JP5419994B2 - Communication device, subscriber-side communication device, point-to-multipoint communication system, and bandwidth control method - Google Patents

Description

  The present invention relates to a communication apparatus on a station side and a subscriber side of a point-to-multipoint communication system.

  The PON (Passive Optical Network) system, which is currently one of the FTTH (Fiber To The Home) methods, is used to achieve point-to-multipoint communication in access networks that connect stations and user homes. It is rapidly becoming popular.

  The PON system has a configuration in which a station side device (OLT: Optical Line Terminal) and a plurality of subscriber side devices (ONU: Optical Network Unit) are connected to a plurality of optical fibers via an optical splitter that branches signal outputs. It has become. A TE (Terminal Equipment) is connected to the subscriber side apparatus via a LAN cable. TE corresponds to HGW (Home Gate Way), VoIP-TA (Voice over Internet Protocol-Terminal Adapter), PC, and the like.

  In the PON system, a power saving protocol for reducing the power consumption of the subscriber side device at the time of standby without performing data communication has been proposed (for example, Non-Patent Document 1). In the conventional power saving method based on this power saving protocol, the station side device uses the power saving cancellation notification band for each subscriber unit in the SLEEP state (= power saving state) every predetermined period (SLEEP CYCLE). (Transmission permission period) is given, and the subscriber side device in which uplink traffic (data to be transmitted from the subscriber side device to the station side device) is generated within the specified period is for SLEEP release in the power save release notification band A signal is transmitted to return to a normal state (non-SLEEP state), and then data is transmitted in a data transmission band given thereafter.

ITU-T SG15Q2 Intended type of document (R-C-TD): GR-4, “ONU Power-Save Annex”, PMC-SIERRA, APRIL 2008

  As described above, according to the above-described conventional technique (the technique described in Non-Patent Document 1), the station side device cancels the power save for each subscriber side device in the SLEEP state at every predetermined cycle (SLEEP CYCLE). By providing a notification band, the subscriber side device can cancel SLEEP. However, when uplink traffic occurs in the subscriber device in the SLEEP state, there is a problem that the delay time increases because data cannot be transmitted until the cycle (SLEEP CYCLE) ends. Specifically, since it is currently considered to set SLEEP CYCLE to 10 ms, the delay time is about 10 ms at maximum compared to the case where the SLEEP state is not set.

  On the other hand, as a method for avoiding the increase in the delay time as described above, for example, a control frame band for notifying SLEEP cancellation (corresponding to the power saving cancellation notification band) is set to SLEEP for each band update period. It is conceivable to individually assign to each subscriber-side device in the state. In this method, it is possible to enable uplink data transmission even at the subscriber side device in the middle of the SLEEP period when an uplink traffic requiring a low delay such as an emergency is required, and the delay time can be reduced. However, when the number of subscriber-side devices in the SLEEP state is large, the control frame bandwidth is increased, which causes another problem that the bandwidth utilization efficiency is lowered (the bandwidth of the transmission path cannot be effectively used).

  The present invention has been made in view of the above, and is capable of effectively using the bandwidth of the transmission path even when there is a subscriber device in the SLEEP state, and can realize low-delay transmission. It is an object to obtain an apparatus, a point-to-multipoint communication system, and a bandwidth control method.

  In order to solve the above-described problems and achieve the object, the present invention allocates a bandwidth for uplink data transmission to each subscriber-side communication device based on a bandwidth request signal notified from a plurality of subscriber-side communication devices. A station-side communication device is provided with a band control unit that allocates a shared band as a band for notification of the band request signal to a plurality of subscriber-side apparatuses that are performing power saving operations.

  The subscriber-side communication device according to the present invention is a subscriber-side communication device that is connected to the station-side communication device while sharing a communication path with other subscriber-side communication devices. A bandwidth request signal used for uplink data communication of the next bandwidth update cycle is transmitted using the bandwidths individually allocated in the division, and during power saving operation, a bandwidth common to other communication devices on the subscriber side during power saving operation And a control means for transmitting the band request signal.

  Also, according to the bandwidth control method of the present invention, the communication device on the station side individually assigns the transmission band of the uplink data or the bandwidth request signal to each subscriber-side communication device in the normal mode, and notifies the allocated frame of the gate frame. Transmitting for each subscriber-side communication device; and the station-side communication device allocates a shared band to a plurality of subscriber-side communication devices in a power saving mode, and a gate frame designating the shared band is stored in the saving frame. Transmitting to the plurality of subscriber side communication devices in the power mode, and when the subscriber side communication device in the power saving mode shifts from the power saving mode to the normal mode and transmits uplink data, A band request signal transmitted using the shared side band and a subscriber-side communication device that has transmitted the band request signal using the shared band. With those containing and transmitting the uplink data.

  The communication device according to the present invention has an effect that it is possible to achieve both effective use of bandwidth and low-delay transmission.

