JP2015023516A - Optical subscriber system, dynamic wavelength band allocation method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately switch a wavelength by detecting or predicting congestion of traffic passing an OSU 12 in a dynamic wavelength band allocation method for allocating a wavelength to a subscriber device in response to a request from the subscriber device at an interval of a predetermined wavelength switching cycle in an optical subscriber system where a plurality of subscriber devices and a single station-side device are connected by PON topology.SOLUTION: In accordance with the dynamic wavelength band allocation method, in the case where signal discarding is incurred in an uplink signal by congestion in any one of ONU 92 issuing requests, a wavelength different from a wavelength being used is allocated among available wavelengths and when signal discarding is incurred in a downlink signal by congestion, a wavelength different from a wavelength being used is allocated among the available wavelengths.

Description

  The present invention relates to a wavelength and band assignment algorithm in PON (Passive Optical Networks) that combines wavelength multiplexing and time division multiplexing.

  With the rapid spread of the Internet in recent years, there has been a demand for an increase in the capacity, sophistication, and economy of access service systems, and research on PON has been promoted as a means for realizing it. The PON is an optical communication system that achieves economy by sharing one station-side device and a part of a transmission path with a plurality of subscriber devices using an optical multiplexer / demultiplexer using an optical passive element.

  Currently, in Japan, GE-PON (Gigabit Ethernet Passive Optical Network) (Ethernet is registered as an economical optical subscriber system that shares a 1 Gbps line capacity with time division multiplexing (TDM) for up to 32 users. Trademark) has been introduced. As a result, FTTH (Fiber To The Home) service has been provided at a realistic fee.

  Further, in order to meet the needs of higher capacity, research on 10G-EPON having a total bandwidth of 10 Gbps as a next-generation optical subscriber system is underway, and international standardization was completed in 2009. This is an optical subscriber system that realizes an increase in capacity while increasing the bit rate of the transmitter / receiver while using the same transmission line portion as the GE-PON.

  In the future, it may be necessary to increase the capacity exceeding 10G class, such as ultra-high definition video service and ubiquitous service. However, simply increasing the bit rate of the transceiver from 10G class to 100G class will upgrade the system. Due to the increase in cost, there is a problem that it is difficult to put into practical use.

  As a means for solving this, wavelength variability is added to the transmitter / receiver so that the transmitter / receiver in the station side device can be added in stages according to the bandwidth requirement, and time division multiplexing (TDM) and wavelength are added. Wavelength-variable WDM / TDM-PON in which division multiplexing (WDM: Wavelength Division Multiplexing) is effectively combined has been reported (for example, see Non-Patent Documents 1 and 2).

  As described in Non-Patent Document 2, wavelength tunable WDM / TDM-PON has been attracting attention in recent years as a system that can increase the total bandwidth step by step and flexibly distribute load according to user requirements. A dynamic wavelength band allocation algorithm is used to change the affiliation OSU (Optical Subscriber Unit). The dynamic wavelength band allocation (DWBA: Dynamic Wavelength and Bandwidth Allocation) is performed in the OSU to which the dynamic wavelength band is allocated (upward dynamic band allocation (DBA: Dynamic Bandwidth Allocation, DBA: Dynamic Bandwidth Allocation)) from ONU (Optical Network Unit: subscriber apparatus) This is realized by a combination of wavelength switching for switching the OSU.

  FIG. 1 shows a configuration diagram of a wavelength tunable WDM / TDM-PON system and a station side device (OLT) and a subscriber unit (ONU) constituting the wavelength tunable WDM / TDM-PON system. The OLT and the ONU are connected by a PON topology having a point-to-multipoint configuration using a power splitter or a wavelength router.

The OLT 91 includes an OSU 12 of OSU1 to OSUm that transmits / receives wavelengths of λ1d _{, u to} λmd _{, u} , and a dynamic wavelength band allocation circuit, and OSU1 to OSUm are λ1d _{, u to} λmd _, Each wavelength signal of _u is transmitted and received. OLT91 ONU92 of h stand ONU1~ONUh is connected to each of ONU92 is set of wavelengths of the downlink and uplink λ1 _d, u ~λm _d, one set of wavelengths of _u or λ1u~ the uplink, either Ramudamu, transmitted and received using any of the wavelength of λ1 _d ~λm _d in the downlink. ONU can be λ1 _u ~λm _u, it switches the wavelengths of λ1 _d ~λm _d transceiver in accordance with an instruction from the OLT.

