JP2011254383A - Communication device and band control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device which improves band utilization efficiency of an uplink communication circuit.SOLUTION: A communication device of the present invention operating as a subscriber side device in an optical communication system where a station side device and the subscriber side devices are connected by one-to-many and an uplink band is shared by the respective subscriber side devices comprises: a circuit state supervision part 22 for supervising a circuit state with the station side device; request band determination means (a state determination part 23, a band control part 24) for determining a request band of an uplink circuit based on data amount of uplink data held in a transmission buffer and a supervising result of the circuit state; and request band notification means (a Report generation part 25, an uplink frame transmission part 27) for generating a frame including information of the request band, and transmitting the frame to the station side device.

Description

  The present invention relates to a communication apparatus that operates as a station side communication apparatus (station side apparatus) or a subscriber side communication apparatus (subscriber side apparatus) in an optical communication system such as a PON (Passive Optical Network) system.

  A PON system represented by a GE-PON (Gigabit Ethernet Passive Optical Network) system described in IEEE802.3ahTM branches a single optical fiber by a splitter, which is a passive element, and shares a bandwidth. Accordingly, a plurality of subscriber side communication devices (ONU: Optical Network Unit) can be accommodated in one station side communication device (OLT: Optical Line Terminal), and FTTH (Fiber To The Home) or FTTB (Fiber To The Building). ) Economically.

  If communication from the ONU to the OLT is defined as the upstream direction, and communication from the OLT to the ONU is defined as the downstream direction, in the PON system, data transmission in the upstream direction is performed by time division multiplexing (TDMA). Is being broadcast.

  The multiplexing method for the uplink data transfer is time division multiplexing, and the uplink band is determined by the OLT based on the uplink data amount held by each ONU in the system. The bandwidth occupied by ONUs that cannot maintain the original line quality, such as the bandwidth occupied by malicious data or the fiber loss caused by construction, etc., and link down frequently occurs. Squeeze.

  For example, Patent Document 1 listed below proposes a traffic control technique that limits SLA (Service Level Agreement) as a countermeasure when an upstream band is compressed by a malicious user or virus. Yes. Further, as a countermeasure for avoiding an error when the line is deteriorated, a FEC (Forward Error Correction) function is defined in Non-Patent Document 1 below.

JP 2006-80582 A

IEEE802.3ah

  Even when the communication line quality deteriorates due to fiber damage due to construction, reflection in the fiber, fiber deterioration, etc., and the communication situation is poor, the ONU is required by the ONU for the ONU that is in a line deteriorated state in the uplink. The OLT performs the allocation of the bandwidth. For this reason, there is a problem that the band occupation that occurs in connection with the ONU that cannot maintain the original line quality presses the band used by the normal line ONU. Further, the ONU in which line degradation has occurred repeats retry control in a protocol that performs retransmission processing such as TCP / IP. For this reason, there is a problem that the bandwidth of the PON line is compressed. Although there is a method for improving the communication state of a line deteriorated by the FEC function described in Non-Patent Document 1, the bandwidth occupation that occurs in connection with an ONU that still cannot maintain the original line quality is used by the normal line ONU. Since this will squeeze the bandwidth, a countermeasure against this problem is required.

  The present invention has been made in view of the above, and in an optical communication system that uses an upstream band in a plurality of subscriber-side devices, such as a PON system, a communication device that improves bandwidth utilization efficiency in the uplink And to obtain a bandwidth control method.

  In order to solve the above-described problems and achieve the object, the present invention provides an optical communication system in which a station-side device and a subscriber-side device are connected in a one-to-many manner, and each subscriber-side device shares an upstream band. A communication apparatus that operates as a subscriber side apparatus, a line state monitoring means for monitoring a line state with a station side apparatus, a data amount of uplink data held in a transmission buffer, and a monitoring result of the line state Request bandwidth determining means for determining the required bandwidth of the uplink based on, request bandwidth notification means for generating a frame including information of the requested bandwidth determined by the request bandwidth determining means and transmitting to the station side device, It is characterized by providing.

  According to the present invention, it is possible to prevent the bandwidth occupied by the subscriber side device whose communication line with the station side device has deteriorated from squeezing the bandwidth used by another subscriber side device. As a result, it is possible to improve the bandwidth utilization efficiency in the uplink.