FIG. 1 is a diagram illustrating a configuration example of the point-to-multipoint communication system according to the first embodiment. FIG. 2 is a flowchart showing a characteristic operation of the station side apparatus according to the first embodiment. FIG. 3 is a diagram illustrating an operation example in a normal state of the subscriber side apparatus. FIG. 4 is a diagram illustrating an operation example in the sleep state of the subscriber side device. FIG. 5 is a flowchart showing an example of the bandwidth calculation operation. FIG. 6 is a sequence diagram illustrating an example of the communication control operation according to the first embodiment. FIG. 7 is a sequence diagram when a bandwidth is allocated by transmitting a GATE frame to a subscriber-side apparatus that can enter a downstream sleep state. FIG. 8 is a diagram illustrating a format example of a GATE frame to be transmitted to a subscriber-side apparatus that can enter a downstream sleep state. FIG. 9 is a sequence diagram showing an operation example when the conventional control method is applied. FIG. 10 is a diagram illustrating an operation example in which a control frame band is allocated to a sleeping subscriber side device for each band update period. FIG. 11 is a diagram showing uplink bandwidth utilization efficiency when a conventional control method is applied. FIG. 12 is a flowchart showing a characteristic operation of the station side apparatus according to the second embodiment. FIG. 13 is a flowchart illustrating an example of a bandwidth calculation operation according to the second embodiment. FIG. 14 is a sequence diagram illustrating an example of a communication control operation according to the second embodiment.

  Embodiments of a communication device, a point-to-multipoint communication system, and a bandwidth control method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a point-to-multipoint communication system (hereinafter simply referred to as “communication system”) according to the first embodiment. As shown in the figure, the communication system according to the present embodiment includes a station-side device 1 and a higher-level device connected thereto, a plurality of subscriber-side devices (subscriber-side communication devices) 2 and lower-level devices connected thereto. The station side device 1 and each subscriber side device 2 are connected via an optical transmission line and a splitter. FIG. 1 also shows a configuration example of the station side device 1 and the subscriber side device 2 corresponding to the communication device according to the present invention. In addition, the structure of each subscriber side apparatus 2 is the same.

  The station apparatus 1 includes a downlink buffer unit 11, a frame multiplexing unit 12, an optical transmission unit 13, an optical reception unit 14, a frame separation unit 15, a frame control unit 16, a sleep management unit (SLEEP management unit) 17, and a bandwidth allocation control unit. 18 is provided.

  In the station apparatus 1, the downlink buffer unit 11 temporarily accumulates data received from the host apparatus. The frame multiplexing unit 12 multiplexes the user frame and the control frame. The optical transmission unit 13 converts the electrical signal output from the frame multiplexing unit 12 into an optical signal and transmits it to the subscriber side device 2. The optical receiver 14 receives the optical signal transmitted from the subscriber side device 2 and converts it into an electrical signal. The frame separation unit 15 separates the user frame and the control frame included in the electrical signal obtained by converting the optical signal. The frame control unit 16 processes a control frame transmitted / received to / from the subscriber side device 2. The sleep management unit 17 (corresponding to the state management unit) manages the sleep (SLEEP) state based on the information of the control frame for SLEEP notified from the frame control unit 16. The bandwidth allocation control unit 18 (corresponding to the bandwidth control means) includes information on the control frame processed by the frame control unit 16, the sleep state of each subscriber-side device 2 notified from the sleep management unit 17, and an SLA (Service Level Agreement). ) Based on one or more information in the parameter and the uplink / downlink traffic history, a band to be allocated to each subscriber side device 2 is determined.

  Each subscriber-side device 2 includes an upstream buffer unit 21, a frame multiplexing unit 22, an optical transmission unit 23, an optical reception unit 24, a frame separation unit 25, a frame control unit 26, and a sleep (SLEEP) management unit 27.

  In each subscriber-side device 2, the upstream buffer unit 21 temporarily stores data received from the lower-level device. The frame multiplexing unit 22 multiplexes the user frame and the control frame. The optical transmission unit 23 converts the electrical signal output from the frame multiplexing unit 22 into an optical signal, and transmits the optical signal to the station apparatus 1. The optical receiver 24 receives the optical signal transmitted from the station side device 1 and converts it into an electrical signal. The frame separation unit 25 separates the downlink user frame and the control frame included in the electrical signal obtained by converting the optical signal. The sleep management unit 27 manages the sleep state according to the buffer amount history accumulated in the upstream buffer unit 21. The frame control unit 26 processes a control frame transmitted / received to / from the station side device 1 according to the buffer accumulation amount of the upstream buffer unit 21 and the sleep state notified from the sleep management unit 27.

  Next, the operation when the station side apparatus 1 and the subscriber side apparatus 2 perform data transmission in the communication system of the present embodiment will be described. Here, an uplink data transmission operation in which the subscriber side apparatus 2 transmits data to the station side apparatus 1 will be described.

  In the uplink data transmission operation, the station-side device 1 and each subscriber-side device 2 repeat the frame transmission / reception operation in units of band update periods. When the frame transmission / reception operation is specifically shown, the station side device 1 determines the subscriber side device 2 to which the bandwidth is allocated in the next bandwidth update period, and the amount of data to be transmitted, and the determined content is determined for each subscriber side device. 2, an indication of the frame transmission start time (grant start time: GST) and the transmission duration time (grant length: GL) for each subscriber side device 2 to which bandwidth is allocated. A control frame (GATE frame) containing information, that is, a control frame indicating a period during which transmission is permitted is transmitted. On the other hand, the subscriber-side device 2 includes a control frame including information on the amount of data stored in the upstream buffer unit 21 (hereinafter referred to as “control frame including upstream data amount information” or “band request signal”). , And a data frame of a size corresponding to the GL notified in the previous bandwidth update cycle. If the subscriber side device 2 does not need to transmit a data frame to the station side device 1 (no bandwidth is required), for example, there is no data stored in the upstream buffer unit 21, the uplink side described above is used. Do not transmit control frames that contain data volume information.

