadcasting is used. However, when there is data addressed to the broadcast of the low-delay class, the broadcast is defined as the low-delay class. It may be divided into two non-low delay classes.

In this embodiment, the delay class is identified using, for example, a VLAN (Virtual Local Area Network) CoS (Class of Service) value, a TCP / IP (Transmission Control Protocol / Internet Protocol) port number, and the like. The write control unit 11b classifies the downlink data received from the host device 4 into low delay data and non-low delay data based on the VLAN CoS value, TCP / IP port number, etc., and further classifies each destination ONU. Then, the data is stored in the corresponding area of the buffer 10b. The buffer management unit 12b obtains the downlink buffer amount for each region, and the read control unit 11b reads the data stored in the buffer 10b for each region.

FIG. 18 is a flowchart showing an example of the power saving control operation of the PON system of the present embodiment. Based on FIG. 18, the operation of the OLT 1b will be described. Step S1 is the same as that in the first embodiment. When the operation determination time comes (step S1 Yes), the transmission timing determination unit 14b acquires the delay class and the buffer accumulation amount for each ONU from the buffer management unit 12b (step S2b). Then, downlink bandwidth allocation is performed based on the delay class and the buffer accumulation amount for each ONU (step S31), and the transmission start time and transmission data amount (transmission duration) of the downlink frame are determined for each ONU (step S3b).

Specifically, for low-delay data, the downlink frame transmission start time and amount of transmission data are determined in the same manner as in the second embodiment, and for non-low-delay data, data received over a plurality of bandwidth update periods are collected together. The transmission start time and transmission data amount of the downstream frame are determined so as to transmit. At that time, when both low-delay data and non-low-delay data are transmitted to one ONU within the same bandwidth update period, the transmission start time and the amount of transmission data are transmitted so that they are transmitted together in one transmission time zone. To decide.

Regarding the transmission timing of non-low delay data, for example, when transmitting a low delay class of an ONU having the same destination as the destination of non-low delay data, it is transmitted within the bandwidth update period for transmitting the data of the low delay class. And Alternatively, if the downstream buffer amount corresponding to the non-low delay data for a certain ONU is equal to or less than a predetermined threshold value, the non-low delay data is not transmitted to the ONU and is stored in the buffer 10b during the bandwidth update period. When the downstream buffer amount corresponding to the non-low delay data of the ONU exceeds a predetermined threshold value, the non-low delay data may be transmitted in the next band update cycle. Alternatively, the cycle for transmitting the non-low delay data is determined as a predetermined number of bandwidth update cycles, and the transmission start time and the transmission are transmitted so that the non-low delay data for each ONU is transmitted for each predetermined number of bandwidth update cycles. The amount of data may be determined.

Step S4 and subsequent steps are the same as those in the first embodiment except that steps S9b and S11b are performed instead of steps S9 and S11, respectively. In step S9b, for each ONU, it is determined whether it is the transmission start time of the data transfer period of low delay data and non-low delay data. In step S11b, the low delay data or non-low delay data in the buffer 10b is determined for each ONU. Read data from the corresponding area.

Further, the operation of the ONU 2 is the same as that of the first embodiment. However, similarly to the second embodiment, the reception timing control unit 29 refers to the broadcast / multicast transfer period information of the GATE frame and activates the downlink transmission unit even in the broadcast / multicast transfer period. The configuration of the GATE frame according to the present embodiment is the same as the configuration of the GATE frame according to the second embodiment. The operations of the present embodiment other than those described above are the same as those of the first embodiment.

