JP2011066615A - Communication equipment, communication system, method for processing received data, and program of equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically switch the validation and invalidation of an error correction function without having to insert a dedicated area into a signal to be transmitted. <P>SOLUTION: When it is detected that a correction encoding part for error correction is included in received data, data that are not subjected to error correction by an error correction step of performing prescribed error correction is output, and when the correction encoding part for error correction is not detected from the received data, data are output without performing error correction by the error correction step. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication apparatus having an error correction function in communication, such as a station side terminal (OLT) in a PON (Passive Optical Network) system and a subscriber side terminal (ONU). The present invention relates to a communication system, a received data processing method, and an apparatus program.

  The communication system of 10G-EPON (10 Gigabit Ethernet (registered trademark) Passive Optical Network) is defined by IEEE Std 802.3. Although it is a communication method based on 10 Gigabit Ethernet and premised on an error correction function, its format is not designed to be used simultaneously with 10 Gigabit Ethernet.

  As a PON system that performs such error correction, the OLT detects a synchronization delimiter (delimiter) from the ONU to establish frame synchronization based on the frame boundary, and the ONU detects the delimiter from the OLT. Then, frame synchronization is established based on the frame boundary, and data is subjected to error correction decoding using the FEC (Forward Error Correction) frame in which synchronization is established (see, for example, Patent Document 1).

  In addition, a bit indicating whether the error correction function is enabled or disabled is inserted into a predetermined area of the header in the frame to be transmitted, and transmitted, and the error correction function is enabled to the receiving device. There is one that attempts to set / invalidity (for example, see Patent Document 2).

JP 2008-67252 A JP 2000-196552 A

  In the PON system, the ONU transmits and receives optical signals from the OLT at various locations via a coupler. For this reason, in order to enable or disable the error correction function, it is unrealistic to directly set the ONUs in various places, and it is desirable to remotely input the settings from the OLT to the ONUs. However, if there is a difference in the error correction function between the OLT and the ONU, the signal does not conduct, so the signal does not conduct during the setting change, and the change operation itself may not be completed.

  In addition, the above-described Patent Document 1 attempts to establish frame synchronization more reliably by detecting a synchronization delimiter or a delimiter, and automatically switches between enabling and disabling the error correction function. It wasn't even taken into account.

  In addition, in the above-described Patent Document 2, if the dedicated device is not used for both the transmission side device and the reception side device, the validity of the error correction function cannot be remotely set in the reception side device. It has not been taken into consideration to make it function even when it is an operation of a standard such as IEEE, or to have compatibility with products of other companies.

  The present invention has been made in view of such a situation, and a communication apparatus and communication that can automatically switch between enabling and disabling an error correction function without the need to insert a dedicated area into a signal to be transmitted It is an object of the present invention to provide a system, a received data processing method, and an apparatus program.

  In order to achieve such an object, the communication device according to the present invention, when it is detected that error correction means for performing a predetermined error correction and the correction code portion for error correction is included in the received data, Data that has been error-corrected by the error correction means is output, and when a correction code portion for error correction is not detected from the received data, an operation selection means for outputting without error correction by the error correction means is provided. Features.

  The communication system according to the present invention is characterized in that a plurality of the communication devices according to the present invention described above are connected to the communication device according to the present invention described above via a branching unit.

  In addition, the received data processing method according to the present invention, when it is detected that the received data includes a correction code portion for error correction, the data that has been error-corrected by an error correction step for performing a predetermined error correction Is output without performing error correction in the error correction step when no correction code portion for error correction is detected from the received data.

  In addition, the program of the communication device according to the present invention, when it is detected that the received data includes a correction code portion for error correction, the data that has been error-corrected by an error correction procedure for performing a predetermined error correction When the correction code part for error correction is not detected from the received data, the computer of the communication apparatus is caused to execute a procedure for outputting without error correction by the error correction procedure.

  As described above, according to the present invention, it is possible to automatically switch between enabling and disabling the error correction function without the need to insert a dedicated area into the transmitted signal.