  In the frame transmission / reception operation, the station-side device 1 also assigns a band for the subscriber-side device 2 in the sleep state to transmit the “control frame including uplink data amount information”. In this bandwidth allocation, GST and GL are set so that each subscriber apparatus 2 in the sleep state shares the frame transmission time (the same frame transmission time is specified for each subscriber apparatus 2 in the sleep state). The control frame is generated and transmitted to each subscriber apparatus 2 in the sleep state, thereby improving the bandwidth utilization efficiency of the transmission path. On the other hand, the subscriber side device 2 shifts to a sleep state (power saving operation state) when a predetermined condition is satisfied, for example, when no uplink data is generated for a certain time, and thereafter, uplink data is generated. For example, the sleep state is continued to reduce power consumption until it is determined that a data frame needs to be transmitted to the station apparatus 1. When it is determined that it is necessary to transmit a data frame to the station side device 1, the information returns to the normal state (non-sleep state) and the information on the amount of data stored in the upstream buffer unit 21 (subscriber side device 2 The frame control unit 26 generates a “control frame including uplink data amount information”, which is a control frame including the uplink data amount information held by the frame multiplexer 22 and the optical transmitter 23. Transmit to the station side device 1. This “control frame including uplink data amount information” is a band pre-assigned from the station side device 1, that is, GST so that each of the above-described “sleep state subscriber side devices 2 shares the frame transmission time”. And a control frame in which GL is set "is transmitted in a band designated by the station-side device 1 (hereinafter, this band is referred to as a" shared band ").

  Next, characteristic operations of the communication apparatuses (station side apparatus 1 and subscriber side apparatus 2) according to the present embodiment will be described with reference to FIGS.

  FIG. 2 is a flowchart showing a characteristic operation of the station side apparatus 1 according to the present embodiment. Specifically, it is a flowchart showing an example of a bandwidth allocation operation for the subscriber side apparatus 2.

  In the bandwidth allocation operation for each subscriber device 2, first, the sleep management unit 17 grasps the sleep state of each subscriber device 2 (step S11). The determination of the sleep state of each subscriber apparatus 2 is performed by the following methods 1 and 2, for example. Of course, other methods may be used.

(Method 1) Method of Notifying the Station Side Device 1 that the Subscriber Side Device 2 Transitions to the Sleep State In this method, the sleep management unit 27 of the subscriber side device 2 inputs an upstream data frame from the lower order device ( The state of the upstream buffer unit 21) is monitored, and when the input of the upstream data frame does not occur for a certain period of time, it is determined to shift to the sleep state and the fact is notified to the frame control unit 26. Then, a control frame indicating the transition to the sleep state (hereinafter referred to as “sleep request control frame”) is generated and transmitted to the station apparatus 1 via the frame multiplexing unit 22 and the optical transmission unit 23. When the station side apparatus 1 receives the sleep request control frame, the station side apparatus 1 determines that the transmission source subscriber side apparatus 2 is in the upstream sleep state.

  3 and 4 are diagrams showing an operation example of the subscriber side apparatus 2 when the method 1 is applied. FIG. 3 shows the operation in the normal state (non-sleep state), and FIG. 4 shows the operation in the sleep state.

  As shown in FIG. 3, the subscriber side device 2 monitors the input of the upstream data frame from the lower device in the normal state, and when the upstream data frame has not been sent from the lower device for a predetermined time (step (S21: Yes), a sleep request control frame is transmitted to the station side device 1 (step S22), and the devices used for transmitting uplink data, such as the frame multiplexing unit 22 and the optical transmitter 23, are set to the uplink sleep mode. Then, a transition is made to the upstream sleep state (step S23). On the other hand, when the upstream data frame is sent from the lower-level device within a certain time (step S21: No), the subscriber-side device 2 sends the normal control frame (control frame including the data amount information) to the station-side device 1. (Step S24).

  As shown in FIG. 4, in the upstream sleep state, the sleep management unit 27 monitors the input of the upstream data frame from the lower device, and when the upstream data frame is sent (step S31: Yes), The upstream sleep mode is canceled and the normal state is restored (step S32). The frame control unit 26 that has received the signal for canceling the upstream sleep mode from the sleep management unit 27 generates a control frame for canceling the sleep, and transmits the generated control frame for canceling the sleep via the frame multiplexing unit 22 and the optical transmission unit 23. It transmits with respect to the side apparatus 1 (step S33). In this step S33, a control frame including uplink data amount information is transmitted as a sleep release control frame in the shared band. On the other hand, when no uplink data frame is sent from the lower apparatus (step S31: No), control frame transmission to the station side apparatus 1 is not performed (step S34).

  In the above-described method, the control frame including the uplink data amount information is transmitted as the sleep release control frame in the shared band. However, the subscriber side apparatus 2 shares the band request signal not including the uplink data amount information. It may be transmitted in a band. That is, the subscriber side device 2 inserts a signal that can specify sleep cancellation into the control frame and transmits the signal to the station side device 1. In the station-side device 1 that has received this control frame, the sleep management unit 17 receives a signal via the frame separation unit 15 and the frame control unit 16, and detects the release of the subscriber-side device 2 from sleep based on this signal. Thereafter, since the subscriber side device 2 is treated as the subscriber side device 2 in the normal state in the bandwidth allocation process, as described with reference to the flowchart of FIG. A control frame including uplink data amount information is transmitted in a separate band. Therefore, the subscriber side device 2 can transmit uplink data as the subscriber side device 2 in the normal state. In this method, there is a possibility that an extra delay corresponding to one band allocation period may occur compared to the above method. However, compared to the case where the shared band is not used, it is possible to realize both effective use of the band and low-delay transmission. is there.

