JP2017046306A - Optical communication device, optical communication network system, and optical communication program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce power consumption by suppressing optical communication with emission light intensity of more than necessary.SOLUTION: The optical communication device includes: a plurality of OSUs 30 connectable to each of a plurality of subscribers' devices with optical communication; and an OLT control section 28 for classifying the subscribers' devices into a plurality of groups for each light intensity range capable of performing optical communication between subscribers' devices and the OSUs 30, each of the OSUs 30 is allocated to subscribers' devices classified into groups, and setting emission light intensity during optical communication by the allocated OSU 30 for each of the groups.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical communication device, an optical communication network system, and the like used in a PON (Passive Optical Network) system defined by IEEE (Institute of Electrical and Electric Engineers) and ITU-T (International Telecommunication Union Telecommunication Standardization Sector), and the like. The present invention relates to an optical communication program.

  In recent years, broadbandization of mobile services has been promoted more and more, and the role of optical access networks is becoming important as a mobile backhaul to solve the shortage of bandwidth in wireless networks.

  As a trend of optical access, XG-PON (ITU-T G.987) has been standardized in parallel with the standardized 10G-EPON (IEEE Standard 802.3av). The system is expected to drive various access services.

  Furthermore, 40G [bps] class NG-PON2 is discussed in FSAN (Full Service Access Network) / ITU-T, and is a hybrid of TDM (Time Division Multiplexing) and WDM (Wavelength Division Multiplexing). T G.989) is adopted as one method.

  The PON consists of an OLT (Optical Line Terminal) installed in the office, an ONU (Optical Network Unit) installed in the user's house, an optical fiber laid from the office to the user, and an optical splitter that branches the optical fiber. Composed. A configuration example of 40G [bps] -based TWDM-PON is shown in FIG. Each OSU (Optical Subscriber Unit) 30 of the OLT 12 is connected to the ONU 14 via the optical fiber 18 and the optical splitter 16, and has a network configuration in which a plurality of ONUs 14 are connected to one OLT 12 by installing the optical splitter 16. . The OLT 12 has a function of transferring a signal from the ONU 14 to a host device or the host network 20, and conversely, transferring a signal from the host device or the host network 20 to the ONU 14. It also has a control monitoring function for the PON section and the ONU 14. The ONU 14 has a function of transferring a signal from the OLT 12 to the user terminal 22 and conversely transferring a signal from the user terminal 22 to the OLT 12.

  As described in Patent Document 1, in the TWDM-PON system, downstream communication (from OSU to ONU) in the PON section is continuously multiplexed by TDM so that signals to each ONU do not overlap in time. Has been. Further, the downstream optical wavelength of each OSU is different, and the downstream signal is transmitted to the ONU as WDM (wavelength division multiplexing communication). The ONU receives only the downstream optical wavelength of the OSU to which the ONU belongs.

  Since upstream (ONU to OSU) communication in the PON section is multiplexed by the optical splitter, it is necessary to control so that the upstream signal from each ONU transmitted at the same wavelength does not collide with the splitter. The ONU signal output timing is controlled by notifying each ONU belonging to the OSU of the transmission permission time, and multiplexed by TDMA (Time Division Multiple Access) that temporally separates the upstream signal from each ONU. .

  In TWDM-PON, load distribution between wavelengths can be performed by switching the transmission / reception wavelength of the OSU according to the traffic volume. For example, referring to FIG. 9, assuming that three ONUs 114 </ b> A to 114 </ b> C belong to the OSU 130 </ b> A as shown in FIG. 9A, when the total traffic volume exceeds the usable bandwidth, By changing the transmission / reception wavelength of any one of the ONUs to belong to the OSU 130B, the usable bandwidth of the OSU 130A is expanded to perform load distribution. Conversely, a method has been proposed in which the traffic of each ONU is efficiently allocated to the bandwidth of the OSU, thereby optimizing the operating OSU and realizing power saving of the OLT device.

