JP2011151565A - Pon system and transmission control processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a burst header length in correspondence with a mutual transmission condition, regarding a PON system and a transmission control processing method. <P>SOLUTION: In the PON system and the transmission control processing method in which a station side device 1 and a plurality of optical subscriber line terminals 20 are connected by an optical transmission line through an optical coupler, the station side device measures a transmission time by an optical signal to/from the optical subscriber line terminals, calculates either or both of a transmission burst header length, and a transmission synchronization pattern value of the optical subscriber line terminals on the basis of the transmission time, instructs the optical subscriber line terminals to measure an error rate of burst data received from the optical subscriber line terminals based on the instruction, and performs recalculation of the transmission burst header length in accordance with the result to perform correction notification, and the optical subscriber line terminals transmit a burst data frame of the burst header length advised by a recalculation result, to the station side device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  In the present invention, transmission / reception is performed between a network side station side device (OLT; Optical Line Terminal) and a plurality of subscriber side terminal devices (ONU; Optical Network Unit) via optical couplers using optical signals. The present invention relates to a PON system to be performed and a transmission control processing method.

  A PON (Passive Optical Network) system that transmits and receives an optical signal via an optical coupler is standardized by ITU-T (TuT), a transmission rate of Gbps-order in IEEE (Institut of Electrical and Electronic Engineering). G-PON was standardized by G984 of Telecommunication Union-Telecommunication Standardization Sector). In such a PON system, optical transmission is performed via an optical coupler between a station side device (OLT; Optical Line Terminal) and a plurality of optical subscriber line terminal devices (ONU; Optical Network Terminal). Each of the optical subscriber line terminal stations (hereinafter abbreviated as “ONU”) is used to transmit various kinds of information by optical signals between each other by a transmission method similar to time division multiplexing transmission. Then, data of a predetermined length is transmitted as a burst optical signal in accordance with the transmission timing designated by the station side device (hereinafter abbreviated as “OLT”). In this case, since the transmission timing from each ONU is specified from the OLT so as to be different, it is transmitted to the OLT while being time-division multiplexed in the optical coupler. In addition, from the OLT, data added with an address designating each ONU is time-division multiplexed and transmitted as an optical signal, and is distributed as an identical frame to each ONU via an optical coupler. The data with its own address is separated and received. The transmission speed was standardized as 10G-PON or 10G-EPON (10Giga-Ethernet (registered trademark) -Passive Optical Network) with a transmission speed of 10 Gbps, which was further increased, although the above-mentioned GE-PON was in the Gbps order. It was done.

  FIG. 4 shows a main part of a burst frame transmission format from ONU to OLT defined by IEEE 802.3av for this 10G-EPON. In the figure, LaserOn is a light emission rising period of a semiconductor laser diode that outputs an optical signal, BH is a burst header including a synchronization pattern SP and a burst delimiter BD, NFECCW is Burst data including N pieces of data FECCW0 to FECCWN, EOB is a burst end delimiter (End Of Burst), and LaserOff is a light emission falling period of the semiconductor laser diode. Each of the data CWFECCC0 to FECCWN of the burst data NFECCW indicates a case including a 223-byte data date and a 32-byte parity PTY according to the Reed-Solomon encoding method (RS (255, 223)). The first burst header BH and the last burst end delimiter EOB do not include an error check code, and the clock is regenerated by the synchronization pattern SP of the burst header BH, and the reception process of the data frame NFECCW is performed based on the clock. Is what you do.

  In general, the transmission timing assigned to each ONU from the OLT is specified to be equally spaced. In this case, the transmission information amount of each ONU is the same. Further, it is conceivable that the OLT repeatedly designates the transmission timing for the requested ONU or designates the transmission allowable time to be longer due to a request from the ONU having a large amount of transmission information. In any case, a burst header or the like is added to transmission data of a predetermined length, and if the same burst header or the like is added to a plurality of transmission data within a continuous allowable transmission time, the same burst header is added. Repeated transmission results in unnecessary transmission time. In view of this, means for improving transmission efficiency has been proposed by concatenating transmission data and adding information indicating a concatenation information amount together with a burst header or the like before and after the transmission data (see, for example, Patent Document 1).