(Method 2) Method in which the station-side device 1 detects the transition of the subscriber-side device 2 to the sleep state. In this method, the station-side device 1 stores data frame transmission / reception history with each subscriber-side device 2. Based on this, it is determined that the subscriber side device 2 that has not performed transmission / reception of the uplink data frame for a certain period of time is in the uplink sleep state. Further, it is determined that the subscriber side apparatus 2 that has not performed transmission / reception of the downlink data frame for a predetermined time is in the downlink sleep state.

  When the operation of grasping the sleep state of each subscriber-side device 2 by the sleep management unit 17 is finished, the bandwidth allocation control unit 18 calculates a bandwidth to be allocated to each subscriber-side device 2 (step S12). In this bandwidth calculation, the bandwidth allocation control unit 18 firstly determines from the sleep management unit 17 information on the sleep state of each subscriber side device 2 (information indicating which device is in the sleep state, such as information on the device in sleep). ) And information on the control frame from the frame control unit 16, and then a bandwidth (more specifically, GL) allocated to each subscriber apparatus 2 based on the acquired information Calculate

  Here, details of the bandwidth calculation operation performed by the bandwidth allocation control unit 18 in step S12 will be described. FIG. 5 is a flowchart showing an example of the bandwidth calculation operation.

  As shown in FIG. 5, in the bandwidth calculation operation, the bandwidth allocation control unit 18 first confirms the information of the control frame acquired from the frame control unit 16 to transmit from the sleeping side apparatus 2. Whether the received control frames (the above-described “control frame including uplink data amount information”) collide with each other, that is, the plurality of sleeping apparatuses 2 do not transmit control frames in the shared band. If no collision has occurred (step S41: Yes), the control frame bandwidth for the subscriber apparatus 2 in the normal state is calculated (step S42). Note that the information on the control frame acquired from the frame control unit 16 includes information on whether or not a control frame collision has occurred.

  Here, when it is determined in step S41 that “no collision has occurred”, no control frame is transmitted (case 1), and a control frame is transmitted from only one subscriber side apparatus 2 in sleep. The case (case 2) is transmitted, but in case 2, the bandwidth calculation in step S42 is performed with the subscriber side device 2 that has transmitted the control frame as a normal state device.

  When the processing in step S42 is completed, a shared band, which is a control frame band for the subscriber side apparatus 2 in the sleep state, is calculated (step S43), and further a data band for the subscriber side apparatus 2 in the normal state. Is calculated (step S45).

  On the other hand, if there is a collision between control frames transmitted from the sleeping subscriber side device 2 (step S41: No), all the subscriber side devices 2 are set as normal devices and the control frame bandwidth is set. Calculate (step S44), and further calculate the data bandwidth for the subscriber side apparatus 2 in the normal state (step S45). In step S44, all the subscriber-side devices 2 are treated as devices in the normal state because, among the subscriber-side devices 2 that have been in the sleep state, the subscriber-side device 2 generates upstream data and is in the normal state. This is because it is not possible to determine whether or not it has returned to. In step S45, among the subscriber side devices 2 that have transmitted the control frame including the uplink data amount information, the data for allocation to the subscriber side device 2 in which the transmitted control frame has not collided with other control frames. Calculate the bandwidth.

  After the bandwidth allocation control unit 18 allocates the control frame bandwidth to all of the subscriber side devices 2 that are in the sleep state, the frame control unit 16 sets the control frame (a control frame including uplink data amount information). ) Is notified to the sleep management unit 17, and the sleep management unit 17 has continued to sleep for the subscriber side device 2 that has not transmitted a control frame. It may be determined that it is not a sleeping subscriber apparatus 2 that has transmitted a control frame in the immediately preceding shared band, and may be handled as a sleeping apparatus. In this way, even when a collision of a control frame transmitted from the sleeping subscriber side device 2 occurs, the subscriber side device 2 that has not transmitted this control frame will receive the next one. It can be handled as a sleeping device in the bandwidth calculation operation, and can prevent the bandwidth for the control frame from being allocated more than necessary.

  Returning to the description of the operation shown in FIG. 2, when the bandwidth allocation control unit 18 finishes calculating the bandwidth, the frame control unit 16 then sends the bandwidth allocation control unit to each subscriber side device 2 in the normal state. A GATE frame in which the GL calculated by the band calculation by 18 and the GST in which the frame transmission time does not collide is generated, and is transmitted via the frame multiplexer 12 and the optical transmitter 13 (step S13). Further, for each subscriber-side device 2 in the sleep state, when there is no control frame collision, a GATE in which a GL calculated by the bandwidth allocation control unit 18 and a GST that shares the frame transmission time are set. A frame is generated and transmitted via the frame multiplexer 12 and the optical transmitter 13 (step S14). When there is a control frame collision, as in the above-described GATE frame for the subscriber-side device 2 in the normal state, the GATE frame in which the band allocation control unit 18 sets GL and GST so that the frame transmission time does not collide Generate and send. Note that the format of the GATE frame is the same regardless of the operation state of the subscriber side device (whether it is in the sleep state or not).