FIG. 1 is a diagram illustrating a configuration example of a communication system according to the first embodiment. FIG. 2 is a block diagram illustrating an internal configuration example of the ONU according to the first embodiment. FIG. 3 is a diagram illustrating an example of a line state determination table. FIG. 4 is a diagram illustrating an example of a correspondence table of occurrence frequency of link breaks and treatment methods. FIG. 5 is a flowchart illustrating an example of an ONU control operation according to the first embodiment. FIG. 6 is a block diagram illustrating an internal configuration example of the OLT according to the second embodiment. FIG. 7 is a diagram illustrating an example of a line state determination table. FIG. 8 is a diagram illustrating an example of a correspondence table between occurrence frequency of link breaks and treatment methods. FIG. 9 is a flowchart illustrating an example of an OLT control operation according to the second embodiment.

  Embodiments of a communication apparatus 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 communication system according to the first embodiment. As illustrated, the communication system of the present embodiment is a PON system, which includes a station side communication device (Optical Line Terminal, hereinafter referred to as “OLT”) 1 and a subscriber side communication device (Optical Network Unit, hereinafter referred to as “Optical Network Unit”). ONU) 2 and an optical splitter 3. The OLT 1 and the optical splitter 3 are connected by a single optical fiber, and each ONU 2 is connected to an optical fiber branched by the optical splitter 3. A portion from the connector of the OLT 1 to the connector of the ONU 2 corresponds to an ODN (Optical Distribution Network) 4. In the PON system, transmission from the ONU to the OLT is defined as the upstream direction, and transmission from the OLT to the ONU is defined as the downstream direction.

  Next, a band control operation that is a characteristic operation in the communication system of the present embodiment will be described. In this embodiment, the bandwidth utilization efficiency in the uplink is improved by limiting the bandwidth in the ONU 2. In this case, the OLT 1 does not perform special control. That is, the OLT 1 of the present embodiment performs the same control as the conventional general OLT. Therefore, a description of the detailed operation of the OLT 1 is omitted.

  First, basic control operations assumed in the communication system (PON system) of the present embodiment will be briefly described. The basic control operation shown here is the same as the control operation of a general PON system.

  The PON uplink uses the MPCP (Multi Point Control Protocol) protocol to perform signal control. The signal control (bandwidth control) using the MPCP protocol will be described by applying it to the communication system shown in FIG. 1. First, each ONU 2 sets the amount of transmission data stored in the buffer in the Report frame and sets the OLT 1. Send to. Next, the OLT 1 determines the transmission permission data amount and the transmission start time for each ONU 2 based on the information (information on the transmission data amount accumulated in the ONU 2) written in the Report frame received from each ONU 2. decide. Then, the OLT 1 sets the determination result (transmission permission data amount and transmission start time) in the Gate frame and transmits it individually to each ONU 2.

  FIG. 2 is a block diagram illustrating an internal configuration example of the ONU 2. The ONU 2 includes a downlink frame reception unit 21, a line state monitoring unit 22, a state determination unit 23, a bandwidth control unit 24, a report generation unit 25, an uplink frame buffer unit 26, and an uplink frame transmission unit 27.

  In the ONU 2 shown in FIG. 2, the downstream frame receiving unit 21 extracts a frame addressed to the own ONU from the downstream signal transmitted from the OLT 1 and received via the optical splitter 3. The line state monitoring unit 22 monitors the line state at regular intervals. The state determination unit 23 has a database for managing a table indicating the treatment method in the ONU 2 according to the line state, and compares the monitoring result by the line state monitoring unit 22 with the database to communicate with the OLT 1. Judge quality. The bandwidth control unit 24 performs measures such as bandwidth limitation according to the determination result by the state determination unit 23 (the monitoring result by the line state monitoring unit 22 and the database comparison result). The report generation unit 25 generates a report frame in accordance with the instruction content from the band control unit 24. The uplink frame buffer unit 26 holds an uplink frame transmitted from the user. The upstream frame transmission unit 27 sends out the report frame generated by the report generation unit 25, the data held in the upstream frame buffer unit 26, and the like to the PON line. The state determination unit 23 and the bandwidth control unit 24 constitute a requested bandwidth determination unit, and the report generation unit 25 and the upstream frame transmission unit 27 constitute a requested bandwidth notification unit.