Each ONU 92 receives an upstream signal from a communication device installed at the user's home, and is transmitted as an upstream optical signal by an optical transceiver inside the ONU 92. Since the upstream signal is multiplexed on one optical fiber from the power splitter or wavelength router on the ONU side toward the OLT 91, the transmission time and the transmission duration time of the upstream signal transmitted by each ONU 92 are set so that the upstream signals do not overlap. Is calculated and controlled. Uplink signals 1 to m received by OSU1 to OSUm are aggregated by the demultiplexing unit 13 in the OLT 91, multiplexed into one uplink signal, and transmitted to the relay network side. On the other hand, the downlink signal from the relay network side to each ONU 92 is transmitted to the OSU1 to OSUm based on the destination ONU92 information written in the downlink signal by the demultiplexing unit 13 and the OSU information to which the ONU92 belongs. Separated. The separated downlink signal 1~m at wavelengths λ1 _d ~λm _d having the OSU1～m, sent to each ONU92. The downstream signal is broadcast by the wavelength of each OSU 12, but since the transmission / reception wavelength of the ONU 92 is set to the transmission / reception wavelength of each OSU 12, the ONU 92 selects the information addressed to it from the received wavelength signal, It is output from the ONU 92 to the communication device at the user's home.

  The dynamic wavelength band allocation circuit 11 includes a DWBA calculation unit 114, a switching instruction signal generation unit 111, a control signal transmission unit 112, and a request signal reception unit 113. The request signal receiving unit 113 receives a request signal including a bandwidth request transmitted from each ONU 92 through each OSU 12. Based on the request from each ONU 92, the DWBA calculation unit 114 calculates the transmission time and transmission duration of the uplink signal and the request signal to be allocated to each ONU 92. The switching instruction signal generation unit 111 generates an instruction signal storing the information. The control signal transmission unit 112 transmits a Gate signal to each ONU 92 through each OSU 12. Further, the DWBA calculation unit 114 manages connection information between the ONU 92 and the OSU 12 in the PON section. When the wavelength is switched, the DWBA calculation unit 114 instructs the demultiplexing unit 13 to change the transfer destination OSU 12 of the downstream signal of the ONU 92 with respect to the ONU 92 whose wavelength has been changed.

  FIG. 2 shows an example of a downlink signal separation and transfer method to OSU1 to OSUm in the demultiplexing unit 13. The demultiplexing unit 13 includes m selectors 131, m buffers 132, a multiplexing unit 134, a demultiplexing unit 135, h ONU buffers 133, a SEL control unit 136, and a buffer monitor unit 137. Prepare.

  As described above, the downlink signal from the relay network side is read in the destination ONU information of the downlink signal in the separation unit 135 and accumulated in the first-in first-out buffers ONU1 to ONUh for each ONU 92 for each destination ONU information. The signals accumulated in the ONU-by-ONU buffer 133 are output in accordance with instructions from the selectors SEL1 to SELm for each OSU 12, and transferred to each selector 131. Each selector 131 transfers the signal to the corresponding OSU 12. The SEL control unit 136 designates the ONU buffer 133 to be read to the selector 131. The selector 131 corresponds to the OSU 12, and the ONU buffer 133 of the ONU 92 belonging to the OSU 12 is designated.

  For example, in FIG. 2, SEL1 is designated to read the buffer of the ONU 92 belonging to OSU1, and thereafter SEL2 reads the downstream signal from the OSU2 and SELm reads the downstream signal from the ONU buffer 133 of the ONU 92 belonging to OSUm. The SEL control unit 136 manages which ONU 92 belongs to which OSU 12. Since the information of the ONU 92 belonging to each OSU 12 is changed by switching the wavelength, the dynamic wavelength band allocation circuit 11 updates the correspondence relationship between the OSU 12 and the ONU 92 to the SEL control unit 136 when wavelength switching occurs.