It is a block diagram which shows the structural example of the optical communication system as this embodiment. It is a figure which shows the frame format at the time of the error correction function effective in 10G-EPON. It is a figure which shows the frame format of 10 Gigabit Ethernet. It is a block diagram which shows the structure of the reception error correction part 41 of ONU4. It is a figure which shows the conditions for the selection logic by the main signal selection part 46 as a table. 5 is a flowchart showing a state transition of selection logic of a main signal selection unit 46. It is a block diagram which shows the structure of the reception error correction part 11 of OLT1.

  Next, an embodiment in which a communication device, a communication system, a received data processing method, and a device program according to the present invention are applied to a 10G-EPON system will be described in detail with reference to the drawings.

First, an outline of the present embodiment will be described.
This embodiment provides an FEC mode automatic selection method for automatically selecting a downlink error correction function in an ONU constituting a 10G-EPON.

  Generally, according to IEEE802.3av, an error correction function is essential in 10G-EPON, and a light reception level specification of an optical module used there is determined on the assumption that the error correction function is enabled. This indicates the worst-case specification where the light reception level is low and there are many errors. However, the error correction function does not work at light levels where there is not enough error, and the usable bandwidth is wasted for the error correction code. Is done.

  Therefore, it is possible to select valid / invalid for error correction, and by operating as 10 Gigabit Ethernet when it is invalid, a 10G-EPON network is designed with a light reception level that does not cause sufficient errors, and the usable bandwidth is increased by removing the error correction function. It is possible to operate.

  Here, the 10G-EPON error correction function is a modification of the 66B frame of 10 Gigabit Ethernet, and the transmission path format is not compatible. Therefore, the encoding side and the correction side indicate whether the function is enabled / disabled. Must be matched.

  If the error correction function is to be disabled after configuring the network with the OLT and ONU in the state where the error correction function is enabled and starting the operation, the setting must be changed to the ONU distributed to the OLT and various places. If the error correction settings are different, the data cannot be normally transferred between the OLT and the ONU due to the difference in the transmission path format, so there is a possibility that the ONU will be in an unknown state as seen from the OLT during the remote setting change.

  Therefore, in this embodiment, all ONUs connected to the OLT determine the presence or absence of the FEC block in 66B block synchronization, and select whether to enable or disable the correction function. Enable / disable can be changed during operation.

  Next, the configuration of the present embodiment will be described in detail. FIG. 1 shows a configuration example of an optical communication system as the present embodiment.

  In the optical communication system according to this embodiment, as shown in FIG. 1, a plurality of ONUs 4 are connected to an OLT 1 via an optical transmission path 2 using an optical fiber or the like and an optical coupler 3 that is an optical branching unit. Composed.

  In FIG. 1, reference numeral 1 denotes an optical line terminal (OLT) in 10G-EPON. The OLT 1 includes a PON interface to be connected to the subscriber side network and a service node interface (SNI) that is an interface to the operator side network side. Also, an OLT correction encoding unit 11 is provided to perform error correction of received data.

  Reference numerals 4a, 4b,... In the downstream direction indicate optical network units (ONUs) in EPON. The ONU 4a and the ONU 4b include a PON interface connected to the provider side network side and a User Node Interface (UNI) that is an interface to the subscriber side network side. Also, an ONU reception error correction unit 41 is provided, and error correction of received data is performed.

  The main signal input from the SNI is output as an optical signal from the PON interface of the OLT 1 and is branched from the optical transmission path 2 by the optical coupler 3 to reach each ONU 4. At this time, if the error correction function is valid as a general operation, the OLT 1 adds an error correction code to the received signal from the SNI and outputs it. In this case, the ONU processes the main signal with an error correction code.

  Similarly, a signal input from the UNI is output as an optical signal from the PON interface of the ONU 4 and reaches the OLT 1 via the optical transmission line 2 and the optical coupler 3. The ONU 4 adds an error correction code to the received signal from the UNI and outputs it. In the OLT 1, a main signal with an error correction code is processed.

  FIG. 2 shows a frame format when the error correction function is valid in 10G-EPON. The 10G-EPON error correction frame format is composed of a data portion and a correction code portion, and is configured by arranging a plurality of 66-bit unit blocks. The correction code part is a block generated from the data part by an encoding algorithm such as Reed-Solomon.

  Each 66-bit block is composed of a 2-bit synchronization header (Sync Header) and the remaining 64-bit data. The data part and the correction code part are distinguished by the synchronization header. When the synchronization header is “01” or “10”, the data part is a data part. When the synchronization header is “00” or “11”, the data part is a correction code part.

FIG. 3 shows a frame format of 10 Gigabit Ethernet. The 10 Gigabit Ethernet frame format is composed of a continuous data portion and a plurality of 66-bit unit blocks arranged.
Each 66-bit block is composed of a synchronization header of the first 2 bits and the remaining 64-bit data. The synchronization header can take only “01” or “10”, and “00” or “11” is treated as a synchronization header error.

  FIG. 4 shows the configuration of the reception error correction unit 41 of the ONU 4. The ONU reception error correction unit 41 includes an FEC synchronization / synchronization detection unit 42, an error correction processing unit 43, a 10 GbE synchronization / synchronization detection unit 44, an error correction bypass unit 45, and a main signal selection unit 46. The The arrows in FIG. 4 indicate the flow of the main signal, and indicate that the main signal is transferred from right to left in FIG.

The FEC synchronization / out-of-synchronization detection unit 42 is a module that detects the synchronization of the FEC frame in 10G-EPON. This detection corresponds to the IEEE 802.3av FEC Block Synchronizer.
The error correction processing unit 43 is an error correction module that uses a Reed-Solomon code or the like and performs error correction defined in a standard such as IEEE.

  The FEC synchronization / synchronization detection unit 42 and the error correction processing unit 43 can process only when the FEC synchronization / synchronization detection unit 42 receives a signal in the 10G-EPON error correction frame format by FEC synchronization.

  The 10 GbE synchronization / out-of-sync detection unit 44 is a module that detects frame synchronization in 10 Gigabit Ethernet. This detection corresponds to IEEE 802.3 clause 49 Block Synchronizer.

  The error correction bypass unit 45 is a module that transfers the frame to the subsequent main signal selection unit 46 as it is. That is, it is simply passed to the subsequent processing unit without special processing such as error correction.

  The main signal selection unit 46 selects one of the data of the error correction processing unit 43 and the error correction bypass unit 45 and transfers it to the subsequent module.

FIG. 5 shows the conditions for selection logic by the main signal selector 46 in a table.
The main signal selection unit 46 discriminates three types of states “in asynchronous”, “in 10 GbE synchronization”, and “in FEC synchronization”, and performs operation selection according to each state.

  “Unsynchronized” indicates a state in which the frame is not synchronized with the 10G-EPON error correction frame or the 10 Gigabit Ethernet frame. In this state, neither the data part shown in FIGS. 2 and 3 nor the correction code part can recognize the received data in any 66-bit block.

  “During 10 GbE synchronization” indicates a state in which the data portion is synchronized with a 10 Gigabit Ethernet frame which is a frame format configured continuously. That is, as shown in FIG. 3, a predetermined number or more of 66-bit unit blocks indicating the data part are continuously detected, and a predetermined number of 66-bit unit blocks indicating the correction code part are not continuously detected.

  “FEC in sync” refers to a state in which the FEC is synchronized with a 10G-EPON error correction frame that is a frame format composed of a data portion and a correction code portion. That is, as shown in FIG. 2, a predetermined number or more of 66-bit blocks indicating the data portion are continuously detected, and a predetermined number of 66-bit blocks indicating the correction code portion are also continuously detected. .

  The main signal selection unit 46 transfers the main signal from the error correction bypass unit to the subsequent module in the “asynchronous” and “10 GbE synchronous” states. In the “FEC synchronized” state, the main signal from the error correction processing unit is transferred to the subsequent module.

  The configuration for transmitting a signal in the ONU is the same as that of a general ONU, and is not directly related to the features of the present invention, and therefore will be omitted. This embodiment shows a method of automatically selecting whether the error correction function is valid or invalid in the receiving section in the PON section of the OLT and ONU.

  Next, the data reception operation in the ONU 4 according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the state transition of the selection logic of the main signal selection unit 46.

  The ONU 4 needs to establish synchronization for data reception prior to data reception and error correction.

  First, since the ONU 4 is not synchronized after the operation is started such as when the power is turned on, the main signal selection unit 46 is in an asynchronous state (step S1).

  When the 10 GbE synchronization / out-of-synchronization detection unit 44 of the ONU reception error correction unit 41 continuously detects a predetermined number of synchronization headers indicating data frames (step S <b> 2; Yes), the main signal selection unit 46 continues the data unit. The operation state during the 10 GbE synchronization, which is in a state of being present (step S4).

  During 10 GbE synchronization, the 10 GbE synchronization / out-of-synchronization detection unit 44 monitors whether or not the 10 GbE synchronization that is the synchronization for receiving the continuous data format is lost. When 10 GbE synchronization is lost, the process returns to the asynchronous state of step S1 (step S5).

  When the FEC synchronization / out-of-sync detection unit 42 of the ONU reception error correction unit 41 continuously detects a predetermined number of synchronization headers indicating data frames and continuously detects a predetermined number of synchronization headers indicating FEC frames (step S3; Yes). ), The main signal selector 46 enters an operation state during FEC synchronization, which is a state in which the data format of the data part and the correction code part is received (step S6).

  During FEC synchronization, the FEC synchronization / out-of-sync detection unit 42 monitors whether or not FEC synchronization, which is synchronization for receiving the data format of the data part and the correction code part, has been lost. When the FEC synchronization is lost, the process returns to the asynchronous state of step S1 (step S7).

The main signal selection unit 46 selects a main signal according to the synchronization state.
In the 10GbE synchronization state, the output signal from the error correction bypass unit 45 is selected and transferred to the subsequent module. As a result, error correction is bypassed and transferred as it is to the subsequent module as a main signal.

  In the FEC synchronization state, the output signal from the error correction processing unit 43 is selected and transferred to the subsequent module. As a result, the main signal is transferred to the succeeding module after performing error correction defined in a standard such as IEEE. Since the error-corrected frame has the same frame format as the 10 Gigabit Ethernet frame, the subsequent module of the main signal selection unit 46 operates in the same manner regardless of which signal is transferred.

  As described above, according to the above-described embodiment, whether the error correction is performed according to the signal state from the OLT 1 can be determined by selectively performing the error correction by the ONU 4 as described above.

  Thus, in the above-described embodiment, when the error correction function is enabled or disabled in 10G-EPON, the ONU 4 side synchronizes with the 10G-EPON error correction frame format including the correction code portion, or the data portion is Automatically select whether to synchronize with a continuous 10 Gigabit Ethernet frame format. Therefore, communication is possible regardless of whether the setting for whether or not error correction is the same between the OLT 1 and the ONU 4.

  For this reason, according to the present embodiment, the error correction function can be validated or invalidated without the need to change the settings at the installation locations of the ONUs 4 installed in various places.

In the description of the above-described embodiment, the case where the OLT 1 performs error correction encoding and the ONU 4 performs error correction, that is, the downlink communication transmitted from the OLT 1 to the ONU 4 is described. Communication can be similarly realized.
In this uplink communication, the OLT reception error correction unit 11 of the OLT 1 is configured as shown in FIG. 7, and the function unit having the same name performs the same operation as that of the above-described embodiment. Will be realized.

  As described above, according to the present embodiment, since the receiving side device determines whether or not to correct the error by synchronizing with the main signal, the error correction operation of the receiving side device follows the operation of the transmitting side device, and the error correction is performed. The function can be automatically enabled or disabled.

