JP2007081510A - Optical burst signal receiving apparatus and burst packet detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical burst signal receiving apparatus and a burst packet detecting method which prevent erroneous reproduction of a burst packet due to a trailing current generated after the end of the burst packet.
An optical burst signal receiving apparatus 1 does not directly input an electric burst signal input to an ATC-IC 120 to a burst packet detection unit 22 but provides a differentiation circuit 30 to input the electric burst signal and output it. A signal is input to the burst packet detector 22.
[Selection] Figure 1

Description

  The present invention relates to an optical burst signal receiving apparatus and a burst packet detecting method for generating a detection signal of a burst packet arranged in a certain section of a signal sequence.

  Currently, the PON (Passive Optical Network) method is used for the network configuration and access line method of FTTH (Fiber To The Home), FTTB / C (Fiber To The Building / Curb), and FTTCab (Fiber To The Cabinet) services. There are many cases. In the PON system, an optical communication network is provided by an OLT (Optical Line Terminal) of a station side terminal device and an ONU (Optical Network Unit) of a user side terminal device. Here, the format of the optical transmission signal from the ONU to the OLT is a burst signal, and the OLT must have a function as an optical burst signal receiver. There are various PON systems such as ATM (Asynchronous Transfer Mode) -PON system, B (Broadband) -PON system, E (Ethernet (registered trademark))-PON system, etc. Signal.

  FIG. 9 shows a block diagram of a typical optical burst signal receiver 9. The optical burst signal receiving device 9 mainly includes an optical module 10 that converts an optical input signal into an electrical burst signal and an ATC-IC (Automatic Threshold Integrated Circuit) 20 that equivalently amplifies the electrical burst signal. The ATC-IC 20 mainly includes a main signal reproducing unit 21 for equivalently amplifying burst signals, a burst packet detecting unit 22 for detecting burst packets, and a burst packet detecting unit among burst signals equivalently amplified by the main signal reproducing unit 21. 22 includes a selector unit 23 that outputs a burst signal only in a section in which a burst packet is detected.

The waveform of the signal in each part of this ATC-IC 20 is shown in FIG. When the signal having the waveform shown in FIG. 9A is input to the ATC-IC 20 at point A (FIG. 9), the ATC-IC 20 is branched into two, one to the main signal reproduction unit 21 (FIG. 9) and the other to It is input to the burst packet detector 22 (FIG. 9). The signal at point B, which is equivalently amplified by the main signal reproducing unit 21, has the waveform shown in (b), and noise (not shown) is output in the non-signal section between burst packets. The signal at point C, which is the output signal of the burst packet detector 22, has the waveform shown in (c), and is at a high level in the detected burst packet section and at a low level in the non-signal section. The signals at the points B and C are input to the selector unit 23 (FIG. 9) provided at the subsequent stage, and are output signals of the main signal reproducing unit 21 using the signal at the point C which is a burst packet detection signal. By masking the signal at point B, a burst signal in which the above-mentioned noise is eliminated is generated. The waveform of the signal at point D, which is the output signal of the selector unit 23, is shown in (d).
Patent Document 1 is known as a conventional technique.
Japanese Patent Laid-Open No. 10-163828

Conventionally, the output signal of the optical module 10 is directly input to the burst packet detection unit 22 as described above. The problems in this configuration are as follows.
The photodiode 11 provided in the optical module 10 of FIG. 9 outputs a current corresponding to the intensity of the optical input signal. However, the trailing current flows after the burst packet, that is, when the burst packet ends and moves to a no-signal section. Produce. When this current is converted to a voltage by the preamplifier 12, a low-frequency voltage signal is generated, and the voltage level rises despite no signal. For example, when the photodiode 11 receives the optical input signal having the waveform shown in FIG. 11A, the electrical signal output from the optical module 10 has the waveform shown in FIG.

  Conventionally, the output signal of the optical module 10 is directly input to the burst packet detector 22 and amplified by a gain amplifier that is an amplifier constituting the burst packet detector 22. FIG. 12 shows the influence caused by the signal caused by the trailing current when the gain amplifier amplifies the electric burst signal including the burst packet period, the non-signal period, and the signal component period caused by the trailing current as described above. I will explain. In general, a gain amplifier compares the voltage of an input signal indicated by a solid line (a) with a reference value indicated by a broken line, amplifies the difference, and outputs the amplified signal. At this time, since the difference from the reference value is also amplified and output even in the non-signal section where signals due to the trailing current are mixed, it is erroneously reproduced as shown in FIG. End up.