  FIG. 3 shows the configuration of the ONU 92. The ONU 92 includes a data reception unit 21, a data transmission unit 30, an upstream buffer memory 22, a downstream buffer memory 29, a destination analysis selection reception unit 28, a frame transmission control unit 23, a frame assembly transmission unit 24, a wavelength tunable optical transceiver 25, a requested bandwidth. The calculation unit 32, the requested band signal generation unit 31, the frame transmission / wavelength control signal reception unit 26, and the wavelength switching control unit 27 are configured.

The uplink signal from the user is received by the data receiving unit 21 and temporarily stored in the uplink buffer memory 22. The frame transmission control unit 23 sends the uplink signal to the frame assembly / transmission unit 24 according to the transmission time and transmission duration of the uplink signal designated by a signal (referred to as a Gate signal) that instructs wavelength switching. The frame assembly transmission unit 24 configures a frame format necessary for transmitting a signal to the OLT 91 in the PON configuration, and transmits the frame format to the wavelength variable optical transceiver 25. Tunable optical transceiver 25 wavelengths .lambda.1 _d specified in the wavelength switch control unit _27, and transmits to the u ~λm _d, converted into an optical signal in one of _u OLT91. The downlink signal from the OSU 12 is received by selecting the designated wavelength in the wavelength tunable optical transceiver 25, and the destination analysis selection receiving unit 28 analyzes the destination of the downlink signal and selects only the information addressed to itself. Store in the downstream buffer memory 29. The data transmission unit 30 transmits information stored in the downlink buffer memory 29 to the user as a downlink signal.

  The wavelength tunable optical transceiver 25 receives the Gate signal from the OLT 91, converts it into an electrical signal, and sends it to the frame transmission and wavelength control signal receiver 26. The frame transmission / wavelength control signal receiving unit 26 analyzes the instruction of the Gate signal, and if the Gate signal includes the wavelength switching instruction, the wavelength after switching, and the switching start time, the switching is performed with the switching destination wavelength at the designated time. An instruction is sent to the wavelength switching control unit 27. The wavelength switching control unit 27 switches the wavelength of the wavelength tunable optical transceiver 25 according to the wavelength switching control.

  The OLT 91 receives information about the bandwidth requested by the ONU 92 from the ONU 92 and uses it for bandwidth allocation. Although there are various methods, for example, the Gate signal may be instructed to transmit the requested bandwidth information to the OLT 91. A signal in which the ONU 92 describes information on the required bandwidth in the OLT 91 is referred to as a report signal. In this case, when the frame transmission and wavelength control receiving unit 26 receives a Gate signal requesting transmission of the Report signal, it instructs the request band signal generation unit 31 to generate the Report signal. The requested band signal generation unit 31 instructs the requested band calculation unit 32 to calculate the requested band. The requested band signal calculation unit 32 measures and measures the amount of uplink signal data stored in the uplink buffer memory 22, determines the requested band amount based on the data amount, and sends the requested band signal generation unit 31 to the requested band signal. Send quantity. The requested band signal generation unit 31 generates a Report signal including the requested amount and sends it to the frame transmission control unit 32.

  The Gate signal may include information on the transmission start time and transmission duration of the Report signal. In that case, the frame transmission / wavelength control signal receiving unit 26 sends the transmission start time and transmission duration information of the Report signal included in the Gate signal to the frame transmission control unit 23, and the frame transmission control unit 23 is instructed. At the time, the Report signal is sent to the frame assembly transmitting unit 24, and the Report signal is transmitted to the OLT 91 via the wavelength tunable optical transceiver 25. The Gate signal transmitted from the OLT 91 includes a transmission start time and a transmission continuation time when the ONU 92 transmits the uplink signal received from the user side to the OLT 91. The frame transmission and wavelength control signal receiving unit 26 sends information on the transmission start time and transmission duration of the uplink signal included in the Gate signal to the frame transmission control unit 23, and the frame transmission control unit 23 transmits the information at the instructed time. The frame is extracted from the uplink buffer memory 22 for the duration of the transmission duration, sent to the frame assembly / transmission unit 24, and transmitted to the OLT 91 via the wavelength tunable optical transceiver.