JP 2011-55407 A

  Conventionally, in order to efficiently allocate the OSU band to which each ONU belongs, the transmission / reception wavelength of the ONU is changed, and the power of the OSU to which the ONU no longer belongs is turned off to reduce power consumption. It was. However, depending on the bandwidth used by the ONU, it cannot be allocated efficiently, and as a result, the OSU cannot be turned off. For example, when the number of belonging ONUs is large and the surplus bandwidth is small, the power saving effect cannot be obtained. Also, since the ONU optical module emits light with a uniform light emission intensity, it emits light with a stronger light intensity than necessary when the distance from the OSU is short. That is, useless power is consumed. The same applies to the OSU. When all of the ONUs under the OSU are close to each other, there is a margin in the received light intensity of the ONU, so the OSU emits light with a stronger light intensity than necessary and consumes power. become.

  The present invention has been made in consideration of the above-described facts, and an object of the present invention is to make it possible to reduce power consumption by suppressing optical communication with an emission intensity more than necessary.

  An optical communication device according to the present invention includes a plurality of connection units connectable to each of a plurality of subscriber side devices by optical communication, and a light intensity range in which optical communication can be performed between the subscriber side device and the connection unit. The plurality of subscriber-side devices are classified into a plurality of groups, and the subscriber-side devices classified into the plurality of groups are respectively assigned to the plurality of connection units, and optical communication by the allocated connection units And a setting unit for setting the emission intensity at each time for each of the plurality of groups.

  An optical communication network system according to the present invention includes the above-described optical communication device, a plurality of subscriber-side devices connectable to the connection unit via an optical fiber, the optical communication device, and the subscriber-side device. And an optical splitter connected to each of the optical communication device and the subscriber side device via an optical fiber.

  The optical communication program according to the present invention causes a computer to function as a setting unit in the optical communication apparatus described above.

  According to the present invention, it is possible to reduce power consumption by suppressing optical communication with an emission intensity more than necessary.

It is a block diagram which shows schematic structure of the optical communication network system which concerns on this embodiment. It is a block diagram which shows the structure of OLT of the optical communication network system which concerns on this embodiment. It is a block diagram which shows the structure of ONU of the optical communication network system which concerns on this embodiment. It is a flowchart which shows an example of the flow of the process performed in the OLT control part 28 of the optical communication network system which concerns on this embodiment. It is a figure for demonstrating an example of operation | movement of the optical communication network system which concerns on this embodiment, and is a figure which shows the state before operation | movement. It is a figure for demonstrating an example of operation | movement of the optical communication network system which concerns on this embodiment, and is a figure which shows the state after operation | movement. It is a block diagram which shows the structural example of OLT when light reception intensity information is produced | generated by the OLT side. It is a figure which shows the structural example of TWDM-PON of 40G [bps] base. In TWDM-PON, it is a figure for demonstrating the example which implements load distribution between wavelengths by switching the transmission / reception wavelength of OSU according to the traffic amount.

  Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an optical communication network system according to the present embodiment. The optical communication network system 10 according to the present embodiment shows an example in which a TWDM-PON type PON system is employed.

  The optical communication network system 10 according to the present embodiment includes an OLT 12 as an optical communication device, an ONU 14 as a subscriber side device, an optical splitter 16, and an optical fiber 18.

  The OLT 12 is installed in the station building, and the ONU 14 is installed in the user's home. An optical splitter 16 is provided between the OLT 12 and the ONU 14. The optical splitter 16 is a device for branching and combining optical signals. The optical fiber 18 connects the OLT 12 and the optical splitter 16, the two optical splitters, and the optical splitter 16 and the ONU 14.

  That is, the OLT 12 is connected to a plurality of ONUs 14 via the optical fiber 18 and the optical splitter 16, and a plurality of ONUs 14 are connected to one OLT 12.

