JP2011160022A - Pon system and optical signal transmission and reception control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a transmitting optical signal level so as to be a predetermined bit error rate, with respect to a PON system and an optical signal transmission and reception control method. <P>SOLUTION: This invention relates to the PON (Passive Optical Network) system and the optical signal transmission and reception control method in which a station side device 1 and a plurality of optical subscriber line terminal device 2 are connected by an optical transmission line through an optical coupler 3 to perform transmission and reception processing by an optical signal, and they have a configuration and a control process in which, a pseudo random signal is transmitted from a PRBS transmitting part 26 provided in the optical subscriber line terminal device 2 designated by an instruction creating part 16 of the station side device 1, a PRBS receiving part 15 of the station side device 1 receives the pseudo random signal to measure a bit error rate, and the instruction creating part 16 instructs an output level adjusting part 27 so as to adjust a transmission optical signal level from an optical signal transmitting and receiving part 21 of the optical subscriber line terminal device 2 such that the bit error rate is within a predetermined range. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a PON (Passive Optical Network) system that transmits and receives an optical signal and an optical signal transmission and reception control method.

  In 2004, the PON system was standardized as GE-PON with a transmission rate of Gbps in IEEE (Institut of Electrical and Electronic Engineering). In addition, G-PON is standardized by G984 of ITU-T (International Telecommunication Union-Telecommunication Standard Sector), and a station side device (OLT) and a plurality of optical subscriber line terminal units (wU); ) Are connected by an optical transmission line via an optical coupler, and various information transmission is performed by optical signals between each other by a transmission method similar to time-division multiplexed transmission. -EPON is being standardized.

  In various PON systems, each optical subscriber line terminal device (hereinafter abbreviated as “ONU”) has a predetermined length of data according to the transmission timing designated by the station side device (hereinafter abbreviated as “OLT”). Is transmitted by a burst optical signal. In this case, since the transmission timing from each ONU is different, it is transmitted to the OLT while being time-division multiplexed in the optical coupler. Also, from the OLT, data with an address specifying each ONU is time-division multiplexed and transmitted as an optical signal, and distributed to each ONU via an optical coupler. Each ONU has its own address added to the OLT side. The data from is separated and received. The OLT can monitor the received optical signal power from each ONU, and can instruct the ONU to change the output power as necessary.

  In 10G-EPON with a transmission rate of 10 Gbit, IEEE802. As a transmission format by av, a burst optical signal transmitted from the ONU has a light emission rise time Ton of 512 ns, and a burst header has a maximum length of 1.2 ns, as shown in FIG. The burst delimiter is 66 bits, and the data is the number of bytes corresponding to the allocated time length from the OLT. The end-of-burst is 198 bits, and the laser emission fall time Toff is 512 ns long. In the OLT, the clock synchronization is pulled in by this burst header to identify the subsequent reception of data. Will do. The end of this burst header is identified by a 66-bit burst delimiter.

  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, in response to a request from the ONU having a large amount of transmission information, the OLT repeatedly designates the transmission timing for the request ONU or designates to increase the allowable transmission time. In either case, the header is added to transmission data of a predetermined length. In particular, if a plurality of pieces of transmission data within a continuous transmission allowable time are connected by adding the same header or the like, the same header is repeatedly transmitted, resulting in unnecessary transmission time. Therefore, means for improving transmission efficiency has been proposed by concatenating transmission data and adding information indicating a concatenation information amount together with a header or the like before and after the transmission data (for example, see Patent Document 1).

  Each ONU generally has a distributed system configuration. In this case, the distance from the OLT is different. As described above, the difference in distance from the OLT of each ONU distributed and distributed is, for example, an allowable value of about several kilometers. Accordingly, since the distance between the OLT and each ONU is different, even if the transmission light level of the OLT and each ONU is the same, the attenuation corresponding to the transmission distance causes, for example, the OLT to support the ONU. The received optical signal levels are 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).