FIG. 19 is a diagram illustrating an example of power saving control according to the present embodiment. In the example of FIG. 19, it is assumed that ONUs # 1 to # 3 having the same configuration as the ONU 2 are connected to the OLT 1b. The OLT 1b receives the low-delay class downlink data addressed to the ONU # 1 and ONU # 3, the non-low-delay class downlink data addressed to the ONU # 2, and the non-low-delay class from the host device 4 in the first bandwidth update cycle. Receive data addressed to the broadcast. The OLT 1b then transmits a low-delay class downlink frame to the ONU # 1, ONU # 3 at the next bandwidth update cycle, and sends a GATE frame 75 addressed to the ONU # 1, a GATE frame 76 addressed to the ONU # 2, and so on. Send. Further, in this band update cycle, the OLT 1b receives the low delay class data from the higher level apparatus 4 to the ONU # 2 and the non-low delay class data to the ONU # 2. Then, in the third band update cycle, the downstream frames of the low delay class and the non-low delay class are transmitted to the ONU # 2, and the GATE frame including the GATE frame 77 addressed to the ONU # 2 is transmitted.

FIG. 20 is a diagram illustrating an example of the contents of a GATE frame 75 transmitted to ONU # 1, and FIG. 21 is a diagram illustrating an example of the contents of a GATE frame 76 transmitted to ONU # 2. FIG. 22 is a diagram showing an example of the contents of a GATE frame 77 transmitted to ONU # 2.

As shown in FIG. 20, the GATE frame 75 transmitted to the ONU # 1 stores the start time # 3 at the transmission start time as the operation determination period information, and the start time # at the transmission start time as the data transfer period information. 2 is stored, the duration # 2 is stored in the transmission duration, the start time # 1 is stored in the transmission start time, and the duration # 1 is stored in the transmission duration as broadcast / multicast transfer period information. And In the GATE frame 76, the start time # 4 is stored at the transmission start time as the operation determination period information, and the transmission start time is not specified as the data transfer period information (because there is no transmission to the ONU # 2). Assume that 0 is stored as the transmission duration, the start time # 1 is stored as the transmission start time, and the duration # 1 is stored as the transmission duration as broadcast / multicast transfer period information.

As shown in FIG. 22, the GATE frame 77 transmitted to the ONU # 2 stores the start time # 7 at the transmission start time as the operation determination period information, and starts at the transmission start time as the data transfer period information. Time # 5 is stored, duration # 5 is stored in the transmission duration, transmission start time is not specified as broadcast / multicast transfer period information (because broadcast data is not transmitted), and transmission duration is 0. Assume that it is stored.

In this case, as shown in FIG. 19, in ONU # 1, in the second bandwidth update cycle, start time # 1 to duration # 1, start time # 2 to duration # 2, and start The downlink receiving unit is activated between time # 3 and duration # 3, and power is saved otherwise. In ONU # 1, since no downlink frame is received in the third band update period, start time # 6 (transmission start time of the operation determination period information notified in the GATE frame of the second band update period) To the downstream time # 6 (transmission continuation time of the operation determination period information notified in the GATE frame of the second bandwidth update period), and power is saved in other cases.

In ONU # 2, in the second bandwidth update cycle, the downlink receiving unit is activated between start time # 1 and duration # 1 and between start time # 4 and duration # 4. In other cases, it saves power. In ONU # 2, in the third band update cycle, the downlink receiving unit is activated between start time # 5 and duration # 5 and between start time # 7 and duration # 7. In other cases, it saves power. As shown in FIG. 19, the OLT 1b receives data addressed to the ONU # 2 in the first bandwidth update cycle and the second bandwidth update cycle, but in the second bandwidth update cycle, the non-low delay class data is received. Without transmission, both the non-low delay class and the low delay class are transmitted in the third bandwidth update period.

In this embodiment, the delay class is classified into two, but may be classified into three or more. For example, based on the delay class, data is classified into three, A, B, and C. A is transmitted in the same manner as in the first embodiment, B is transmitted together every three band update periods, and C is transmitted. The frequency of transmission is changed based on the delay class, such as transmitting in batches every five band update periods.

In this embodiment, the data is classified based on the delay class for each ONU, but the data of all ONUs may be classified based on the delay class without being distinguished for each destination. In this case, low-delay data is transmitted in the same manner as in the first embodiment, and for non-low-delay data, data received at one or more bandwidth update cycles are collected together in one bandwidth update cycle regardless of the ONU destination. To send in.

