JP2003169068A - Optical transmitting device and optical receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evade a collision between light signals i<SB>0</SB>and i<SB>1</SB>at low facility cost without lowering transmission efficiency by an optical transmitting device 30 which receives a light multiplex signal (i<SB>0</SB>+i<SB>1</SB>) generated by multiplexing the light signals i<SB>0</SB>and i<SB>1</SB>sent asynchronously from subscribers A and C. <P>SOLUTION: The optical transmitting device 30 is equipped with a collision detection signal output means 31 which converts the received light multiplex signal (i<SB>0</SB>+i<SB>1</SB>) into an electric signal E and outputs a collision detection signal showing a collision between the light signals i<SB>0</SB>and i<SB>1</SB>sent asynchronously from the subscribers A and C when the level of the electric signal E exceeds a specified threshold e<SB>0</SB>, and control means 33 to 37 which controls the transmission of the light signals by the subscribers A and B according to whether the collision detection signal is received. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission device for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed, and an optical transmission device provided in the optical transmission device. Relating to a receiving device.

[0002]

2. Description of the Related Art Conventionally, as an optical transmission system for receiving an optical multiplexed signal in which optical signals transmitted from a plurality of subscribers are multiplexed and multiplexing and transmitting optical signals addressed to a plurality of subscribers,
A typical example is time division multiple access (TDMA: Time).
Division Multiple Acces
s) method is known. Generally, a TDMA method is used in a PON (passive optical network) type optical access network.

When transmitting a TDMA optical signal in a PON type network, different wavelengths are used for an upstream optical signal from a subscriber to a communication station and a downstream optical signal from the communication station to a subscriber. Also, in order to avoid collision of optical signals, the communication station allocates a time slot for each subscriber in the wavelengths for the upstream optical signal and the wavelengths for the downstream optical signal, and in each time slot, the time slots are allocated to multiple subscribers. To transmit optical signals.

However, in such a TDMA system, it is always necessary to manage the time slot for each subscriber (in addition, the management accuracy of the time slot may be questioned). There is a problem that a complicated optical transmission device is required and the equipment cost is increased. In addition, since the same function is required for the optical transmission device on the subscriber side, there is a problem that the equipment cost is also increased.

Further, in such a TDMA system, when the data signal to be transmitted has a variable length, a padding process for filling the time slot is required, and the overhead due to this padding process reduces the transmission efficiency. There was a problem to say.

[0006] At present, a wide area LAN system is being studied in order to speed up the Internet connection of subscribers. In a wide-area LAN system, it is desired that the equipment cost is low in place of the best-effort communication quality, and that the optical transmission method is used to speed up the subscriber's Internet connection. ing. Therefore, in such a wide area LAN system, when the TDMA transmission method is applied, the equipment cost increases,
The application of other optical transmission systems is under consideration.

That is, as in the case of the conventional LAN system, the development of an optical transmission system of the best-effort communication quality, which has a low equipment cost, has been a problem in expanding the broadband LAN system.

As one method for solving this problem, P
In the ON-type network configuration, the wavelengths for the upstream optical signal and the wavelengths for the downstream optical signal are different from each other.
Granting method of t-PON (EPON) communication ”
It has been known.

In the "EPON communication", unlike the case of the TDMA transmission system, the communication station is
The optical signal addressed to each subscriber is multiplexed, and the multiplexed optical multiplexed signal is delivered to each subscriber by multicast, and each subscriber filters the received optical multiplexed signal with its own address and sends it to itself. While obtaining the Ethernet frame, each subscriber asynchronously transmits an upstream optical signal to the communication station in upstream communication.

Therefore, there is a high possibility that a "data garbled phenomenon" will occur on the communication station side, such that the upstream optical signals from the respective subscribers collide with each other and the transmission data contained in the upstream optical signals change. there were.

The "Granting system" is a transmission system which is conceived in order to avoid the collision of the upstream optical signals from the respective subscribers, and the respective subscribers are arranged so as to avoid the collision of the upstream optical signals. A "Grant signal" having "schedule data" as a parameter for scheduling the transmission timing of the upstream optical signal from is distributed from the communication station to each subscriber, and each subscriber includes the "Grant signal" included in the received "Grant signal". The upstream optical signal is transmitted according to "schedule data".

The operation of the conventional optical transmission device will be described in detail with reference to FIG. FIG. 9 shows an example of an optical receiving circuit 31 provided in a conventional optical transmission device.

As shown in FIG. 9, the optical receiving circuit 31 includes a photodiode 41, a preamplifier 42, a limiter amplifier 43, and a CDR (Clock Data Rec).
44) and PLL (Phase Locke)
d Loop) 45 and a bias / power supply 46.

First, the photodiode 41 receives the optical signal I transmitted via the optical subscriber line (uplink) 7 and converts the optical signal I into a minute electric signal I. Second
Then, the preamplifier 42 linearly amplifies the minute electric signal I and outputs the electric signal E (see FIG. 11). Thirdly, the limiter amplifier 43 waveform-shapes the input electric signal E and outputs the digital signal V (see FIG. 12).

Fifth, the CDR 44 extracts a clock component from the bit string of the input digital signal V. Sixth
Then, the CDR 44 outputs the “data signal” and the “clock signal” generated by the PLL 45 in phase synchronization with each other (see FIG. 10). Further, the PLL 45 outputs the “unlock signal” when the clock component is not extracted (the out-of-synchronization state of the received data signal occurs) (see FIG. 10).

Seventh, when the optical transmission device receives the above-mentioned "unlock signal", it sends a "PAUSE signal (transmission stop signal)" for instructing each subscriber to stop the transmission of the upstream optical signal. , Deliver by multicast to each subscriber. Eighth, the optical transmission device uses the above "unlock signal".
"Grant signal" including the "schedule data" that was rescheduled when the status of not receiving
To each subscriber.

On the other hand, usually, each subscriber transmits an upstream optical signal in accordance with the "schedule data" designated by the "Grant signal".
When the "signal" is received, the transmission of the upstream optical signal is stopped, the above "schedule data" is discarded, and a new "Gra
It becomes a standby state for receiving the "nt signal".

Then, each subscriber receives a new "Grant".
When the "signal" is received, the transmission of the upstream optical signal is restarted according to the "schedule data" included in the "Grant signal".

[0019]

However, the conventional optical transmission device 30 performs processing as if the "data garbled phenomenon" occurs when the "unlock signal" is generated. As the cause of the "phenomenon", in addition to the collision of the upstream optical signal from each subscriber, for example, a surge due to lightning, a change in the subscriber line state due to a sudden change in temperature and humidity, and the like can be considered. Therefore, in the conventional optical receiving circuit 31, even when the "unlocked signal (data garbled phenomenon)" is detected, it is not possible to accurately determine whether or not the collision of the upstream optical signal has occurred. Therefore, "G
There is a problem that the transmission control of the upstream signal by the "rant signal" does not work well.

That is, the optical transmission system between the communication station and each subscriber is performed asynchronously, the data signal included in the upstream optical signal has a variable length, and the delay on the optical subscriber line is present. Considering the influences of different times and different processing times of the optical transmission devices on the subscriber side, in order to make the transmission control of the upstream signal by the “Grant signal” work well, It is necessary to detect the collision accurately.

In addition, when transmission timing with a margin is scheduled according to the "unlock signal" so as to avoid collision of the upstream optical signal on the communication station side, the data signal included in the upstream optical signal is scheduled. There is a problem that the transmission efficiency is impaired.

Further, as shown in FIG. 11, small input current _{I (i a, i b,} i c) linearly amplifies the output voltage E of
Unlike the preamplifier 42 that outputs (e _a , e _b , e _c ), the limiter amplifier 43 outputs the output voltage V _h when the input voltage E equal to or higher than the threshold voltage e _a is input, as shown in FIG. Since it is output, the digital signal V has a discrete value, and as a result, it is difficult to detect a transient change in the digital signal V due to collision of the upstream optical signal.

Therefore, the present invention has been made in view of the above points, and an optical transmission apparatus for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed is transmitted. It is an object of the present invention to avoid optical signal collision at a low equipment cost without reducing efficiency.

[0024]

An optical transmission apparatus and an optical receiving apparatus according to the present invention receive an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed. Converting the received optical multiplexed signal into an electric signal, and when the level of the electric signal exceeds a predetermined threshold value, a collision occurs between the optical signals asynchronously transmitted from the plurality of subscribers. Collision detection signal output means for outputting a collision detection signal indicating that the collision detection signal is output, and control means for controlling the transmission of the optical signal by the plurality of subscribers according to whether or not the collision detection signal is received. It is characterized by.

According to the above-mentioned optical transmission device and optical receiving device, the level of the electric signal after the collision detection signal output means converts the received optical signal and before waveform shaping (digitization) has a predetermined threshold value. A collision detection signal indicating that a collision of optical signals has occurred is output when the number exceeds, and a plurality of collision detection signals are output depending on whether the control unit receives the "collision detection signal" instead of the "unlock signal". Since the transmission of the optical signal by the subscriber is controlled, it is possible to accurately detect the occurrence of the optical signal collision and avoid the optical signal collision. Further, since the optical signals are transmitted by a plurality of subscribers in an asynchronous manner, it is not necessary to manage the time slots, so that the equipment cost can be kept low. Further, it is possible to improve the transmission efficiency without requiring the overhead due to the padding process described above.

The optical transmission apparatus and the optical receiving apparatus according to the present invention are for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed, The optical multiplexed signal is converted into an electric signal, the displacement amount per unit time of the electronic signal is calculated, and when the calculated displacement amount is different from a predetermined value, the signals are asynchronously transmitted from the plurality of subscribers. Collision detection signal output means for outputting a collision detection signal indicating that a collision has occurred between the optical signals, and transmission of the optical signals by the plurality of subscribers depending on whether or not the collision detection signal is received. And a control means for controlling.

According to the above-mentioned optical transmission device and optical reception device, the collision detection signal output means transforms the received optical signal and then shifts the electric signal before waveform shaping (digitization) per unit time. Outputs a collision detection signal indicating that an optical signal collision has occurred, and the control means outputs the "collision detection signal" instead of the "unlock signal".
Controls the transmission of optical signals by multiple subscribers depending on whether or not the optical signal is being received, so that it is possible to accurately detect that an optical signal collision has occurred, and avoid an optical signal collision. It becomes possible to do. Further, since the optical signals are transmitted by a plurality of subscribers in an asynchronous manner, it is not necessary to manage the time slots, so that the equipment cost can be kept low. Further, it is possible to improve the transmission efficiency without requiring the overhead due to the padding process described above.

In the above-mentioned optical transmission device and optical receiving device, the transmission stop signal for instructing the control means to stop the transmission of the optical signal by the plurality of subscribers while receiving the collision detection signal. When the reception of the collision detection signal is completed, it is preferable to transmit a transmission restart signal instructing to restart the transmission of the optical signal by the plurality of subscribers.

In such a case, the control means determines whether or not there is a collision detection signal to be received when the optical signal collision is detected, and depending on the presence or absence of the collision detection signal, a transmission stop signal (PAUSE signal) and a transmission restart signal (Grant signal). ) Is transmitted, it is possible to avoid collision of optical signals without scheduling transmission timing with a margin and without impairing transmission efficiency.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION (Configuration of Optical Transmission Device According to One Embodiment of the Present Invention) A configuration of an optical transmission device according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a PON type network including an optical transmission device according to this embodiment.

The PON type network in the present embodiment has subscribers A (1), B (2), C (3) and P
The ON-type repeater 10, the communication station 20, and the Internet 4 are included.

Further, as shown in FIG. 1, the PON type repeater (star coupler) 10 includes an upstream line repeater 11 and
The downlink repeater 12 is provided. The communication station 20 also includes a router 21 and an asynchronous optical transmission device 30.

The signal flow in the PON type network in this embodiment will be described below.

As shown in FIG. 1, in the upstream communication,
Subscribers A and C are optical subscriber lines (uplink) 5 ₁ , 5 ₃
The upstream optical signals i ₀ and i ₁ are asynchronously transmitted with the wavelength λ _a via the. Then, the uplink repeater 11 of the PON repeater 10 transmits the optical multiplexed signal (i ₀ + i ₁ ) obtained by multiplexing the received upstream optical signals i ₀ and i ₁ to the optical subscriber line (uplink) 7 To send via. Then, the communication station 20 transmits the data signal included in each upstream optical signal i ₀ , i ₁ in the received upstream optical multiplexed signal (i ₀ + i ₁ ) to the Internet network 4 via the router 21.

On the other hand, in the downlink communication, the communication station 20
However, the data signal addressed to each of the subscribers A, B and C received from the Internet network 4 via the router 41 is multiplexed on the downlink optical signal of wavelength λ _p via the optical subscriber line (downlink) 8. Send. Then, the downlink repeater 12 of the PON type repeater 10 demultiplexes the received downlink optical signals and demultiplexes the optical subscriber lines to the subscribers A, B, and C (downlink).
6 ₁ , 6 ₂ , and 6 ₃ are transmitted.

In the asynchronous optical transmission device 30, the upstream optical signals asynchronously transmitted from a plurality of subscribers A, B and C are PON.
1 is an optical transmission device for receiving an optical multiplexed signal multiplexed by an upstream repeater 11 of a type repeater 10.

Asynchronous optical transmission device 30 according to the present embodiment
Is a non-synchronous optical transmission device 30 installed in the communication station 20 in which the length of the transmission line (optical subscriber line) between the communication station 20 and each of the subscribers A, B and C is A method for easily detecting a collision of an upstream optical signal from each of the subscribers A, B, and C when the transmission path length is within a range in which the collision of the optical signal from C can be detected by the light intensity. It is a thing.

As shown in FIG. 1, the asynchronous optical transmission device 30 includes an optical receiver circuit 31, a received signal processing circuit 32, and
It includes a PAUSE signal generation circuit 33, a Grant signal generation circuit 34, a transmission signal processing circuit 35, a priority-assigned selector 36, and an optical transmission circuit 37.

The optical receiving circuit 31 is connected to the optical subscriber line (uplink) 7, the received signal processing circuit 32, the PAUSE signal generating circuit 33, and the selector with priority 36, and receives the optical multiplexed signal ( i ₀ + i ₁ ) is converted into an electric signal E, and when the level of the electric signal E exceeds a predetermined threshold value e ₀ , the optical signals i ₀ , i transmitted asynchronously from the plurality of subscribers A and C collision between ₁ constitutes a collision detection signal output means for outputting a collision detection signal indicating occurrence.

The optical receiving circuit 31 performs optical receiving processing according to the optical multiplexed signal (i ₀ + i ₁ ) received via the optical subscriber line (uplink) 7, and the result is the "received signal".
Is transmitted to the reception signal processing circuit 32. Here, the "received signal" includes a "data signal", a "clock signal", and an "unlock signal" described later.

Further, when the optical receiving circuit 31 generates a collision detection signal signal as a result of the optical receiving process, it transmits it to the received signal processing unit 32, the PAUSE signal generating circuit 33, and the selector 36 with priority.

FIG. 2 shows an example of the configuration of the optical receiving circuit 31. Specifically, as shown in FIG. 2, the optical receiving circuit 31 includes a photodiode 41, a preamplifier 42, a limiter amplifier 43, a CDR 44, a PLL 45, a bias / power supply 46, and a comparison / detection circuit 47. It is composed by.

The photo diode 41 includes an optical subscriber line (uplink line) 7, a preamplifier 42, and a bias / power supply 46.
Is connected to and detects the optical multiplexed signal (i ₀ + i ₁ ) received through the optical subscriber line (uplink) 7,
The minute electric signal (i ₀ + i ₁ ) is output to the preamplifier 42.

The preamplifier 42 is the photodiode 4
1 and the limiter amplifier 43 and the comparison and detection circuit 47, linearly amplifying the minute electric signal (i ₀ + i ₁ ) output from the photo diode 41, and the electric signal E to the limiter amplifier 43. It is output to the comparison detection circuit 47.

The limiter amplifier 43 is connected to the preamplifier 42 and the CDR 44, shapes the waveform of the electric signal E output from the preamplifier 42, and outputs the digital signal V to the CDR 44.

The CDR 44 includes a limiter amplifier 43 and a PL.
It is connected to L45, extracts a clock component from the digital signal V output from the limiter amplifier 43, and transmits the extracted clock component to the PLL45. Also, C
The DR 44 outputs the “data signal” extracted from the digital signal V and the “clock signal” generated by the PLL 45 in phase synchronization with each other.

The PLL 45 is connected to the CDR 44, generates a clock signal according to the clock component from the CDR 44, and transmits it to the CDR 44. In addition, PLL45
Outputs an "unlock signal" when the clock component is not extracted (the out-of-sync state of the received data signal occurs).

The bias / power supply 46 is connected to the photo diode 41 and applies a bias to the photo diode 41.

The comparison / detection circuit 47 is connected to the preamplifier 42, and when the level of the electric signal E output from the preamplifier 42 exceeds a predetermined threshold value e ₀ , a plurality of subscribers A, B, C are provided. Asynchronously transmitted optical signal i ₀ ,
A collision detection signal indicating that a collision has occurred between i ₁ is output.

FIG. 3 is a diagram showing in chronological order the state of each signal when a collision has occurred between the optical signals i ₀ and i ₁ .
In this embodiment, it is assumed that the upstream optical signal i ₀ transmitted by the subscriber A and the upstream optical signal i ₁ transmitted by the subscriber B collide with each other.

[0051] 3 (a) shows an upstream optical signal _{i 0} which is transmitted via an optical subscriber line _{5. 1} by subscriber A, Figure 3
(B) shows the upstream optical signal i ₁ transmitted by the subscriber C via the optical subscriber line 5 ₃ . FIG. 3C shows a minute electric signal (i ₀ + i) detected by the photodiode 41.
₁ ) is shown. FIG. 3D shows the electric signal E output by the preamplifier 42, and FIG. 3E shows the collision detection signal output by the comparison detection circuit 47.

In this embodiment, as shown in FIGS. 3A and 3B, the period from t _{3 to} t ₄ and t _{11 to} t.
_In the period of ₁₃ , a collision has occurred between the optical signals i ₀ and i ₁ . Further, in the present embodiment, the level of the upstream optical signal (micro electrical signal) i ₀ and the upstream optical signal (micro electrical signal) i 0
_Since the levels of ₁ are equal, the predetermined threshold value e ₀ set in the comparison / detection circuit 47 is equal to the small electric signal i _0.
The level of the electric signal amplified by 2 (that is, the level of the electric signal obtained by amplifying the minute electric signal i ₁ by the preamplifier 42)
Has become.

As a result, as shown in FIG.
_Since the electronic signal E exceeds the predetermined threshold value e ₀ in the period from _{15 to} t _{16 and} the period from t _{11 to} t ₁₀ , the comparison detection circuit 47 causes the optical signals i ₀ , i _{1 to be in} these periods. It is judged that a collision has occurred between
As shown in (e), a collision detection signal is output.

Here, the optical signal i is actually₀, I₁Clash between
Period (t_ThreeTo t_FourPeriod, and t₁₁
To t_ThirteenPeriod), the period during which the collision detection signal is output
(T ₁₅To t₁₆Period, and t₁₁To t₁₀Period of
However, due to the high speed of the optical signal, this
The deviation of can be an error within an allowable range.

Further, in this embodiment, the level of the upstream optical signal (micro electrical signal) i ₀ and the upstream optical signal (micro electrical signal)
Since the levels of i ₁ are equal, a predetermined threshold value e ₀
Is the level of the electric signal obtained by amplifying the small electric signal i ₀ by the preamplifier 42, and the upstream optical signal (small electric signal) i
_When the level of _{0 and} the level of the upstream optical signal (micro electrical signal) i ₁ are not equal, a predetermined threshold value e ₀ is set to the level of the upstream optical signal (micro electrical signal) i ₀ and the upstream optical signal (micro electrical signal). The larger level of i ₁ shall be set. Here, the level of the upstream optical signal (micro electrical signal) i _{0 and} the level of the upstream optical signal (micro electrical signal) i ₁ are known because they are measured at the time of network design.

The reception signal processing circuit 32 is connected to the router 21 and the optical receiving circuit 31, and transmits the data signal included in the “reception signal” received from the optical receiving circuit 31 to the router 21. . In addition, the reception signal processing circuit 3
When receiving the collision detection signal from the optical receiving circuit 31, the second device 2 may stop the transmission of the above-mentioned data signal to the router 21.

The PAUSE signal generating circuit 33 is connected to the optical receiving circuit 31, the Grant signal generating circuit 34, and the selector with priority 36, and while receiving the collision detection signal output from the optical receiving circuit 31. , A “PAUSE signal (transmission stop signal) E _p ” instructing to stop the transmission of the upstream optical signals by the plurality of subscribers A, B, and C is transmitted to the prioritized selector 36. Also, PA
The USE signal generating circuit 33 notifies the Grant signal generating circuit 34 of the collision detection signal output from the optical receiving circuit 31.

The Grant signal generating circuit 34 has a PAUS
It is connected to the E signal generation circuit 33 and the transmission signal processing circuit 35, and when the reception of the collision detection signal from the PAUSE signal generation circuit 33 is completed, the transmission of the optical signals by the plurality of subscribers A, B, C is restarted. The transmission signal processing circuit 35 is transmitted with a “transmission restart signal (Grant signal)” instructing to do so. Here, "transmission restart signal (Gran
The “t signal)” includes the above-mentioned “schedule data”.

The transmission signal processing circuit 35 includes a router 21 and a G
It is connected to the rant signal generation circuit 34 and the selector 36 with priority, and selects the data signals addressed to the plurality of subscribers A, B, and C transmitted from the router 21 by the selector 36 with priority.
Is to be sent to. In addition, the transmission signal processing circuit 35
Selects the “transmission restart signal (Grant signal)” transmitted from the Grant signal generation circuit 34 with the priority-assigned selector 36.
Send to.

The prioritized selector 36 is provided in the optical receiving circuit 31.
And PAUSE signal generation circuit 33 and transmission signal processing circuit 35
And an optical receiver circuit 31 connected to the optical transmitter circuit 37.
The optical transmission circuit 37 and the PAUSE signal generation circuit 33 are connected to each other or the optical transmission circuit 37 and the transmission signal processing circuit 35 are connected to each other depending on whether the collision detection signal is received from the optical transmission circuit 37.

