JP6477072B2 - Optical communication apparatus and optical communication network system - Google Patents

Description

  The present invention relates to an optical communication apparatus and an optical communication network system used in a PON (Passive Optical Network) system or the like defined by IEEE (Institute of Electrical and Electrical Engineers) or ITU-T (International Telecommunication Union Telecommunication Standardization Sector).

  A PON (Passive Optical Network) branches optical fibers from an Optical Line Terminal (OLT) installed in a central office, an Optical Network Unit (ONU) installed in a user's house, and an optical fiber laid from the central office to the user It consists of an optical splitter. Here, a general PON configuration is shown in FIG.

  The OLT 112 is connected to the ONUs 114 via the optical fiber 118 and the optical splitter 116, and by installing the optical splitter 116, a plurality of ONUs 114 are connected to one OLT 112.

  The OLT 112 has a function of transferring the signal from the ONU 114 to the upper network 120, and conversely transferring the signal from the upper network 120 to the ONU 114. Also, it has a control monitoring function of the PON section and the ONU 114. In order to execute these functions, the OLT 112 performs an upper network interface (IF) 124, a frame control unit 126, an optical transmission / reception unit 128, a reception buffer unit 130, a transmission buffer unit 132, and a DBA (Dynamic Bandwidth Allocation) processing unit 134. Etc.

  On the other hand, the ONU 114 has a function of transferring a signal from the OLT 112 to the user terminal and transferring a signal from the user terminal to the OLT 112.

  The downstream communication (communication from OLT 112 to ONU 114) in the PON section is multiplexed by TDM (Time Division Multiplexing) so that the signals to each ONU 114 do not overlap in time. In addition, since upstream communication in the PON section (communication from ONU 114 to OLT 112) is multiplexed by the optical splitter 116, it is necessary to control so that upstream signals from each ONU 114 do not collide at the optical splitter 116. Therefore, as described in Patent Document 1, transmission permission is notified from the OLT 112 to each ONU 114, and control is performed so as not to cause collision by TDMA (Time Division Multiple Access) that temporally separates upstream signals from each ONU 114. It is carried out. The procedure of this upstream communication collision avoidance is shown in FIG.

  As shown in FIG. 5, the OLT 112 sends a control frame called “GATE” (“G” shown in FIG. 5) indicating transmission permission from the DBA processing unit 134 of the OLT 112 to each ONU 114. The GATE frame contains the data transmission start time and the amount of transmission data to the ONU 114, that is, the information that it is possible to send an uplink signal from any time, and the ONU 114 transmits an uplink signal according to the instruction. . The first GATE frame describes only the transmission start time of a control frame called "REPORT" ("R" shown in FIG. 5), and does not include information about data, but the second and subsequent GATE frames contain REPORT frames. , The transmission start time of the data frame ("D" shown in FIG. 5) and the amount of transmission data.

  The ONU 114 transmits to the OLT 112 the amount of data waiting for transmission, which is stored in the buffer of the ONU 114 by the REPORT frame.

  From the accumulated data amount of each ONU 114, the upstream band (uplink transmission start time and transmission amount of ONU 114) to be allocated to each ONU 114 is calculated.

  The OLT 112 accommodates and transmits the calculated value as a REPORT frame, a transmission start time of a data frame, and transmission data amount information in a GATE frame.

  The ONU 114 notifies the amount of uplink data stored in the buffer again for bandwidth allocation in the next DBA cycle at the REPORT transmission start time specified in the received GATE frame. Also, transmit uplink data.

  The DBA period (period of band control) is a period for the OLT 112 to collect and calculate the accumulated data amount of each ONU 114 for allocating a band to the ONU 114. The calculation result of the allocation band in a certain period is reflected by inserting it into the GATE frame in the next DBA period and notifying the ONU 114.

Unexamined-Japanese-Patent No. 2010-252062

  However, in the configuration of the PON as in Patent Document 1, although it is necessary to add the PON as the number of ONUs 114 is added, there is a concern about an increase in mounting space and an increase in cost and power consumption.

  The present invention has been made in consideration of the above facts, and aims to reduce the mounting space and reduce the cost and power consumption.

In the optical communication apparatus according to the present invention, a plurality of connection units for connecting a plurality of subscriber apparatuses and a predetermined higher-level apparatus by optical communication, and each of the connection sections connect the subscriber apparatuses to the upper apparatus And an allocating unit for allocating a transmission permission time zone for permitting transmission of information to the connection unit, the allocation unit allocates different transmission permission time zones to the respective connection units, and a frame for allocating the transmission permission time zone The transmission / reception of signals is performed by dividing each of the connection portions, and while the frame signal is being transmitted / received, the transmission permission time zone of another connection portion is calculated .