  The ONU 14 has a function of converting an optical signal from the OLT 12 into an electrical signal, and also converting an electrical signal from a user terminal device (for example, a personal computer) into an optical signal and transferring it to the OLT 12. The OLT 12 has a role of transferring an optical signal from the ONU 14 to a host device (for example, the Internet), transferring a signal from the host device to the ONU 14, and controlling and monitoring the PON section and the ONU 14.

  FIG. 2 is a block diagram showing a configuration of the OLT 12 of the optical communication network system 10 according to the present embodiment. 2 indicate the flow of data signals, and the solid line indicates the flow of signals in the control system.

  The OLT 12 includes an upper network interface unit 22, an OLT reception processing unit 24, an OLT transmission processing unit 26, an OLT control unit 28 as a setting unit, and a plurality of OSUs 30 as connection units. Each OSU 30 has the same configuration, and includes an OSU control unit 32, a signal processing unit 34, and an optical transmission / reception unit 36 as a reception unit and a detection unit, and can be connected to a plurality of ONUs 14 by optical communication. .

  The upper network interface unit 22 terminates the signal from the upper network and outputs the terminated data signal to the OLT reception processing unit 24. The upper network interface unit 22 receives a data signal from each OSU 30, converts it into a format corresponding to the interface of the upper network, and outputs it.

  The OLT reception processing unit 24 distributes the signal terminated at the upper network interface unit 22 to each OSU 30 based on information instructed by the OLT control unit 28. For example, the association between the ONU 14 and a virtual identification number (VID: VLAN Identifier) assigned to the user is registered in advance, and control is performed so as to output a signal to the OSU 30 linked to the registered ONU 14.

  The OLT transmission processing unit 26 multiplexes the data signal from each OSU 30 and outputs the multiplexed data signal to the upper network interface unit 22.

  The OLT control unit 28 performs monitoring control of the OLT 12. In particular, the OST 30 power on / off control, the OSU 30 data distribution instruction to the OLT reception processing unit 24, the collection of control information from each OSU 30 and the control signal Insertion instruction etc. are performed. Here, examples of the control signal include a wavelength switching instruction, and examples of the control information include optical reception power information of the ONU 14 (information on received light intensity of the optical signal).

  The signal processing unit 34 multiplexes the control signal generated based on the information from the OSU control unit 32 and the data signal from the OLT reception processing unit 24, and outputs data to the optical transmission / reception unit 36. Further, the control signal and the data signal are discriminated from the signal from the optical transmission / reception unit 36, and in the case of the control signal, the signal is extracted and the information is transmitted to the OLT control unit 28 via the OSU control unit 32. The signal from which the control signal is extracted becomes only the data signal and is output to the OLT transmission processing unit 26.

  The optical transmission / reception unit 36 is set with light emission power (emission intensity) and wavelength upon transmission according to an instruction from the OSU control unit 32, and converts the serial electrical signal from the signal processing unit 34 into a signal of the set optical wavelength. And output. Further, only the wavelength set through the wavelength filter is received with respect to the optical signal from the ONU 14, converted from the optical signal to the electrical signal, and output to the signal processing unit 34. The optical transmitter / receiver 36 has a function of detecting the light intensity of the optical signal from the ONU 14.

  FIG. 3 is a block diagram showing a configuration of the ONU 14 of the optical communication network system 10 according to the present embodiment. Note that the dotted lines in FIG. 3 indicate the flow of data signals, and the dotted lines indicate the flow of signals in the control system.

  The ONU 14 includes a user interface unit 44, a signal processing unit 42, an optical transmission / reception unit 40, and an ONU control unit 38.

  The user interface unit 44 terminates the signal from the user terminal device and outputs a data signal to the signal processing unit 42. Further, it receives a data signal from the signal processing unit 42, converts the received data signal into an interface of a user terminal device, and outputs it.

