JP6309468B2 - Optical burst signal preamble control apparatus and optical burst signal preamble control method - Google Patents

Description

  In an optical transmission system in which burst signals having different optical intensities (hereinafter referred to as optical burst signals) are transmitted, the present invention provides a threshold value (hereinafter referred to as a 1/0 determination threshold value) used to determine 1 level and 0 level for each optical burst signal. The present invention relates to an optical burst signal preamble control apparatus and an optical burst signal preamble control method for controlling a preamble for setting (a).

  Examples of optical transmission systems that transmit optical burst signals include PON (Passive Optical Network) systems and regenerative repeater transmission systems. An optical burst signal in which the optical signal transmitted from each optical transmitter has a different light intensity due to variations in the output power of the light source of each optical transmitter in the PON system or the regenerative repeater transmission system, and also due to the difference in transmission distance And is received and processed by the optical receiver of the OLT or the regenerative repeater node (Non-patent Document 1).

FIG. 4 shows a configuration example of an optical receiver that receives an optical burst signal. FIG. 5 shows a configuration of an optical burst signal and an example of reception processing.
In FIG. 4, the optical receiver includes an optical / electrical converter 51, a threshold setting unit 52, and an amplitude limiting amplifier 53. The optical / electrical converter 51 converts the input optical burst signal into an electrical signal. The electric signal indicates a voltage value corresponding to the light intensity of the optical burst signal. The threshold setting device 52 is configured to set a 1/0 determination threshold in the amplitude limiting amplifier 53, which is obtained from an average value of the voltage values of the 1st level and 0th level of the electrical signal with respect to the optical burst signal. Is used.

  As shown in FIG. 5, the optical burst signal is composed of a preamble part and a data part. The preamble part has a predetermined length threshold setting preamble for setting a 1/0 determination threshold value, and a clock data recovery (CDR). ) It is composed of a CDR preamble used for clock extraction for timing recovery in the circuit. A normal threshold setting preamble having a pattern in which the ratio of 1 level to 0 level (mark ratio) is about 1: 1 is used.

  The amplitude limiting amplifier 53 discriminates between the 1 level and 0 level of the electrical signal corresponding to the optical burst signal with reference to the 1/0 determination threshold, and amplifies it to a predetermined level and outputs it as shown in FIG. That is, a predetermined 1-level signal is output when the level of the electrical signal is greater than the 1/0 determination threshold, and a predetermined 0-level signal is output when the level of the electrical signal is less than the 1/0 determination threshold.

  Here, for optical burst signals having different optical intensities, it is necessary to set a 1/0 determination threshold for each optical burst signal, and a 1/0 determination threshold is set from a threshold setting preamble provided at the head of the optical burst signal. Then, clock extraction and data identification are performed from the subsequent bit pattern.

K. Hattori, M. Nakagawa, N. Kimishima, M. Katayama, A. Misawa, and A. Hiramatsu, “Optical Layer-2 switch network based on WDM / TDM nano-sec wavelength switching,” Proc. ECOC 2012, Sept . 2012.

  The optical intensity of the optical burst signal input to the optical receiver is not only the difference between the 0 level and the 1 level, but also the 0 level changes for each optical burst signal. As shown in FIG. 5, if the 1/0 determination threshold can be set in the threshold setting preamble period, the clock can be extracted from the CDR preamble and the data can be normally identified from the data portion.

  However, as shown in FIG. 6A, when the 0 level of the optical burst signal increases, it takes time until the 1/0 determination threshold reaches the average value of the 1 level and the 0 level in the threshold setting unit 52. Until the / 0 determination threshold exceeds the 0 level, the amplitude limiting amplifier 53 outputs 1 level. For this reason, if the 1/0 determination threshold is 0 level or less even during the CDR preamble or data part period, the output of the amplitude limiting amplifier 53 becomes 1 level, so that clock extraction and data identification are normally performed. Can not be.

  On the other hand, if the light intensity of the threshold setting preamble is uniformly increased as shown in FIG. 6 (b) in anticipation that the light intensity greatly changes for each optical burst signal, the 1/0 determination threshold value becomes 1 level and 0. The time required to reach the average value of the level is shortened, the clock is extracted from the CDR preamble, and the data can be normally identified from the data portion.