  Generally, in burst packet detection, it is necessary to provide a margin so that a burst packet detection signal is not output even though an optical burst signal reproducible by the optical burst signal receiving device is input. Practically, it is desirable to be able to detect a burst packet smaller by about −3 dB than the minimum value of the reproducible optical burst signal. However, it has been difficult to detect a burst packet correctly for the reasons described above.

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide an optical burst signal receiving apparatus and burst packet detection method that prevent erroneous reproduction of burst packets due to tailing current that occurs after the end of burst packets. Is to provide.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The invention according to claim 1 is directed to an optical module that inputs an optical burst signal, converts the optical burst signal into an electrical burst signal, and outputs the electrical burst signal. In an optical burst signal receiving apparatus comprising a main signal regeneration unit that performs equivalent amplification and outputs, and a burst packet detection unit that inputs the electrical burst signal and outputs a burst bucket detection signal, the optical burst signal detection unit inputs the burst signal detection unit. An optical burst signal receiving apparatus comprising: a differentiating circuit that inputs an electrical burst signal, cancels a low frequency component, and outputs the signal to the burst packet detector.

  According to a second aspect of the present invention, the optical burst signal receiving device according to the first aspect further includes an input buffer that inputs an electric burst signal input to the differentiating circuit, performs impedance conversion, and outputs the converted signal to the differentiating circuit. It is characterized by comprising.

  According to a third aspect of the present invention, in the optical burst signal receiving device according to the first or second aspect, the differentiating circuit has a capacitance element having both ends connected to an input terminal and an output terminal, and one end connected to the output terminal. A resistor connected to a power source at the other end, amplifies a voltage difference between a signal input from the differentiating circuit to the burst packet detecting unit and a power source of the differentiating circuit, and outputs the amplified voltage to the burst packet detecting unit And a gain buffer.

  According to a fourth aspect of the present invention, in the optical burst signal receiving device according to the third aspect, the resistance of the differentiating circuit is a variable resistance.

  According to a fifth aspect of the present invention, there is provided an optical module that receives an optical burst signal, converts the optical burst signal into an electrical burst signal, and outputs the optical burst signal; a main signal regeneration unit that receives the electrical burst signal and performs equivalent amplification and outputs; In an optical burst signal receiving apparatus comprising a burst packet detection unit that inputs a signal and outputs a burst bucket detection signal, the optical module outputs two signals of a normal phase signal and a negative phase signal of the electrical burst signal, A first differentiating circuit that inputs one of two signals of a normal phase signal and a negative phase signal of the electric burst signal input to the burst packet detection unit, cancels and outputs a low frequency component, and the burst packet detection unit A second differentiating circuit which inputs the other of the two signals of the normal phase signal and the negative phase signal of the input electric burst signal, cancels the low frequency component and outputs the second differential circuit; An optical burst comprising: a gain buffer that amplifies a voltage difference between an output signal of the first differentiating circuit and an output signal of the second differentiating circuit and outputs the amplified difference to the burst packet detecting unit. It is a signal receiving device.

  According to a sixth aspect of the present invention, in the optical burst signal receiving device according to the fifth aspect of the present invention, a signal input to the first differentiating circuit is input, impedance conversion is performed, and the signal is output to the first differentiating circuit. An input buffer and an input buffer for inputting a signal input to the second differentiating circuit, performing impedance conversion, and outputting the input signal to the second differentiating circuit are further provided.

  The invention according to claim 7 is an optical module that inputs an optical burst signal, converts it into an electrical burst signal and outputs it, a main signal regeneration unit that receives the electrical burst signal, equivalently amplifies it, and outputs it, and the electrical burst In a burst bucket detection method using an optical burst signal receiving device including a burst packet detection unit that inputs a signal and outputs a burst bucket detection signal, an electric burst signal input to the burst packet detection unit is input to a differentiation circuit The burst bucket detection method includes a step of canceling a low frequency component and outputting the canceled low frequency component to the burst packet detection unit.

  According to an eighth aspect of the present invention, in the burst bucket detecting method according to the seventh aspect, an electric burst signal input to the differentiating circuit is input to an input buffer, impedance conversion is performed, and the electric burst signal is output to the differentiating circuit. It further has these.

  According to a ninth aspect of the present invention, in the burst bucket detection method according to the seventh or eighth aspect, the differentiating circuit includes a capacitive element having both ends connected to an input terminal and an output terminal, and one end connected to the output terminal. A terminal having a resistor connected to a power source, a signal input from the differentiating circuit to the burst packet detector and a power source of the differentiating circuit are input to a gain buffer, and a difference between these voltages is amplified. The method further includes a step of outputting to the burst packet detector.