  In the optical communication network system according to the present invention, the optical communication device described above, a plurality of subscriber-side devices that transmit and receive information to and from the optical communication device, the optical communication device, and the plurality of subscriptions And an optical splitter provided between the user side device and each of the optical communication device and the plurality of subscriber side devices via an optical fiber.

  According to the present invention, the mounting space can be reduced, and the cost and power consumption can be reduced.

FIG. 1 is a block diagram showing a schematic configuration of an optical communication network system according to an embodiment of the present invention. It is a time chart which shows the procedure of the process of the allocation calculation process of the zone | band for every PON in the optical communication network system which concerns on 1st Embodiment. It is a time chart which shows the procedure of the process of the allocation calculation process of the zone | band for every PON in the optical communication network system which concerns on 2nd Embodiment. It is a figure which shows the structure of a general PON. It is a time chart which shows the procedure of uplink communication collision avoidance by TDMA.

  Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a view showing a schematic configuration of an optical communication network system according to the present embodiment.

First Embodiment
The optical communication network system 10 according to the present embodiment includes an OLT 12, an ONU 14, an optical splitter 16, and an optical fiber 18.

  The OLT 12 corresponds to the optical communication device of the present invention, and is installed in the central office, and the ONU 14 corresponds to the subscriber-side device of the present invention, and is installed in the user's home. An optical splitter 16 is provided between the OLT 12 and the ONU 14. The optical splitter 16 is a device that splits and combines optical signals, and the OLT 12 and the optical splitter 16, and the optical splitter 16 and the ONU 14 are connected by an optical fiber 18, respectively.

  That is, the OLT 12 is connected to the plurality of ONUs 14 through the optical fiber 18 and the optical splitter 16, and one OLT 12 and the plurality of ONUs 14 are connected by the optical splitter 16. The number of ONUs 14 connected to the optical splitter 16 is not limited to a plurality, and one or more ONUs 14 are connected.

  The ONU 14 has a role of converting an optical signal from the OLT 12 into an electric signal and converting an electric signal from a user's terminal device (for example, a personal computer or the like) into an optical signal and transferring the optical signal to the OLT 12. The OLT 12 has a role of transferring an optical signal from the ONU 14 to a higher-level device (for example, the Internet), a role of transferring a signal from the higher-level device to the ONU 14, and a role of controlling and monitoring the PON section and the ONU 14.

  By the way, although it is general that a single PON is accommodated in the PON interface board of the OLT 10 in the PON system, in the present embodiment, a plurality of PONs are intended to improve accommodation efficiency and save power. Is housed. In the following, an example in which two PONs (PON # 1 and PON # 2) are accommodated is shown.

  The OLT 12 in the optical communication network system 10 according to the present embodiment includes upper network interface (IF) units 20A and 20B, frame control units 22A and 22B, optical transmission and reception units 24A and 24B, reception buffer units 26A and 26B, and transmission buffer units. 28A and 28B are provided for each PON (PON # 1 and PON # 2). Further, one DBA processing unit 30 is provided for a plurality of PONs. The upper network interface (IF) units 20A and 20B, frame control units 22A and 22B, light transmission / reception units 24A and 24B, reception buffers 26A and 26B, and transmission buffers 28A and 28B correspond to the connection unit of the present invention. On the other hand, the DBA processing unit 30 corresponds to the allocation unit of the present invention.

  The upper network IF units 20A and 20B correspond to the upper device connection unit of the present invention, and transmit and receive signals to and from the upper network as the upper device. Specifically, the upper network IF units 20A and 20B terminate the signal from the upper network or convert the signal from the frame control units 22A and 22B into the format of the upper network and transmit the signal.

  The frame control units 22A and 22B correspond to the control unit of the present invention, and control the communication between the upper network and the ONU 14. Specifically, the control frame is inserted into the frame data input from the upper network, or the control frame is extracted from the signals from the light transmitting / receiving units 24A and 24B.

  The optical transmission / reception units 24A and 24B convert an electrical signal into an optical signal, transmit the optical signal to the ONU 14, receive the optical signal from the ONU 14, and convert the optical signal into an electrical signal. That is, the optical transmission / reception units 24A and 24B convert the signals from the frame control units 22A and 22B into optical signals and transmit them to the ONU 14, or convert the optical signals from the ONU 14 into electrical signals to convert the frame control units 22A and 22B. Send to

  The reception buffer units 26A and 26B temporarily accumulate the control frames extracted by the frame control units 22A and 22B and pass them to the DBA processing unit 30.