  The signal processing unit 42 multiplexes the control signal generated based on the information from the ONU control unit 38 and the data signal from the user interface unit 44, and outputs data to the optical transmission / reception unit 40. Further, the signal processing unit 42 determines a control signal and a data signal from the signal from the optical transmission / reception unit 40, and extracts the signal in the case of the control signal and transmits the information to the ONU control unit 38. The signal from which the control signal is extracted becomes only the data signal and is output to the user interface unit 44.

  The optical transmission / reception unit 40 sets a wavelength according to an instruction from the ONU control unit 38, converts the serial electrical signal from the signal processing unit 42 into an optical signal having the set wavelength, and outputs the optical signal. The optical transceiver 40 receives only the set wavelength of the optical signal from the OLT 12 through the wavelength filter, converts the received optical signal into an electrical signal, and outputs the converted electrical signal to the signal processor 42. To do. The optical transmitter / receiver 40 has a function of detecting the light intensity of the optical signal from the OLT 12.

  The ONU control unit 38 collects control information transmitted from the OLT 12 and instructs the insertion of the control signal into the uplink signal. Examples of the control information include the wavelength switching instruction described above, and examples of the control signal include optical reception power information of the ONU 14 (information on received light intensity of the optical signal).

  Next, the operation of the optical communication network system 10 according to the present embodiment configured as described above will be described.

  In the initial state, the optical transceiver 36, which is an optical module of the OLT 12, and the optical transceiver 40, which is an optical module of the ONU, in the initial state, have a light intensity that allows constant optical communication in consideration of a power budget and a loss budget similar to those of the prior art. Starts operation at (light output). Therefore, the OLT 12 and the ONU 14 can receive optical signals from each other. In this state, each ONU 14 once belongs to one of the OSUs 30 and is in a state where data can be transmitted and received. As a result, the ONU 14 can notify the OLT 12 of the received light intensity from the OLT 12 through the control signal generated by the signal processing unit 42. The received light intensity of the ONU 14 is detected by the receiving circuit of the optical transmission / reception unit 40, and the result can be read from the ONU control unit 38. An optical module that conforms to MSA (Multi Source Agreement) and has a received light intensity detection function can be realized by accessing a predetermined register in the optical module with I2C-BUS. Further, since the OLT 12 collects the received light intensity from each ONU 14 and performs data communication, it is possible to grasp the traffic amount of each ONU 14.

  On the other hand, based on the received light intensity collected from each ONU 14, the OLT control unit 28 classifies the plurality of ONUs 14 into groups for each light intensity range in which optical communication between the ONU 14 and the OSU 30 is possible, and connects to the ONUs 14 for each group. Each OSU 30 to be assigned is assigned. Then, the emission intensity when each OSU 30 performs optical communication is set for each group.

  Here, specific processing performed by the OLT control unit 28 will be described. FIG. 4 is a flowchart illustrating an example of a flow of processing performed by the OLT control unit 28 of the optical communication network system according to the present embodiment.

  First, in step 100, the OLT control unit 28 collects control signals for each ONU 14, thereby collecting information on the received light intensity of each ONU 14, and proceeds to step 102.

  In step 102, the OLT control unit 28 groups the ONUs 14 for each collected received light intensity while considering traffic, and proceeds to step 104. In the grouping, for example, when the light emission intensity of the light transmitting / receiving unit 36 is two types, it is classified into two groups, and when it is three or more types, it is classified into three or more groups.

  In step 104, the OLT control unit 28 assigns the OSU 30 for each group and proceeds to step 106. That is, the OSU 30 is assigned to each group by switching to a different optical signal frequency for each group. Alternatively, the OSU 30 is assigned to each group by transmitting a wavelength change instruction so that communication with the OSU 30 assigned to each ONU 14 is possible.

  In step 106, the OLT control unit 28 sets the light emission intensity of the optical transmission / reception unit 36 for each group and ends the series of processes. Thereby, since the light intensity can be set for each group, it is possible to suppress the optical communication with the light emission intensity more than necessary and to reduce the power consumption.

  Next, the above-described processing of FIG. 4 performed by the OLT control unit 28 will be described with a specific example.