  Each ONU generally has a distributed system configuration, and therefore the distance from the OLT is different. The allowable difference between the distances from the OLTs of the ONUs distributed in this way is, for example, about several kilometers. Therefore, since the distance between the OLT and each ONU is different, even if the transmission light levels of the OLT and each ONU are the same, the reception light corresponding to the ONU is attenuated by the attenuation corresponding to the transmission distance. Each signal level is different. Therefore, the reception function unit of the OLT amplifies the received optical signal level corresponding to each ONU so as to be almost the same level by the automatic gain control means, and performs a reception process on the received optical signal corresponding to the ONU. Become. Therefore, the OLT collects the received light level information from the OLT corresponding to each ONU, obtains the attenuation rate α corresponding to each ONU with respect to the reference received light level, and sets the optical transmission level corresponding to each ONU to 1 / α times. To instruct. As a result, the optical signal level received from each ONU in the OLT is substantially the same, and means for simplifying the configuration of the automatic gain control means and improving the error rate has been proposed (for example, Patent Documents). 2).

  Further, in 10G-EPON or the like that receives and processes burst optical signals as shown in FIG. 4, it is necessary to detect and establish synchronization pattern SP of burst header BH having a predetermined length. If the synchronization pattern SP cannot be normally received before the BD is received, the synchronization cannot be established, and the subsequent data frame NFECCW cannot be received. Therefore, by providing a plurality of buffers, the received burst header BH is received and stored in a state that is sequentially shifted by 1 bit with respect to each buffer, and synchronization establishment processing is performed on the synchronization pattern SP received and accumulated in each buffer, Means have been proposed for increasing the probability of synchronization pull-in compared to the case of using only a single reception pattern (see, for example, Patent Document 3).

JP2003-069591A WO98 / 13959 JP 2008-67252 A

  In a PON system, burst data reception synchronization processing becomes difficult due to an increase in the transmission speed of burst data, such as 10G-EPON. For example, since the transmission distances of a plurality of ONUs connected to the OLT via optical couplers are different from each other and not all have the same characteristics, the transmission from each ONU received in the OLT The reception quality of burst frames is different. Regarding the difference in the reception level in the OLT in such a case, as shown in the aforementioned Patent Document 2, the transmission level is instructed from the OLT to each ONU, and the reception level in the OLT is abbreviated. It can be the same. However, even if the reception level is a desired value, the extinction ratio of the intensity-modulated received optical signal is in a state where the inversion frequency of “1” and “0” is reduced due to the influence of the transmission characteristics of the optical transmission path, Clock extraction becomes difficult. For example, there is a standard that the synchronization pattern SP is 0xBF401E5C549BB59 having a 66-bit configuration. Due to a decrease in transmission quality, there is a case where clock synchronization cannot be acquired within the period of the synchronization pattern SP of the burst header BH shown in FIG. There is a problem that the delimiter BD cannot be detected, and subsequent data reception processing is impossible.

Also, the above-mentioned Patent Document 3 proposes means for receiving the burst header BH, sequentially storing it in a plurality of buffers in a state shifted corresponding to one bit, and performing synchronous pull-in based on the contents of each buffer. However, it is necessary to provide a plurality of buffers and means for synchronous pull-in corresponding to the buffers, which raises a problem of increasing costs. Further, there is a problem that it cannot be remedied when the transmission quality deteriorates due to the deterioration of the transmission characteristics of the optical signal. If the burst header BH period is extended, the chance of synchronization pull-in increases, but the maximum length TBHmax (μs) has a condition shown in the following equation.
TBHmax = Ton + Treceiver_setting + Tcdr ≦ 1.7
Note that Ton is the maximum startup time of the semiconductor laser 512 ns, Treceiver_setting is the time required to stabilize the photoelectric conversion unit that converts the received optical signal into an electrical signal, the maximum value is 800 ns, and Tcd is the time required for clock extraction. The maximum value is 400 ns. Therefore, there is a limit to extending the length of the burst header BH. The burst delimiter BD does not include an error correction code FEC (Forward Error Correction). If the burst delimiter BD cannot be detected, it is impossible to receive and identify subsequent data. If it is possible to reduce the length of the burst header BH, it is possible to increase the amount of data transmitted for transmission within the transmittable period assigned to the ONU.

  An object of the present invention is to solve the above-described problems of the conventional example, to facilitate establishment of reception synchronization for a plurality of ONUs connected to an OLT via optical couplers, and to make the burst header BH length as long as possible. This is intended to shorten the data transmission amount.

  The PON system of the present invention is a PON system in which a station-side device and a plurality of optical subscriber line terminal stations are connected by an optical transmission line via an optical coupler, and the station-side device is an optical subscriber. Based on the transmission time by the optical signal to and from the optical terminal and the transmission time measuring means by the optical signal between the optical terminal and the transmission time by the transmission time measuring means, the optical subscriber Means for obtaining one or both of transmission burst header length and transmission synchronization pattern value of line end station apparatus and notifying optical subscriber line end station apparatus, and received burst data from optical subscriber line end station apparatus Error rate measuring means, and means for notifying the correction of the transmission burst header length of the optical subscriber line terminal equipment based on the error rate by the error rate measuring means, and the optical subscriber line The terminal device is an optical signal between the station device According to the transmission / reception means, the response means for sending a response message according to the transmission time measurement request message by the transmission time measurement means of the station side device, and the burst header according to one or both of the notified burst header length and transmission synchronization pattern value And a means for transmitting a burst data frame with the burst header added thereto.

  The station-side device includes an error rate calculation unit for obtaining an error rate of received burst data from the optical subscriber line terminal device, and an optical subscriber line terminal device based on the error rate calculated by the error rate calculation unit. And a burst header length change instructing section for generating and sending a burst header length notification message for obtaining the burst header length of the transmission burst frame and notifying the optical subscriber line terminal equipment.

  The transmission control processing method of the present invention is a transmission control processing method in which a station side device and a plurality of optical subscriber line terminal devices are connected by an optical transmission line via an optical coupler and data is transmitted by an optical signal. The station side device transmits an RTT request message to the optical subscriber line terminal device, receives an RTT measurement response message from the optical subscriber line terminal device in response to the RTT request message, and A process of measuring a transmission time between the subscriber line terminal devices and an initial value of a burst header length corresponding to the length of the transmission time, and determining the initial value of the burst header length as an optical subscriber line terminal station A process of notifying the apparatus, transmitting a burst data frame to which a burst header according to an initial value of the burst header length is added from the optical subscriber line terminal apparatus, receiving the burst data frame, Seeking Rareto, is intended to include the steps of recalculating the burst header length, a process of notifying a burst header length determined by recalculation Optical Line Termination.

  The station side device measures the transmission time with the optical subscriber line terminal station device based on the transmission time information and the reception time of the RTT measurement response message from the optical subscriber line terminal station device in response to the RTT measurement request message. The process of obtaining the length of the burst header length according to the magnitude value relative to the standard value of the transmission time and notifying the optical subscriber line terminal device with a burst header length notification message, and the optical subscriber line terminal device, A process of transmitting a burst data frame to which a burst header having a burst header length according to a burst header length notification message is added to the station side device, whether the burst data frame is received by the station side device, whether or not reception of a burst delimiter is detected, and an error rate Measurement process and burst header length reduction for low error rate, burst error delimiter detection for high error rate The burst header length recalculation process to extend the burst header length if possible, and the burst header length from the burst header length recalculation process to the optical subscriber line terminal equipment using a burst length notification message. It is a waste.

  Based on the result of RTT measurement by the station side device and the error rate, the burst header length of the burst data frame transmitted by the optical subscriber line terminal device is obtained and notified, and if the transmission conditions between them are good, the burst There is an advantage that it is possible to extend the transmission time of burst data by shortening the header length, it is possible to improve the transmission efficiency, it is only necessary to add a relatively simple processing function to the station side device, and Even for changes in transmission conditions during operation, burst header length readjustment processing including re-RTT measurement processing can be executed, which has the advantage that the PON system can be operated stably.

It is explanatory drawing of Example 1 of this invention. It is a sequence chart of Example 1 of this invention. It is a flowchart of Example 1 of this invention. It is explanatory drawing of the transmission burst frame of ONU.

  Referring to FIG. 1, the PON system of the present invention is a PON system in which a station-side device 1 and a plurality of optical subscriber line terminal devices 20 are connected by an optical transmission line via an optical coupler. The station-side apparatus 1 includes a transmission / reception means using an optical signal with the optical subscriber line terminal station apparatus 20, a transmission time measuring means using an optical signal with the optical subscriber line terminal station apparatus, and this transmission. Based on the transmission time by the time measuring means, one or both of the transmission burst header length and the transmission synchronization pattern value of the optical subscriber line terminal station device 20 are obtained and notified to the optical subscriber line terminal station device 20. Means including a BH length / SP value change instructing unit 7 and the like, an error rate measuring unit for received burst data from the optical subscriber line terminal device 20 including an error rate calculating unit 8 and the like, and an error by the error rate measuring unit Optical subscriber line end based on rate The optical subscriber line terminal station device 20 includes a transmission / reception unit using an optical signal with the station side device 1, and the station side device 1. A response means for sending a response message according to a transmission time measurement request message by the transmission time measurement means, and generating a burst header according to one or both of the notified burst header length and transmission synchronization pattern value, And a means including a burst delimiter / SP insertion unit 29 for transmitting the added burst data frame.

  The transmission control processing method of the present invention is a transmission control in which data is transmitted by an optical signal by connecting the station side device 1 and a plurality of optical subscriber line terminal devices 20 via an optical coupler via an optical transmission line. In this processing method, the station side apparatus 1 transmits an RTT request message to the optical subscriber line terminal station apparatus 20, and sends an RTT measurement response message from the optical subscriber line terminal station apparatus 20 to the RTT request message. The process of receiving and measuring the transmission time between the optical subscriber line terminal equipment 20 and the initial value of the burst header length corresponding to the length of the transmission time are obtained, and the initial value of the burst header length is obtained as an optical value. A process of notifying the subscriber line terminal device 20 and a burst data frame to which a burst header with an initial value of the burst header length is added are transmitted from the optical subscriber line terminal device 20, and the burst data frame is received. To determine the error rate, is intended to include the steps of recalculating the burst header length, a process of notifying a burst header length determined by recalculation Optical Line Termination 20.

  FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention, and a PON system has a configuration in which a plurality of ONUs are connected via an OLT and an optical coupler, but the illustration of the optical coupler is omitted. The main parts of the OLT and the ONU are shown in a state where the OLT and the ONU are connected to each other by an optical transmission line. In the figure, 1 is an OLT, 2 is an O / E converter, 3 is a clock extractor and S / P converter, 4 is a burst delimiter / SP detector, 5 is an FEC decoder, and 6 is 64B / 66B. Decoding unit, 7 is a BH length / SP value change instruction unit, 8 is an error rate calculation unit, 9 is a selector (SEL), 10 is a 64B / 66B encoding unit, 11 is an FEC encoding unit, 12 is a P / S conversion unit, Reference numeral 13 denotes an E / O converter, and 14 denotes a controller. 20 is an ONU, 21 is an O / E converter, 22 is a clock extractor and S / P converter, 23 is an FEC decoder, 24 is a 64B / 66B decoder, 25 is a BH length notification message analyzer, and 26 is Demultiplexer (DMUX) 27 is a 64B / 66B encoder, 28 is an FEC encoder, 29 is a burst delimiter / SP inserter, 30 is a P / S converter, 31 is an E / O converter, and 32 is a controller Indicates.

  The ONU 20 controls each unit by the control unit 32 and performs transmission / reception processing between the terminal device (not shown) and the OLT 1. The ONU 20 receives data from the terminal device and the like, and the 64B / 66B encoding unit 27 receives the data. , 64 bits are encoded into 66-bit data, and Reed-Solomon encoding is performed by the FEC encoder 28. The encoding process or the like indicates a case of processing as parallel data. Therefore, the P / S conversion unit 30 converts the data into serial data by parallel serial conversion. For example, it is instructed from the OLT 1 as a burst frame in the format shown in FIG. The E / O conversion unit 31 converts the signal into an optical signal according to the transmission time, and burst-transmits the signal to the OLT 1 via the optical transmission line.

  The OLT 1 controls each unit by the control unit 14 and performs transmission / reception processing with the ONU 20. The OLT 1 receives a burst frame by an optical signal from the ONU 20 side via the optical transmission path, and receives an O / E conversion unit. 2 is converted into an electrical signal, the clock extraction unit and the S / P conversion unit 3 perform clock extraction and serial-parallel conversion, and the burst delimiter / SP detection unit 4 performs a burst delimiter and a synchronization pattern ( SP (Synchronization Pattern) is detected and transferred to the FEC decoder 5. The FEC decoding unit 5 decodes the Reed-Solomon encoded data as shown as (RS (239.255)), and the 64B / 66B decoding unit 6 decodes the 66-bit data into a 64-bit configuration. , Forward to upper layer (not shown). The error rate calculation unit 8 calculates the error rate based on the number of error bits from the burst delimiter / SP detection unit 4 processed for the received burst data and the FEC frame discard information, and instructs to change the BH length / SP value. Notification to part 7. The BH length / SP value change instruction unit 7 creates a BH length (burst header length) or SP value (synchronization pattern value) change instruction message for the ONU 20 based on the notified error rate, and sends the message via the selector 9. To transmit to the ONU.

  Also, transmission data from an upper layer (not shown) to the ONU 20 or a BH length notification message from the BH length / SP value change instruction unit 7 is input via the selector 9 of the OLT 1, and the 64B / 66B encoding unit 10 The 64 bits are encoded into a 66-bit configuration, Reed-Solomon encoded by the FEC encoder 11, converted to serial data by the P / S converter 12, and converted to an optical signal by the E / O converter 13 and transmitted. In this case, burst data transmitted to the illustrated ONU 20 and a plurality of other ONUs not illustrated are continuously transmitted as time-division multiplexed optical signals through an optical transmission path via an optical coupler.

  The ONU 20 converts the received optical signal into an electrical signal by the O / E conversion unit 21, performs clock extraction and conversion into parallel data by the clock extraction unit and the S / P conversion unit 22, and uses the Reed Solomon by the FEC decoding unit 23. The encoded data is decoded, the 64B / 66B decoding unit 24 decodes the 66-bit data into 64-bit data, and the BH length notification message analysis unit 25 includes the BH length information notified from the ONU 1 If demultiplexed by the demultiplexer 26, the demultiplexer 26 notifies the burst delimiter / SP inserter 29 as a BH length change instruction or SP value change instruction. Thereby, the burst delimiter / SP insertion unit 29 changes the length of the burst header BH added to the burst data to be transmitted next or the value of the synchronization pattern SP. Further, in the case of normal reception data that does not include a BH length change instruction / SP value change instruction, the received data is transferred as reception data via the demultiplexing unit 26 to a terminal device (not shown).

  FIG. 2 shows a sequence chart between the OLT and the ONU according to the first embodiment of the present invention, and shows a main part of a burst header length instruction sequence from the OLT to the ONU. When the ONU is newly connected or at every predetermined period or when transmission characteristics change, etc., the OLT 1 is controlled by the control unit 14 according to the optical signal from the E / O conversion unit 13 to the ONU 20 shown in FIG. An RTT (Round Trip Time) request message is transmitted. The measurement of the RTT by this RTT request message is the same as the processing already known as the Discovery Process for the OLT when an ONU is newly connected. A description will be given below with reference to the OLT 1 and the ONU 20 shown in FIG. In the OLT 1, the 64B / 66B encoding unit 10, the FEC encoding unit 11, the P / S conversion unit 12, and the E / O conversion unit 13 are controlled in accordance with the control of the control unit 14 as in the RTT measurement. RTT request message is sent via The ONU 20 that has received this RTT request message performs the O / E conversion unit 21, the clock extraction unit and S / P conversion unit 22, the FEC decoding unit 23, and the 64B / 66B conversion unit 24 by the control process of the control unit 32. The RTT request message is transferred to the control unit 32, the content of the RTT request message is identified, the 64B / 66B encoding unit 27, the FEC encoding unit 28, the burst delimiter / SP insertion unit 29, and the P Control is performed to transmit the RTT measurement response message with the transmission time information added thereto to the OLT 1 via the / S conversion unit 30 and the E / O conversion unit 31.

  The OLT 1 obtains the transmission time between the OLT and the ONU based on the reception time of the RTT measurement response message and the transmission time information from the ONU 10 as the RTT processing by the control unit 14, and determines the difference from the reference transmission time. Correspondingly, the initial value of the burst header length (BH length) is calculated. For example, when the transmission time is shorter than the reference, it is estimated that the distance from the OLT 1 to the ONU 20 is short and the transmission conditions are good, and the burst header length (BH length) is made shorter than the reference value. On the contrary, when the transmission time is longer than the reference, it is estimated that the distance from the OLT 1 to the ONU 20 is long and the transmission conditions are not good, and the burst header length (BH length) is set longer than the reference value. In this case, since the maximum length of the burst header length (BH length) is determined as TBHmax as described above, it is set to a value not exceeding this. The initial value of the burst header length (BH length) obtained in this way is transmitted to the ONU 20 as a BH length notification message.

  The ONU 20 receives the BH length notification message, analyzes it by the BH length notification message analysis unit 25, and transfers the notified BH length change instruction to the burst delimiter / SP insertion unit 29. Based on this BH length change instruction, the burst delimiter / SP insertion unit 29 creates a burst frame (SP + BD + data) to which a burst header BH is added according to the BH length change instruction, and passes through the P / S conversion unit 30. The E / O converter 31 converts the signal into an electrical signal and transmits it to the OLT 1. The OLT 1 receives the burst frame, detects the burst delimiter BD and the synchronization pattern SP by the burst delimiter / SP detection unit 4, checks the error of the data data, and transfers the number of error bits to the error rate calculation unit 8. Then, an error rate is obtained and notified to the BH length / SP value change instruction unit 7. The BH length / SP value change instruction unit 7 instructs the ONU 20 to change the BH length or SP value depending on whether or not the notified error rate is an allowable value. If the error rate is a small value including 0 for the allowable reference value, the burst header length is shortened corresponding to the difference value. When the error rate is large, a BH length notification message for instructing a change to be lengthened is created and transmitted to the ONU 20. If no change is required as a result of recalculating the BH length, it is possible to set a process for notifying the ONU 20 of a message with no change. As the reception waiting time elapses, it is possible to shift to the subsequent transmission process without changing the previous BH length.

  When the ONU 20 receives the BH length notification message as a result of recalculation of the BH length in the OLT 1, the ONU 20 sends a burst frame (SP + BD + data) whose burst header length is changed to the OLT 1 in the same manner as when the first BH length notification message is received. Send to. When the OLT 1 receives this burst frame and the error rate is not significantly different from the initial error rate, the OLT 1 ends the burst header length setting process. When the transmission path is not stabilized, it is also possible to perform BH length notification message transmission by BLT length recalculation on the OLT 1 side and burst frame retransmission processing on the ONU 20 side. By shortening such a burst header BH for ONUs with good transmission conditions and setting the amount as the data transmission allocation time, the transmission efficiency can be improved.

  FIG. 3 is a flowchart of the first embodiment of the present invention, showing processing in the OLT by steps (a) to (h), and by detecting the received signal (signal detect) (a) and the synchronization pattern SP. Search for the burst delimiter BD (b), either the sync pattern SP detection (1), or the processing result (c) of either the reception signal interruption or the burst header BH maximum time elapse (signal detection interruption / TBHmax) (2) ), In the case of synchronous pattern SP detection (1), the burst delimiter BD is searched within the maximum time of the burst header BH (d), and the burst delimiter BD detection (1) is detected. ) Or timeout Time out (2) (e), and in the case of burst delimiter BD detection, an error rate is calculated (f) Determine either error rate (low BER) (1) or high bit error rate (high BER) (2). If the bit error rate is low (1), burst header BH shortened (g), In the case of a high bit error rate, the burst header BH is extended or the synchronization pattern SP value is changed (h). In step (c), if the reception signal is interrupted or the maximum time has elapsed, the process proceeds to step (h). In step (e), if a time-out occurs, the process proceeds to step (h). Therefore, when the bit error rate of the transmission data between the ONU and the OLT is low, the burst header BH can be shortened, the data transmission allocation time can be increased, and the transmission efficiency can be improved. When the rate is high, the burst header BH is changed to the above-mentioned maximum length TBHmax (μs) or less, thereby facilitating detection of the synchronization pattern SP and clock synchronization and avoiding burst data reception errors. It becomes possible. Further, changing the value of the synchronization pattern SP indicates that the frequency of inversion of “1” and “0” of the bit is increased, so that the burst delimiter BD can be reliably detected and the frame loss can be reduced.

1 OLT
2 O / E conversion section 3 Clock extraction section and S / P conversion section 4 Burst delimiter / SP detection section 5 FEC decoding section 6 64B / 66B decoding section 7 BH length / SP value change instruction section 8 Error rate calculation section 9 Selector ( SEL)
10 64B / 66B encoding unit 11 FEC encoding unit 12 P / S conversion unit 13 E / O conversion unit 14 control unit 20 ONU
21 O / E conversion unit 22 Clock extraction unit and S / P conversion unit 23 FEC decoding unit 24 64B / 66B decoding unit 25 BH length notification message analysis unit 26 Demultiplexing unit (DMUX)
27 64B / 66B Encoding Unit 28 FEC Encoding Unit 29 Burst Delimiter / SP Insertion Unit 30 P / S Conversion Unit 31 E / O Conversion Unit 32 Control Unit

Claims (4)

In a PON system in which a station-side device and a plurality of optical subscriber line terminal devices are connected by an optical transmission line via an optical coupler,
The station-side device includes a transmission / reception unit using an optical signal with the optical subscriber line terminal station device, a transmission time measuring unit using an optical signal with the optical subscriber line terminal station device, and the transmission time measurement. Means for determining one or both of a transmission burst header length and a transmission synchronization pattern value of the optical subscriber line terminal equipment based on a transmission time by means, and notifying the optical subscriber line terminal equipment; Means for measuring an error rate of received burst data from the optical subscriber line terminal equipment, and means for notifying the correction of the transmission burst header length of the optical subscriber line terminal equipment based on the error rate by the error rate measuring means; Having a configuration including
The optical subscriber line terminal station device includes a transmission / reception unit that transmits and receives an optical signal to and from the station side device, and a response unit that transmits a response message according to a transmission time measurement request message by the transmission time measurement unit of the station side device; And a means for generating a burst header in accordance with one or both of the notified burst header length and transmission synchronization pattern value, and transmitting a burst data frame with the burst header added thereto. PON system.   The station side device includes an error rate calculation unit for obtaining an error rate of received burst data from the optical subscriber line terminal station device, and the optical subscriber line terminal station based on the error rate calculated by the error rate calculation unit. A burst header length change instructing unit that generates and sends out a burst header length notification message for determining a burst header length of a transmission burst frame of the device and notifying the optical subscriber line terminal device of the burst header length The PON system according to claim 1. In a transmission control processing method of transmitting data by an optical signal by connecting a station side device and a plurality of optical subscriber line terminal stations through an optical coupler via an optical transmission line,
The station side device transmits an RTT request message to the optical subscriber line terminal station device, receives an RTT measurement response message from the optical subscriber line terminal station device in response to the RTT request message, and A process of measuring the transmission time with the subscriber line terminal equipment;
Obtaining an initial value of a burst header length corresponding to the length of the transmission time, and notifying the initial value of the burst header length to the optical subscriber line terminal equipment;
A burst data frame to which a burst header according to an initial value of the burst header length is added is transmitted from the optical subscriber line terminal station, and the burst data frame is received and a burst according to the notification of the burst header length of an error rate It includes a process of receiving a burst data frame having a header length, obtaining an error rate, recalculating the burst header length, and notifying the optical subscriber line terminal equipment of the burst header length obtained by the recalculation. A transmission control processing method. The station side device transmits a transmission time between the RTT measurement request message and the RTT measurement request message from the optical subscriber line terminal station device according to the transmission time information and the reception time of the RTT measurement response message from the optical subscriber line terminal station device. Measuring the burst header length according to the magnitude of the standard value of the transmission time, and notifying the optical subscriber line terminal device by a burst header length notification message,
The optical subscriber line terminal device transmits a burst data frame to which a burst header of a burst header length by the burst header length notification message is added to the station side device;
The station side device receives the burst data frame and performs burst delimiter detection detection and error rate measurement, burst header length reduction for low error rate, burst error delimiter detection for high error rate A burst header length recalculation process to extend the burst header length if not possible, a process of notifying the burst header length by the burst header length recalculation process to the optical subscriber line terminal equipment by a burst length notification message; The transmission control processing method according to claim 3, further comprising:

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