  Each of the above-described embodiments is a preferred embodiment of the present invention, and the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, by recording the processing procedure for realizing OLT1 and ONU4 in the above-described embodiment on a recording medium as a program, the above-described functions according to the embodiment of the present invention can be performed by a program supplied from the recording medium. This can be realized by causing a CPU of a computer constituting the system to perform processing.
In this case, the present invention can be applied even when an information group including a program is supplied to the output device from the above recording medium or from an external recording medium via a network.
That is, the program code itself read from the recording medium realizes the novel function of the present invention, and the recording medium storing the program code and the signal read from the recording medium constitute the present invention. It will be.
As this recording medium, for example, flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, non-volatile Sex memory cards, ROM, etc. may be used.

  According to the program according to the present invention, each function in the above-described embodiment can be realized by the OLT and the ONU controlled by the program.

1 OLT
2 Optical transmission line 3 Optical coupler 4 ONU
11, 41 ONU reception error correction unit 12, 42 FEC synchronization / synchronization detection unit 13, 43 Error correction processing unit 14, 44 10 GbE synchronization / synchronization detection unit 15, 45 Error correction bypass unit 16, 46 Main signal selection unit

Claims (10)

Error correction means for performing predetermined error correction;
When it is detected that the correction code part for error correction is included in the received data, the data corrected by the error correction means is output, and the correction code part for error correction is not detected from the reception data In this case, the communication apparatus further comprises operation selection means for outputting without performing error correction by the error correction means. Data continuous frame detection means for detecting whether or not the received data is a frame format constituted by a continuation of the data portion;
A frame detection means with correction for detecting whether or not the received data is a frame format composed of a data part and a correction code part,
The operation selection means includes
If the data continuous frame detection means detects that the data format is a continuous frame format, the data output without error correction by the error correction means,
2. The communication apparatus according to claim 1, wherein when the frame format including a data part and a correction code part is detected by the frame detection means with correction, data corrected by the error correction means is output.   The data continuous frame detection means detects that the data format is a continuous frame format when a predetermined number or more of synchronization headers are continuously detected as frames of the data portion from the received data. The communication device according to claim 2, wherein:   The frame detection means with correction detects, from the received data, a predetermined number or more of synchronization headers as frames of the data part and continuously detects a predetermined number or more of synchronization headers as frames of the correction code part. 4. The communication apparatus according to claim 2, wherein the communication apparatus detects that the frame format is composed of a data part and a correction code part.   The communication apparatus according to any one of claims 1 to 4, wherein the communication apparatus is a station-side termination apparatus or a subscriber-side termination apparatus in an optical communication system.   A plurality of the communication devices according to any one of claims 1 to 5 are connected to the communication device according to any one of claims 1 to 5 via a branching unit. A communication system. When it is detected that the received data includes a correction code portion for error correction, the data corrected by the error correction process for performing a predetermined error correction is output,
A received data processing method, wherein when a correction code portion for error correction is not detected from received data, the error correction process is performed without error correction. A data continuous frame detection step for detecting whether or not the received data is in a frame format composed of continuous data parts;
A frame detection step with correction for detecting whether or not the received data is a frame format composed of a data portion and a correction code portion, and
When the frame format composed of a data part and a correction code part is detected by the frame detection process with correction, the data corrected by the error correction process for performing a predetermined error correction is output,
A received data processing method comprising: outputting data without performing error correction by the error correction step when a frame format in which a data portion is continuously detected is detected by the data continuous frame detection step. When it is detected that the received data includes a correction code part for error correction, the data corrected by the error correction procedure for performing a predetermined error correction is output,
A program for a communication apparatus, which causes a computer of a communication apparatus to execute a procedure of outputting without performing error correction by the error correction procedure when a correction code part for error correction is not detected from received data. A data continuous frame detection procedure for detecting whether or not the received data is in a frame format composed of continuous data parts;
Causing the computer of the communication apparatus to execute a frame detection procedure with correction for detecting whether or not the received data is a frame format composed of a data part and a correction code part,
When the frame format composed of a data part and a correction code part is detected by the frame detection procedure with correction, the data corrected by the error correction procedure for performing a predetermined error correction is output,
If the data continuous frame detection procedure detects that the data format is a continuous frame format, causing the computer of the communication apparatus to execute a data output procedure without performing error correction by the error correction procedure. A program for a communication device.

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