  According to a tenth aspect of the present invention, in the burst packet detecting method according to the ninth aspect, the resistance of the differentiating circuit is a variable resistance.

  The invention according to claim 11 is an optical module that inputs an optical burst signal, converts it into an electrical burst signal and outputs it, a main signal regeneration unit that receives the electrical burst signal, performs equivalent amplification and outputs it, and the electrical burst In a burst bucket detection method using an optical burst signal receiving device comprising a burst packet detection unit that inputs a signal and outputs a burst bucket detection signal, a positive phase signal of an electrical burst signal input to the burst packet detection unit, One of the two out-of-phase signals is input to the first differentiating circuit to cancel and output the low frequency component, and the other of the two signals is input to the second differentiating circuit to cancel the low frequency component. The first process of outputting the output, the output signal of the first differentiating circuit and the output signal of the second differentiating circuit are input to a gain buffer, A burst bucket detection method characterized in that it comprises a second step of amplifying and outputting a difference voltage to the burst packet detecting unit.

  According to a twelfth aspect of the present invention, in the burst bucket detection method according to the eleventh aspect, an input for inputting a signal input to the first differentiating circuit, performing impedance conversion, and outputting the signal to the first differentiating circuit. It further comprises a buffer and an input buffer for inputting a signal input to the second differentiating circuit, performing impedance conversion, and outputting it to the second differentiating circuit.

  According to the present invention, it is possible to reproduce a waveform by canceling a low-frequency signal component generated in an electric burst signal due to a trailing current generated after the end of a burst packet. In addition, it is possible to reproduce a waveform by canceling a bias component included in an electrical signal output from an optical module when an optical burst signal having a small extinction ratio is received.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an optical burst signal receiving apparatus 1 according to the first embodiment. The optical burst signal receiving apparatus 1 does not directly input the electric burst signal input to the ATC-IC 120 to the burst packet detection unit 22 but provides a differentiating circuit 30 to input the electric burst signal. It differs from the conventional optical burst signal receiver 9 in that the output signal is input to the burst packet detector 22.

Differentiating circuit 30 is a capacitor 31, the resistance value resistor for R 32, a power source 33 of the voltage V _T is the volume element of the electrostatic capacitance C as shown in FIG. An electric burst signal input to the ATC-IC 120 (FIG. 1) is input to the input terminal 34, and a signal output from the output terminal 35 is input to the burst packet detection unit 22. The differentiating circuit 30 has the effect of a high-pass filter that passes high-frequency components and attenuates low-frequency components. Attenuation amount is 0 dB for a frequency component of (1 / 2πCR) Hz or more, −6 dB for a frequency component of (1 / 4πCR) Hz, (1 / 20πCR), depending on the capacitance C of the capacitor 31 and the resistance value R of the resistor 23. The frequency component of Hz is −20 dB. As shown in FIG. 3, generally, a burst packet of an electric signal output from the optical module 10 (FIG. 1) is a burst signal sequence, and thus has a high frequency component of 50 M to 1.25 GHz. The signal has a low frequency component of 100 k to 2 MHz. Therefore, by selecting the capacitance C of the capacitor 31 and the resistance value R of the resistor 23, the frequency component of the signal due to the trailing current is cut in the differentiation circuit 30 (FIG. 1) as shown in FIG. And output to the burst packet detector 22 (FIG. 1).

Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing a configuration of the optical burst signal receiving apparatus 2 in the second embodiment. The optical burst signal receiving apparatus 2 is configured to input an electric burst signal input to the ATC-IC 220 to the input buffer 40 and input this output signal to the differentiating circuit 30. Different from the signal receiving device 1. In FIG. 5, the main signal reproduction unit 21, the burst packet detection unit 22, and the selector unit 23 shown in FIG. 1 are omitted, and one of the signals branched into the ATC-IC 220 is input to the burst packet detection unit 22. Only the configuration up to this point is shown. That is, the output terminal of the differentiation circuit 30 is connected to the burst packet detection unit 22.
The input buffer 40 in FIG. 5 converts the electrical signal output from the optical module 10 into a low output impedance and inputs the converted signal to the differentiation circuit 30. Thereby, the transmission efficiency of signal power can be improved.

Next, a third embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration of the optical burst signal receiving device 3 in the third embodiment. This optical burst signal receiving device 3 is provided with a gain buffer 50 subsequent to the differentiation circuit 30 of the optical burst signal receiving device 2 in the second embodiment. The gain to one input terminal of the buffer 50 is input the output signal of the differentiating circuit 30, the other input terminal is connected to the power supply 33 of the voltage V _T constituting a differential circuit 30. With this configuration, the gain buffer 50 amplifies and outputs the difference between the voltage of the output signal of the differentiating circuit 30 and the voltage V _T using the voltage V _T as a reference value. Other configurations are the same as those of the optical burst signal receiving apparatus 2.