  Next, the overall operation of the ONU 2 configured as described above will be described. In the ONU 2, first, the line state monitoring unit 22 monitors the line state. The channel state is determined, for example, by monitoring the downlink frame receiving unit 21 and determining the error rate of the downlink frame, the number of times the Gate frame is received with respect to the number of transmissions of the Report frame, and the number of link downs within a certain time. When the monitoring result by the line state monitoring unit 22 is obtained, the state determination unit 23 then compares the line state (monitoring result by the line state monitoring unit 22) with the database to determine the treatment method. For example, the state determination unit 23 holds information (line state determination table) describing the treatment method according to the line state and priority as shown in FIG. 3 in a database, and is monitored by the line state monitoring unit 22. Information on the treatment method according to the result (each treatment method for each priority described in the column corresponding to the monitoring result) is notified to the bandwidth control unit 24 as a determination result. FIG. 4 is a correspondence table (correspondence table of occurrence frequency of link breakage and treatment method) when link breakage occurs. The state determination unit 23 also stores the correspondence table shown in FIG. 4 in the database, and selects a treatment method corresponding to the line state from the correspondence table of FIG. Then, the bandwidth control unit 24 is notified as a determination result. 3 and 4 are examples, and the determination operation by the state determination unit 23 is not limited to this content. In FIG. 3, BER (Bit Error Rate) is used as the line state, but other information may be used.

The bandwidth control unit 24 determines the amount of data (requested bandwidth) to be notified to the OLT 1 in the Report frame based on the notification content from the state determination unit 23 and the upstream frame data amount held by the upstream frame buffer unit 26. To do. For example, when the BER is 1.0 × 10 ^{−7 to} 1.0 × 10 ⁻⁶ and the priority of the upstream frame is 1 (the lowest priority), a bandwidth of 50% of the stored data amount is requested. Determine the bandwidth. Further, when the BER has reached 1.0 × 10 ⁻² and the priority of the stored uplink frame is 1, it is determined that no bandwidth is required. On the other hand, when the priority is 8 (highest priority), all the stored data amount (100% bandwidth) is determined as the requested bandwidth regardless of the BER (line quality) (bandwidth restriction is performed). Absent).

  Here, the reason for considering the priority when determining the data amount (requested bandwidth) to be notified to the OLT 1 will be described. For example, communications related to human life, such as calls to the police and fire departments, need to improve the communication quality even if line degradation occurs. Therefore, in the communication system according to the present embodiment, a band is provided for information that requires high communication quality with respect to the ONU 2 in which line degradation has occurred (while ONU 2 does not limit the requested band), while performing retransmission. In addition, communication is ensured, and at the same time, it is avoided that the communication of other ONUs 2 is unnecessarily compressed, and the minimum required communication quality can be guaranteed for the ONU 2 in which the line degradation has occurred.

FIG. 5 is a flowchart illustrating an example of the control operation of the ONU 2 according to the present embodiment. In the ONU 2, the line state monitoring unit 22 measures the line state (step S11), and the state determination unit 23 compares the monitoring result by the line state monitoring unit 22 with the line state determination table shown in FIG. It is confirmed whether or not the deterioration is more than a predetermined threshold (step S12). That is, it is confirmed whether the BER has reached 1.0 × 10 ⁻⁷ . As a result of the confirmation, if the line has deteriorated (step S12: Yes), the ONU 2 limits the data amount (required bandwidth to the OLT 1) set in the report frame in a stepwise manner according to the priority of the data. When this operation is shown in detail, the state determination unit 23 notifies the bandwidth control unit 24 of treatment method candidates according to the line state (treatment methods with priorities 1 to 8 corresponding to the detected line state). Upon receiving the notification, the bandwidth control unit 24 checks the data amount and priority of the upstream frame held by the upstream frame buffer unit 26. If the priority is low and adjustment of the requested bandwidth notified to the OLT 1 with the Report frame is necessary (step S13: No), the bandwidth control unit 24 determines the uplink frame data amount, the uplink frame priority, and the state determination. Based on the treatment method candidate notified from the unit 23, the requested bandwidth to be notified to the OLT 1 by the Report frame is determined (adjusted) (step S14). On the other hand, if the priority is high (step S13: Yes), the bandwidth control unit 24 decides not to adjust the requested bandwidth notified to the OLT 1 in the report frame, and the uplink frame buffer unit 26 holds the uplink. Based on the data amount of the frame (in the same procedure as before), the requested bandwidth to be notified to the OLT 1 with the Report frame is determined (step S19).