  The transmission buffer units 28A and 28B temporarily accumulate the control frame from the DBA processing unit 30 in order to multiplex the control frame with the data frame in the frame control units 22A and 22B.

  Then, the DBA processing unit 30 shares a plurality of PONs, performs GATE frame and REPORT frame processing, and performs band calculation processing. In addition, the DBA processing unit 30 performs processing for allocating different transmission permission time zones to each PON so that no collision of upstream transmission from the ONU 14 occurs.

  Here, the procedure of the process of the allocation calculation of the band for each PON in the optical communication network system 10 according to the present embodiment configured as described above will be described. FIG. 2 is a time chart showing a procedure of processing of bandwidth allocation calculation for each PON in the optical communication network system 10 according to the first embodiment.

  First, as a first step, the OLT 12 sequentially transmits GATE frames (“G” shown in FIG. 2) from the DBA processing unit 30 to all the ONUs 14. The GATE frame includes the transmission start time and the amount of transmission data of the REPORT frame ("R" shown in FIG. 2) and the data frame ("D" shown in FIG. 2). The time information can be sequentially received on the OLT 12 side. Also, these pieces of information are generated based on the result calculated in the previous DBA cycle. FIG. 2 shows an example in which the GATE frame of PON # 2 is transmitted after the transmission of the GATE frame of PON # 1.

  As a second step, each ONU 14 that has received the GATE frame transmits information on the amount of data accumulated so far as a REPORT frame at a designated time. Similarly, data frames are transmitted at designated times.

  In the third step, when the REPORT frames are received from all ONUs 14 under the control of one PON (PON # 1), the DBA processing unit 30 starts an operation for obtaining an allocation band.

  Also, as a fourth step, calculation is desired to be started when REPORT frames are received from all ONUs 14 under the other PON (PON # 2), but calculation processing is still performed in one PON (PON # 1). As it is being implemented, it will be in a waiting state. The operation is started after the operation of one PON (PON # 1) is completed.

  Then, as the fifth step, one DBA cycle is ended when the computation of both PONs is completed, and the process shifts to the next DBA cycle.

  By sequentially repeating this procedure, control is performed by the OLT 12 so that the upstream data from each ONU 14 does not collide.

  As described above, by accommodating a plurality of PONs and performing control so that upstream data from each ONU 14 does not collide, it is possible to increase the number of ONUs 14 joined to the OLT 12. In addition, even if the number of slots accommodating the PON interface board is a limited number, a plurality of PONs can be accommodated, and therefore, the number of ONUs 14 joined to the OLT 12 can be increased.

  Further, by sharing the DBA processing unit 30 with a plurality of PONs, it is possible to reduce the mounting space and the cost and the power consumption.

  In the above procedure, the GATE frame transmission, the REPORT frame reception, and the DBA calculation are respectively performed by the DBA processing unit 30 since they can not simultaneously execute the same processing.

Second Embodiment
As in the first embodiment, when a plurality of PONs are accommodated in the PON interface board and the DBA processing unit 30 is shared, the bandwidth allocation calculation for each PON is sequentially processed as described above. Therefore, the total calculation time is approximately doubled compared to the case of processing by itself as in the conventional case (FIG. 5). Also, the ONU 14 has to store data until the transmittable time allocated in the GATE frame of the next DBA cycle after transmitting the REPORT frame, which causes the problem of increase in memory size and delay. is there.

  Therefore, in the second embodiment, transmission and reception of frame signals (GATE frame and REPORT frame) for allocating a transmission permission time zone is performed by dividing each PON, and transmission and reception of frame signals are performed while another PON transmission is performed. It is designed to calculate the permission time zone. The optical communication network system 10 according to the second embodiment has the same configuration as that of the first embodiment, and thus detailed description will be omitted.

  Subsequently, a procedure of processing of bandwidth allocation calculation for each PON in the optical communication network system 10 according to the second embodiment will be described. FIG. 3 is a time chart showing the procedure of processing of bandwidth allocation calculation for each PON in the optical communication network system 10 according to the second embodiment.

  In the first embodiment, an example in which GATE frames are transmitted to all ONUs 14 subordinate to each PON of the OLT 12 and after all REPORT frames that are responses are received, the DBA operation of each PON is sequentially performed Indicated. That is, the DBA period is required for the time from the transmission of the GATE frame to the reception of the REPORT frame and the DBA calculation time of each PON.