JP2003-069591A WO98 / 13959

  For example, in the EPON system, a frame transmitted / received between the OLT and each ONU has an 8-byte preamble including a start of frame delimiter (SFD) at the head and a transmission destination of 6 bytes. A header including an address, a 6-byte transmission source address, a 2-byte frame type and a frame length (Type / Length) is added to the head of the transmission data, and an error check (FCS; Frame Check Sequence) is added to the rear of the transmission data. ) Is known, and a transmission frame addressed to each ONU is transmitted at a predetermined frame interval in accordance with a clock in the OLT. Each ONU extracts the clock from the preamble of the header of the transmission frame of the OLT, establishes clock synchronization, and performs reception processing by separating and identifying the frame with its own address added. Each ONU can perform transmission processing in synchronization with the extracted clock. Each ONU generally has a different distance from the OLT. Therefore, the clock phase of the received frame from each ONU in the OLT is different. It is necessary to recover the clock from the reception processing.

  As described above, in the OLT, it is necessary to extract the received burst optical signal clock corresponding to each ONU, and to receive and process data based on the clock. For this purpose, the clock is extracted at the head of the burst optical signal. A burst header having a preset length is added. By extracting the clock from this burst header, the burst data subsequent to the burst header can be received and processed. Therefore, in order to reliably receive and reproduce the clock, it is conceivable to lengthen the burst header for clock extraction. However, since data is also transmitted within the transmission / reception allocation time, the time for data transmission is shortened, resulting in a problem that transmission efficiency is lowered. It is also conceivable to increase the transmission power of the ONU. In that case, there is a case where the transmission power becomes more than necessary, and there is a problem in that unnecessary power consumption is caused and energy saving should be promoted. Regarding the transmission power of the optical signal in each ONU as described above, in the above-mentioned Patent Document 2, the transmission light level for each ONU is set so that the reception light level in the OLT is within a predetermined range. This is an instruction to control the transmission, and is not considered for improvement of transmission efficiency and power saving. With the spread of PON systems, the number of installed ONUs tends to increase, and there is a demand for improved transmission efficiency and reduced power consumption.

  An object of the present invention is to solve the above-described conventional problems, and to provide a configuration and a control method for reducing power consumption of an ONU and facilitating reproduction of a received clock from an ONU in an OLT. is there.

  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 devices are connected by an optical transmission line via an optical coupler. A PRBS transmission unit that generates and transmits a pseudo-random signal for bit error rate measurement to the station side device, an instruction reception unit that receives instruction information from the station side device, and an optical signal transmission / reception that transmits and receives an optical signal A PRBS receiving unit that receives a pseudo-random signal from the optical subscriber line terminal station device and measures a bit error rate, and a bit error rate measurement result by the PRBS receiving unit. Based on the above, there is provided a configuration including an instruction creating unit that transmits instruction information for transmission control of the optical subscriber line terminal station device, and an optical signal transmitting / receiving unit that transmits and receives optical signals.

  The station side device receives a pseudo-random signal from the designated optical subscriber line terminal station device and measures a bit error rate, and based on a bit error rate measurement result by the PRBS reception unit, And an instruction creating unit for instructing a transmission optical signal level from the optical signal transmission / reception unit of the optical subscriber line terminal apparatus.

  Further, the optical subscriber line terminal device is configured to perform pseudo-simulation according to an instruction receiving unit that receives instruction information from the instruction creating unit of the station-side device and pseudo-random signal transmission instruction information for bit error rate measurement from the station-side device. An output level for controlling the optical signal level transmitted from the optical signal transmission / reception unit to the station side device according to the instruction information of the output level control instruction from the PRBS transmission unit for generating and transmitting a random signal and the instruction creation unit of the station side device And an adjustment unit.

  The station side device receives a pseudo-random signal from the designated optical subscriber line terminal station device and measures a bit error rate, and based on a bit error rate measurement result by the PRBS reception unit, And an instruction creating unit for instructing the header length for clock recovery from the optical subscriber line terminal equipment.

  Further, the optical subscriber line terminal device is configured to perform pseudo-simulation according to an instruction receiving unit that receives instruction information from the instruction creating unit of the station-side device and pseudo-random signal transmission instruction information for bit error rate measurement from the station-side device. A PRBS transmitter that generates and transmits a random signal, and a header length adjuster that adjusts the header length added to the frame transmitted to the station side device in accordance with the header length instruction for clock recovery from the instruction creation unit of the station side device And a configuration including

  The optical signal transmission / reception control method of the present invention is 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 and perform transmission / reception processing using an optical signal. In this optical signal transmission / reception control method, the station side device receives the pseudo random signal, an instruction creating unit that designates the optical subscriber line terminal station device and performs a pseudo random signal transmission instruction and an output level instruction. A PRBS receiver that measures a bit error rate, and an optical subscriber line terminal device includes a PRBS transmitter that outputs a pseudo-random signal and an instruction receiver that receives an instruction from the station-side device And a pseudo-random signal transmission is instructed by designating the optical subscriber line terminal device by the instruction creating unit of the station side device, and from the PRBS transmission unit of the designated optical subscriber line terminal station device. Pseudo random signal to station side device A process of transmitting, a process of measuring a bit error rate by receiving a pseudo-random signal by a PRBS receiving unit of the station side apparatus, and a transmission optical signal level of the subscriber line terminal apparatus based on a measurement result of the bit error rate. A process of creating an adjustment instruction by the instruction creating unit and sending it to the subscriber line terminal equipment, and a transmission optical signal level adjustment instruction received by the instruction receiving part of the optical subscriber line terminal equipment, and this transmitted optical signal And a process of controlling to a transmission optical signal level according to a level adjustment instruction.

  Also, this is an optical signal transmission / reception control method 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 and perform transmission / reception processing using an optical signal. The station side device designates an optical subscriber line terminal station device and instructs the pseudo random signal transmission instruction and the output level instruction, and receives the pseudo random signal and measures the bit error rate. The optical subscriber line terminal station apparatus has a configuration including a PRBS transmission section that outputs a pseudo-random signal and an instruction reception section that receives an instruction from the station-side apparatus. Specify the optical subscriber line terminal equipment by instructing the optical subscriber line terminal equipment by the side device, and send the pseudo random signal from the PRBS transmitter of the designated optical subscriber line terminal equipment to the station side equipment. Process and pseudo-random A signal is received by the PRBS receiver of the station side device and the bit error rate is measured, and a header length adjustment instruction of a frame transmitted from the subscriber line terminal device is transmitted based on the bit error rate measurement result And a process of receiving the header length adjustment instruction by the instruction receiving unit and adjusting the header length of the frame transmitted to the station side apparatus.

  In order to measure the transmission bit error rate between a plurality of optical subscriber line terminal equipment and station equipment, a pseudo-random signal is transmitted from the PRBS transmitter of each optical subscriber line terminal equipment, By receiving the PRBS reception unit, measuring the bit error rate corresponding to the optical subscriber line terminal equipment, and instructing the adjustment of the transmission optical signal level of the optical subscriber line terminal equipment based on the bit error rate Therefore, it becomes possible to maintain a transmission optical signal level that can maintain a desired transmission condition, and an optical subscriber line terminal device having a short distance from the station side device has a low transmission bit error rate. Even if the transmission optical signal level is reduced, the desired transmission conditions can be maintained, and the power consumption of the optical subscriber line terminal equipment can be reduced. In addition, by controlling the header length for clock extraction based on the transmission bit error rate, if the transmission bit error rate is low, the data transmission time can be extended by shortening the header length to improve the transmission efficiency. It becomes possible.

It is a principal part functional block diagram of Example 1 of this invention. It is explanatory drawing of control outline | summary of Example 1 of this invention. It is an outline explanatory view of a control sequence of Example 1 of the present invention. It is control frame explanatory drawing of Example 1 of this invention. It is a principal part functional block diagram of Example 2 of this invention. It is control operation outline explanatory drawing of Example 2 of the present invention. It is control frame explanatory drawing of Example 2 of this invention. It is explanatory drawing of the transmission format of 10G-EPON.

  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 devices are connected by an optical transmission line via an optical coupler. A PRBS transmission unit that generates and transmits a pseudo-random signal for bit error rate measurement to the station side device, an instruction reception unit that receives instruction information from the station side device, and an optical signal transmission / reception unit that transmits and receives optical signals The station side device receives a pseudo-random signal from the optical subscriber line terminal station device and measures the bit error rate, and a bit error rate measurement result by the PRBS reception unit. In addition, a configuration is provided that includes an instruction creation unit that transmits instruction information for transmission control of the optical subscriber line terminal equipment, and an optical signal transmission / reception unit that transmits and receives optical signals.

  The optical signal transmission / reception control method of the present invention is 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 and perform transmission / reception processing using an optical signal. In this optical signal transmission / reception control method, the station side device receives the pseudo random signal, an instruction creating unit that designates the optical subscriber line terminal station device and performs a pseudo random signal transmission instruction and an output level instruction. A PRBS receiving unit that measures a bit error rate, and the optical subscriber line terminal device receives a PRBS transmitting unit that outputs a pseudo-random signal and an instruction reception that receives an instruction from the station side device. A PRBS transmission unit of the designated optical subscriber line terminal station device, instructing the pseudo-random signal transmission by designating the optical subscriber line terminal device by the instruction creating unit of the station side device. Pseudorandom from station to device Signal transmission process, a process of measuring a bit error rate by receiving a pseudo-random signal by the PRBS receiver of the station side apparatus, and a transmission light of the subscriber line terminal station apparatus based on the measurement result of the bit error rate A signal level adjustment instruction is created by the instruction creating unit and transmitted to the subscriber line terminal equipment, and a transmission optical signal level adjustment instruction is received by the instruction receiving unit of the optical subscriber line terminal equipment. And a process of controlling to a transmission optical signal level according to a transmission optical signal level adjustment instruction.

  FIG. 1 is a functional block diagram of a main part of Embodiment 1 of the present invention, and a PON system is configured by connecting a plurality of ONUs 2 to an OLT 1 via an optical coupler 3. The OLT 1 includes an optical signal transmission / reception unit 11, a serial-parallel conversion unit 12, an access control unit 13, a core-side functional unit 14 that transmits and receives between other networks, and PRBS (Pseudo Random Bit Sequence; pseudo-random signal). A network that includes a receiving unit 15 and an instruction creating unit 16 and that is not shown is connected to the core-side functional unit 14. The ONU 2 includes an optical signal transmission / reception unit 21, a serial / parallel conversion unit 22, an access control unit 23, a UNI (User Network Interface) side functional unit 24 that transmits and receives data to and from a terminal device, an instruction reception unit 25, It has a configuration including a PRBS (Pseudo Random Bit Sequence) transmission unit 26 and an output level adjustment unit 27, and a user terminal device or the like (not shown) is connected to the UNI-side function unit 24.

  The serial-parallel converter 12 of the OLT 1 and the serial-parallel converter 22 of the ONU 2 are a series of high-speed transmission data that is transmitted and received via the optical coupler 3 and parallel data that is internally parallelized and processed as low-speed data. Parallel conversion between internal parallel data and external transmission / reception serial data in the core side functional unit 14 of the OLT 1 and the UNI side functional unit 24 of the ONU 2 In addition, a serial-parallel conversion function (not shown) that performs serial-parallel conversion is provided. Further, the ONU 2 receives an instruction receiving unit 25 that receives instruction information from the OLT 1, a PRBS transmission unit 26 that transmits a pseudo random signal PRBS for bit error rate measurement according to the instruction information, and a transmission output of the optical signal transmission / reception unit 21. And an output level adjustment unit 27 for controlling the level. The OLT 1 includes a PRBS receiving unit 15 that receives the PRBS from the ONU 2 and measures the bit error rate, and an instruction creating unit 16 that instructs the optical signal output level control of the ONU 2 according to the bit error rate measurement result. It has a configuration. In this case, if the measured bit error rate is within a predetermined range, the OLT 1 side transmits no response or transmits an instruction content for maintaining the optical signal output level as it is. If the measurement bit error rate is worse than the predetermined range, the instruction content for increasing the optical signal output level is used. On the contrary, if the measurement bit error rate is better than the predetermined range, the instruction content for decreasing the optical signal output level is used. In this way, after adjusting the optical signal output level of the ONU 2, it is possible to make a PRBS transmission instruction from the PRBS transmission unit 26 again to confirm whether or not the measured bit error rate is within a predetermined range. The access control units 13 and 23 have a transmission / reception control function known as MAC (Media Access Control).

  FIG. 2 is an explanatory diagram of the control operation outline, and shows an outline of the control operation between the OLT 1 and the ONU 2. The ONU 2 sends a BER measurement frame by the PRBS transmission unit 26 according to an instruction from the OLT 1 through a path not shown. It is created (1) and transmitted from the optical signal transmitting / receiving unit 21 to the OLT 1 (2). The OLT 1 receives the BER measurement frame by the PRBS receiving unit 15 (3), performs BER measurement based on the PRBS by the BER measurement frame, and notifies the measurement result to the instruction creating unit 16 (4). The instruction creating unit 16 determines whether the BER is within a predetermined range, creates an output instruction frame corresponding to the determination result (5), and transmits the output instruction frame from the optical signal transmitting / receiving unit 11 (6). The ONU 2 receives this output instruction frame by the instruction receiving unit 25 (7) and transfers it to the output level adjusting unit 27 (8). The output level adjusting unit 27 adjusts the output level of the optical signal transmitting / receiving unit 21 in accordance with the output instruction by the output instruction frame (9). The optical signal transmitter / receiver 21 starts data transmission by this output level adjustment (10).

This BER measurement process and ONU2 output level control are executed at an arbitrary time interval at the time of system startup, communication restart, etc., and the output level of the optical signal transmitting / receiving unit 21 is adjusted according to the BER measurement result, By ensuring the clock recovery on the OLT 1 side and controlling the transmission output level of the ONU 2 to a predetermined range, normal transmission / reception processing is executed with the minimum necessary transmission power, and power saving of a large number of ONUs 2 is achieved, It is possible to achieve stable operation of the PON system. In the above-mentioned 10G-EPON standard IEEE 802.3av, the bit error rate is required to be 10 ⁻³ or less at a reception sensitivity of −28 dBm. It is desired to improve the bit error rate to ^-12 or less.

  FIG. 3 is a schematic explanatory diagram of a control sequence. The ONU transmits a measurement frame including a PRBS pattern to the OLT in accordance with an instruction from the OLT. The OLT receives this measurement frame, receives the BER by the PRBS receiver 15 and measures the bit error rate, determines whether the bit error rate BER is within a predetermined range, and determines the BER from the predetermined range. When OLT is small, the OLT indicates a state in which an optical signal from the ONU can be received with sufficient power, and therefore transmits an output instruction frame for reducing the transmission output power of the ONU. On the other hand, when the BER is larger than the predetermined range, it indicates that a reception error occurs frequently due to a low optical signal level received from the ONU in the OLT. Therefore, an output instruction frame for increasing the transmission output power of the OLT Send. The ONU controls the output power of the optical signal transmitting / receiving unit 21 in accordance with the instruction from the OLT. That is, the instruction content of the transmission output level from the OLT 1 is received by the instruction receiving unit 25 of the ONU 2 shown in FIG. 1, notified to the output level adjusting unit 27, and the output of the laser diode for optical signal output of the optical signal transmitting / receiving unit 21 Control the level. As a result, the optical signal output laser diode of the optical signal transmission / reception unit 21 of the ONU 2 is driven with the optimum power, the reception bit error rate in the OLT 1 is set within a predetermined range, and the power consumption in the ONU 2 is optimized. You can plan.

  FIG. 4 is an explanatory diagram of a control frame, and shows an example when an output adjustment instruction is given from the OLT to the ONU. The numerical value on the right side shows an example of the number of bytes, and 0/4, 0/2 are Indicates that 0, 4 or 2 bytes can be applied. For example, a destination address DA (Destination address) (6 bytes), a source address SA (Source address (6 bytes), a length and type (Length type) (2 bytes)), and an operation code (Opcode) (2 bytes) ), Time stamp (Times stamp) (4 bytes), number of permitted groups and number of flags (Number of grants / flags) (4 bytes), transmission start time and data length of # 1 to # 4 respectively permitted (Grant # 1 start time), (Grant # 1 length) to (Grant # 4 start time), (Grant # 4 length), synchronization time (Sync time), output adjustment instruction, pad or Indicates the case of having a configuration of reserved (Pad / Reserved) (13 to 39 bytes) and a frame check code (FCS) (4 bytes), and the ONT is transmitted from the OLT to the output adjustment instruction area indicated by a thick frame The output level control instruction for the ON is performed by designating by the address DA.

  5 is a functional block diagram of the main part of the second embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same name parts, and 28 denotes a header length adjusting part. The header length adjusting unit 28 adjusts the burst header length for clock extraction at the head of a frame to be transmitted to the OLT. As described above, a longer length is preferable for clock extraction, but a data area is narrow. Become. Therefore, as in the first embodiment, the ONU 2 is designated from the OLT 1, the PRBS signal transmission from the PRBS transmission unit 26 is instructed, the pseudo random signal from the PRBS transmission unit 26 is transmitted to the OLT 1, and the PRBS of the OLT 1 is transmitted. The bit error rate is received by the receiving unit 15 to determine whether the bit error rate is within a predetermined range. If the bit error rate is larger than the predetermined range, the clock extraction burst header is lengthened. If the bit error rate is smaller than the predetermined range, the clock extraction burst header is instructed to be shortened. Thereby, the ONU 2 can improve the transmission efficiency by setting the necessary minimum header length and extending the data transmission possible time.

  FIG. 6 is an explanatory diagram of the control operation outline, and shows an outline of the control operation between the OLT 1 and the ONU 2 based on the configuration shown in FIG. 5, and the ONU 2 transmits PRBS according to an instruction from the OLT 1 through a path not shown. A BER measurement frame is generated by the unit 26 (1), and transmitted from the optical signal transmitting / receiving unit 21 to the OLT 1 (2). The OLT 1 receives the BER measurement frame from the ONU 2 by the PRBS reception unit 15 (3), performs BER measurement based on the PRBS by the BER measurement frame, and notifies the instruction creation unit 16 of the measurement result (4). The instruction creation unit 16 determines whether the BER is within a predetermined range, creates a header length instruction frame corresponding to the determination result (5), and transmits the header length instruction frame from the optical signal transmission / reception unit 11 (6). ). The ONU 2 receives the header length instruction frame by the instruction receiving unit 25 (7) and transfers it to the header length adjustment unit 28 (8). The header length adjustment unit 28 notifies the optical signal transmission / reception unit 21 of the result of adjustment of the burst header length according to the instruction by the header length instruction frame (9). The optical signal transmitter / receiver 21 starts data transmission with the burst header length adjusted (10). This BER measurement process is executed at an arbitrary time interval when the system is started up, communication is resumed, etc., and the burst header length transmitted from the optical signal transmitting / receiving unit 21 to the OLT 1 is adjusted and set according to the BER measurement result. Accordingly, when the reception bit error rate on the OLT 1 side is lower than the reference value, the burst header length is lengthened to facilitate clock recovery in the OLT 1, and conversely, when the reception bit error rate is higher than the reference value, By shortening the burst header length, the time for data transmission can be extended, and the transmission efficiency can be improved.

  FIGS. 7A to 7D are explanatory diagrams of the frame format, and FIG. 7A shows an example of the frame configuration of the burst length adjustment instruction from the OLT to the ONU in the above-described second embodiment. The number on the right side of indicates the number of bytes. FIG. 7A shows a burst length adjustment instruction frame transmitted from the instruction creating unit 16 of the OLT 1 to the ONU 2 in the above-described second embodiment. The “output adjustment” in the frame in FIG. This corresponds to the case where “instruction” is “burst length adjustment instruction”, and the OLT notifies the ONU of the minimum burst length necessary for clock recovery. The ONU 2 (see FIG. 5) that has received the burst length adjustment instruction frame notifies the access control unit 23 by the header length adjustment unit 28, performs the burst header length control processing of the transmission burst frame, and the transmission conditions are good. The burst header length can be shortened to improve transmission efficiency, and when the transmission conditions are bad, the burst header length can be lengthened to ensure clock recovery in the OLT, thereby avoiding retransmission processing. Become.

  7B to 7D show examples of the frame configuration in the discovery process. FIG. 7B shows a register request (Register Request) frame from the ONU to the OLT in the FRBS (PRBS transmission unit 26 ( FIG. 1 and FIG. 5) shows a case of transmission including a pseudo-random signal), which is substantially the same as each item in the frame of FIG. 1A, but includes discovery information (Discovery information) and a laser. The case where the rise time (Laser On time) (Ton; see FIG. 8) and the laser fall time (Laser Off time) (Toff; see FIG. 8) are included is shown. That is, the pseudo random signal (PRBS) generated from the PRBS transmission unit 26 (see FIG. 5) of the ONU is indicated as “PRBS” in the registration request (Register Request) frame of the P2MP discovery when the ONU is newly connected. In this example, the OLT side can detect how much the bit error rate of the optical signal transmission line is by transmitting from the ONU to the OLT.

  FIG. 7C shows a case where a P2MP discovery register request (Register Request) frame is used when a new ONU is connected, and is transmitted in a frame having an “output adjustment instruction”. A case where the same items as (A) and (B) are included, and items of “Assigned mode”, “Sync time”, and “Echoed pendant grants” are included is shown. FIG. 7D is the same as the frame shown in FIG. 7C, but shows a case where transmission is performed with a frame including a “burst length adjustment instruction” instead of an output adjustment instruction item. . That is, the OLT can transmit an output adjustment instruction or a burst length adjustment instruction to the ONU with reference to a transmission state with another ONU when the ONU is newly connected.

1 OLT
2 ONU
DESCRIPTION OF SYMBOLS 3 Optical coupler 11 Optical signal transmission / reception part 12 Serial / parallel conversion part 13 Access control part 14 Core side functional part 15 PRBS receiving part 16 Instruction preparation part 21 Optical signal transmission / reception part 22 Serial / parallel conversion part 23 Access control part 24 UNI side functional part 25 Instruction receiving unit 26 PRBS transmitting unit 27 Output level adjusting unit 28 Header length adjusting unit

Claims (7)