  However, as shown in FIG. 7 (a), when the light intensity of the threshold setting preamble is uniformly increased and the 0 level of the optical burst signal is low, the 1/0 determination threshold is 1 level and 0 level. There is a margin in the time to reach the average value. Therefore, the effective band (the amount of traffic that can be transmitted per unit band) can be improved by shortening the length of the threshold setting preamble and relatively increasing the length of the data portion. However, when the 0 level of the optical burst signal becomes high, as shown in FIG. 7B, it takes time until the 1/0 determination threshold reaches the average value of the 1 level and the 0 level again, as shown in FIG. As in the case of, clock extraction and data identification cannot be performed normally.

  Thus, in the situation where the light intensity (especially 0 level) of the optical burst signal changes, the length of the threshold setting preamble and the light intensity that improve the effective bandwidth and enable the normal reception of the optical burst signal are related. Therefore, the length of the threshold setting preamble and the light intensity cannot be set uniformly.

  The present invention relates to an optical burst signal preamble control apparatus capable of controlling the length and optical intensity of a threshold setting preamble on the transmission side according to the optical intensity of an optical burst signal received by an optical receiver, and improving the effective band. An object of the present invention is to provide an optical burst signal preamble control method.

  The first invention is a 1/0 determination threshold value that is disposed at a node of an optical transmission system that transmits and receives optical burst signals having different optical intensities and is used for determination of 1 level and 0 level for each optical burst signal at a receiving side node. In the optical burst signal preamble control apparatus for controlling the length and optical intensity of the threshold setting preamble for setting the test light including the predetermined length and optical intensity threshold setting preamble and the test data in the transmission side node A test optical transmitter for transmitting a burst signal, and a preamble controller for controlling the length and optical intensity of a test optical burst signal and a threshold setting preamble for an optical burst signal transmitted from a node, are provided at a receiving node. The test data is identified based on the 1/0 determination threshold set by the threshold setting preamble of the test optical burst signal, and the test data is A test data error detector that transmits error rate information obtained by error detection processing to a preamble controller of a transmitting node, and the preamble controller has a test data error rate of a predetermined value according to the error rate information. Until the above is reached, transmit a test optical burst signal with the length of the threshold setting preamble sequentially shortened and the light intensity sequentially increased, and the threshold setting preamble immediately before the error rate of the test data exceeds a predetermined value The length and the light intensity are determined and set as the threshold value setting preamble length and the light intensity of the optical burst signal transmitted from the transmission-side node.

  In the optical burst signal preamble control apparatus according to the first aspect of the invention, the preamble controller uses each test optical burst signal transmitted between the transmission-side node and the plurality of reception-side nodes. The length of the threshold setting preamble and the light intensity in each node are determined, and the length and light intensity of the threshold setting preamble of the optical burst signal transmitted from the transmitting node are set according to each receiving node. .

  The second invention is arranged at a node of an optical transmission system that transmits and receives optical burst signals having different optical intensities, and is used to determine 1 level and 0 level for each optical burst signal at a receiving side node. In the optical burst signal preamble control apparatus for controlling the length and optical intensity of the threshold setting preamble for setting the test light including the predetermined length and optical intensity threshold setting preamble and the test data in the transmission side node A test optical transmitter for transmitting a burst signal, and a preamble controller for controlling the length and optical intensity of a test optical burst signal and a threshold setting preamble for an optical burst signal transmitted from a node, are provided at a receiving node. The test data is identified based on the 1/0 determination threshold set by the threshold setting preamble of the test optical burst signal, and the test data is A test data error detector that transmits error rate information obtained by error detection processing to a preamble controller of a transmitting node, and the preamble controller has a test data error rate of a predetermined value according to the error rate information. Until the above is reached, a step of transmitting a test optical burst signal in which the length of the threshold setting preamble is sequentially shortened and the light intensity is sequentially increased, and the threshold setting immediately before the error rate of the test data exceeds a predetermined value Determining the length and light intensity of the preamble for setting, and setting the length and light intensity of the determined threshold setting preamble as the length and light intensity of the threshold setting preamble of the optical burst signal transmitted from the transmitting side node. And have.