  On the other hand, in the second embodiment, transmission and reception of GATE frames and REPORT frames are performed separately for each PON, and DBA operations of another PON are performed while transmission and reception of those frames are performed. As a result, as shown in FIG. 3, the DBA period can be shortened only by the time from the transmission of the GATE frame of each PON to the reception of the REPORT frame and the DBA calculation time. The detailed procedure is shown below.

  First, as a first step, the OLT 12 of one PON (PON # 1) indicates transmission permission of the REPORT frame ("R" shown in FIG. 3) and the data frame ("D" shown in FIG. 3) to the ONU 14 The GATE frame ("G" shown in FIG. 3) is transferred from the DBA processing unit 30 of the OLT 12 to the transmission buffer unit 28A. Then, the transferred GATE frame is multiplexed with the data frame from the upper network IF unit 20A by the frame control unit 22A, converted into light by the optical transmission / reception unit 24A, and transmitted to the ONU 14.

  As the second step, the ONU 14 having received the GATE frame transmitted from the optical transmission / reception unit 24A in the first step describes the amount of uplink data accumulated so far in the REPORT frame according to the described REPORT transmission start time information. Send to the OLT 12 Also, according to the data transmission start time and the amount of transmission data, the transmission-waiting upstream data accumulated in the buffer of the ONU 14 is transmitted. The OLT 12 converts the received REPORT frame into an electric signal by the optical transmission / reception unit 24A, extracts it by the frame control unit 22A, and stores it in the reception buffer unit 26A.

  As a third step, the DBA processing unit 30 uses the REPORT frame reception of one PON (PON # 1) as a trigger, and the PON frame to the ONU 14 in the other PON (PON # 2) from the DBA processing unit 30 of the OLT 12 Transfer to the transmission buffer unit 28B. The transferred GATE frame is multiplexed with the data frame from the upper network IF unit 20B by the frame control unit 22B, converted into light by the optical transmission / reception unit 24B, and transmitted to the ONU 14. Here, in the present embodiment, reception of a REPORT frame of one PON (PON # 1) (“R process” in FIG. 3) and transmission of a GATE frame of the other PON (PON # 2) (“FIG. G) ") at the same time. In FIG. 3, the processing of the REPORT frame of one PON (PON # 1) (R processing of FIG. 3) and the processing of the GATE frame of the other PON (PON # 2) (G processing of FIG. 3) Since it is done at the same time, it is shown as being done overlapping, but it is not overlapping because it can not be processed simultaneously. For example, after either one is completely processed, the other is entirely processed. Alternatively, the R process and the G process may be performed alternately. Alternatively, priority may be given to the G process and the R process may be waited until the buffer overflows. Alternatively, the R process may be waited until necessary. Either of these makes it possible to shorten the processing time.

  Thereafter, as the fourth step, the DBA processing unit 30 reads the REPORT frame received in the second step from the reception buffer unit 26A, and based on the amount of data waiting for transmission accumulated in the buffer of each ONU 14 described therein. The upstream band (uplink transmission start time and transmission amount of ONU 14) to be allocated to each ONU 14 is calculated.

  Further, as the fifth step, in the other PON (PON # 2), the amount of uplink data accumulated so far according to the transmission start time information of the REPORT frame in which the ONU 14 which received the GATE frame of the third step is described And transmit to the OLT 12. Also, according to the data transmission start time and the amount of transmission data, uplink data waiting for transmission accumulated in the buffer of the ONU 14 is transmitted. The OLT 12 converts the REPORT frame from each ONU 14 into an electric signal by the optical transmission / reception unit 24B, extracts it by the frame control unit 22B, and stores it in the reception buffer unit 26B.

  Next, as a sixth step, in one PON (PON # 1), the GATE frame including the upstream bandwidth information to be allocated to each ONU 14 calculated above is triggered by the start of a new DBA cycle as a trigger and the DBA processing of the OLT 12 It transfers from the part 30 to the transmission buffer part 28A. Then, the transferred GATE frame is multiplexed with the data frame from the upper network IF unit 20A by the frame control unit 22A, converted into light by the optical transmission / reception unit 24A, and transmitted to the ONU 14.

  Thereafter, as a seventh step, the DBA processing unit 30 reads the REPORT frame received in the fifth step from the reception buffer unit 26B, and from the amount of data waiting for transmission accumulated in the buffer of each ONU 14 described therein, The upstream band (uplink transmission start time and transmission amount of ONU 14) to be allocated to each ONU 14 is calculated.