  The light transmitting / receiving unit 36, which is an optical module on the OLT 12 side, can change the light emission intensity by setting from the outside. In general, an optical module used in a PON system is operated by designating different current values depending on the temperature so that the light emission intensity is determined by a current value passed through an LD (Laser Diode) and the light emission intensity does not fluctuate due to temperature fluctuation. Therefore, when changing the light emission intensity, it is necessary to have a current value table for each light emission intensity for each temperature (for example, for each predetermined temperature range). Although there are aspects that are convenient depending on the system that can realize light output with various intensities, preparing multiple tables with an optical module leads to an increase in the size of the storage device and an increase in the number of inspection steps, resulting in an increase in cost. Therefore, it may be determined by the system. Instead of a plurality of tables, a correction formula for correcting light output fluctuation due to temperature may be prepared and stored. In the following description, it is assumed that light output with two types of light emission intensities is possible, but not limited to two types of light emission intensities, light output with three or more types of light emission intensities may be possible. The OSU controller 32 can determine which of the two types of light emission intensity is used to operate the optical module. An optical module having an emission intensity changing function and compliant with MSA can be realized by accessing a predetermined register in the optical module via the I2C bus. In addition, as the higher emission intensity of the two types of emission intensity, for example, as described above, a certain light intensity capable of optical communication in consideration of the power budget and the loss budget can be applied. On the other hand, as the lower emission intensity, the light intensity determined according to the light loss such as the distance to the ONU 14 connected to the OLT 12, the light intensity lower by a predetermined amount than the higher light intensity, or the like is applied. Is possible.

  The OLT control unit 28 selects the ONU 14 that can receive light at the lower emission intensity of the two types of emission intensity of the OLT 12. As an example of the selection method, the usage band and the traffic amount of the ONU 14 are determined so as not to exceed the usage band in order from the ONU 14 having the higher light reception intensity based on the collected light reception intensity information of each ONU 14.

  For example, assume that there are ONUs 14A to 14C belonging to the OLT 12 in FIG. The physical distance of each ONU 14 from the OLT 12 is ONU 14A <ONU 14C <ONU 14B, and the received light intensity in each ONU 14 is b <c <a. In this case, initially, each optical transmission / reception unit (optical module) 36 operates at the higher emission intensity of the two types of emission intensity. The ONU 14A and ONU 14C are ONUs 14 that can receive light even when the light emission intensity of the OLT 12 is low, and the ONUs 14B are ONUs 14 that cannot receive light when the light emission intensity is low. Further, it is assumed that the traffic volume of the three ONUs 14 is equal to or greater than the usage band of one OSU 30. Since three ONUs 14 cannot belong to one OSU 30, they are assigned separately. Here, it is assumed that ONUs 14B and 14C belong to OSU 30A and ONU 14A belongs to OSU 30B. Since the ONU 14A and the ONU 14C can receive light even when the light emission intensity of the OLT 12 is lower, first, a control signal is transmitted to the ONU 14B so that the OSU 30 to which it belongs is changed from the OSU 30A to the OSU 30B. The ONU 14B receives the change instruction, and changes the transmission wavelength from the wavelength c to the wavelength d and the reception wavelength from the wavelength a to the wavelength b. At this time, ONU 14C belongs to OSU 30A, and ONU 14A and ONU 14B belong to OSU 30B.

  Next, a control signal is transmitted so that the OSU 30 belonging to the ONU 14A is changed from the OSU 30B to the OSU 30A. The ONU 14A receives the change instruction, and changes the transmission wavelength from the wavelength d to the wavelength c and the reception wavelength from the wavelength b to the wavelength a. Therefore, as shown in FIG. 6, finally, the ONU 14A and ONU 14C belong to the OSU 30A, and the ONU 14B belongs to the OSU 30B. Since only the ONU 14 that can receive light belongs to the OSU 30A even if the light emission intensity of the OLT 12 is low, the OSU 30A is instructed to change the light emission intensity of the OSU 30A from the higher one to the lower light emission intensity. Thereby, since the power consumption of the optical module of OSU30A is suppressed, it becomes possible also as OLT12 to reduce power consumption.