  In step S14, a treatment method candidate and priority are collated to identify one treatment method, and further, the amount of uplink frame data held by the uplink frame buffer unit 26 is adjusted according to the identified treatment method. The later data amount is determined as the requested bandwidth. On the other hand, in step S19, the uplink frame data amount held by the uplink frame buffer unit 26 is determined as the requested bandwidth.

  When the upstream frame buffer unit 26 holds a plurality of types of data (upstream frames) having different priorities, the bandwidth control unit 24 determines a requested bandwidth for each data having the same priority. For example, when priority level 1 data and priority level 2 data exist, a request band for priority level 1 data and a request band for priority level 2 data are determined. Although not shown, after determining the requested bandwidth in step S14 or step S19, the bandwidth control unit 24 notifies the report generation unit 25 of the determination result, and the report generation unit 25 reports the report frame according to the notification content. Is generated. When data with different priorities is accumulated in the upstream frame buffer unit 26, the requested bandwidth for each data with the same priority is notified to the report generation unit 25, and the report generation unit 25 Is set in the Report frame. When a plurality of LLIDs are assigned to the ONU 2, the report generation unit 25 calculates the total value for each LLID and sets it in the report frame. The total value of the requested bandwidths may be calculated by the bandwidth control unit 24 instead of being calculated by the report generation unit 25.

  Further, the line state monitoring unit 22 monitors the frequency of occurrence of link disconnection, and after executing step S14, the ONU 2 has reached a certain level of frequency of occurrence of link disconnection (the line quality has deteriorated). ), The operation corresponding to the occurrence frequency is executed. Specifically, when the link breakage has occurred slightly (step S15: Yes), the ONU 2 shifts to the sleep mode (step S16). On the other hand, when the link breakage frequently occurs (step S17: Yes), the ONU 2 shifts to the link breakage state (step S18). In the processing of these steps S15 to S18, the table shown in FIG. 4 is referred to. Therefore, when the link breakage occurs at a frequency of once every 5 minutes, it is determined that the link breakage has occurred slightly in step S15. If link breakage occurs at a frequency of one or more times per minute, it is determined in step S17 that link breakage occurs frequently. Note that the ONU 2 also shifts to the sleep mode after executing step S19.

  The ONU 2 cancels the sleep mode only when data with high priority is received after shifting to the sleep mode. Even when the ONU 2 is in the sleep mode, the OLT 1 periodically checks the transmission request of the ONU 2 in preparation for the release of the sleep mode. Steps S17 and S18 are control operations for forcibly turning ONU 2 into a link disconnection state when link disconnection frequently occurs and the line does not make sense. However, these steps are treated as options. And may be configured not to be executed.

  Further, when the line quality has not deteriorated beyond a predetermined threshold (step S12: No), and when the frequency of occurrence of link disconnection has not reached a certain level (step S15: No, step S17: No), End the process. When the line quality has not deteriorated beyond a predetermined threshold, when transmitting a Report frame, the amount of data held in the upstream frame buffer unit 26 is set as a required bandwidth (the same operation as in the prior art). Do).

  As described above, in the communication system according to the present embodiment, the ONU monitors the line quality and, when detecting the line deterioration, reports frames based on the deterioration state (line quality) and the priority of the uplink data. Thus, the bandwidth adjustment amount requested to the OLT 1 is determined, and the bandwidth according to the determination result is notified (requested) in the Report frame. As a result, the bandwidth occupation of the ONU whose communication line with the OLT has deteriorated may squeeze the bandwidth used by other normal line ONUs (ONUs whose communication line with the OLT has not deteriorated). Therefore, it is possible to prevent the bandwidth utilization efficiency in the uplink.

  In addition, since the amount of bandwidth adjustment required for the OLT 1 is determined according to the priority of the data, the minimum required communication quality is guaranteed even for an ONU whose communication line with the OLT has deteriorated. it can.