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 optical subscriber line terminal device generates a PRBS transmitter for generating and transmitting a pseudo-random signal for bit error rate measurement to the station side device, and receives an instruction for receiving instruction information from the station side device. And a configuration including an optical signal transmission / reception unit that transmits and receives an optical signal,
The station side device receives the pseudo random signal from the optical subscriber line terminal station device and measures a bit error rate, and a PRBS receiving unit that measures the bit error rate based on the PRBS receiving unit. A PON system comprising a configuration including an instruction creating unit that transmits instruction information for transmission control of a subscriber line terminal station device, and an optical signal transmitting / receiving unit that transmits and receives an optical signal.   The station side device receives a pseudo-random signal from the designated optical subscriber line terminal station device and measures a bit error rate, and based on a bit error rate measurement result by the PRBS reception unit, 2. The PON system according to claim 1, further comprising: an instruction creating unit that instructs a transmission optical signal level from the optical signal transmitting / receiving unit of the optical subscriber line terminal station device.   The optical subscriber line terminal device includes an instruction receiving unit that receives instruction information from the instruction creating unit of the station side device, and a pseudo random signal transmission instruction information for measuring a bit error rate from the station side device. PRBS transmission unit for generating and transmitting a pseudo-random signal according to the above, and the transmission optical signal level from the optical signal transmission / reception unit to the station side device according to the instruction information of the output level control instruction from the instruction creation unit of the station side device The PON system according to claim 1, further comprising: an output level adjusting unit that controls the PON system.   The station side device receives a pseudo-random signal from the designated optical subscriber line terminal station device and measures a bit error rate, and based on a bit error rate measurement result by the PRBS reception unit 2. The PON system according to claim 1, further comprising: an instruction creating unit for instructing a header length for clock recovery from the optical subscriber line terminal equipment.   The optical subscriber line terminal device includes an instruction receiving unit that receives instruction information from the instruction creating unit of the station side device, and a pseudo random signal transmission instruction information for measuring a bit error rate from the station side device. A PRBS transmission unit that generates and transmits a pseudo-random signal according to the above, and adjusts the header length added to the frame to be transmitted to the station side device in accordance with a clock recovery header length instruction from the instruction creation unit of the station side device The PON system according to claim 1, further comprising: a header length adjusting unit. In an optical signal transmission / reception control method 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 and perform transmission / reception processing using an optical signal. ,
The station side device designates the optical subscriber line terminal station device to give a pseudo random signal transmission instruction and an output level instruction, and receives a pseudo random signal and measures a bit error rate PRBS The optical subscriber line terminal station apparatus includes a PRBS transmitter that outputs the pseudo-random signal and an instruction receiver that receives an instruction from the station-side apparatus. Have
The instruction creating unit of the station side device designates an optical subscriber line terminal station device to instruct a pseudo random signal transmission, and the PRBS transmission unit of the designated optical subscriber line terminal station device transmits the instruction to the station side device. A process of transmitting a pseudo-random signal;
Receiving the pseudo-random signal by the PRBS receiver of the station side device and measuring a bit error rate;
A step of creating an instruction to adjust the transmission optical signal level of the subscriber line terminal device based on the measurement result of the bit error rate by the instruction creating unit and sending the instruction to the subscriber line terminal device;
Receiving the transmission optical signal level adjustment instruction by the instruction receiving unit of the optical subscriber line terminal equipment and controlling the transmission optical signal level according to the transmission optical signal level adjustment instruction. An optical signal transmission / reception control method. In an optical signal transmission / reception control method 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 and perform transmission / reception processing using an optical signal. ,
The station side device designates the optical subscriber line terminal station device to give a pseudo random signal transmission instruction and an output level instruction, and receives a pseudo random signal and measures a bit error rate PRBS The optical subscriber line terminal station apparatus includes a PRBS transmitter that outputs the pseudo-random signal and an instruction receiver that receives an instruction from the station-side apparatus. Have
The instruction creating unit of the station side device designates an optical subscriber line terminal station device to instruct a pseudo random signal transmission, and the PRBS transmission unit of the designated optical subscriber line terminal station device transmits the instruction to the station side device. A process of transmitting a pseudo-random signal;
Receiving the pseudo-random signal by the PRBS receiver of the station side device and measuring a bit error rate;
Transmitting a header length adjustment instruction of a frame to be transmitted from the subscriber line terminal device based on the measurement result of the bit error rate;
Receiving the header length adjustment instruction by the instruction receiving unit and adjusting a header length of a frame to be transmitted to the station side device.

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