  FIG. 6 is a sequence diagram showing an example of the communication control operation of the station side device 1 and the subscriber side device 2 of the present embodiment.

  In the communication system according to the present embodiment, the station side device 1 generates the GATE frame and transmits it to each subscriber side device 2 by executing the operations shown in FIGS. This is performed (step S51). At this time, the same GATE frame (Normal GATE # 1, # 2) as the conventional one is transmitted to each of the subscriber side devices 2 (corresponding to the subscriber side devices # 1, # 2 in FIG. 6) in the normal state. Allocate individual bands. Further, for the subscriber side device 2 (corresponding to the subscriber side devices # 3 to #N in FIG. 6) in the upstream sleep mode, a GATE frame (SLEEP GATE # 3 to #N) and allocate the same band (shared band). Note that the GATE frame for the subscriber side device 2 in the sleep mode may be a multicast frame. Further, the shared bands do not have to be completely the same, and even if they are slightly shifted, if there is a shared band, the band can be effectively used.

  Upon receiving the GATE frame (Normal GATE) transmitted in step S51, the subscriber side device 2 in the normal state receives a control frame (upstream data amount information) in a period (data band) indicated by the GST and GL stored in the GATE frame (Normal GATE). And a data frame are transmitted (step S52). In addition, when the subscriber-side device 2 in the sleep state receives the GATE frame (SLEEP GATE) transmitted in step S51, the subscriber-side device 2 shifts from the sleep state to the normal state and receives it if the uplink data is held at that time. The control frame (SLEEP release control frame, which is a control frame including uplink data amount information) is transmitted in a period (shared band) indicated by GST and GL stored in the GATE frame. On the other hand, if the uplink data is not held, the subscriber side apparatus 2 continues the sleep state without transmitting the control frame (step S53). Although not shown, the subscriber-side device 2 (corresponding to the subscriber-side device # 3 in FIG. 6) that has transmitted a control frame in the shared band transmits an individual GATE frame at the next bandwidth update period. A control frame and a data frame are transmitted using the data band assigned by the GATE frame (operates as a device in a normal state).

  In the above description, for simplification, the shared band is assigned to the sleeping apparatus 2 in each band update period, but the shared band is assigned in a period longer than the band update period. For example, a shared band is allocated every m-band update period (m is an integer of 2 or more). After a shared band is allocated, the shared band is retransmitted at the first band update period after a certain period of time has elapsed. May be assigned. In this case, the station-side device 1 checks whether or not it is necessary to allocate a shared band to the sleeping subscriber-side device in the operation shown in FIG. 2, and if necessary, it is shared in step S12 of FIG. The bandwidth is calculated and step S14 is executed. If it is not necessary, the shared bandwidth is not calculated in step S12, and step S14 is not executed.

  Further, the description so far has focused on the control operation when the subscriber side device 2 is in the upstream sleep state (when only the upstream direction shifts to the sleep state), but the subscriber side device 2 is in the upstream sleep state. In addition, the same control can be applied to a case where it is possible to shift to the downstream sleep state as well. Hereinafter, a control operation corresponding to the case where the subscriber-side device 2 enters the downstream sleep state will be described. FIG. 7 is a sequence diagram when a bandwidth is allocated by transmitting a GATE frame to a subscriber-side apparatus that can enter a downstream sleep state. FIG. 8 is a diagram illustrating a format example of a GATE frame to be transmitted to a subscriber-side apparatus that can enter a downstream sleep state. The GATE frame shown in FIG. 8 includes DA (destination address), SA (source address), header information including information such as a frame type, the number of grants (information on the number of grants set in the frame), and grants. Information (GST # NX, GL # NX). Also, the GATE frame shown in FIG. 8 is transmitted as an uplink / downlink SLEEP Gate frame shown in FIG.

  As shown in FIG. 7 and FIG. 8, the subscriber-side device 2 is in the upstream sleep state with respect to the subscriber-side device 2 in which the station-side device 1 can shift to the sleep state in both the upstream and downstream directions. Then, before entering the downstream sleep state, a GATE frame (see FIG. 8) in which a plurality of GLs are set is transmitted in advance and a shared band for canceling the upstream sleep is designated, so that in the case of upstream sleep (in the upstream direction) As in the case where only the mobile terminal enters the sleep state, effective use of the band and low-delay transmission can be realized.

  That is, when uplink transmission data is generated in the subscriber-side device 2 that is in the sleep state in both the uplink and downlink directions, the subscriber-side device 2 uses the shared band for canceling the uplink sleep that has been allocated in advance from the station-side device 1. Then, a control frame for canceling sleep is transmitted, the upstream direction is returned to the normal state, and upstream data is transmitted. In this way, the same control as the above-described subscriber-side device that shifts to the sleep state only in the uplink direction can be applied to the subscriber-side device that can shift to the sleep state in both the uplink and downlink directions. . Further, since the same bandwidth is allocated to each subscriber side device as the bandwidth for canceling the upstream sleep, the upstream bandwidth can be effectively used.

  In addition, as operation | movement when the subscriber side apparatus 2 will be in a down sleep state, for example, the subscriber side apparatus 2 will send the control frame which shows that to the station side apparatus at the time of determining changing to a down sleep state. 1, and the station side apparatus 1 that has received this control frame transmits a GATE frame for allocating a shared bandwidth for (up) sleep release to the subscriber side apparatus 2 that is the transmission source of the frame. When transmitting this GATE frame, if there is another subscriber-side device already in the (upstream) sleep state, GST and GL are set so that the same bandwidth as that already assigned to this device is assigned.