  In the optical burst signal preamble control method according to the second invention, the preamble controller uses each test optical burst signal transmitted between the transmission-side node and the plurality of reception-side nodes. The length of the threshold setting preamble and the light intensity in each node are determined, and the length and the light intensity of the threshold setting preamble of the optical burst signal transmitted from the transmitting node are set according to each receiving node.

  The present invention discriminates test data at a transmitting node and a receiving node based on a threshold value setting preamble length of a test optical burst signal and a 1/0 determination threshold corresponding to the light intensity, and its error rate. , Determine the length of the threshold setting preamble and the optical intensity immediately before the error rate of the test data exceeds a predetermined value (error is detected), and set the threshold value of the optical burst signal transmitted from the transmitting node By setting the length and light intensity of the preamble for use, the minimum threshold setting preamble length and light intensity at which the optical burst signal can be normally received are set at the receiving side node, and the effective bandwidth can be improved. it can.

It is a figure which shows the structure of Example 1 of the optical burst signal preamble control apparatus of this invention. It is a figure which shows the structural example of the optical burst signal for a test. It is a figure which shows the structure of Example 2 of the optical burst signal preamble control apparatus of this invention. It is a figure which shows the structural example of an optical receiver. It is a figure which shows the structure and reception processing example of an optical burst signal. It is a figure which shows the example of a reception process according to the level of an optical burst signal. It is a figure which shows the example of a receiving process according to the length of the optical burst signal threshold value setting preamble, and light intensity.

Example 1
FIG. 1 shows the configuration of a first embodiment of an optical burst signal preamble control apparatus according to the present invention. Here, an example applied to a node of a regenerative relay transmission system will be described, but the same applies to an ONU and an OLT of a PON system.

  In FIG. 1, node 1 and node 2 are connected via an optical transmission line 21. Another node may be inserted between the node 1 and the node 2. The node 1 and the node 2 include a regenerative repeater 11, an optical transmitter 12, an optical switch 13, and an optical receiver 14. Further, as a configuration corresponding to the optical burst signal preamble control apparatus of the present invention, the node 1 includes a test light. A transmitter 15 and a preamble controller 16 are provided, and a test data error detector 17 is provided at the node 2. Here, node 1 is assumed to be the transmitting side and node 2 is assumed to be the receiving side. However, node 1 can be the receiving side with respect to the preceding node, and node 2 can be the transmitting side with respect to the subsequent node. Is omitted.

  The regenerative repeater 11 receives the optical burst signal transmitted from the preceding node via the optical transmission line 21 by the optical receiver shown in FIG. 4, and receives the electrical signal in which 1 level and 0 level are identified as the optical transmitter. The optical signal is converted to an optical signal having a predetermined wavelength and output to the optical switch 13. At this time, as shown in FIG. 5 or FIG. 6, in the process of setting the 1/0 determination threshold according to the light intensity of the optical burst signal, it is impossible to distinguish between the 1 level and the 0 level of the preamble part, and the signal waveform is Change.

  The optical transmitter 12 converts a transmission signal of an external device connected to each of the node 1 and the node 2 into an optical signal having a predetermined wavelength and outputs the optical signal to the optical switch 13.

  The optical switch 13 switches between the optical signal transmitted from the next node and the optical signal output to the external device for the optical signal input from the regenerative repeater 11, and outputs the optical signal to the optical transmission path 21 or the optical receiver 14, respectively. A switching process is performed to output an optical signal transmitted from the optical transmitter 12 to the subsequent node to the optical transmission line 21. As the optical switch 13, for example, AWG (Arrayed Waveguide Grating) is used.

  The optical receiver 14 has the same configuration as that of the optical receiver shown in FIG. 4, receives the optical signal switched by the optical switch 13, and outputs the signal identified based on the 1/0 determination threshold to an external device. . Note that a CDR circuit is connected to the optical receiver 14 as necessary, and clock extraction is performed.