As described above, in this embodiment, the data addressed to each ONU is classified for each delay class and stored in the buffer 10b, and the transmission timing determination unit 14b of the OLT 1b determines the downlink frame based on the downlink buffer amount for each ONU. When determining the transmission time zone, for non-low delay data that allows a delay, transmission is waited, and the non-low delay data received within a plurality of band update periods are collectively transmitted within one band update period. I made it. Therefore, the same effect as that of the second embodiment can be obtained, and a longer period of the power saving state can be secured.

In the above-described embodiment, the subscriber-side device makes a bandwidth request based on the buffer amount in the Report frame. However, the bandwidth request based on the buffer amount is not essential, and the present invention is not limited to this. Therefore, as long as the bandwidth request can be made, the subscriber side apparatus may transmit any information to the station side apparatus.

In the above-described embodiment, the example of the time division multiplexing PON system has been described. However, the data transfer band of the downlink data is notified in advance as a band allocation result, and the subscriber side apparatus is based on the band allocation result. Needless to say, the configuration can be applied to a communication system other than time division multiplexing as long as the configuration can shift to the power saving state. For example, the present invention can be applied to a point-to-multipoint communication system using wavelength division multiplexing, code division multiplexing, or the like.

Further, the present invention is not limited to optical communication but can be applied to a wired or wireless communication system. In that case, the subscriber side apparatus intermittently controls the power receiving state of the receiver that receives the electric signal based on the band allocation result, not the optical receiver, and more efficiently saves power. Can do.

As described above, the PON system, the subscriber-side device, the station-side device, and the communication method according to the present invention are useful for a PON system that saves power, and in particular, saves power without reducing the bandwidth. Suitable for PON system.