  As described above, in this embodiment, the OLT 12 collects the received light intensity at each ONU 14, and based on the information, the group that can communicate even if the emission intensity of the OSU 30 is lowered, and the group that cannot communicate when the emission intensity is lowered. And a plurality of ONUs 14 are classified. Then, the transmission / reception wavelength of the ONU 14 is changed to change the OSU 30 to which it belongs, so that the OSU 30 that can communicate even if the light emission intensity is lowered is divided into the OSU 30 that cannot communicate, and the light emission intensity of the communicable OSU 30 is lowered. Therefore, power saving can be achieved.

  In the above embodiment, the light emission intensity of the optical module on the OLT 12 side is reduced to save power. However, on the ONU 14 side, the light emission intensity is similarly reduced to further reduce power consumption as a system. Is possible.

  In the above embodiment, the power saving control is realized based on the light reception intensity information of each ONU 14, but the light reception intensity information can be generated on the OLT 12 side. In that case, the OLT 12 needs to obtain information on the received light intensity from the optical module at the timing when the light is received from each ONU 14. Therefore, as in the configuration shown in FIG. 7, the optical transmission / reception unit 36 as an optical module of the OLT 12 receives the timing signal from the signal processing unit 34, holds the received light intensity at the received timing, and receives a read request from the OSU control unit 32. The received light intensity is notified by.

  Note that the processing performed by the OLT control unit 28, the OSU control unit 32, the ONU control unit 38, and the like in the above-described embodiment may be performed by hardware. Or it is good also as a process performed with the software performed by running a program. Alternatively, the processing may be a combination of both software and hardware.

  Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

10 Optical communication network system 12 OLT
14 ONU
16 Optical splitter 18 Optical fiber 28 OLT control unit 30 OSU
36, 40 Optical transceiver

Claims (7)

A plurality of connection units connectable to each of a plurality of subscriber side devices by optical communication;
The plurality of subscriber-side devices are classified into a plurality of groups for each light intensity range in which optical communication can be performed between the subscriber-side device and the connection unit, and the subscriber side classified into the plurality of groups A setting unit that assigns a device to each of the plurality of connection units, and sets emission intensity during optical communication by the allocated connection units for each of the plurality of groups;
An optical communication device comprising:   Each of the plurality of connection units uses the detection result of the received light intensity of the optical signal received by the subscriber side device as intensity information indicating the light intensity range in which the optical communication is possible, and each of the plurality of subscriber side devices. The optical communication apparatus according to claim 1, further comprising: a receiving unit that receives from the optical communication device.   Each of the plurality of connection units includes a detection unit that detects a light intensity in an optical signal received from each of the plurality of subscriber side devices as the light intensity range in which optical communication is possible. Item 4. The optical communication device according to Item 1.   The setting unit categorizes the plurality of groups by switching the wavelength of the optical signal for each of the plurality of groups used in optical communication between the subscriber side device and the connection unit to a different wavelength. The optical communication device according to any one of claims 1 to 3, wherein the subscriber-side device thus assigned is assigned to each of the plurality of connection units.   The setting unit reduces the light emission intensity at the time of optical communication by the connecting unit assigned as a group of light intensity capable of optical communication even when the light intensity is decreased from a predetermined initial state from the initial state. The optical communication device according to claim 1, wherein the light emission intensity is set. The optical communication device according to any one of claims 1 to 5,
A plurality of subscriber-side devices connectable to the connection unit via optical fibers;
An optical splitter provided between the optical communication device and the subscriber side device, and connected to each of the optical communication device and the subscriber side device via an optical fiber;
Optical communication network system equipped with. The optical communication program for functioning a computer as a setting part in the optical communication apparatus of any one of Claims 1-5.

Images