  The problem in the conventional control method and the effect in the communication system of the present embodiment will be described with reference to FIG. 9, FIG. 10, and FIG. FIG. 9 is a sequence diagram showing an operation example when a conventional control method (the protocol described in Non-Patent Document 1 described above) is applied. As shown in the figure, in the conventional control method, the station side device (OLT) transmits a GATE frame to the sleeping subscriber side device (ONU) every time the sleep cycle elapses, and the bandwidth is increased. Therefore, there is a problem that the delay time from when uplink data is generated until it is transmitted can be the same as the sleep cycle length. As a countermeasure for this problem, a method of preventing an increase in delay time by allocating a control frame band to a sleeping subscriber side apparatus for each band update period as shown in FIG. However, in this case, as shown in FIG. 11, as the number of subscriber-side devices connected to the station-side device increases, the utilization efficiency of the upstream bandwidth decreases, and the bandwidth is effectively used. Can not do. For example, in a system in which the bandwidth update cycle is 250 μs and 64 subscriber side devices are connected to one station side device, when 48 out of 64 units are in SLEEP, SLEEP is in progress The bandwidth utilization efficiency is reduced from 82% to 38% by giving the control frame bandwidth to the 48 units.

  On the other hand, in the present embodiment, the same bandwidth as the control frame bandwidth is allocated to each sleeper side device, so the number of subscriber side devices connected to the station side device increases. Even in this case, the bandwidth utilization efficiency does not decrease, and the bandwidth can be effectively used.

  As described above, in the communication system according to the present embodiment, the station side device transmits a sleep release control frame (a control frame including uplink data amount information) to each sleeper side device as a transmission band. Therefore, a common band (shared band) is allocated to each subscriber-side apparatus in the sleep state. Accordingly, even when the number of subscriber-side devices in the sleep state increases, it is not necessary to allocate a large band for the sleep release control frame, so that effective use of the band can be realized. Also, even if the period for assigning the bandwidth for the sleep release control frame is shortened, the bandwidth utilization efficiency does not drop greatly, and therefore it is possible to achieve both effective bandwidth utilization and low-delay transmission.

Embodiment 2. FIG.
Next, the second embodiment will be described. In Embodiment 1 described above, the bandwidth is shared by all the subscriber-side devices that are sleeping. Next, when the subscriber-side devices 2 that are sleeping are grouped, the bandwidth is shared for each group. The embodiment will be described. The configurations of the communication system, the station side device, and the subscriber side device of the present embodiment are the same as those of the first embodiment (see FIG. 1). Further, the subscriber side device 2 performs the same operation as that of the first embodiment (see FIGS. 3 and 4).

  FIG. 12 is a flowchart showing a characteristic operation of the station-side device according to the second embodiment. Like FIG. 2 used in the description of the first embodiment, an example of a bandwidth allocation operation for the subscriber-side device 2 is shown. Is shown. The same step number is assigned to the same process as the bandwidth allocation operation shown in FIG. That is, the bandwidth allocation operation of the present embodiment is obtained by replacing steps S11, S12, and S14 included in the bandwidth allocation operation of Embodiment 1 with steps S11a, S12a, and S14a. Here, only parts different from the band allocation operation described in the first embodiment will be described.

  In the bandwidth allocation operation of the present embodiment for each subscriber-side device 2, first, the sleep management unit 17 grasps the sleep state of each subscriber-side device 2, and further groups each subscriber-side device in the sleep state. (Step S11a). The sleep state of each subscriber side device 2 is grasped by the same method as the station side device of the first embodiment. Further, the grouping of the subscriber side devices 2 during sleep is performed by the following method, for example.

(Method a) Grouping is performed according to the sleep duration time.
(Method b) Grouping is performed according to the minimum guaranteed bandwidth of the SLA (service level agreement) parameter.
(Method c) Grouping is performed according to the delay class of the SLA parameter.
(Method d) Grouping is performed based on the presence or absence of downstream traffic.
(Method e) Grouping is performed according to the rate (1G / 10G) of the subscriber side apparatus 2.

  Two or more conditions may be used in combination. For example, grouping is performed based on the sleep duration and the minimum compensation band.

  When the sleep management unit 17 finishes grasping the sleep state of each subscriber-side device 2 and grouping the subscriber-side devices in the sleep state, the bandwidth allocation control unit 18 then assigns the bandwidth allocated to each subscriber-side device 2 Is calculated (step S12a). In this bandwidth calculation, the bandwidth allocation control unit 18 first acquires the sleep state and grouping result of each subscriber side device 2 from the sleep management unit 17, and acquires control frame information from the frame control unit 16, Next, based on the acquired information, a bandwidth (GL) allocated to each subscriber apparatus 2 is calculated.

  FIG. 13 is a flowchart illustrating an example of a bandwidth calculation operation according to the second embodiment. Note that the same step number is assigned to the same process as the bandwidth calculation operation (see FIG. 3) described in the first embodiment. That is, the bandwidth calculation operation of the present embodiment is obtained by replacing step S43 included in the bandwidth calculation operation of the first embodiment with step S43a and further replacing step S44 with steps S46 to S48. Here, only parts different from the bandwidth calculation operation described in the first embodiment will be described.

  In the bandwidth calculation operation of the present embodiment, if no control frame collision has occurred (step S41: Yes), the bandwidth for the control frame to be allocated to the subscriber side device 2 in the normal state is calculated (step S42), Further, a bandwidth for a control frame to be allocated to the subscriber side device 2 in sleep is calculated (step S43a). In this step S43a, a common band allocated to each group of the subscriber side apparatus 2 in sleep is calculated. Thus, the station side apparatus 1 of this Embodiment allocates a shared band for every group of the subscriber side apparatus 2 in sleep.

  On the other hand, when a control frame collision has occurred (step S41: No), first, a control frame assigned to the subscriber side apparatus 2 in the normal state by executing the same process as step S42 described in the first embodiment. Next, the bandwidth for control frames to be allocated to the sleeping subscriber apparatus 2 of the group in which the collision has occurred (there may be two or more) is calculated (step S47). ). Further, a control frame band (shared band) to be allocated to the sleeping subscriber side devices 2 of the group in which no collision has occurred is calculated (step S48).

  After executing step S43 or after executing step S48, the data band for the subscriber side apparatus 2 in the normal state is calculated (step S45).

  Returning to the description of the operation shown in FIG. 12, when the bandwidth calculation by the bandwidth allocation control unit 18 is completed, the frame control unit 16 generates and transmits a GATE frame to each of the subscriber side devices 2 in the normal state (steps). S13).

  Further, a GATE frame is generated and transmitted to each subscriber side device 2 in the sleep state (step S14a). In this step S14a, a GATE frame in which GST and GL are set is generated and transmitted so that each subscriber-side apparatus 2 of the group in which the control frame collision has occurred is assigned with a separate control frame band, A GATE frame in which GST and GL are set is generated and transmitted so that the same control frame band (shared band) is allocated to each subscriber apparatus 2 of the group in which no control frame collision has occurred.

  FIG. 14 is a sequence diagram showing an example of the communication control operation of the station side device 1 and the subscriber side device 2 of the present embodiment. Steps S51 and S52 in the figure are the same operations as steps S51 and S52 of the communication control operation (see FIG. 6) described in the first embodiment.

  In the communication system according to the present embodiment, the station apparatus 1 performs the operations shown in FIGS. 12 and 13 for each band update period to generate a GATE frame and transmit it to the subscriber apparatus 2. (Step S51).

  When the subscriber apparatus 2 in the normal state receives the GATE frame (Normal GATE) transmitted in step S51, it transmits a control frame and a data frame in a band (data band) indicated by the GST and GL stored in the GATE frame (Normal GATE). (Step S52).

  When the subscriber side apparatus 2 in the sleep state receives the GATE frame (SLEEP GATE) transmitted in step S51, the GST and GL stored in the received GATE frame if the uplink data is held at that time. If the control frame (SLEEP release control frame, which is a control frame including uplink data amount information) is transmitted in the shared band indicated by, and the uplink data is not held, the sleep state is continued without transmitting the control frame. (Steps S54 and S55). The subscriber side device 2 (subscriber side device # 3) that has transmitted the control frame in the shared band transmits the control frame and the data frame in the data band allocated within the next band update period.

  In the present embodiment, since a common control frame band is allocated to each group of subscriber-side devices in which the station-side device 1 is sleeping, control frames transmitted from subscriber-side devices in different groups do not collide with each other. It reaches the side device 1 (see steps S54 and S55).

  Note that the control operation described in the present embodiment can be applied to the control of the subscriber side apparatus 2 in the downlink sleep state, as in the first embodiment. Also in the control operation of the present embodiment, it is sufficient to operate so as to designate a plurality of grants in advance before going into the downstream sleep state. Further, the GATE frame for the subscriber side apparatus 2 in the sleep state may be a multicast frame for each group. Further, the transmission period of the GATE frame for the subscriber-side apparatus 2 in the sleep state may be a period longer than this, not every band update period. Furthermore, the transmission cycle of the GATE frame may be variable. For example, the cycle is shortened when the number of sleeping terminals reaches a predetermined number, and the cycle is shortened when a collision occurs n times or more of the past N transmission cycles. In such a case, the control can be conceived such as shortening the cycle when it occurs, and increasing the cycle when no collision has occurred over the past M transmission cycle or X time. Furthermore, it is good also as a period of a different length for every group.

  As described above, the station-side device according to the present embodiment groups the sleep-side subscriber-side devices based on the sleep duration, the SLA parameter, the device type (corresponding rate), etc., and is common to each group. It was decided to allocate the control frame bandwidth. As a result, the same effects as those of the first embodiment can be obtained. For example, the maximum delay time required for returning from the sleep state to the normal state and transmitting data can be set differently for each group. The operation can be differentiated according to the service contents contracted by the user side device.

  In each of the above embodiments, a communication device (station side device) that performs band control and a communication device (subscriber side device) that transmits a signal according to the band control result are connected via an optical transmission line. The band control operation in the existing optical communication system has been described, but this band control operation can be applied to other than the optical communication system. In the same manner as described above, the communication device on the band control side performs control for giving a transmission opportunity (allocating a band) by specifying a transmission start time (corresponding to GST) and a transmission continuation time (corresponding to GL). Any communication system can be applied as long as the above condition is satisfied.

  As described above, the communication device according to the present invention is suitable for a device that performs bandwidth allocation control on a communication device on the subscriber side that performs a power saving operation by shifting to a sleep state when data transmission is not performed.

DESCRIPTION OF SYMBOLS 1 Station side apparatus 2 Subscriber side apparatus 11 Downstream buffer part 12, 22 Frame multiplexing part 13, 23 Optical transmission part 14, 24 Optical reception part 15, 25 Frame separation part 16, 26 Frame control part 17, 27 SLEEP management part 18 Bandwidth allocation control unit 21 Upstream buffer unit

Claims (17)

A station-side communication device that allocates a bandwidth for uplink data transmission to each subscriber-side communication device based on a bandwidth request signal notified from a plurality of subscriber-side communication devices,
When there are multiple subscriber-side communication devices in power-saving operation, the same bandwidth is allocated to each subscriber-side communication device in power-saving operation, and a signal is transmitted to each subscriber-side communication device in power-saving operation A communication apparatus, comprising: a bandwidth control unit that matches a period during which permission is granted.   2. The state management means for handling a subscriber-side communication device having a stored amount of uplink data specified in the band request signal of zero for a predetermined period as a subscriber-side communication device in a power-saving operation. The communication device described. The communication apparatus according to claim 2, wherein the state management unit determines that the amount of uplink data accumulated is zero for a subscriber-side communication device that does not notify the amount of uplink data accumulated. A state management unit that manages the communication devices on the subscriber side during the power saving operation by grouping them based on the contents of the service contract, the sleep duration, the corresponding transmission rate of the devices or the presence or absence of downlink traffic,
The communication device according to claim 1, wherein the bandwidth control unit allocates the same bandwidth to a subscriber-side communication device in a power saving operation of the same group. The communication apparatus according to claim 4, wherein the service contract content is a minimum guaranteed bandwidth or a delay class. When the band request signals transmitted from the plurality of subscriber-side communication devices in power saving operation collide with each other in the same band, the band control means sets the next uplink data accumulation amount notification band. The communication device according to claim 1, 2 or 3, wherein in the process of assigning to the subscriber side communication device, individual bands are assigned to the plurality of subscriber side communication devices assigned to the same bandwidth. . The bandwidth control means is a process of allocating a next uplink data storage amount notification bandwidth to each subscriber-side communication device when bandwidth request signals transmitted from subscriber-side communication devices in power saving operation collide with each other. Then, a separate band is allocated to a plurality of subscriber-side communication devices in the same group as the subscriber-side communication device that has transmitted the collided signal.   The bandwidth control means allocates the same bandwidth in a plurality of bandwidth update periods to the subscriber-side communication device in power-saving operation in advance and notifies the subscriber-side communication device. 8. The communication device according to any one of items 7.   The bandwidth control means allocates the same bandwidth for each of the plurality of bandwidth update periods, and notifies it by one gate frame, thereby reducing gate frame reception processing of the subscriber side communication device. The communication apparatus according to claim 8. A subscriber side communication device connected to a station side communication device while sharing a communication path with other subscriber side communication devices,
During normal operation, a bandwidth request signal for requesting the uplink data communication bandwidth of the next bandwidth update cycle is transmitted using the bandwidth allocated individually in time division, and during power saving operation, multiple subscriptions during power saving operation are transmitted. A subscriber-side communication apparatus comprising: a control unit that transmits the band request signal using a shared band assigned as a usable band for any of the subscriber-side communication apparatuses. When the bandwidth request signal transmitted in the power saving operation collides with the bandwidth request signal transmitted by the other subscriber-side communication device in the shared bandwidth, the bandwidth request signal is transmitted using the individually allocated bandwidth. The subscriber side communication apparatus according to claim 10, wherein the signal is retransmitted. The communication device according to any one of claims 1 to 9,
The subscriber side communication device according to claim 10 or 11,
A point-to-multipoint communication system comprising: The station-side communication device individually assigns a transmission band for uplink data or a bandwidth request signal to each subscriber-side communication device in normal operation, and transmits a gate frame for notifying the assigned bandwidth to each subscriber-side communication device. And steps to
The station-side communication device allocates the same band to a plurality of subscriber-side communication devices in power saving operation, and the plurality of subscriber-side communication devices in which the same frame is designated in the power saving operation Sending to
When the subscriber-side communication device in the power saving operation shifts from the power saving operation to the normal operation and transmits uplink data, the step of transmitting a band request signal using the same band,
A step of band request signals subscriber communication device that transmitted the is, using a bandwidth assigned from the communication device of the station transmits the uplink data using the same band,
A bandwidth control method comprising: The station-side communication device determining that the subscriber-side communication device in which the accumulated amount of uplink data included in the bandwidth request signal is zero for a predetermined period or more is a subscriber-side communication device in a power saving mode; The band control method according to claim 13, further comprising: The band control method according to claim 13, comprising a step in which the station side communication apparatus determines that the subscriber side communication apparatus that does not notify the band request signal is in a power saving mode. The plurality of communication devices on the subscriber side during the power saving operation are grouped based on service contract contents, sleep duration, corresponding transmission rate of the device or presence / absence of downlink traffic, and for subscriber communication devices in the same group The band control method according to claim 13, wherein the same band is allocated for each group. When band request signals transmitted from a plurality of subscriber side communication devices in power saving operation collide with each other in the same band, the station side communication device is in the power saving operation in the next band update cycle. The band control method according to claim 13, 14 or 15, further comprising a step of transmitting a gate frame designating an individual band to the plurality of subscriber side communication devices.

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