Specifically, while the priority-added selector 36 is receiving the collision detection signal from the optical receiving circuit 31, it outputs P
The “PAUSE signal (transmission stop signal) E _p ” from the AUSE signal generation circuit 33 is transferred to the optical transmission circuit 37, and while the collision detection signal from the optical reception circuit 31 is not received, the transmission signal processing circuit 35 outputs The data signal or the “transmission restart signal (Grant signal)” is transferred to the optical transmission circuit 37.

The optical transmission circuit 37 is connected to the optical subscriber line (downlink) 8 and the priority-assigned selector 36, and the "PAUSE signal (transmission stop signal) E _p transferred from the priority-assigned selector 36. The “data signal” and the “transmission restart signal (Grant signal)” are transmitted to the optical subscriber line (downlink line) 8 as a downstream optical signal of wavelength λ _p .

In this embodiment, it is determined whether the PAUSE signal generating circuit 33, the Grant signal generating circuit 34, the transmission signal processing circuit 35, the priority selector 36 and the optical transmission circuit 37 receive the collision detection signal. Accordingly, a control means for controlling the transmission of the upstream optical signal by the plurality of subscribers A, B, C is configured.

(Operation of Optical Transmission Device According to this Embodiment) The operation of the asynchronous optical transmission device 30 according to this embodiment will be described with reference to the drawings. FIG. 4 is a flowchart showing the operation of controlling the transmission of upstream optical signals from a plurality of subscribers A, B, C in the PON type network including the asynchronous optical transmission device 30 according to this embodiment. FIG. 5 is a flowchart showing the operation of the optical receiving circuit 31 in the asynchronous optical transmission device 30 for controlling the transmission of upstream optical signals from a plurality of subscribers.

As shown in FIG. 4, in step 401, the plurality of subscribers A and C transmit the upstream optical signals i ₀ and i ₁ of the wavelength λ _a containing the data signal to be transmitted to the optical subscriber line (uplink circuit). ) Send via 5 ₁ , 5 ₃ . And P
The upstream line repeater 11 of the ON-type repeater 10 multiplexes the received upstream optical signals i ₀ and i ₁ into an optical multiplexed signal (i ₀
+ I ₁ ) is transmitted via the optical subscriber line (uplink) 7. Then, the optical receiving device 31 in the asynchronous optical transmission device 30 installed in the communication station 20 causes the optical multiplexed signal (i
₀ + i ₁ ) is received.

In step 402, the optical receiver 31
Performs "optical reception processing" on the received optical multiplexed signal (i ₀ + i ₁ ). In step 403, the optical receiver 31 outputs the collision detection signal as a result of the above-mentioned “optical reception processing” to the reception signal processing unit 32, the PAUSE signal generation circuit 33, and the priority-assigned selector 36.

If the collision detection signal is output (not 0) in step 404, the PAUSE signal generation circuit 33 generates the PAUSE signal in step 405.

In step 406, the selector with priority 36 transfers the PAUSE signal output from the PAUSE signal generation circuit 33 to the optical transmission circuit 37. Then, the optical transmission circuit 37 transmits the PAUSE signal to the optical subscriber line (downline) 8, and the plurality of subscribers A, B, C
PAUS through the downlink repeater 12 of the PON type repeater 10 and the optical subscriber lines (downlinks) 6 ₁ , 6 ₂ , 6 _3.
Receive E signal. And a plurality of subscribers A, B, C
Stops the transmission of the upstream optical signal according to the received PAUSE signal.

On the other hand, in step 404, when the collision detection signal is not output (it becomes 0),
In step 407, the Grant signal generation circuit 34
Generates the Grant signal in order to restart the transmission of the upstream optical signal from the plurality of subscribers A, B, and C.

In step 408, the prioritized selector 36 transfers the Grant signal output from the Grant signal generation circuit 34 to the optical transmission circuit 37. Then, the optical transmission circuit 37 transmits the Grant signal to the optical subscriber line (downline) 8, and the plurality of subscribers A, B, C
Gran via the repeater 12 for the downlink of the PON type repeater 10 and the optical subscriber lines (downlinks) 6 ₁ , 6 ₂ and 6 _3.
Receive the t signal. And a plurality of subscribers A, B, C
Restarts the transmission of the upstream optical signal according to the received Grant signal.

The above-mentioned "light receiving process" will be described with reference to FIG. Here, only what is related to the operation of the optical receiving circuit 31 in the asynchronous optical transmission device 30 controlling the transmission of the upstream optical signals from a plurality of subscribers will be described.

As shown in FIG. 5, in step 501, the photodiode 41 transmits the optical multiplexed signal (i ₀ + i ₁ ) transmitted through the optical subscriber line (uplink) 7.
It receives and converts the optical multiplex signal _(i 0 + i ₁₎ the minute electrical signal _(i 0 + i _1).

In step 502, the preamplifier 42
Outputs the electric signal E by linearly amplifying the minute electric signal (i ₀ + i ₁ ).

In step 503, the comparison detection circuit 4
7 compares the level of the electric signal E output from the preamplifier 42 with a predetermined threshold value e ₀ . And the electrical signal E
If the level of which exceeds a predetermined threshold value e _0, in step 504, comparison detection circuit 47 sends a collision detection signal, when the level of the electric signal E does not exceed the predetermined threshold value e _0, comparison detection circuit This operation ends without 47 transmitting a collision detection signal.

(Operation and Effect of Optical Transmission Device According to this Embodiment) According to the asynchronous optical transmission device 30 according to this embodiment, the comparison detection circuit 47 of the optical receiving circuit 31 receives the optical multiplexed signal ( The level of the electric signal E after the conversion of i ₀ + i ₁ ) and before the waveform shaping (digitization) is a predetermined threshold value e
_When it exceeds ₀ , a collision detection signal indicating that a collision of optical signals has occurred is output, and a PAUSE signal generation circuit 33, a Grant signal generation circuit 34, a transmission signal processing circuit 35, a priority assigned selector 36, and an optical transmission circuit. 37 controls the transmission of optical signals by a plurality of subscribers A, B, and C according to whether or not 37 receives the "collision detection signal" instead of the "unlock signal", and therefore collision of optical signals It is possible to accurately detect the occurrence of the occurrence of, and it is possible to avoid collision of optical signals. Further, since the optical signals are transmitted by a plurality of subscribers in an asynchronous manner, it is not necessary to manage the time slots, so that the equipment cost can be kept low. Further, it is possible to improve the transmission efficiency without requiring the overhead due to the padding process described above.

Further, according to the asynchronous optical transmission device 30 of this embodiment, the PAUSE signal generating circuit 33 and the Gra
The nt signal generating circuit 34 sends a transmission stop signal (PAUSE signal) and a transmission restart signal (Grant signal) depending on the presence or absence of a collision detection signal received when detecting that a collision of optical signals has occurred. Since transmission is performed, it is possible to avoid collision of optical signals without scheduling transmission timing with a margin and without impairing transmission efficiency.

(Structure of Optical Transmission Device According to Modification) The structure of the asynchronous optical transmission device 30 according to a modification of the present invention will be described with reference to the drawings. The overall configuration of the PON network including the asynchronous optical transmission device 30 according to this modification is the same as that of the above-described embodiment. Further, the asynchronous optical transmission device 30 according to the present invention has the same configuration as the asynchronous optical transmission device 30 according to the above-described embodiment, except for the optical receiving circuit 31. Hereinafter, the optical receiving circuit 3 of this modification example
Among the functions of No. 1, the optical receiver circuit 31 according to the above-described embodiment.
Only those different from are described.

The optical receiving circuit 31 is connected to the optical subscriber line (uplink line) 7, the reception signal processing circuit 32, the PAUSE signal generating circuit 33, and the selector with priority 36, and the optical subscriber line (uplink line). ) 7, the optical multiplexed signal (i ₀ + i ₁ ) is converted into an electric signal E, and the electronic signal E
Displacement amount per unit time is calculated, and the calculated displacement amount is a predetermined value “+ r ₁ ”, “−r ₁ ”, “+ r ₂ ”, and “−r ₂ ”.
Collision detection signal output means for outputting a collision detection signal indicating that a collision has occurred between the optical signals i ₀ and i ₁ asynchronously transmitted from the plurality of subscribers A, B, and C when different from “0” Make up.

FIG. 6 shows an example of the configuration of the optical receiving circuit 31. Specifically, as shown in FIG. 6, the optical receiving circuit 31 includes a photodiode 41, a preamplifier 42, a limiter amplifier 43, a CDR 44, a PLL 45, a bias / power supply 46, and a comparison / detection circuit 47. , Differentiation circuit 4
8 and.

Photodiode 41, preamplifier 4
2, the limiter amplifier 43, the CDR 44, the PLL 45, and the bias / power supply 46 are the same as those in the above-described embodiment.

The differentiating circuit 48 is connected to the preamplifier 42 and the comparison detecting circuit 47 and differentiates the electric signal E output from the preamplifier 42 to calculate the displacement amount R of the electronic signal E per unit time. The calculated displacement amount R is output to the comparison detection circuit 47.

The comparison detection circuit 47 is connected to the differentiating circuit 48, and the calculated amount R output from the differentiating circuit 48 is
Predetermined value "+ _{r 1",} "-r _1", "+ _{r 2",} "-r _2"
When it is different from "0", it outputs a collision detection signal indicating that a collision has occurred between the optical signals i ₀ and i ₁ asynchronously transmitted from the plurality of subscribers A, B, and C. Here, predetermined values “+ r ₁ ” “−r ₁ ” “+ r ₂ ” “−
Since “r ₂ ” is measured at the time of network design,
It is known.

FIG. 7 is a diagram showing the state of each signal in a time series when a collision occurs between the optical signals i ₀ and i ₁ .
In the present embodiment, it is assumed that the upstream optical signal i ₀ transmitted by the subscriber A and the upstream optical signal i ₁ transmitted by the subscriber C collide with each other.

[0084] 7 (a) shows an upstream optical signal _{i 0} which is transmitted via an optical subscriber line _{5. 1} by subscriber A, Figure 7
(B) shows the upstream optical signal i ₁ transmitted by the subscriber C via the optical subscriber line 5 ₃ . FIG. 7C shows a small electric signal (i ₀ + i) detected by the photodiode 41.
₁ ) is shown. FIG. 7D shows the electric signal E output by the preamplifier 42, and FIG.
7 (f) shows the collision detection signal output by the comparison / detection circuit 47. FIG.

In the present embodiment, as shown in FIGS. 7A and 7B, collision occurs between the optical signals i ₀ and i ₁ in the period of t _{3 to} t _{6 and} the period of t _{7 to} t _8. Is occurring.

A predetermined value set in the comparison / detection circuit 47.
Value of "+ r₁Is the optical signal i₀At the start of (for example,
0 to t in FIG.₀Of period) set to "+ A"
The predetermined value "-r₁Is the optical signal i₀At the fall of
(For example, t in FIG.₁To t_TwoPeriod)
It is set to "-A" and the predetermined value "+ r_TwoIs the optical signal i
₁Rises (for example, t in FIG. 7B)._ThreeTo t_Fourof
The period is set to "+ C" and the predetermined value "-r"_Two"
Is the optical signal i₁At the falling edge (for example, t in FIG. 7B)
₅To t₆Is set to "-C".

The differentiating circuit 48 differentiates the electric signal E output from the preamplifier 42 shown in FIG.
As shown in (e), the displacement amount R of the electronic signal E per unit time is calculated.

In FIG. 7D, the slope of the electronic signal E
(That is, the displacement amount R of the electronic signal E per unit time)
Is 0 to t₀"+ A", t during the period₀To t₁Period of
"0", t₁To t_Two"-A", t_TwoTo t
_Three"0", t in the period_ThreeTo t _Four“+ B”, t
_FourTo t₁₁“+ C”, t₁₁To t₁₂Period of
Between "0", t₁₂To t₅-C, t in the period₅No
To t₆"-B", t₆To t_ThirteenIn the period of
"0", t_ThirteenTo t₁₄“+ C”, t₁₄No
To t₁₅"0", t in the period₁₅To t₇During the period
C ", t₇To t₈“+ D”, t₈To t₉of
“0”, t in the period₉To t₁₀"-A" during the period
It

As a result, as shown in FIG. 7 (e), t ₃
In the period from t ₄ to t _{4 and} the period from t _{7 to} t ₈ , the displacement amount R of the electronic signal E per unit time is a predetermined value “+”.
Since r ₁ ”,“ −r ₁ ”,“ + r ₂ ”,“ −r ₂ ”, and“ 0 ”are different from each other, the comparison detection circuit 47 causes the optical signal i in these periods.
It is determined that a collision has occurred between ₀ and i ₁ , and FIG.
As shown in, a collision detection signal is output.

Here, the collision detection signal is output during the period in which the collision actually occurs between the optical signals i ₀ and i ₁ (the period from t _{3 to} t _{6 and} the period from t _{7 to} t ₈ ). Period (t
There is a deviation between the period of _{3 to} t _{4 and} the period of t _{7 to} t ₈ ), but due to the high speed of the optical signal, this deviation can be an error within an allowable range.

(Operation of Optical Transmission Device According to This Modification) The operation of the asynchronous optical transmission device 30 according to this modification will be described with reference to the drawings. The operation in which the asynchronous optical transmission device 30 according to the present modification controls the transmission of the upstream optical signals from the plurality of subscribers A, B, and C excludes the operation of the optical receiving circuit 31 in the asynchronous optical transmission device 30. The operation is the same as that of the asynchronous optical transmission device 30 according to the above-described embodiment. Therefore, hereinafter, the optical receiving circuit 31 in the asynchronous optical transmission device 30 will be described.
Only the operation of will be described.

FIG. 8 is a flow chart showing the operation in which the optical receiving circuit 31 in the asynchronous optical transmission device 30 controls the transmission of upstream optical signals from a plurality of subscribers. here,
Only what is related to the operation of the optical receiving circuit 31 in the asynchronous optical transmission device 30 controlling the transmission of the upstream optical signals from a plurality of subscribers will be described.

As shown in FIG. 8, in step 801, the photodiode 41 transmits the optical multiplexed signal (i ₀ + i ₁ ) transmitted via the optical subscriber line (uplink) 7.
It receives and converts the optical multiplex signal _(i 0 + i ₁₎ the minute electrical signal _(i 0 + i _1).

In step 802, the preamplifier 42
Outputs the electric signal E by linearly amplifying the minute electric signal (i ₀ + i ₁ ).

At step 803, the differentiation circuit 48
Detects the displacement amount R of the electronic signal E per unit time by differentiating the electric signal E output from the preamplifier 42, and outputs the calculated displacement amount R to the comparison detection circuit 47.

In step 804, the comparison / detection circuit 4
7 is a displacement amount R of the electronic signal E output from the differentiating circuit 48 per unit time and a predetermined value “+ r ₁ ” “−r ₁ ”.
Compare with “+ r ₂ ”, “−r ₂ ”, and “0”. Then, the displacement amount R of the electronic signal E per unit time is a predetermined value “+
If it is different from r ₁ ”“ -r ₁ ”“ + r ₂ ”“ -r ₂ ”“ 0 ”, in step 805, the comparison detection circuit 47 transmits a collision detection signal, and the displacement amount of the electronic signal E per unit time. R is a predetermined value "+ _{r 1"} "-r _1" "+ _{r 2"}
If “−r ₂ ” and “0” are the same, this operation ends without the comparison detection circuit 47 transmitting a collision detection signal.

(Operation and Effect of Optical Transmission Device According to This Modification) According to the asynchronous optical transmission device 30 according to this modification,
The displacement amount R per unit time of the electric signal before the waveform shaping (digitization) after the comparison detection circuit 47 of the optical receiving circuit 31 converts the received optical multiplexed signal (i ₀ + i ₁ ).
But the predetermined value "+ _{r 1"} "-r _1" "+ _{r 2"} "-
A collision detection signal indicating that a collision of optical signals has occurred when r ₂ ”and“ 0 ”is different, and a PAUSE signal generation circuit 33, a Grant signal generation circuit 34, a transmission signal processing circuit 35, and a priority-assigned selector 36 are output. And the optical transmission circuit 37
Since the transmission of the optical signal by the plurality of subscribers A, B, C is controlled according to whether or not the "collision detection signal" is received instead of the "unlock signal", the optical signal collision occurs. It is possible to accurately detect that there is a collision, and it is possible to avoid collision of optical signals. Further, since the optical signals are transmitted by a plurality of subscribers in an asynchronous manner, it is not necessary to manage the time slots, so that the equipment cost can be kept low. Further, it is possible to improve the transmission efficiency without requiring the overhead due to the padding process described above.

Further, according to the asynchronous optical transmission device 30 of this embodiment, the PAUSE signal generation circuit 33 and the Grause signal generation circuit 33
The nt signal generating circuit 34 sends a transmission stop signal (PAUSE signal) and a transmission restart signal (Grant signal) depending on the presence or absence of a collision detection signal received when detecting that a collision of optical signals has occurred. Since transmission is performed, it is possible to avoid collision of optical signals without scheduling transmission timing with a margin and without impairing transmission efficiency.

[0099]

According to the present invention, a plurality of subscribers A, C
Optical signal i transmitted asynchronously from₀, I ₁Was multiplexed
Optical multiplexed signal (i₀+ I₁) Receiving optical transmission device 30
, The equipment cost is low without reducing the transmission efficiency.
Optical signal i at strike₀, I₁It is possible to avoid the collision of
Become.

[Brief description of drawings]

FIG. 1 shows a P including an optical transmission device according to an embodiment of the present invention.
It is a whole block diagram of an ON type network.

FIG. 2 is a diagram showing an example of an optical receiving circuit provided in an optical transmission device according to an embodiment of the present invention.

FIG. 3 is a diagram showing in time series the state of each signal when a collision occurs between the optical signals.

FIG. 4 shows a P including an optical transmission device according to an embodiment of the present invention.
It is a flowchart figure which shows the operation | movement which controls the transmission of the upstream optical signal from a some subscriber in an ON type network.

FIG. 5 is a flow chart diagram showing an operation in which the optical receiving circuit in the optical transmission apparatus according to the embodiment of the present invention controls transmission of upstream optical signals from a plurality of subscribers.

FIG. 6 is a diagram showing an example of an optical receiving circuit provided in an optical transmission device according to a modification of the present invention.

FIG. 7 is a diagram showing in time series the state of each signal when a collision occurs between optical signals.

FIG. 8 is a flow chart diagram showing an operation in which the optical receiving circuit in the optical transmission apparatus according to the modified example of the present invention controls transmission of upstream optical signals from a plurality of subscribers.

FIG. 9 is a diagram showing an example of an optical receiving circuit provided in an optical transmission device according to a conventional technique.

FIG. 10 is a diagram showing a data signal, a clock signal, and an unlock signal output from a conventional optical receiving circuit.

FIG. 11 is a graph showing how an input optical signal I is converted into a minute electric signal E in a conventional optical receiving circuit.

FIG. 12 is a graph showing how the minute electric signal E is waveform-shaped into the digital signal Vni in the conventional optical receiving circuit.

[Explanation of symbols]

1, 2, 3 ... Subscriber 4 ... Internet network 5 ₁ , 5 ₂ , 5 ₃ , 7 ... Optical subscriber line (uplink) 6 ₁ , 6 ₂ , 6 ₃ , 8 ... Optical subscriber line (downlink) 10 ... PON type repeater 11 ... Uplink repeater 12 ... Downlink repeater 20 ... Communication station 21 ... Router 30 ... Asynchronous optical transmission device 31 ... Optical receiving circuit 32 ... Received signal processing circuit 33 ... PAUSE signal generation Circuit 34 ... Grant signal generation circuit 35 ... Transmission signal processing circuit 36 ... Priority selector 37 ... Optical transmission circuit 41 ... Photo diode 42 ... Preamplifier 43 ... Limiter amplifier 44 ... CDR 45 ... PLL 46 ... Bias / power supply 47 ... Comparison Detection circuit 48 ... Differentiation circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5K002 AA03 AA05 DA01 DA05 DA12                       DA91                 5K033 CA08 DA15

Claims (5)

[Claims] 1. An optical transmission device for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed, wherein the received optical multiplexed signal is converted into an electric signal, Collision detection signal output means for outputting a collision detection signal indicating that a collision has occurred between the optical signals asynchronously transmitted from the plurality of subscribers when the level of the electric signal exceeds a predetermined threshold value, An optical transmission apparatus comprising: a control unit that controls transmission of an optical signal by the plurality of subscribers according to whether or not the collision detection signal is received. 2. An optical transmission device for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed, wherein the received optical multiplexed signal is converted into an electric signal, A displacement amount of the electronic signal per unit time is calculated, and when the calculated displacement amount is different from a predetermined value, it indicates that a collision has occurred between the optical signals asynchronously transmitted from the plurality of subscribers. A collision detection signal output unit that outputs a collision detection signal, and a control unit that controls transmission of an optical signal by the plurality of subscribers according to whether or not the collision detection signal is received are provided. Optical transmission equipment. 3. The control means transmits a transmission stop signal instructing to stop transmission of an optical signal by the plurality of subscribers while receiving the collision detection signal, The optical transmission device according to claim 1 or 2, wherein when the reception is completed, a transmission restart signal for instructing to restart the transmission of the optical signal by the plurality of subscribers is transmitted. 4. An optical receiving device provided in an optical transmission device for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed, the received optical multiplexed signal. Is converted into an electric signal, and when the level of the electric signal exceeds a predetermined threshold value, a collision detection signal indicating that a collision has occurred between the optical signals asynchronously transmitted from the plurality of subscribers is output. An optical receiving device characterized by the above. 5. An optical receiving apparatus provided in an optical transmission apparatus for receiving an optical multiplexed signal in which optical signals asynchronously transmitted from a plurality of subscribers are multiplexed, the received optical multiplexed signal. Is converted into an electric signal, the displacement amount per unit time of the electronic signal is calculated, and when the calculated displacement amount is different from a predetermined value, between the optical signals asynchronously transmitted from the plurality of subscribers. An optical receiving apparatus, which outputs a collision detection signal indicating that a collision has occurred.