  A feature of the present invention is that a test optical burst signal including test data is transmitted and received between the transmission-side node 1 and the reception-side node 2 while changing the length of the threshold setting preamble and the light intensity. Light that is transmitted from the node 1 (the optical transmitter 14 and the regenerative repeater 11) on the transmission side after determining the length and optical intensity of the shortest threshold setting preamble that can be received with no error in the test data or with a predetermined error rate or less. The length of the burst signal threshold setting preamble and the light intensity are adjusted.

  As shown in FIG. 2, the test optical transmitter 15 of the transmission-side node 1 adds test data to the reception-side node 2 after a predetermined length and light intensity threshold setting preamble. Send a burst signal. The length of the threshold setting preamble and the light intensity are set by the preamble controller 16. The test optical burst signal is output from the node 1 to the optical transmission line 21 via the optical switch 13 and received by the optical receiver 14 via the regenerative repeater 11 and the optical switch 13 of the node 2.

  The optical receiver 14 of the node 2 identifies the test data based on the 1/0 determination threshold set during the threshold setting preamble period of the test optical burst signal, and outputs the test data to the test data error detector 17. The test data error detector 17 performs error detection processing of the test data, and transmits error rate information indicating the presence or absence of an error or an error rate to the preamble controller 16 of the node 1 on the transmission side via a predetermined control channel. Here, the control channel may be set to the optical transmission line 21 or may be set to another transmission means. Moreover, the structure which forms a control channel via a centralized control apparatus may be sufficient.

  The preamble controller 16 of the node 1 transmits the test optical transmission when no error is detected or the error rate is equal to or less than a predetermined value based on the error rate information transmitted from the test data error detector 17 of the node 2. The length of the threshold setting preamble generated by the device 15 is shortened, for example, by 1 bit, and the light intensity is increased. The above processing is repeated, and error rate information indicating that an error in the test data is detected by the test data error detector 17 of the node 2 or that the error rate has exceeded a predetermined value is the preamble controller 16 of the node 1. Is notified, the length of the threshold setting preamble and the light intensity set in the optical burst signal transmitted from the node 1 immediately before are notified.

  When the length of the threshold setting preamble and the light intensity are determined, the preamble controller 16 stops transmitting the test optical burst signal to the test optical transmitter 15 and sets the determined length and light intensity thresholds. Control is performed to set the preamble for the optical burst signal output from the optical transmitter 12. Furthermore, the length of the threshold setting preamble and the optical intensity of the optical burst signal output from the optical transmitter in the regenerative repeater 11 may be similarly controlled. Thereby, the length and optical intensity of the shortest threshold setting preamble that can normally receive the optical burst signal transmitted from the node 1 to the node 2 are set, and the effective band can be improved.

(Example 2)
FIG. 3 shows the configuration of a second embodiment of the optical burst signal preamble control apparatus of the present invention. Here, an example applied to a node of a regenerative repeater transmission system will be described.

  The optical burst signal preamble control apparatus according to the first embodiment is configured to set the minimum required threshold setting preamble length and light intensity in a one-to-one relationship between the node 1 and the node 2. The optical burst signal preamble control apparatus according to the second embodiment is characterized in that the minimum threshold setting preamble length and optical intensity are set for each destination node of the optical burst signal.

  3, in addition to the configuration of the first embodiment shown in FIG. 1, the node 1 and the node 2 of the second embodiment are configured to connect a node-preamble correspondence table 18 to the preamble controller 16 of the node 1 on the transmission side. is there. By using the test optical transmitter 15 and preamble controller 16 of the node 1 on the transmission side and the test data error detector 17 of the node 2 on the reception side, the threshold value setting preamble of the optical burst signal for test is set as in the first embodiment. Length and light intensity are controlled. The length of the threshold setting preamble and the light intensity are stored in the node-preamble length correspondence table 18 in association with the node 2. Next, the node 1 on the transmission side switches the node n on the reception side and performs the same processing, and the minimum length of the threshold setting preamble and the light intensity between the node 1 and the node n are set. It is stored in the node-preamble correspondence table 18.

