JP2015154399A - Twdm-pon system and wavelength control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TWDM-PON wavelength control method and TWDM-PON system capable of changing over a wavelength between an OLT and ONU with low delay.SOLUTION: A wavelength control method for a TWDM-PON system in which an OLT including a first line card and a second line card are connected with a plurality of ONUs each of which includes a first light transmission/reception unit and a second light transmission/reception unit through optical fibers, includes the steps of: activating, through the first light transmission/reception unit, the second light transmission/reception unit to which a wavelength set differing from that of the first light transmission/reception unit is set, from the first line card having a communication path established with the same wavelength set as that of the first light transmission/reception unit; establishing, after completion of activating the second light transmission/reception unit, a new communication path between the second line card and the second light transmission/reception unit by using the wavelength set differing from that of the first light transmission/reception unit; and, after establishing the new communication path, shutting down the first light transmission/reception unit.

Description

  The present invention relates to wavelength switching in a wavelength-tunable optical access network system. In particular, according to the present invention, a master station optical communication device (OLT) and a slave station optical communication device (ONU: Optical Network Unit) perform 1-to-N communication via an optical transmission line, and each optical communication. The present invention relates to wavelength switching of a passive optical network (TWDM-PON: Time and Wavelength Division Multiplexing-Passive Optical Network) in which a device can freely change a communication wavelength.

  In TWDM-PON with wavelength and time division multiplexing that will lead to further development of communication networks such as future broadband and flexible integration of radio base stations, low-delay transmission specifications for radio systems when OLT switches the wavelength used It is desired to provide a wavelength control technique corresponding to the above.

  Currently, with the increase in broadband services, the number of FTTH (Fiber To The Home) subscribers using optical fibers is rapidly increasing. In an optical access network from a telecommunications carrier building to a customer's home, a PON (Passive Optical Network) system that performs point-to-multipoint communication excellent in economic efficiency is widely used. The PON system has a PDS (Passive Double Star) type optical line configuration, and is installed in a communication carrier building, an OLT connected to the OLT, an optical fiber connected to the OLT, and an optical splitter that optically branches the optical fiber And an ONU installed in the subscriber's house, and a branch optical fiber corresponding to the ONU on a one-to-one basis.

  On the other hand, wireless cellular systems such as cellular phones also require a broadband and efficient wireless access network configuration due to explosive spread. In addition, in a radio access network, it is considered that a base station is separated into a signal processing unit (BBU: Base Band Unit) and an RF unit (RRH: Remote Radio Head) and is physically separated. . In this BBU-RRH network, a single BBU can accommodate a plurality of RRHs. As a result, the BBUs required for each RRH can be collected in one place, and the operation / installation cost can be reduced and a highly coordinated operation among a plurality of RRHs is possible.

  As a configuration in which one BBU as described above accommodates a plurality of RRHs, a configuration in which a part of the optical fiber is shared instead of a point-to-point is considered. This is a PON configuration used in so-called FTTH. In the application of this PON system, it is conceivable to lower the optical fiber introduction cost by using PON technologies such as TDM-PON (Time Division Multiplexed-PON) and WDM-PON (Wavelength Division Multiplexed-PON) as communication methods. ing. In particular, if a TWDM-PON using both WDM and TDM is used, each ONU and OLT can construct an efficient NW configuration in real time while taking an arbitrary wavelength, so that a very efficient network can be configured (for example, non- (See Patent Document 1).

  In this TWDM-PON system, communication is performed while switching the wavelength between the OLT and the ONU. For this wavelength switching, optical device control such as changing the transmission wavelength of the wavelength tunable filter in the ONU is necessary.

D. Iida, et al. , “A proposal of dynamic TWDM-PON for mobile radio access network,” APMP2013, TuA-3

  In the TWDM-PON system, since the wavelength between the OLT and the ONU is switched, it is necessary to change the wavelength setting of an optical device such as a wavelength tunable filter in the ONU even during communication. However, in communication over a radio access network, communication characteristics with very low delay are required by the standard. Specifically, only a delay of about several hundred μsec is allowed. However, wavelength switching of an optical device, for example, a wavelength tunable filter, requires a delay on the order of msec and is difficult to cope with.