1,1a, 1b OLT
2 ONU
3 Splitter 4 Upper device 5

Lower device

10, 10a, 10b, 20

Buffer

11, 11a, 11b, 21

Write control unit

12, 12a, 12b, 22

Buffer management unit

13, 13a, 13b, 23

Read control unit

14, 14a, 14b Transmission

timing determination unit

15, 24

Frame multiplexing unit

16, 25 Optical transmitter 17, 27 Optical receiver 18, 28

Frame separation unit

19, 26 PON control unit 29 Reception timing instruction unit

Claims

A PON (Passive Optical Network) system comprising a plurality of subscriber-side devices and a station-side device that allocates an uplink communication band to each subscriber-side device and performs multiplex communication,
The station side device
A control means for specifying a part of a period in a bandwidth update cycle after the next time as a data transfer period of downlink data and notifying the subscriber side device as a band allocation result before transferring the downlink data,
The subscriber side device is:
Receiving means for receiving the downlink data transmitted from the station side device;
Based on the data transfer period included in the band allocation result, state control means for causing the receiving means to shift to a power saving state or a normal state;
Comprising
PON system characterized by that.
The control means allocates a transfer period of the downlink data and a transfer period for transmitting the band allocation result within the band update cycle,
The state control means shifts the receiving means to a power saving state in a transfer period assigned to another subscriber side device in a transfer period for transmitting the band allocation result.
The PON system according to claim 1.
The control means allocates the data transfer period as a common transfer period to the plurality of subscriber side devices, and specifies the bandwidth allocation result without specifying a transfer period for each subscriber side device within the transfer period. The PON system according to claim 1 or 2, wherein the transmission is performed.
3. The PON system according to claim 1, wherein the control unit transmits the band allocation result by designating different data transfer periods to a plurality of subscriber-side devices.
The said control means specifies the period information for unicast communication and the period information for multicast communication to the said band allocation result transmitted using one gate frame, The period information for multicast communication is characterized by the above-mentioned. PON system.
When there is no downlink data to be transmitted to a specific subscriber-side device in the next bandwidth update cycle, the control means sets the data transfer period for the specific subscriber-side device as a period of subsequent bandwidth update cycles. 6. The PON system according to claim 1, wherein the PON system is designated.
The station side device further includes a buffer for storing downlink data to be transmitted from the own device to the subscriber side device,
The control means of the station side device, transmission timing determination means for determining a data transfer period that is a downlink data transfer period for each band update period;
The PON system according to claim 1, further comprising: a PON control unit that controls transmission of the band allocation result based on the data transfer period.
The subscriber side device is:
An upstream transmission means for performing upstream communication transmission processing;
A subscriber-side PON control unit that shifts the uplink transmission unit to a power saving state or a normal state in a period different from that of the reception unit based on a bandwidth allocation result of the uplink communication;
In addition,
The PON system according to claim 1.
Destination classification means for storing the downlink data for each of the subscriber side devices as destinations in the buffer;
Further comprising
The transmission timing determining means determines the data transfer period for each of the subscriber side devices based on the accumulated amount of the downlink data stored in the buffer for each of the subscriber side devices.
The PON system according to claim 7.
Including a bandwidth update period for not transmitting the bandwidth allocation result for each subscriber-side device,
The PON system according to claim 9.
Delay class classification means for classifying the downlink data into a plurality of delay classes based on a request for delay, and storing the classified downlink data in the buffer for each delay class;
The transmission timing determination means is configured to transmit the downlink data received at one or more bandwidth update periods within one bandwidth update period for the downlink data of a delay class for which low delay is not required. To decide,
The PON system according to claim 7.
Delay class classification for classifying the downlink data for each of a plurality of delay classes and for each destination subscriber based on a request for delay, and storing the downlink data in the buffer for each delay class and for each subscriber of the destination means,
Further comprising
The transmission timing determining means determines the data transfer period for each of the subscriber-side devices based on an accumulation amount of the downlink data stored in the buffer for each of the subscriber-side devices, and has a low delay. For the downlink data of the delay class that is not required, the data transfer period is determined so as to transmit the downlink data received in one or more bandwidth update periods within one bandwidth update period.
The PON system according to claim 9 or 10.
At each predetermined bandwidth update period with the subscriber side device, the subscriber side device is assigned a bandwidth for uplink communication, which is communication in the direction from the subscriber side device to the own device, and the assigned bandwidth is added to the subscriber side device. A subscriber-side device in a PON system comprising: a station-side device that notifies a subscriber-side device as a bandwidth allocation result,
Receiving means for performing predetermined reception processing on downlink data received from the station side device;
Receiving the bandwidth allocation result to which a downlink data transfer period is added from the station side device, and shifting the downlink receiving means to a power saving state or a normal state based on the data transfer period included in the band allocation result Receiving timing instruction means for
Comprising
A subscriber-side device.
The subscriber side device allocates an uplink communication band, which is communication in the direction from the subscriber side device to the own device, to the subscriber side device at every predetermined bandwidth update period, and A station-side device in a PON system comprising a station-side device that notifies a person-side device as a band allocation result,
A buffer for storing downlink data to be transmitted from the own device to the subscriber side device;
Transmission timing determining means for determining a data transfer period, which is a transfer period of the downlink data, for each band update period;
PON control means for adding the data transfer period to the bandwidth allocation result and transmitting the bandwidth allocation result after the addition to the subscriber side device;
Comprising
The station side device characterized by the above-mentioned.
A step of transmitting a bandwidth allocation result specifying a period in which downlink data is transferred in a bandwidth update cycle after the next time from the station side device to the subscriber side device;
In the bandwidth update period after the bandwidth allocation result transmission, the station side device transmits the downlink data;
Based on the band allocation result received by the subscriber side device, setting the optical receiver that receives the downlink data to a power saving state in a partial period within the band update period;
Based on the band allocation result received by the subscriber side device, setting the optical receiver to a reception state in another period within the band update period;
A communication method for a point-to-multipoint communication system, comprising: