JP5681654B2 - Optical subscriber line termination device and network coding method thereof - Google Patents

Description

  The present invention relates to a technique for performing network coding for reducing a downstream band when optical network termination devices communicate with each other in a passive optical network.

  In recent years, smart communities that efficiently manage local energy using communication technology have attracted attention. In a communication network used for a smart community, terminals communicate with each other within a region, and low latency and security are required between the terminals.

  As a communication network used in the smart community, a wireless network such as Zigbee (registered trademark) and a broadband access network (Non-Patent Document 1), an IP (Internet Protocol) based such as a passive optical network (PON), etc. There is an optical access network.

  A PON is composed of one optical subscriber line terminal (OLT), a plurality of optical network terminal units (ONU), an optical fiber transmission line, and a 1 to N optical power splitter (N is N). This is a network that performs point-to-multipoint communication via a natural number).

  In recent years, network coding technology has attracted attention. The network coding technique has a great effect on improving transmission efficiency in multicast communication and improving fault tolerance by adding coding redundancy. Non-Patent Document 2 discloses a technique for performing network coding that saves a downstream band when ONUs communicate with each other in a PON.

  As a goal, the first ONU sends the first data to the second ONU via the OLT, and the second ONU sends the second data to the first ONU via the OLT. First, the OLT receives first data from the first ONU and receives second data from the second ONU. Next, the OLT generates encoded data obtained by combining the first data and the second data, and transmits the encoded data to the first ONU and the second ONU. Here, the combination of the first data and the second data is, for example, an exclusive OR (XOR) of the first data and the second data.

  Next, the first ONU receives the encoded data from the OLT, and restores the second data from the encoded data by using the buffered first data. Also, the second ONU receives the encoded data from the OLT, and restores the first data from the encoded data using the buffered second data. Here, the restoration of the second data from the encoded data is, for example, an exclusive OR (XOR) of the encoded data and the buffered first data. The restoration of the first data from the encoded data is, for example, an exclusive OR (XOR) of the encoded data and the buffered second data.

  When network coding is used, the payload can be used more efficiently in downstream communication than when no network coding is used, and a maximum bandwidth of 50% can be saved. The property is excellent.

Young-Jin Kim et al. , "A secure declarative data-centric information infrastructure grid," IEEE Communications Magazine, Vol. 48, no. 11, pp. 58-65, November 2010. Konstantin Miller et al. , "Network Coding in Passive Optical Networks," NetCod, pp. 1-6, 2010.

  As described above, the OLT generates encoded data obtained by combining the first data and the second data using network coding. Thus, the OLT desirably receives the first data and the second data almost simultaneously, but may wait for a long time after receiving the first data until receiving the second data.

  Here, no problem occurs when there is a sufficient margin in the available downlink band or when the number of network coding groups that can be registered in the PON is sufficiently secured. However, when the number of network coding groups that can be registered in the PON is not sufficiently secured, or when a plurality of network coding groups are generated or complicated, the number of network coding groups that can be newly registered in the PON is reduced. .

  Then, not only multicast coding by network coding becomes difficult, but also other multicast services such as video may be compressed and may be restricted. Furthermore, since it is necessary to secure a sufficient number of network coding groups that can be registered in the PON, there is a possibility that the memory area of the OLT and ONU will be compressed, and the resulting increase in power consumption and reduction in processing speed. There is also sex.

  Therefore, in order to solve the above problems, the present invention improves the use efficiency of network coding that can be registered in the PON, thereby compressing the memory area of the OLT and ONU, increasing the power consumption associated therewith, and reducing the processing speed. The purpose is to prevent the decrease.

  When the OLT does not receive the second data from the second ONU even after a predetermined time has elapsed after receiving the first data from the first ONU, the OLT receives the first ONU and the second ONU. We decided to release the network coding between

Specifically, the present invention is an optical subscriber line termination device to which a first optical network termination device and a second optical network termination device are connected in a passive optical network, wherein the first optical network termination device is connected. Alternatively, the first optical network termination device receives first data destined for the second optical network termination device or the subordinate device as a transmission source from the first optical network termination device, or the second optical network termination device or A data receiving unit for receiving, from the second optical network termination device, second data having the subordinate device as a transmission source and the first optical network termination device or the subordinate device as a destination; the first data; The destination of the first data and the second data is extracted from the second data, and the destination of the first data and the second data is any A grouping table storing unit which generates a grouping table indicating whether performing network coding in between the optical network termination apparatus, by using the network coding, the encoded data combining the first data and the second data The encoded data generation unit to generate and the data reception unit receive the first data from the first optical network terminator before the predetermined time elapses. When the second data is received from the second optical network terminating device, it waits for the encoded data generation unit to generate the encoded data, and the encoded data is stored in the first group according to the grouping table. and broadcast transmission on the optical network device and the second optical network device, wherein the encoded The chromatography data after sending broadcast, the first data, the second data, while deleting the encoded data and the grouping table, wherein the data receiving unit is the first data and the first The encoded data generation unit when the data reception unit does not receive the second data from the second optical network termination device even after the predetermined time has elapsed since reception from the optical network termination device. Transmits the first data to the second optical network terminator in accordance with the grouping table without generating the encoded data, and transmits the first data to the second optical network terminator. Later, the buffering of the first data is instructed to the first optical network terminating device, and the first data and the grouping test are instructed. An optical subscriber line terminating device comprising: a data transmitting unit that deletes a cable .

  According to this configuration, by improving the use efficiency of network coding that can be registered in the PON, it is possible to prevent compression of the memory areas of the OLT and the ONU, an accompanying increase in power consumption, and a decrease in processing speed.

  Further, the present invention is the optical subscriber line terminating apparatus, wherein the predetermined time is set based on a traffic amount in the passive optical network.

  According to this configuration, the time-limited release time for the network coding between the first ONU and the second ONU can be set based on the communication amount in the PON.

  According to the present invention, the predetermined time is set longer as the time required for one network coding between the first optical network termination device and the second optical network termination device is longer. An optical subscriber line terminating device is characterized.

  According to this configuration, the timed release time for the network coding between the first ONU and the second ONU is based on the time required for one network coding between the first ONU and the second ONU. Can be set.

  Further, the present invention is the optical subscriber line terminating apparatus characterized in that the predetermined time is set shorter as the number of network coding groups that can be newly registered in the passive optical network is smaller.

  According to this configuration, the time-limited release time for the network coding between the first ONU and the second ONU can be set based on the number of network coding pairs that can be newly registered in the PON.

  According to the present invention, the predetermined time is substantially equal to a natural number times the time required for one network coding between the first optical network termination device and the second optical network termination device. It is an optical subscriber line terminating device that is set.

  According to this configuration, the timed release time for the network coding between the first ONU and the second ONU is based on the time required for one network coding between the first ONU and the second ONU. Can be set.

  The present invention also provides the optical subscriber line terminating device described above, the first data is transmitted to the optical subscriber line terminating device, and the encoded data is received from the optical subscriber line terminating device. A first optical network terminator that restores the second data from the encoded data using the first data, and the second data is transmitted to the optical subscriber line terminator, A second optical network termination device that receives the encoded data from the optical subscriber line termination device and restores the first data from the encoded data using the second data. This is a passive optical network system characterized by the above.

  According to this configuration, by improving the use efficiency of network coding that can be registered in the PON, it is possible to prevent compression of the memory areas of the OLT and the ONU, an accompanying increase in power consumption, and a decrease in processing speed.

  The present invention improves the use efficiency of network coding that can be registered in the PON, thereby preventing the compression of the memory area of the OLT and ONU, the accompanying increase in power consumption, and the reduction in processing speed.

It is a figure which shows the structure of PON of this invention. It is a figure which shows the structure of OLT of this invention. 4 is a time chart of network coding according to the first embodiment. 4 is a time chart of network coding according to the first embodiment. 4 is a time chart of network coding according to the first embodiment. It is a figure which shows the report information of Embodiment 1. It is a figure which shows the ONU registration table of Embodiment 1. FIG. It is a figure which shows the grouping table of Embodiment 1. FIG. It is a figure which shows the grouping table of Embodiment 2. It is a figure which shows the depletion coefficient of Embodiment 3. It is a figure which shows the grouping table of Embodiment 3. It is a figure which shows the grouping table of Embodiment 4.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Outline of the present invention)
The configuration of the PON of the present invention is shown in FIG. PON, OLT1, ONU2-1, ..., 2-N, gateway (GW: Gateway) 3-1, ..., 3-N, 1 to N optical power splitter (OPS) 4. And an optical fiber transmission line 5 and an optical fiber transmission line 6.

  The OLT 1 is connected to the OPS 4 via the optical fiber transmission line 5. The ONUs 2-1,..., 2-N are connected to the OPS 4 via the optical fiber transmission line 6. GW3-1, ..., 3-N are connected to ONU2-1, ..., 2-N as subordinate devices of ONU2-1, ..., 2-N, respectively. The MAC address of GW3-1 is XX: XX: XX: XX: XX: XX, and the MAC address of GW3-N is ZZ: ZZ: ZZ: ZZ: ZZ: ZZ. Here, as identification information of the GWs 3-1,..., 3-N, IP or other IDs may be used in addition to the MAC address.

  As a target, GW3-1 transmits Data # a to GW3-N via OLT1, and GW3-N transmits Data # b to GW3-1 via OLT1. First, the ONU 2-1 receives Data # a from the GW 3-1. Moreover, ONU2-N receives Data # b from GW3-N. Next, the OLT 1 receives Data # a from the ONU 2-1 and receives Data # b from the ONU 2 -N. Next, OLT1 produces | generates encoding Data # c which combined Data # a and Data # b, and transmits encoding Data # c to ONU2-1 and ONU2-N. Here, the combination of Data # a and Data # b is, for example, an exclusive OR (XOR) of Data # a and Data # b.

  Next, the ONU 2-1 receives the encoded Data # c from the OLT 1, restores Data # b from the encoded Data # c using the buffered Data # a, and restores the restored Data # b. Transmit to GW3-1. Further, the ONU 2-N receives the encoded Data # c from the OLT 1 and uses the buffered Data # b to recover the Data # a from the encoded Data # c, and restores the recovered Data # a to the GW3. -Send to N. Here, the restoration of Data # b from the encoded Data # c is, for example, an exclusive OR (XOR) of the encoded Data # c and the buffered Data # a. The restoration of Data # a from the encoded Data # c is, for example, an exclusive OR (XOR) of the encoded Data # c and the buffered Data # b.

  The configuration of the OLT of the present invention is shown in FIG. The OLT 1 includes a data reception unit 11, a data storage unit 12, an encoded data generation unit 13, a data transmission unit 14, an ONU registration table storage unit 15, a grouping table storage unit 16, and a grouping release timer unit 17.

  The data receiving unit 11 receives Data # a from the ONU 2-1 and receives Data # b from the ONU 2 -N. Then, the data receiving unit 11 acquires the MAC address of the GW 3-1 from the ONU 2-1, and acquires the MAC address of the GW 3-N from the ONU 2-N. Further, the data receiving unit 11 acquires the MAC address of the destination GW3-N and the MAC address of the transmission source GW3-1 from the ONU 2-1, and sets the MAC address of the destination GW3-1 and the MAC address of the transmission source GW3-N to ONU2. Obtain from -N.

  The data storage unit 12 stores Data # a and Data # b. The encoded data generation unit 13 generates encoded Data # c obtained by combining Data # a and Data # b using network coding. Here, the combination of Data # a and Data # b is, for example, an exclusive OR (XOR) of Data # a and Data # b.

  Before the data receiving unit 11 receives Data # a (#b) from the ONU 2-1 (2-N) and before a predetermined time elapses, the data receiving unit 11 sets Data #b (#a) to ONU2. When received from -N (2-1), the data transmitter 14 performs the following processing. That is, the data transmission unit 14 waits for the encoded data generation unit 13 to generate the encoded Data # c, and broadcasts the encoded Data # c to the ONU 2-1 and the ONU 2-N. As described above, the OLT 1 performs network coding between the ONU 2-1 and the ONU 2-N.

  Even after a predetermined time has elapsed since the data receiving unit 11 received Data # a (#b) from the ONU 2-1 (2-N), the data receiving unit 11 sets Data #b (#a) to ONU2. When not receiving from -N (2-1), the data transmitter 14 performs the following processing. That is, the data transmission unit 14 transmits Data #a (#b) to the ONU 2-N (2-1) without the encoded data generation unit 13 generating encoded Data #c. In this way, the OLT 1 releases the network coding between the ONU 2-1 and the ONU 2-N in a timely manner.

  The ONU registration table storage unit 15 performs ONU registration based on the MAC address of the GW 3-1 acquired by the data receiving unit 11 from the ONU 2-1 and the MAC address of the GW 3-N acquired by the data receiving unit 11 from the ONU 2-N. Create and store a table. The ONU registration table is a table indicating which GW 3 is under which ONU 2.

  The grouping table storage unit 16 includes the MAC address of the destination GW3-N and the MAC address of the transmission source GW3-1 acquired by the data reception unit 11 from the ONU 2-1, or the destination GW3- of the data reception unit 11 acquired from the ONU 2-N. A grouping table is generated and stored based on the MAC address of 1 and the MAC address of the transmission source GW3-N. The grouping table is a table indicating which ONU 2 performs network coding. Here, the grouping table storage unit 16 determines which ONU 2 performs network coding by finding the MAC address of the destination GW 3 and the MAC address of the transmission source GW 3 in the ONU registration table.

  The grouping cancellation timer unit 17 confirms that the grouping cancellation time as the predetermined time has elapsed since the data reception unit 11 received Data # a (#b) from the ONU 2-1 (2-N). To do. When the grouping cancellation timer unit 17 confirms that the grouping cancellation time has elapsed, the grouping cancellation timer unit 17 causes the data transmission unit 14, the data storage unit 12, and the grouping table storage unit 16 to perform the following processing.

  That is, the grouping cancellation timer unit 17 causes the data transmission unit 14 to transmit Data # a (#b) to the ONU 2-N (2-1). Then, the grouping cancellation timer unit 17 causes the data storage unit 12 to delete Data # a (#b). Further, the grouping cancellation timer unit 17 causes the grouping table storage unit 16 to delete the network coding between the ONU 2-1 and the ONU 2-N.

  As described above, the OLT 1 receives the Data #a (#b) from the ONU 2-1 (2-N), and even after the grouping release time has elapsed, the OLT 1 transmits the Data #b (#a) to the ONU 2-N ( When not receiving from 2-1), the network coding between the ONU 2-1 and the ONU 2-N is released in a timely manner. Then, the OLT 1 transmits Data #a (#b) to the ONU 2-N (2-1). Further, the OLT 1 deletes Data # a (#b).

  Thereby, it is possible to improve the use efficiency of network coding that can be registered in the PON, and the compression of the memory area (data storage unit 12, grouping table storage unit 16) of the OLT 1 and the accompanying increase in power consumption and processing speed. A decrease can be prevented.

(Embodiment 1)
3 to 5 show network coding time charts according to the first embodiment. Here, in FIG. 3, when the data reception unit 11 receives Data # b from the ONU 2 -N before the grouping release time elapses after the data reception unit 11 receives Data # a from the ONU 2-1. Will be described. 4 and 5, when the data reception unit 11 does not receive Data # b from the ONU 2 -N even after the grouping release time has elapsed since the data reception unit 11 received Data # a from the ONU 2-1. Will be described.

  First, FIG. 3 will be described. The ONU 2-1 and ONU 2-N obtain the MAC address of the GW 3-1 and the MAC address of the GW 3-N by using the MAC address learning function, describe them in the report information for bandwidth control, and store them in the OLT 1. Send.

  The report information of the first embodiment is shown in FIG. The ONU 2-1 and the ONU 2 -N are assigned 1 and N as user LLIDs (Logic Link IDs), respectively. The Report information transmitted by the ONU 2-1 describes the MAC address of the GW 3-1 under the control of the ONU 2-1. The Report information transmitted by the ONU 2-N describes the MAC address of the GW 3-N subordinate to the ONU 2-N. However, since network coding between the ONU 2-1 and the ONU 2-N has not yet been performed, the destination information (DA: Destination Address) is described in the report information transmitted by the ONU 2-1 and the ONU 2-N. Absent.

  The data receiving unit 11 acquires the MAC address of the GW 3-1 and the MAC address of the GW 3-N from the ONU 2-1 and the ONU 2-N, respectively. The ONU registration table storage unit 15 generates and stores an ONU registration table based on the MAC address of the GW 3-1 acquired from the ONU 2-1 and the MAC address of the GW 3-N acquired from the ONU 2-N.

  FIG. 7 shows the ONU registration table of the first embodiment. For the ONU 2-1, the MAC address of the GW 3-1 under the ONU 2-1 is described. For ONU2-N, the MAC address of GW3-N under the control of ONU2-N is described.

  The GW 3-1 transmits Data # a addressed to the GW 3-N to the ONU 2-1. The ONU 2-1 describes the MAC address of the destination GW 3 -N and the MAC address of the transmission source GW 3-1 in the band control report information and transmits it to the OLT 1. The MAC address of the destination GW3-N is described as the destination address (DA) in FIG. The MAC address of the transmission source GW 3-1 is described as the transmission source address (SA: Source Address) in FIG. 6. Then, the ONU 2-1 buffers Data # a addressed to GW3-N.

  The data reception unit 11 acquires the MAC address of the destination GW3-N and the MAC address of the transmission source GW3-1 from the ONU 2-1. The grouping table storage unit 16 generates and stores a grouping table based on the MAC address of the destination GW3-N and the MAC address of the transmission source GW3-1 acquired from the ONU 2-1.

  FIG. 8 shows the grouping table of the first embodiment. The grouping table storage unit 16 determines to perform network coding between the ONU 2-1 and the ONU 2-N by finding the MAC address of the destination GW3-N and the MAC address of the transmission source GW3-1 in the ONU registration table. . For LLID (broadcast LLID) 1 for performing multicast, 1 (ONU2-1) and N (ONU2-N) are registered as a group to be multicast (user LLID).

  The OLT 1 notifies the transmission permission to the ONU 2-1, and the ONU 2-1 transmits Data # a addressed to the GW 3 -N to the OLT 1. The ONU 2-1 continues to buffer Data # a addressed to GW3-N in order to restore the desired data from the encoded data.

  The data receiving unit 11 receives Data # a addressed to GW3-N from ONU 2-1. The data storage unit 12 stores Data # a addressed to GW3-N. The grouping cancellation timer unit 17 starts measuring the grouping cancellation time from the time when the data reception unit 11 receives Data # a addressed to GW3-N from the ONU 2-1.

  GW3-N transmits Data # b addressed to GW3-1 to ONU2-N. The ONU 2-N writes the MAC address of the destination GW 3-1 and the MAC address of the transmission source GW 3-N in the report information for bandwidth control, and transmits them to the OLT 1. The MAC address of the destination GW3-1 is described as the destination address (DA) in FIG. The MAC address of the transmission source GW3-N is described as the transmission source address (SA: Source Address) in FIG. And ONU2-N buffers Data # b addressed to GW3-1.

  The data receiving unit 11 acquires the MAC address of the destination GW3-1 and the MAC address of the transmission source GW3-N from the ONU 2-N. The grouping table storage unit 16 does not need to newly generate and store a grouping table based on the MAC address of the destination GW3-1 and the MAC address of the transmission source GW3-N acquired from the ONU 2-N.

  The OLT 1 notifies the ONU 2-N of the transmission permission, and the ONU 2-N transmits Data # b addressed to the GW 3-1 to the OLT 1. The ONU 2-N continues to buffer the Data # b addressed to the GW 3-1 in order to restore the desired data from the encoded data.

  The data receiving unit 11 receives Data # b addressed to GW3-1 from ONU2-N. The data storage unit 12 stores Data # b addressed to GW3-1. The grouping cancellation timer unit 17 has not finished measuring the grouping cancellation time from the time when the data reception unit 11 receives Data # a addressed to GW3-N from the ONU 2-1.

  The encoded data generation unit 13 generates encoded Data # c obtained by combining Data # a addressed to GW3-N and Data # b addressed to GW3-1 using network coding. The data transmission unit 14 broadcasts the encoded Data # c to the ONU 2-1 and the ONU 2-N using the broadcast LLID: 1 of FIG. The data storage unit 12 deletes Data # a addressed to GW3-N and Data # b addressed to GW3-1.

  The ONU 2-1 receives the encoded Data # c from the OLT 1 and uses the buffered Data # a addressed to the GW3-N to restore the Data # b addressed to the GW3-1 from the encoded Data # c. Then, the restored Data # b addressed to GW3-1 is transmitted to GW3-1. The ONU 2-1 deletes the buffered Data # a addressed to the GW3-N.

  The ONU2-N receives the encoded Data # c from the OLT 1 and restores the Data # a addressed to the GW3-N from the encoded Data # c using the buffered Data # b addressed to the GW3-1. Then, Data # a addressed to the restored GW3-N is transmitted to the GW3-N. The ONU 2-N deletes the buffered Data # b addressed to the GW 3-1.

  Next, FIG. 4 will be described. 4 differs from FIG. 3 in that GW3-N does not transmit Data # b addressed to GW3-1 to ONU2-N.

  The grouping cancellation timer unit 17 ends the measurement of the grouping cancellation time from the time when the data reception unit 11 receives Data # a addressed to GW3-N from the ONU 2-1.

  The data transmission unit 14 transmits the Data # a addressed to the GW3-N to the ONU 2-N using the user LLID: N of FIG. 8, and uses the user LLID: 1 of FIG. A buffering release instruction is transmitted to the ONU 2-1. The data storage unit 12 deletes Data # a addressed to GW3-N. The grouping table storage unit 16 deletes the network coding between the ONU 2-1 and the ONU 2-N.

  The ONU 2-N receives the Data # a addressed to the GW3-N from the OLT 1 and transmits the received Data # a addressed to the GW3-N to the GW3-N. The ONU 2-1 receives from the OLT 1 an instruction to cancel the buffering of the ONU 2-1, and deletes the buffered Data # a addressed to the GW3-N. As a result, it is possible to prevent compression of the memory area of the ONU 2-1, an increase in power consumption and a decrease in processing speed associated therewith.

  Next, FIG. 5 will be described. FIG. 5 is different from FIG. 4 in that the data transmission unit 14 does not transmit an ONU 2-1 buffering release instruction to the ONU 2-1.

  The ONU 2-1 starts measuring the buffering release time instructed in advance from the OLT 1 from the time when the Data # a addressed to the GW 3 -N is transmitted to the OLT 1. When the ONU 2-1 transmits the Data # a addressed to the GW 3 -N to the OLT 1 and completes the measurement of the buffering release time designated in advance from the OLT 1, the ONU 2-1 addresses the Data # addressed to the GW 3 -N being buffered. Delete a. As a result, it is possible to prevent compression of the memory area of the ONU 2-1, an increase in power consumption and a decrease in processing speed associated therewith.

  The grouping cancellation time is set based on the communication amount in the PON. Specifically, the grouping cancellation time is set shorter as the communication amount in the PON is larger. More specifically, the grouping cancellation time is set based on the second to fourth embodiments.

(Embodiment 2)
In the second embodiment, the grouping release time is set longer as the time required for one network coding between the ONU 2-1 and the ONU 2-N is longer.

  The grouping table of the second embodiment is exemplarily shown in FIG. The number of communications using network coding is the number of network codings between ONUs 2 in a certain time domain. The average time interval is an average time required for one network coding between the ONUs 2 in the time domain. The safety coefficient X is a proportional coefficient for determining the grouping release time in proportion to the average time interval.

  Here, when the grouping cancellation time is shorter than the average time interval, even if the network coding between the ONUs 2 is registered, the grouping cancellation time elapses before the network coding between the ONUs 2 is completed, and the network coding between the ONUs 2 is completed. May be repeated. Therefore, the grouping release time is desirably equal to or greater than the average time interval, and the safety factor X is desirably 1 or greater.

  As described above, the second embodiment has an effect of making it difficult to delete the network coding between the ONUs 2 by securing the grouping elimination time.

(Embodiment 3)
In the third embodiment, the grouping cancellation time is set shorter as the number of network coding groups that can be newly registered in the PON is smaller.

  The depletion coefficient of Embodiment 3 is shown in FIG. The number of broadcast LLIDs that can be newly registered is S if all broadcast LLIDs are not used, and is 0 if all broadcast LLIDs are used. The depletion coefficient is a proportional coefficient for setting the actual grouping cancellation time in proportion to the reference grouping cancellation time T. The reference grouping cancellation time T is a default grouping cancellation time set in advance prior to setting the actual grouping cancellation time.

  The depletion coefficient is set to 1 if the number of broadcast LLIDs that can be newly registered is equal to or greater than the threshold value L, and the broadcast LLID is not depleted. The depletion coefficient is set to be smaller and smaller than 1 when the number of new broadcast LLIDs that can be newly registered is less than the threshold L and the number of new broadcast LLIDs that can be newly registered is smaller. . The depletion coefficient is assumed to be j when the number of broadcast LLIDs that can be newly registered is J.

  FIG. 11 shows an example of the grouping table of the third embodiment. Assume that the number of broadcast LLIDs that can be newly registered is J. The actual grouping release time is obtained by multiplying the reference grouping release time T by the depletion coefficient j. Here, as described in the second embodiment, it is desirable that the actual grouping cancellation time is equal to or longer than the average time interval.

  As described above, the third embodiment has an effect of making it difficult to deplete the broadcast LLID by shortening the grouping elimination time.

(Embodiment 4)
In the fourth embodiment, the grouping cancellation time is set to be approximately equal to a natural number times the time required for one network coding between the ONU 2-1 and the ONU 2-N.

  The grouping table of the fourth embodiment is exemplarily shown in FIG. The service / priority is a service / priority applied to network coding between the ONUs 2. The higher the service / priority, the higher the priority of the communication. When the service / priority applied to the network coding between the ONUs 2 is set, an average time v required for one network coding between the ONUs 2 in a certain time region is set. The weighting coefficient is a proportional coefficient for setting the actual grouping cancellation time in proportion to the reference grouping cancellation time T. The reference grouping cancellation time T is a default grouping cancellation time set in advance prior to setting the actual grouping cancellation time.

  Here, when the actual grouping cancellation time is n times the average time interval v (m−1 <n <m, where m is a natural number), (m−1) times of network coding between the ONUs 2 is terminated. However, the remaining one network coding between the ONUs 2 cannot be terminated due to the elapse of the actual grouping release time. Therefore, it is desirable that the actual grouping cancellation time is approximately n times (n is a natural number) the average time interval v.

  As described above, the fourth embodiment has an effect of making it difficult to delete the network coding between the ONUs 2 by securing the grouping elimination time.

(Modification)
In the first to fourth embodiments, the GW3-1 subordinate to the ONU 2-1 and the GW3-N subordinate to the ONU2-N transmit data to the OLT 1. Here, as a modification, the ONU 2-1 and the ONU 2 -N may transmit data to the OLT 1 without involving the subordinate GW 3-1 of the ONU 2-1 and the subordinate GW 3 -N of the ONU 2 -N.

  In the second embodiment to the fourth embodiment, each embodiment is used alone. Here, as a modification, the second to fourth embodiments may be used in combination.

  The optical subscriber line terminating apparatus and the network coding method thereof according to the present invention are useful in applying PON in a smart community or the like that efficiently performs local energy management using communication technology.

1: OLT
2: ONU
3: GW
4: OPS
5: Optical fiber transmission line 6: Optical fiber transmission line 11: Data receiving unit 12: Data storage unit 13: Encoded data generation unit 14: Data transmission unit 15: ONU registration table storage unit 16: Grouping table storage unit 17: Grouping Release timer section

Claims (6)

An optical subscriber line terminating device to which a first optical network terminating device and a second optical network terminating device are connected in a passive optical network,
Receiving, from the first optical network termination device, first data having the first optical network termination device or its subordinate device as a transmission source and the second optical network termination device or its subordinate device as a destination, A data receiving unit that receives, from the second optical network termination device, second data having the second optical network termination device or its subordinate device as the transmission source and the first optical network termination device or its subordinate device as the destination When,
A destination of the first data and the second data is extracted from the first data and the second data, and any one of the optical network termination devices is selected from the destinations of the first data and the second data. A grouping table storage unit for generating a grouping table indicating whether to perform network coding between;
An encoded data generation unit that generates encoded data obtained by combining the first data and the second data using network coding;
Before the data receiving unit receives the first data from the first optical network termination device and before a predetermined time elapses, the data receiving unit transmits the second data to the second optical data. When received from the network terminator, the coded data generator waits for the coded data to be generated, and the coded data is sent to the first optical network terminator and the second according to the grouping table . While broadcasting to an optical network termination device and broadcasting the encoded data, the first data, the second data, the encoded data and the grouping table are deleted ,
Even after the predetermined time has elapsed since the data reception unit received the first data from the first optical network termination device, the data reception unit received the second data as the second data. when not received from the optical network termination apparatus, without the encoded data generating unit to generate the encoded data, transmits the first data to the second optical network terminator according to the grouping table, wherein said After the first data is transmitted to the second optical network terminator, the first optical network terminator is instructed to cancel the buffering of the first data, and the first data and the grouping table are displayed. A data transmitter to be deleted ;
An optical subscriber line termination device comprising:   2. The optical subscriber line terminating apparatus according to claim 1, wherein the predetermined time is set based on a communication amount in the passive optical network.   2. The predetermined time is set longer as a time required for one network coding between the first optical network termination device and the second optical network termination device is longer. Or an optical subscriber line terminating device according to 2;   4. The optical subscriber line termination according to claim 1, wherein the predetermined time is set to be shorter as the number of network coding groups that can be newly registered in the passive optical network is smaller. apparatus.   The predetermined time is set to be approximately equal to a natural number times a time required for one network coding between the first optical network termination device and the second optical network termination device. An optical subscriber line terminating device according to any one of claims 1 to 4. An optical subscriber line terminating device according to any one of claims 1 to 5,
The first data is transmitted to the optical subscriber line terminator, the encoded data is received from the optical subscriber line terminator, and the first data is used to obtain the first data from the encoded data. A first optical network terminator for restoring two data;
The second data is transmitted to the optical subscriber line terminator, the encoded data is received from the optical subscriber line terminator, and the second data is used to generate the second data from the encoded data. A second optical network terminator that restores one data;
A passive optical network system comprising:

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