  In order to solve such problems, it is an object of the present invention to provide a TWDM-PON wavelength control method and a TWDM-PON system that can switch the wavelength between OLT and ONU with low delay.

  Further, in a situation where the wavelength between the OLT and the ONU is switched, it is necessary to provide a standby system for flexible operation. In order to solve such a problem, another object is to provide a TWDM-PON system including a standby system that can be operated flexibly and a wavelength control method thereof.

  In the present invention, the second optical transmission / reception unit set to a wavelength different from that of the first optical transmission / reception unit is activated through the first optical transmission / reception unit of the ONU in which the communication path is secured. After the start-up, the communication path is secured by the second optical transmission / reception unit, and then the first optical transmission / reception unit is shut down.

Specifically, the present invention provides:
An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. Wavelength control method for a TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
This is a wavelength control method for a TWDM-PON system that shuts down the first optical transceiver after securing the new communication path.

Specifically, the present invention provides:
An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
The TWDM-PON system shuts down the first optical transceiver after securing the new communication path.

  According to the present invention, the TWDM-PON system can switch the wavelength between the OLT and the ONU with low delay.

  In the present invention, the first optical transmission / reception unit set to the same wavelength as the second optical transmission / reception unit is activated through the second optical transmission / reception unit of the ONU in which the communication path is secured, and the first optical transmission / reception unit is started. After the start of the unit is completed, the first optical transmission / reception unit secures a communication path, and then the second optical transmission / reception unit is shut down.

Specifically, the present invention provides:
An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. Wavelength control method for a TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
This is a wavelength control method for a TWDM-PON system that shuts down the second optical transceiver after securing the new communication path.

Specifically, the present invention provides:
An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
The TWDM-PON system shuts down the second optical transceiver after securing the new communication path.

  According to the present invention, the TWDM-PON system can include a standby system that can be operated flexibly.

  Furthermore, in the present invention, the second optical transmitter / receiver is activated by starting the second optical transmitter / receiver set to a wavelength different from that of the first optical transmitter / receiver through the first optical transmitter / receiver in which the communication path is secured. After the start-up, the communication path is secured by the second optical transmission / reception unit, and then the first optical transmission / reception unit is shut down. Subsequently, the first optical transmitter / receiver set to the same wavelength as the second optical transmitter / receiver is activated through the second optical transmitter / receiver in which a communication path is secured, and after the first optical transmitter / receiver is activated Then, after securing the communication path in the first optical transceiver, the second optical transceiver is shut down.

Specifically, the present invention provides:
An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. The optical fiber has a branching ratio smaller than that of the first optical transceiver, and the second optical transceiver includes an optical amplifier for optically amplifying an optical signal to be transmitted / received. A wavelength control method for a PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
After securing the new communication path, shut down the first optical transceiver,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
This is a wavelength control method for a TWDM-PON system that shuts down the second optical transceiver after securing the new communication path.

Specifically, the present invention provides:
An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. The optical fiber has a branching ratio smaller than that of the first optical transceiver, and the second optical transceiver includes an optical amplifier for optically amplifying an optical signal to be transmitted / received. A PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
After securing the new communication path, shut down the first optical transceiver,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
The TWDM-PON system shuts down the second optical transceiver after securing the new communication path.

  According to the present invention, the TWDM-PON system can switch the wavelength between the OLT and the ONU with a low delay, and can include a standby system that can be operated flexibly.

  The above inventions can be combined as much as possible.

  According to the present invention, even if there is a delay in wavelength switching of the optical device, the TWDM-PON system can switch the wavelength between the OLT and the ONU while continuing communication. Alternatively, a standby system that can be operated flexibly can be provided.

It is a block diagram which shows the structure of the TWDM-PON system of this invention. It is a block diagram which shows the structure of ONU of this invention. It is a flowchart which shows the procedure of wavelength switching of the TWDM-PON system by this invention. It is a sequence diagram which shows the procedure of wavelength switching of the TWDM-PON system by this invention. It is a flowchart which shows the procedure of wavelength switching of the TWDM-PON system by this invention. It is a sequence diagram which shows the procedure of wavelength switching of the TWDM-PON system by this invention. It is a flowchart which shows the procedure of wavelength switching of the TWDM-PON system by this invention. It is a sequence diagram which shows the procedure of wavelength switching of the TWDM-PON system by this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
The configuration of the TWDM-PON system of the present invention is shown in FIG. A TWDM-PON system is configured by the OLT 4, the plurality of ONUs 5 and the optical splitter 3. The OLT 4 is a branching optical circuit 23 that branches an optical signal, a line card (LC: Line Card) 26 including an optical transmission function and an optical reception function, and a demultiplexing unit that exchanges signals between the OLT 4 and an external device and the LC 26. 27, a dynamic wavelength band allocation circuit 28 for controlling TWDM between the LC 26 and the ONU 5 is provided. The branching optical circuit 23 may be one that splits and joins optical signals without depending on the wavelength, or one that splits and combines optical signals according to wavelength sets.