Embodiment 2. FIG.
Next, the second embodiment will be described. The configuration of the communication system of the present embodiment is the same as that of the first embodiment (see FIG. 1). In the first embodiment, the bandwidth utilization efficiency in the uplink is improved by limiting the bandwidth in the ONU 2, but in the communication system according to the present embodiment, one or more ONUs 2 compress the bandwidth of other users. When such data is transmitted, the bandwidth utilization efficiency in the uplink is improved by limiting the bandwidth in the OLT 1. In this case, the ONU 2 does not perform special control. That is, the ONU 2 of the present embodiment performs the same control as a conventional general ONU. Therefore, a description of the detailed operation of the ONU 2 is omitted.

  FIG. 6 is a block diagram illustrating an internal configuration example of the OLT 1. The OLT 1 includes an upstream frame reception unit 11, a line state monitoring unit 12, a state determination unit 13, a bandwidth control unit 14, a gate generation unit 15, a downstream frame buffer unit 16, and a downstream frame transmission unit 17.

  In the OLT 1 illustrated in FIG. 6, the upstream frame reception unit 11 receives an upstream signal transmitted from the ONU 2 via the optical splitter 3. The line state monitoring unit 12 monitors the line state at regular intervals. The state determination unit 13 has a database for managing a table indicating the treatment method in the OLT 1 according to the line state, and compares the monitoring result by the line state monitoring unit 12 with the database to communicate with the ONU 2. Judge quality. The bandwidth control unit 14 performs measures such as bandwidth limitation according to the determination result by the state determination unit 13 (the monitoring result by the line state monitoring unit 12 and the database comparison result). The gate generation unit 15 generates a gate frame in accordance with the instruction content from the bandwidth control unit 14. The downlink frame buffer unit 16 holds a downlink frame to be transmitted to the ONU 2 side. The downlink frame transmission unit 17 sends out the Gate frame generated by the Gate generation unit 15, the data held in the downlink frame buffer unit 16, and the like to the PON line. The state determination unit 13 and the bandwidth control unit 14 constitute a permitted bandwidth determination unit, and the gate generation unit 15 and the downlink frame transmission unit 17 constitute a permitted bandwidth notification unit.

  Next, the overall operation of the OLT 1 configured as described above will be described. In the OLT 1, first, the line state monitoring unit 12 monitors the line state. The line state is determined, for example, by monitoring the uplink frame receiver 11 and determining the error rate of the uplink frame, the ratio of actual data reception to the number of transmissions of the Gate frame, and the number of link downs within a certain time. When the monitoring result by the line state monitoring unit 12 is obtained, the state determination unit 13 then compares the line state (monitoring result by the line state monitoring unit 12) with the database to determine the treatment method. For example, the state determination unit 13 holds information (line state determination table) describing the treatment method according to the line state and priority as shown in FIG. 7 in a database, and is monitored by the line state monitoring unit 12 Information on the treatment method according to the result (each treatment method for each priority described in the column corresponding to the monitoring result) is notified to the bandwidth control unit 14 as a determination result. As the priority shown in FIG. 7, for example, the priority of LLID is used. In FIG. 7, priority 1 is the highest priority. FIG. 8 is a correspondence table (correspondence table of link breakage occurrence frequency and treatment method) when link breakage occurs. The state determination unit 13 also stores the correspondence table shown in FIG. 8 in the database, and selects the treatment method corresponding to the line state from the correspondence table of FIG. Then, the bandwidth control unit 14 is notified as a determination result. The treatment methods shown in FIGS. 7 and 8 are examples, and the determination operation by the state determination unit 13 is not limited to this content. In FIG. 7, BER is used as the line state, but other information may be used.

The bandwidth control unit 14 is based on the notification content from the state determination unit 13 and the uplink data amount (requested bandwidth) for each LLID held in the ONU 2 that is notified in the Report frame received from each ONU 2. The amount of data (permitted bandwidth) to be notified to each ONU 2 is determined using the Gate frame. For example, when the BER is 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻⁴ and the priority of the requested bandwidth notified in the Report frame (priority of the LLID corresponding to the requested bandwidth) is N ( In the case of the lowest priority), it is determined that 50% of the normal bandwidth (when the BER is less than 1.0 × 10 ⁻⁵ ) is allocated as the permitted bandwidth. Further, when the priority is 1 (highest priority), the same band as the normal band (when the BER is less than 1.0 × 10 ⁻⁵ ) is allocated as the permitted band regardless of the BER (line quality). To decide (no bandwidth limitation).

FIG. 9 is a flowchart showing an example of the control operation of the OLT 1 of the present embodiment. In the OLT 1, the line state monitoring unit 12 measures the line state (step S21), and the state determination unit 13 compares the monitoring result by the line state monitoring unit 12 with the line state determination table shown in FIG. It is confirmed whether or not the deterioration is more than a predetermined threshold (step S22). That is, it is confirmed whether the BER has reached 1.0 × 10 ⁻⁵ . As a result of the confirmation, if the line has deteriorated (step S22: Yes), the OLT 1 sets the data amount (permitted bandwidth to the ONU 2) set in the Gate frame according to the priority of the data that the ONU 2 intends to transmit. Limit in stages. When this operation is shown in detail, the state determination unit 13 notifies the bandwidth control unit 14 of treatment method candidates (treatment methods of priority levels 1 to N corresponding to the detected line state) according to the line state. Receiving the notification, the bandwidth control unit 14 confirms each requested bandwidth notified from the Report frame from the ONU 2 using the transmission line with a deteriorated line, and the priority corresponding to the requested bandwidth. If the priority is low and the adjustment of the permitted bandwidth notified by the Gate frame is necessary (step S23: No), the bandwidth control unit 14 determines the requested bandwidth from the ONU 2, the priority corresponding to the requested bandwidth, and the state. Based on the treatment method candidate notified from the determination unit 13, the permitted bandwidth to be notified by the Gate frame is determined (step S24). On the other hand, when the priority is high (step S23: Yes), the bandwidth control unit 14 determines not to adjust the permitted bandwidth notified by the Gate frame, and based on the requested bandwidth from the corresponding ONU 2 (conventional and In the same procedure), the permitted bandwidth to be notified to the OLT 1 by the Gate frame is determined (step S31).

  In step S24, a treatment method candidate and a priority are collated to identify one treatment method, and the requested bandwidth from the ONU 2 is adjusted according to the identified treatment method, and the permitted bandwidth is determined based on the adjusted requested bandwidth. decide. On the other hand, in step S31, the permitted bandwidth is determined based on the requested bandwidth without adjusting the requested bandwidth from the ONU 2.

  The line state monitoring unit 12, the state determination unit 13, and the bandwidth control unit 14 execute the above steps S21 to S24 and S31, and determine the permitted bandwidth for each requested bandwidth for each LLID notified from the ONU 2. In addition, for each of all the ONUs 2 connected to the OLT 1, the permitted bandwidth for the requested bandwidth for each LLID is determined.

  Further, the bandwidth control unit 14 determines whether there is a surplus bandwidth after determining the permitted bandwidth for each requested bandwidth for each LLID from all ONUs 2 (step S25). If there is a surplus bandwidth (step S25: Yes), the surplus bandwidth is reassigned to the ONU 2 that has adjusted the permitted bandwidth by executing step S24 (step S26). When the permitted bandwidth is adjusted for a plurality of ONUs 2, for example, the surplus bandwidth is preferentially allocated from the ONU 2 attempting to transmit data with higher priority. When there are a plurality of ONUs 2 to transmit data with the same priority, the surplus bandwidth is allocated to the ONUs 2 with the same priority in the order determined in advance according to the service contents and contract conditions. Alternatively, the surplus bandwidth is allocated fairly to each ONU 2 that intends to transmit data with the same priority (distributed according to the ratio of the requested bandwidths with the same priority).