  Next, a fourth embodiment of the present invention will be described. FIG. 7 is a block diagram showing a configuration of the optical burst signal receiving apparatus 4 in the fourth embodiment. The optical module 410 of the optical burst signal receiver 4 is obtained by further providing a buffer 13 in the optical module 10 of the conventional optical burst signal receiver 9, and the output signal of the preamplifier 12 is input to the buffer 13 to be corrected. Outputs phase and negative phase signals.

  The ATC-IC 420 inputs a normal phase signal and a negative phase signal of the electrical burst signal output from the optical module 410. The positive phase signal is input to the input buffer 40a, and the output signal is input to the differentiation circuit 30a. On the other hand, the reverse phase signal is input to the input buffer 40b, and the output signal is input to the differentiation circuit 30b. A gain buffer 50 is provided at the subsequent stage of the differentiation circuits 30a and 30b. The output signal of the differentiation circuit 30a is input to one input terminal of the gain buffer 50, and the output signal of the differentiation circuit 30b is input to the other input terminal. Is done. The gain buffer 50 amplifies and outputs the voltage difference between these input signals. Other configurations are the same as those of the optical burst signal receiving apparatus 2. Thereby, the gain of the gain buffer 50 can be doubled as compared with the optical burst signal receiving device 3 in the third embodiment.

  Next, a fifth embodiment of the present invention will be described. FIG. 8 is a block diagram showing a configuration of the optical burst signal receiving apparatus 5 in the fifth embodiment. The differential circuit 30c of the ATC-IC 520 of the optical burst signal receiver 5 is provided in the ATC-IC 520 by replacing the resistor 32 of the differential circuit 30 of the ATC-IC 320 of the optical burst signal receiver 3 in FIG. Both ends of the variable resistor 38 are connected to the terminals 36 and 37 from the outside. As described above, the low-band cutoff frequency in the differentiation circuit 30 is determined by the capacitance of the capacitor and the resistance value of the resistor. Therefore, the low-band cutoff frequency can be appropriately set by providing the variable resistor 38 outside the ATC-IC 520 as in the differentiation circuit 30c so that the resistance value can be adjusted.

  The present invention is used in an optical burst signal receiving apparatus.

It is a block diagram which shows the structure of the optical burst signal receiver 1 in the 1st Embodiment of this invention. 2 is a diagram showing a configuration of a differentiation circuit 30. FIG. It is a figure which shows the waveform of the electric signal which the optical module 10 outputs. 3 is a diagram illustrating waveforms of an input signal and an output signal of a differentiating circuit 30. FIG. It is a block diagram which shows the structure of the optical burst signal receiver 2 in the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the optical burst signal receiver 3 in the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the optical burst signal receiver 4 in the 4th Embodiment of this invention. It is a block diagram which shows the structure of the optical burst signal receiver 5 in the 5th Embodiment of this invention. It is a block diagram which shows the structure of the conventional optical burst signal receiver 9. FIG. It is a figure which shows the waveform of the signal in each part of the conventional optical burst signal receiver 9. FIG. It is a figure which shows the waveform of the optical signal input into the optical module 10, and the electrical signal output. 3 is a diagram illustrating waveforms of an input signal and an output signal of a gain amplifier that constitutes a burst packet detection unit 22. FIG.

Explanation of symbols

1, 2, 3, 4, 5, 9 ... optical burst signal receiving device 10, 410 ... optical module 11 ... photodiode 12 ... preamplifier 13 ... buffer 20, 120, 220, 320, 420, 520 ... ATC-IC
DESCRIPTION OF SYMBOLS 21 ... Main signal reproduction | regeneration part 22 ... Burst packet detection part 23 ... Selector part 30, 30a, 30b, 30c ... Differentiation circuit 31 ... Capacitor 32 ... Resistance 33 ... Power supply 34 ... Input terminal 35 ... Output terminal 36, 37 ... Terminal 38 ... Variable resistors 40, 40a, 40b ... input buffer 50 ... gain buffer

Claims (12)

An optical module that inputs an optical burst signal, converts it into an electrical burst signal, and outputs it; a main signal regenerator that inputs the electrical burst signal and performs equivalent amplification; and outputs a burst bucket detection signal that receives the electrical burst signal. In an optical burst signal receiving device comprising a burst packet detector for outputting,
An optical burst signal receiving apparatus comprising: a differentiation circuit that inputs an electric burst signal input to the burst packet detection unit, cancels a low frequency component, and outputs the signal to the burst packet detection unit.   2. The optical burst signal receiving apparatus according to claim 1, further comprising an input buffer that inputs an electrical burst signal input to the differentiating circuit, performs impedance conversion, and outputs the converted signal to the differentiating circuit.   The differentiating circuit includes a capacitive element having both ends connected to an input terminal and an output terminal, and a resistor having one end connected to the output terminal and the other end connected to a power source, and the differentiating circuit is connected to the burst packet detection unit. 3. The optical burst signal reception according to claim 1, further comprising a gain buffer that amplifies a voltage difference between an input signal and a power source of the differentiating circuit and outputs the amplified difference to the burst packet detection unit. apparatus.   4. The optical burst signal receiver according to claim 3, wherein the resistance of the differentiating circuit is a variable resistance. An optical module that inputs an optical burst signal, converts it into an electrical burst signal, and outputs it; a main signal regenerator that inputs the electrical burst signal and performs equivalent amplification; and outputs a burst bucket detection signal that receives the electrical burst signal. In an optical burst signal receiving device comprising a burst packet detector for outputting,
The optical module outputs two signals of a normal phase signal and a negative phase signal of an electrical burst signal,
A first differentiating circuit for inputting one of two signals of a normal phase signal and a negative phase signal of an electric burst signal input to the burst packet detection unit, canceling a low frequency component, and outputting the canceled signal;
A second differentiating circuit that inputs the other of the positive phase signal and the negative phase signal of the electric burst signal input to the burst packet detector, cancels the low frequency component, and outputs the canceled signal;
A gain buffer that amplifies the voltage difference between the output signal of the first differentiating circuit and the output signal of the second differentiating circuit and outputs the amplified difference to the burst packet detector;
An optical burst signal receiving apparatus comprising: An input buffer that inputs a signal input to the first differentiating circuit, performs impedance conversion, and outputs the converted signal to the first differentiating circuit;
An input buffer that inputs a signal input to the second differentiating circuit, performs impedance conversion, and outputs the signal to the second differentiating circuit;
The optical burst signal receiver according to claim 5, further comprising: An optical module that inputs an optical burst signal, converts it into an electrical burst signal, and outputs it; a main signal regenerator that inputs the electrical burst signal and performs equivalent amplification; and outputs a burst bucket detection signal that receives the electrical burst signal. In a burst bucket detection method using an optical burst signal receiving device comprising a burst packet detector for outputting,
A burst bucket detection method comprising: inputting an electric burst signal input to the burst packet detection unit to a differentiating circuit, canceling a low frequency component, and outputting the signal to the burst packet detection unit.   The burst bucket detection method according to claim 7, further comprising a step of inputting an electric burst signal input to the differentiating circuit to an input buffer, performing impedance conversion, and outputting the converted signal to the differentiating circuit.   The differentiating circuit includes a capacitive element having both ends connected to an input terminal and an output terminal, and a resistor having one end connected to the output terminal and the other end connected to a power source, and the differentiating circuit is connected to the burst packet detection unit. 9. The method according to claim 7, further comprising a step of inputting an input signal and a power source of the differentiating circuit into a gain buffer, amplifying a difference between these voltages, and outputting the amplified difference to the burst packet detecting unit. The burst bucket detection method described.   The burst packet detection method according to claim 9, wherein the resistance of the differentiating circuit is a variable resistance. An optical module that inputs an optical burst signal, converts it into an electrical burst signal, and outputs it; a main signal regenerator that inputs the electrical burst signal and performs equivalent amplification; and outputs a burst bucket detection signal that receives the electrical burst signal. In a burst bucket detection method using an optical burst signal receiving device comprising a burst packet detector for outputting,
One of the positive and negative phase signals of the electrical burst signal input to the burst packet detector is input to the first differentiating circuit to cancel and output the low frequency component, and the two signals A first step of inputting the other of the above to the second differentiating circuit, canceling and outputting the low frequency component,
A second step of inputting an output signal of the first differentiating circuit and an output signal of the second differentiating circuit into a gain buffer, amplifying a difference between these voltages and outputting the amplified difference to the burst packet detecting unit;
A burst bucket detection method comprising: An input buffer that inputs a signal input to the first differentiating circuit, performs impedance conversion, and outputs the converted signal to the first differentiating circuit;
An input buffer that inputs a signal input to the second differentiating circuit, performs impedance conversion, and outputs the signal to the second differentiating circuit;
The burst bucket detection method according to claim 11, further comprising:

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