  A plurality of LCs 26 are provided, each capable of transmitting and receiving optical signals with an arbitrary wavelength set. Each ONU 5 sets the transmission wavelength of the wavelength variable filter in the ONU 5 according to the wavelength set of the LC 26 with which it communicates, and limits the wavelength of the received optical signal. Each ONU 5 sets the wavelength of the optical signal to be transmitted according to the wavelength set of the LC 26 with which it communicates. Thereby, virtual PON can be comprised for every wavelength set to transmit / receive. Each ONU 5 does not need to have a different wavelength set, and a plurality of ONUs 5 can use the same wavelength set, and access control is performed by the conventional TDM in the PON of the ONU 5 of the wavelength set. Thus, since WDM and TDM are used together, it is called a TWDM-PON system.

  The configuration of the ONU 5 of the present invention is shown in FIG. The ONU 5 includes a plurality of optical transmission / reception units 9, an optical branch circuit 10, and a switching unit 15. The optical transmission / reception unit 9 includes an optical transmission unit 12 that changes the wavelength of an optical signal transmitted by the wavelength tunable laser, an optical reception unit 14 that receives an optical signal, and a wavelength that limits the wavelength of the optical signal received by the optical reception unit 14. The variable filter 13 includes a wavelength multiplexer / demultiplexer 11 that wavelength-multiplexes and demultiplexes an optical signal to be transmitted and a received optical signal using a wavelength difference. For simplicity, the number of the optical transmission / reception units 9 is two, but may be three or more.

  The switching unit 15 switches signals to be communicated between devices outside the ONU 5 according to the switching of the optical transmission / reception unit 9.

  In the TWDM-PON system of the present embodiment, the optical transmission / reception unit set to a wavelength set different from that of the optical transmission / reception unit 9 # 1 through the optical transmission / reception unit 9 # 1 from the LC 26 # 1 in which the communication path is secured with the same wavelength set. 9 # 2 is activated, and after completing the activation of the optical transceiver 9 # 2, a new communication path is secured between the LC 26 # 2 and the optical transceiver 9 # 2 with the different wavelength set, and a new communication path is established. After securing, the optical transceiver 9 # 1 is shut down.

  A procedure for switching the communication wavelength between the OLT 4 and the ONU 5 will be described. FIG. 3 shows a flowchart divided into the OLT 4 and the ONU 5, and FIG. 4 shows a sequence diagram between the OLT 4 and the ONU 5. In FIG. 4, the operation represented by () represents the execution of the step () of FIG.

Step (1)
In step (1), the OLT 4 determines to switch the communication wavelength from the wavelength set 1 to the wavelength set 2. For example, in a situation where the optical transceiver 9 # 1 in the ONU 5 # n is communicating with the LC 26 # 1 in the OLT 4 with the wavelength set 1, the wavelength is switched because the communication amount in the wavelength set 1 has increased. OLT4 must switch from wavelength set 1 to wavelength set 2 for communication with ONU5 # n because it belongs to a small cell group different from the current one, or it is desired to use it in a wireless system different from the current one. to decide.
Of the optical transmission / reception units 9 of the ONU 5, the wavelength transmission destination optical transmission / reception unit 9 # 2 cannot be used because it is in the sleep state.

Step (2)
In step (2), the OLT 4 starts the optical transceiver 9 # 2 of the ONU 5 # n with the wavelength set 2 through the communication path from the LC 26 # 1 to the optical transceiver 9 # 1 of the ONU 5 # n with the wavelength set 1. Instruct.

Step (3)
In step (3), the ONU 5 # n activates the optical transmitter / receiver 9 # 2 with the wavelength set 2.

Step (4)
The LC 26 # 2 in the OLT 4 communicates with the wavelength set 2. In step (4), according to the normal TWDM band control mechanism, the OLT 4 passes through the communication path from the LC 26 # 2 to the optical transceiver 9 # 2 of the ONU 5 # n according to the wavelength set 2 to the LC 26 # 2. The transmission permission signal and the transmission schedule are transmitted to the optical transmitter / receiver 9 # 2.

Step (5)
In step (5), the optical transceiver 9 # 2 of the ONU 5 # n activated with the wavelength set 2 receives the transmission permission signal and the transmission schedule. The ONU 5 # n transmits a participation request signal to the PON of the wavelength set 2 from the optical transmission / reception unit 9 # 2 according to the received transmission schedule.

Step (6)
When the OLT 4 receives the participation request signal in step (6), the transmission band and the transmission timing of the optical transmission / reception unit 9 # 2 of the wavelength set 2 with respect to the LC 26 # 2 of the wavelength set 2 are the optical transmission / reception unit of the wavelength set 1 The GATE signal is transmitted so as to be the same as 9 # 1. In the first place, since the wavelength set 2 has a margin, the wavelength is switched and the switching destination from the wavelength set 1 to the wavelength set 2 is used. Therefore, such band and timing control is possible in the wavelength set 2.
Further, the GATE signal for shutting down the optical transceiver 9 # 1 of the wavelength set 1 is transmitted to the LC 26 # 1 of the wavelength set 1.

Step (7)
When the ONU 5 # n receives the GATE signal from the LC 26 # 2 to the optical transmitter / receiver 9 # 2 by the wavelength set 2 in step (7), the optical transmitter / receiver 9 # 2 receives the wavelength set 2 from the LC 26 # 2. Take over the communication by.
On the other hand, when receiving a GATE signal from LC 26 # 1 to optical transceiver 9 # 1 by wavelength set 1, optical transceiver 9 # 1 is shut down. The optical transmitter / receiver 9 # 1 can be shut down by shutting off the power supply to the optical transmitter / receiver 9 # 1 or shutting off the clock supply. Thereafter, the optical transceiver 9 # 1 can be handled as the next wavelength switching destination.

Step (8)
In step (8), the OLT 4 continues the communication with the wavelength set 2 and when the request signal from the optical transmission / reception unit 9 # 1 of the wavelength set 1 does not reach, excludes the optical transmission / reception unit 9 # 1 from the PON of the wavelength set 1 To do.

  All of these controls are performed at a timing that does not affect other communications, particularly the communications of wavelength set 2 that is already being communicated by another LC 26, by scheduling control of the dynamic wavelength band allocation circuit 28 of the OLT 4. Is done.

  In this way, even if there is a delay in wavelength switching of the optical device, the TWDM-PON system can switch the wavelength between the OLT and the ONU while continuing communication.

(Embodiment 2)
The configuration of the TWDM-PON system of the present embodiment is the same as that of the TWDM-PON system of the first embodiment.

  In the TWDM-PON system of the present embodiment, the optical transmission / reception unit set to a wavelength set different from that of the optical transmission / reception unit 9 # 1 through the optical transmission / reception unit 9 # 1 from the LC 26 # 1 in which the communication path is secured with the same wavelength set. 9 # 2 is activated, and after completion of activation of the optical transceiver # 2, a new communication path is secured between the LC 26 # 2 and the optical transceiver 9 # 2 with the different wavelength set, and a new communication path is secured. After that, the optical transceiver 9 # 1 is shut down.

  A procedure for switching the communication wavelength between the OLT 4 and the ONU 5 will be described. FIG. 5 shows a flowchart divided into the OLT 4 and the ONU 5, and FIG. 6 shows a sequence diagram between the OLT 4 and the ONU 5. In FIG. 6, the operation represented by () represents the execution of the step () of FIG.

Step (1)
In step (1), the OLT 4 determines to switch the communication wavelength from the wavelength set 1 to the wavelength set 2. For example, in a situation where the optical transceiver 9 # 1 in the ONU 5 # n is communicating with the LC 26 # 1 in the OLT 4 with the wavelength set 1, the wavelength is switched because the communication amount in the wavelength set 1 has increased. OLT4 must switch from wavelength set 1 to wavelength set 2 for communication with ONU5 # n because it belongs to a small cell group different from the current one, or it is desired to use it in a wireless system different from the current one. to decide.
Of the optical transmission / reception units 9 of the ONU 5, the wavelength transmission destination optical transmission / reception unit 9 # 2 cannot be used because it is in the sleep state.

Step (2)
In step (2), the OLT 4 starts the optical transceiver 9 # 2 of the ONU 5 # n with the wavelength set 2 through the communication path from the LC 26 # 1 to the optical transceiver 9 # 1 of the ONU 5 # n with the wavelength set 1. Instruct.

Step (3)
In step (3), the ONU 5 # n starts to activate the optical transceiver 9 # 2 with the wavelength set 2.
The ONU 5 # n continues communication with the optical transceiver 9 # 1 in the wavelength set 1 until the optical transceiver 9 # 2 is activated in the wavelength set 2.

Step (4)
The LC 26 # 2 in the OLT 4 transmits using the wavelength set 2, but the optical transceiver 9 # 2 of the ONU 5 # n is not activated, so the LC 26 # 1 and the optical transceiver 9 # 1 of the ONU 5 # n are not activated. Just being communicated.
In step (4), the OLT 4 changes from the LC 26 # 1 according to the wavelength set 1 to the optical transmitter / receiver 9 # 1 of the ONU 5 # n according to the desired transmission signal from the optical transmitter / receiver 9 # 1 of the ONU 5 # n according to the wavelength set 1. The GATE signal for instructing the transmission permission and the transmission schedule is transmitted to the optical transmission / reception unit 9 # 1 of the ONU 5 # n through the communication path.
At the same time, the OLT 4 instructs the same transmission permission and transmission schedule as above to the optical transceiver 9 # 2 of the ONU 5 # n through the communication path from the LC 26 # 2 to the optical transceiver 9 # 2 of the ONU 5 # n by the wavelength set 2. A GATE signal is transmitted.

Step (5)
In step (5), when the optical transmission / reception unit 9 # 2 is activated, the ONU 5 # n takes over the communication using the wavelength set 2 according to the received transmission schedule.
At the same time, the ONU 5 # n shuts down the optical transmission / reception unit 9 # 1.

Step (6)
In step (6), when the LC 26 # 2 in the wavelength set 2 receives the signal from the optical transmitter / receiver 9 # 2, the OLT 4 continues communication with the LC 26 # 2 in the wavelength set 2.
At the same time, the OLT 4 excludes the optical transmission / reception unit 9 # 1 of the ONU 5 # n from the PON of the wavelength set 1.

  All of these controls are performed at a timing that does not affect other communications, particularly the communications of wavelength set 2 that is already being communicated by another LC 26, by scheduling control of the dynamic wavelength band allocation circuit 28 of the OLT 4. Is done.

  In this way, even if there is a delay in wavelength switching of the optical device, the TWDM-PON system can switch the wavelength between the OLT and the ONU while continuing communication.

(Embodiment 3)
The configuration of the TWDM-PON system of the present embodiment is the same as that of the TWDM-PON system of the first embodiment.

  In the TWDM-PON system of this embodiment, the optical transmission / reception unit 9 set to the same wavelength set as the optical transmission / reception unit 9 # 2 through the optical transmission / reception unit 9 # 2 from the LC 26 # 2 in which the communication path is secured with the same wavelength set. # 1 is activated, and after completing the activation of the optical transceiver 9 # 1, a new communication path is secured between the LC 26 # 2 and the optical transceiver 9 # 1 with the same wavelength set, and a new communication path is secured. After that, the optical transceiver 9 # 2 is shut down.

  A procedure for switching the communication wavelength between the OLT 4 and the ONU 5 will be described. A flowchart divided into OLT 4 and ONU 5 is shown in FIG. 7, and a sequence diagram between OLT 4 and ONU 5 is shown in FIG. In FIG. 8, the operation represented by () represents the execution of the step () of FIG.

Step (1)
In step (1), it is determined that the OLT 4 switches the communication with the ONU 5 # n from the optical transceiver 9 # 2 to the optical transceiver 9 # 1 with the same wavelength set. For example, it is desired to switch to the optical transceiver 9 # 1 to maintain the optical transceiver 9 # 2, and to switch the communication with the ONU 5 # n from the standby optical transceiver 9 # 2 to the active optical transceiver 9 # 1. For such reasons, the OLT 4 determines that communication with the ONU 5 # n must be switched from the optical transceiver 9 # 2 to the optical transceiver 9 # 1 with the same wavelength set.
At this time, since the optical transceiver 9 # 1 of the ONU 5 is in the sleep state, it cannot be used as it is.

Step (2)
In step (2), the OLT 4 starts the optical transceiver 9 # 1 of the ONU 5 # n with the wavelength set 2 through the communication path from the LC 26 # 2 to the optical transceiver 9 # 2 of the ONU 5 # n with the wavelength set 2. Instruct.

Step (3)
In step (3), the ONU 5 # n activates the optical transceiver 9 # 1 with the wavelength set 2.

Step (4)
In step (4), the OLT sends a transmission permission signal and a transmission schedule to the optical transceiver 9 # 1 of the ONU 5 # n through the communication path from the LC 26 # 2 to the optical transceiver 9 # 1 of the ONU 5 # n according to the wavelength set 2. Send it.

Step (5)
In step (5), the ONU 5 # n transmits a participation request signal to the PON of the optical wavelength set 2 from the optical transmission / reception unit 9 # 1 according to the received transmission schedule.
On the other hand, optical transmitter / receiver 9 # 2 continues communication.

Step (6)
When the OLT receives the participation request signal in step (6), the optical transmission / reception unit 9 # is set so that the transmission band and transmission timing are the same as those of the optical transmission / reception unit 9 # 2 with respect to the LC 26 # 2 of the wavelength set 2. A GATE signal is transmitted to 1.
Further, the LC 26 # 2 of the wavelength set 2 is caused to transmit a GATE signal toward the optical transmission / reception unit 9 # 2 so as to shut down the optical transmission / reception unit 9 # 2.

Step (7)
Step (7) When the ONU 5 # n receives the GATE signal from the LC 26 # 2 by the wavelength set 2 to the optical transmission / reception unit 9 # 1, the ONU 5 # n performs communication by the wavelength set 2 between the optical transmission / reception unit 9 # 1 and the LC 26 # 2. take over.
On the other hand, when the ONU 5 # n receives a GATE signal from the LC 26 # 2 to the optical transmission / reception unit 9 # 2 by the wavelength set 2, the optical transmission / reception unit 9 # 2 is shut down. Thereafter, the optical transceiver 9 # 2 can be handled as the next switching destination.

Step (8)
In step (8), the OLT 4 continues the communication with the wavelength set 2 and when the request signal from the optical transmission / reception unit 9 # 2 of the wavelength set 2 does not reach, excludes the optical transmission / reception unit 9 # 2 from the PON of the wavelength set 2 To do.

  All of these controls are executed at a timing that does not affect the communication of the wavelength set 2 in which communication is performed by the LC 26 by the scheduling control of the dynamic wavelength band allocation circuit 28 of the OLT 4.

  In this way, the TWDM-PON system can include a standby system that can be operated flexibly.

  The procedure so far in the third embodiment may be executed after the first or second embodiment. In this case, in addition to the effects of the first embodiment, wavelength switching from the wavelength set 1 to the wavelength set 2 can be performed using the standby optical transmission / reception unit 9 # 2, and after the wavelength switching is completed, the active optical transmission / reception is performed. Switch back to section 9 # 1.

  In particular, it is preferable to provide the standby optical transceiver 9 # 2 with an optical amplifier. For example, in FIG. 2, the optical transmission / reception unit 9 # 2 has a smaller branching ratio of the optical branch circuit 10 to the optical fiber than the optical transmission / reception unit 9 # 1, and the optical transmission / reception unit 9 # 2 receives optical signals to be transmitted and received. An optical amplifier to be amplified is provided to compensate for the power drop caused by the optical branch circuit 10.

  Provision of an optical amplifier enables provisional communication by the spare optical transmission / reception unit 9 # 2, and by using only at the time of wavelength switching, power supply to the optical amplifier is large if only at that time. Does not increase power consumption. Further, it is possible to reduce the cost increase of the currently used optical transceiver 9 # 1.