  When the length of the threshold setting preamble and the light intensity are determined for each node on the reception side, the preamble controller 16 refers to the node-preamble correspondence table 18 for each node on the reception side of the optical burst signal transmitted from the node 1, Control is performed to set a length and light intensity threshold setting preamble corresponding to the receiving node in the optical burst signal output from the optical transmitter 12. Furthermore, the length of the threshold setting preamble and the optical intensity of the optical burst signal output from the optical transmitter in the regenerative repeater 11 may be similarly controlled. Thereby, the length and optical intensity of the shortest threshold setting preamble that can normally receive the optical burst signal transmitted from the node 1 to the node n are individually set, and the effective bandwidth can be improved.

DESCRIPTION OF SYMBOLS 11 Regenerative repeater 12 Optical transmitter 13 Optical switch 14 Optical receiver 15 Test optical transmitter 16 Preamble controller 17 Test data error detector 18 Node-preamble correspondence table 51 Optical / electric converter 52 Threshold setting unit 53 Amplitude limit amplifier

Claims (4)

Threshold value for setting a 1/0 determination threshold value that is arranged at a node of an optical transmission system that transmits and receives optical burst signals having different optical intensities and is used for determination of 1 level and 0 level for each optical burst signal at a receiving side node In an optical burst signal preamble control device that controls the length and light intensity of a setting preamble,
A test optical transmitter for transmitting a test optical burst signal including a preamble for setting a threshold value of a predetermined length and light intensity and test data to a transmission side node, a test optical burst signal, and an optical burst signal transmitted from the node A preamble controller for controlling the length of the threshold setting preamble and the light intensity,
The test data is identified based on the 1/0 decision threshold set in the threshold setting preamble of the test optical burst signal at the receiving side node, and error rate information obtained by error detection processing of the test data is stored. A test data error detector for transmitting to a preamble controller of the transmitting node;
The preamble controller reduces the length of the threshold setting preamble and sequentially increases the light intensity until the error rate of the test data reaches a predetermined value or more according to the error rate information. Transmitting a signal, determining the length and optical intensity of the threshold setting preamble immediately before the error rate of the test data exceeds a predetermined value, and transmitting the threshold value setting preamble of the optical burst signal transmitted from the transmitting side node An optical burst signal preamble control device characterized in that the length and the light intensity are set. The optical burst signal preamble control device according to claim 1,
The preamble controller uses the test optical burst signal transmitted between the transmitting node and a plurality of receiving nodes, respectively, to determine the length of the threshold setting preamble in each receiving node. An optical burst signal characterized in that the optical intensity is determined, and the length and optical intensity of the threshold setting preamble of the optical burst signal transmitted from the transmitting side node are set according to each receiving side node. Preamble control device. Threshold value for setting a 1/0 determination threshold value that is arranged at a node of an optical transmission system that transmits and receives optical burst signals having different optical intensities and is used for determination of 1 level and 0 level for each optical burst signal at a receiving side node In an optical burst signal preamble control device that controls the length and light intensity of a setting preamble,
A test optical transmitter for transmitting a test optical burst signal including a preamble for setting a threshold value of a predetermined length and light intensity and test data to a transmission side node, a test optical burst signal, and an optical burst signal transmitted from the node A preamble controller for controlling the length of the threshold setting preamble and the light intensity,
The test data is identified based on the 1/0 decision threshold set in the threshold setting preamble of the test optical burst signal at the receiving side node, and error rate information obtained by error detection processing of the test data is stored. A test data error detector for transmitting to a preamble controller of the transmitting node;
The preamble controller is
Transmitting a test optical burst signal in which the length of the threshold setting preamble is sequentially shortened and the light intensity is sequentially increased until an error rate of the test data reaches a predetermined value or more according to the error rate information; ,
Determining the length and light intensity of the threshold setting preamble immediately before the error rate of the test data is equal to or higher than a predetermined value;
And setting the determined threshold setting preamble length and optical intensity as the threshold setting preamble length and optical intensity of the optical burst signal transmitted from the transmission-side node. Preamble control method. The optical burst signal preamble control method according to claim 3,
The preamble controller uses the test optical burst signal transmitted between the transmitting node and a plurality of receiving nodes, respectively, to determine the length of the threshold setting preamble in each receiving node. An optical burst signal preamble control method, comprising: determining an optical intensity, and setting a length and an optical intensity of the threshold setting preamble of an optical burst signal transmitted from the transmitting side node according to each receiving side node .

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