  Further, the line status monitoring unit 12 monitors the frequency of occurrence of link disconnection, and after executing step S26, the OLT 1 has reached a certain level of occurrence of link disconnection (the line quality has deteriorated). ), The operation corresponding to the occurrence frequency is executed. Specifically, when the link disconnection has occurred slightly (step S27: Yes), the OLT 1 transmits a message instructing the transition to the sleep mode to the ONU 2 in which the link disconnection has occurred slightly. To shift to the sleep mode (step S28). Note that the ONU 2 that has shifted to the sleep mode automatically starts up and cancels the sleep mode only when high priority data is received. Even when the ONU 2 is in the sleep mode, the OLT 1 periodically checks the transmission request of the ONU 2 in preparation for the release of the sleep mode. Further, when the link disconnection frequently occurs (step S29: Yes), the OLT 1 transmits a message instructing the transition to the link disconnection state to the ONU 2 in which the link disconnection frequently occurs, and the ONU 2 Is forcibly shifted to the link-disconnected state (step S30). In the processing of these steps S27 to S30, the table shown in FIG. 8 is referred to. Therefore, when the link breakage occurs at a frequency of once every 5 minutes, it is determined that the link breakage has occurred slightly in step S27. If link breakage occurs at a frequency of one or more times per minute, it is determined in step S29 that link breakage occurs frequently. Steps S29 and S30 are control operations for forcibly bringing the corresponding ONU 2 into a link disconnection state when link disconnection frequently occurs and the line does not make sense, but for these steps, It may be configured as an option and not executed.

  In addition, when the line quality is not deteriorated more than a predetermined threshold (step S22: No), and when the frequency of occurrence of link disconnection has not reached a certain level (step S27: No, step S29: No), End the process. In the case where the line quality has not deteriorated beyond the predetermined threshold value, the gate generation unit 15 applies only the requested bandwidth notified by the Report frame from the ONU 2 without considering the line quality and the data priority. Based on this, the permitted bandwidth for this ONU 2 is determined (the same operation as in the prior art is performed).

  Note that when all the ONUs 2 are in a link disconnection state, the OLT 1 cancels the connection setting of each ONU 2 and shifts to a standby state, and waits for the ONU 2 to recover.

  As described above, in the communication system according to the present embodiment, the OLT monitors the line quality, and when line deterioration is detected, the deterioration state (line quality) and each ONU under its control desires transmission. Based on the amount of uplink data (required bandwidth) and the priority of uplink data, the bandwidth (permitted bandwidth) to be assigned to each ONU is determined. As a result, the bandwidth occupation of the ONU whose communication line with the OLT has deteriorated may squeeze the bandwidth used by other normal line ONUs (ONUs whose communication line with the OLT has not deteriorated). Therefore, it is possible to prevent the bandwidth utilization efficiency in the uplink.

  Further, similar to the ONU of the first embodiment, the OLT determines the permitted band for the ONU whose communication quality is deteriorated according to the priority of the uplink data, and therefore the ONU whose communication quality is deteriorated. The minimum required communication quality can be guaranteed.

  As described above, the communication apparatus according to the present invention is useful for an optical communication system, and in particular, a subscriber side apparatus or a station side of an optical communication system in which a plurality of subscriber side apparatuses share an upstream band. Suitable for equipment.

1 Station side communication equipment (OLT)
2 Subscriber side communication equipment (ONU)
3 Optical splitter 4 ODN (Optical Distribution Network)
DESCRIPTION OF SYMBOLS 11 Uplink frame reception part 12,22 Line state monitoring part 13,23 State determination part 14,24 Band control part 15 Gate generation part 16 Downstream frame buffer part 17 Downstream frame transmission part 21 Downstream frame reception part 25 Report generation part 26 Upstream frame Buffer unit 27 Upstream frame transmission unit

Claims (14)