(Embodiment 4)
In the present embodiment, it is assumed that the wavelength control method of the TWDM-PON system or the TWDM-PON system described in the first to third embodiments is applied to a wireless cellular system such as a mobile phone.

  The amount of mobile communication traffic such as mobile phones is rapidly increasing, and the future wireless cellular systems will have a multi-layer network consisting mainly of macrocells that handle only communication control signals and large numbers of small cells that handle user data communication. Has been taken into account.

  In the case of the first embodiment, the second embodiment, and the third embodiment, another optical transmission / reception unit 9 in the ONU 5 is activated to perform wavelength switching or the like. In a multi-layered wireless cellular system, switching to a PON operating in a wavelength set having the most bandwidth in an adjacent small cell is assumed, and wavelength switching to the PON wavelength set can be considered.

  Similarly, as a multi-layered wireless cellular system, the ONU 5 in the macro cell handling the control signal, which includes a plurality of so-called small cells handling user data signals, is equipped with the switching optical transmission / reception unit 9, and the same procedure is followed. Switching to the optical transmitter / receiver 9 is possible. The first, second, and third embodiments that suppress the influence on existing communications can be used in the same manner.

  Since the two optical transmission / reception units 9 of this embodiment are only used for communication in another cell or communication outside the role, as described in the third embodiment, the communication with the original optical transmission / reception unit 9 is performed once again according to the procedure. It is preferable to switch back.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, you may delete a some component from all the components shown by embodiment. Furthermore, you may combine the component covering different embodiment suitably.

  For example, the present invention is not limited to the network between base stations of wireless terminals such as mobile phones, but can be applied to a fixed network.

  The present invention can be applied to the information communication industry.

3: Optical splitter 4: OLT
5: ONU
9: Optical transmission / reception unit 10: Optical branching circuit 11: Wavelength multiplexer / demultiplexer 12: Optical transmission unit 13: Wavelength variable filter 14: Optical reception unit 15: Switching unit 23: Branching optical circuit 26 for branching an optical signal 26: Line card 27: Demultiplexing unit 28: Dynamic wavelength band allocation circuit

Claims (8)

An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. Wavelength control method for a TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
A wavelength control method for a TWDM-PON system that shuts down the first optical transceiver after securing the new communication path. An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. Wavelength control method for a TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
A wavelength control method for a TWDM-PON system that shuts down the second optical transmission / reception unit after securing the new communication path. An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. The optical fiber has a branching ratio smaller than that of the first optical transceiver, and the second optical transceiver includes an optical amplifier for optically amplifying an optical signal to be transmitted / received. A wavelength control method for a PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
After securing the new communication path, shut down the first optical transceiver,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
A wavelength control method for a TWDM-PON system that shuts down the second optical transmission / reception unit after securing the new communication path. An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
A TWDM-PON system that shuts down the first optical transceiver after securing the new communication path. An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
A TWDM-PON system that shuts down the second optical transceiver after securing the new communication path. An optical fiber terminal (OLT) having a first line card and a second line card is connected to a plurality of ONUs (Optical Network Units) each having a first optical transceiver and a second optical transceiver. The optical fiber has a branching ratio smaller than that of the first optical transceiver, and the second optical transceiver includes an optical amplifier for optically amplifying an optical signal to be transmitted / received. A PON (Time and Wavelength Division Multiplexing-Passive Optical Network) system,
The second optical transmission / reception unit set to a different wavelength set from the first optical transmission / reception unit through the first optical transmission / reception unit from the first line card in which a communication path is secured with the same wavelength set. Start
After completing the start of the second optical transceiver, a new communication path is secured between the second line card and the second optical transceiver with the different wavelength set,
After securing the new communication path, shut down the first optical transceiver,
Activating the first optical transmitter / receiver set to the same wavelength set as the second optical transmitter / receiver through the second optical transmitter / receiver from the second line card having a communication path secured with the same wavelength set And
After completing the start of the first optical transceiver, secure a new communication path between the second line card and the first optical transceiver in the same wavelength set,
A TWDM-PON system that shuts down the second optical transceiver after securing the new communication path.   An OLT (Optical Line Terminal) constituting the TWDM-PON system according to claim 4, 5 or 6.   An ONU (Optical Network Unit) constituting the TWDM-PON system according to claim 4, 5 or 6.

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