  As an eighth step, the ONU 14 having received the GATE frame in the sixth step describes the amount of uplink data accumulated so far in the REPORT frame and transmits it to the OLT 12 according to the described transmission start time information of the REPORT frame. Also, according to the data transmission start time and the transmission data amount, the transmission waiting upstream data accumulated in the buffer of the ONU 14 is transmitted. The OLT 12 converts the REPORT frame from each ONU 14 into an electric signal by the optical transmission / reception unit 24A, extracts it by the frame control unit 22A, and stores it in the reception buffer unit 26A.

  As the ninth step, in the other PON (PON # 2), the GATE frame including the upstream bandwidth information to be allocated to each ONU 14 calculated above is triggered by the start of a new DBA cycle from the DBA processing unit 30 of the OLT 12 Transfer to the transmission buffer unit 28B. Then, the transferred GATE frame is multiplexed with the data frame sent from the upper network IF unit 20B in the frame control unit 22B, and is transmitted to the ONU 14 from the optical transmission / reception unit 24B. Thereafter, the fourth to ninth steps are repeated.

  As described above, according to the present embodiment, the DBA processing unit 30 is shared by the OLT 12 accommodating a plurality of PONs, and transmission and reception of GATE frames and REPORT frames are divided into PONs. Further, by performing the DBA operation of another PON while performing the transmission and reception of those frames, the DBA cycle can be shortened more than in the first embodiment, and the data delay can be expected to be shortened.

  In the above embodiment, an example in which two PONs are accommodated in the PON interface board of the OLT 12 has been described. However, the number of PONs is not limited to two, and three or more PONs may be used in a single PON interface board. You may store it.

  Further, the processing of each part of the OLT 12 in the above embodiment may be processing performed by hardware, may be processing performed by software performed by executing a program, or may be processing combining the both. .

  Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the scope of the invention.

10 Optical Communication Network System 12 OLT
14 ONU
16 Optical Splitter 18 Optical Fiber 20A, 20B Upper Network IF
22A, 22B Frame control unit 24A, 24B Optical transmission / reception unit 26A, 26B Reception buffer unit 28A, 28B Transmission buffer unit 30 DBA processing unit

Claims (5)

A plurality of connection units for connecting a plurality of subscriber apparatuses and a predetermined higher-level apparatus by optical communication;
An assignment unit for assigning a transmission permission time zone for permitting transmission of information from the subscriber unit to the host apparatus to each of the connection units;
Equipped with
The allocation unit allocates different transmission permission time zones to each of the connection units, divides transmission and reception of a frame signal for allocating the transmission permission time period into the connection units, and transmits and receives the frame signals. An optical transmission device for calculating the transmission permission time zone of another connection part while the communication is in progress. The plurality of connections are:
A host device connection unit that transmits and receives signals to and from the host device;
It is provided between the subscriber side device and the host device connection unit, converts a signal received from the host device into an optical signal and transmits it to the subscriber side device, and the subscriber side device transmits the optical signal An optical transmission / reception unit that receives, converts to an electrical signal, and outputs the signal to the host device connection unit;
A control unit connected to each of the light transmitting / receiving unit and the upper apparatus connection unit to control communication between the upper apparatus and the subscriber apparatus;
The optical communication device according to claim 1, wherein The allocation unit transmits a first of the first frame signal for notifying the transmission permitted time period as said frame signal to the subscriber unit, the first of the second frame corresponding to the first of the first frame signal upon receiving a signal from the subscriber unit, according to claim 1 for transmitting Oite, to the subscriber units of the third frame signal for notifying the transmission permitted time period to another of said connecting portion Or the optical communication apparatus as described in 2 .   The optical communication apparatus includes at least a first connection unit and a second connection unit as the plurality of connection units,
  The allocation unit calculates the transmission permission time zone for the first connection unit prior to the second connection unit, and transmits and receives the frame signal at the second connection unit. Calculation of the transmission permission time zone for the first connection unit while
  The optical communication device according to any one of claims 1 to 3, characterized in that: The optical communication device according to any one of claims 1 to 4.
A plurality of subscriber side devices that transmit and receive information to and from the optical communication device;
An optical splitter provided between the optical communication device and the plurality of subscriber side devices, and connected to each of the optical communication device and the plurality of subscriber side devices via an optical fiber;
Optical communication network system equipped with

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