In an optical communication system in which station-side devices and subscriber-side devices are connected one-to-many and each subscriber-side device shares an upstream band, the communication device operates as the subscriber-side device,
A line state monitoring means for monitoring a line state between the station side device,
Requested bandwidth determining means for determining the requested bandwidth of the uplink based on the amount of uplink data held in the transmission buffer and the monitoring result of the channel status;
Request bandwidth notification means for generating a frame including information of the requested bandwidth determined by the requested bandwidth determination means and transmitting the frame to the station side device;
A communication apparatus comprising: The required bandwidth determining means includes
The communication apparatus according to claim 1, further comprising: determining the required bandwidth based on a priority of the uplink data. The required bandwidth determining means includes
If there is no degradation in the channel quality with the station side device, the amount of uplink data held in the transmission buffer is determined as the requested bandwidth,
If the line quality with the station side device has deteriorated, the amount of uplink data held in the transmission buffer is adjusted based on the line quality and the priority, and the adjusted data The communication apparatus according to claim 2, wherein an amount is determined as the required bandwidth. The frequency of occurrence of link breakage is calculated based on the monitoring result of the line status, and when the calculated frequency of occurrence reaches a predetermined value, the sleep mode is entered. The communication device described. In an optical communication system in which station-side devices and subscriber-side devices are connected one-to-many and each subscriber-side device shares an upstream band, the communication device operates as the station-side device,
A line state monitoring means for monitoring a line state between each subscriber side device;
An allowed bandwidth determining means for determining an allowed bandwidth that is an uplink bandwidth allocated to each subscriber side device based on the uplink requested bandwidth notified from each subscriber side device and the monitoring result of the channel state;
A permitted bandwidth notification means for generating a frame including the determination result in the permitted bandwidth determination means and transmitting the frame to each subscriber side device;
A communication apparatus comprising: The allowed bandwidth determination means includes
The communication apparatus according to claim 5, further comprising: determining the permitted band based on a priority of an LLID corresponding to the requested band. The allowed bandwidth determination means includes
When determining the permitted bandwidth for a subscriber side device whose line quality has not deteriorated, determine the permitted bandwidth based on the requested bandwidth of the uplink notified from the subscriber side device,
When determining the permitted bandwidth for the subscriber side device in which the line quality has deteriorated, the requested bandwidth of the uplink notified from the subscriber side device is the line quality between the subscriber side device and the subscriber side device. The communication apparatus according to claim 6, wherein the permitted bandwidth is determined based on the adjusted requested bandwidth obtained as a result of the adjustment based on the priority. The allowed bandwidth determination means includes
After determining the permitted bandwidth for all subscriber side devices, if there is a surplus bandwidth and there is a subscriber side device with degraded line quality, the subscriber side with degraded line quality The communication device according to claim 7, wherein the permitted bandwidth for the device is adjusted based on the surplus bandwidth. Based on the monitoring result of the line state, the occurrence frequency of link breakage is calculated for each subscriber side device, and the subscriber side device whose calculated occurrence frequency reaches a predetermined value is instructed to shift to the sleep state. The communication device according to any one of claims 5 to 8, wherein: A bandwidth control method executed in an optical communication system in which a station-side device and a subscriber-side device are connected one-to-many, and each subscriber-side device shares an upstream band,
A request bandwidth determining step in which the subscriber side device determines the required bandwidth of the uplink based on the data amount of the uplink data held in the transmission buffer and the channel state with the station side device;
A bandwidth allocation step in which the station side device allocates an upstream bandwidth to the subscriber side device based on the requested bandwidth determined in the requested bandwidth determination step;
A bandwidth control method comprising: In the required bandwidth determination step,
If there is no degradation in the line quality with the station side device, the amount of uplink data held in the transmission buffer is determined as the requested bandwidth,
When the line quality with the station side device has deteriorated, adjust the amount of uplink data held in the transmission buffer based on the line quality and the priority of the uplink data, and adjust The bandwidth control method according to claim 10, wherein a later data amount is determined as the required bandwidth. In an optical communication system in which a station-side device and a subscriber-side device are connected one-to-many and each subscriber-side device shares an upstream band, a bandwidth control method executed by the station-side device,
Request bandwidth acquisition step of acquiring uplink request bandwidth information from each subscriber side device;
An authorized bandwidth determination step for determining an authorized bandwidth, which is an uplink bandwidth allocated to each subscriber device, based on the requested bandwidth information acquired in the requested bandwidth acquisition step and the line state between each subscriber device. When,
A bandwidth control method comprising: In the allowed bandwidth determination step,
When determining the permitted bandwidth for a subscriber side device whose line quality has not deteriorated, determine the permitted bandwidth based on the requested bandwidth of the uplink notified from the subscriber side device,
When determining the permitted bandwidth for the subscriber side device in which the line quality has deteriorated, the requested bandwidth information acquired from the subscriber side device is used as the channel quality and the required bandwidth for the subscriber side device. The band control method according to claim 12, wherein the band is adjusted based on the priority of the LLID corresponding to the information, and the permitted band is determined based on the adjusted request band obtained as a result. In the allowed bandwidth determination step,
After determining the permitted bandwidth for all subscriber side devices, if there is a surplus bandwidth and there is a subscriber side device with degraded line quality, the subscriber side with degraded line quality The bandwidth control method according to claim 13, wherein the permitted bandwidth for the device is adjusted based on the surplus bandwidth.

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