Kazutaka Hara et al, “Flexible load balancing technology using dynamic wavebandwidth allocation (DWBA) upward 100 Gbit / s-class-WDM-TDM-TDM-TDM-TDM-TDM. 3. B. 2, ECOC2010, 2010 S. Kimura, “WDM / TDM-PON Technologies for Future Flexible Optical Access Networks”, 6A1-1, OECC 2010, 2010.

In the WDM / TDM-PON dynamic wavelength band allocation, an upstream or downstream signal band is dynamically allocated according to a band used or requested by the ONU 92. Since WDM / TDM-PON becomes the conventional technology TDM-PON itself when focusing on a set of one wavelength, a dynamic bandwidth allocation (DBA) algorithm can be applied to upstream bandwidth allocation. The DBA algorithm can perform fair bandwidth control and dynamic bandwidth allocation according to bandwidth requirements, and various DBAs have been proposed so far. On the other hand, when realizing a total bandwidth of 100 Gbit / s to the relay side network by combining 4 wavelengths with a transmission rate of 25 Gbit / s for each of the upstream and downstream, the maximum rate at which one OSU 12 and one ONU 92 can transmit is 25 Gbit / s s. At this time, if the total uplink or downlink bandwidth for one OSU exceeds 25 Gbit / s, congestion occurs.

  Here, the congestion can be avoided by selecting one or several belonging ONUs 92 and changing the accommodation to the OSU 12 having another vacant bandwidth. That is, as an excellent function of dynamic wavelength band allocation in WDM / TDM-PON, congestion is detected when the total bandwidth of one OSU exceeds the transmission rate of the OSU 12, and the ONU 92 switches the wavelength and moves the OSU 12 to which it belongs. Thus, it is possible to distribute the load.

  On the other hand, it usually takes some time to change the wavelength of the wavelength tunable optical transceiver 25. Further, since the signal communication of the wavelength tunable optical transmitter / receiver 25 becomes impossible during wavelength switching, traffic interruption during wavelength switching is unavoidable. Since a long wavelength switching time causes an increase in delay and buffer overflow in the apparatus, the shorter the switching time, the less influence on communication. However, parts with a short wavelength switching time are generally expensive. It is not suitable for the economicization of optical access systems. In order to prioritize the economics of the optical access system, it is conceivable that the wavelength switching time is defined longer than the DBA cycle so that more types of wavelength switching components can be applied. In this case, when deciding to perform load distribution accompanied by wavelength switching, the means of detecting the tightness of the band and the availability of the load can be achieved even if communication disruption occurs due to wavelength switching. It is desirable to be. That is, it is necessary to reliably perform the load distribution effect and the congestion avoidance by wavelength switching. Until now, no method has been proposed for distributing the load by detecting or predicting congestion of traffic passing through the OSU 12 and switching wavelengths appropriately.

  In an optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology, the present invention sets a wavelength according to a request from the subscriber device at every predetermined wavelength switching period. An object of the dynamic wavelength band allocation method to be allocated to a subscriber apparatus is to detect or predict congestion of traffic passing through the OSU 12 and appropriately switch wavelengths.

An optical subscriber system according to the present invention includes:
An optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology,
The station side device includes a dynamic wavelength band allocation circuit that allocates a wavelength to the subscriber device in response to a request from the subscriber device for each predetermined wavelength switching period,
The dynamic wavelength band allocation circuit includes:
When signal loss due to congestion occurs at any wavelength used for upstream or downstream signals, one of the subscriber devices using the wavelength can be selected as a wavelength switching candidate and can be used for the wavelength switching candidate. Of the wavelengths, a wavelength different from the wavelength at which congestion occurs is assigned.

An optical subscriber system according to the present invention includes:
An optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology,
The station side device includes a dynamic wavelength band allocation circuit that allocates a wavelength to the subscriber device in response to a request from the subscriber device for each predetermined wavelength switching period,
The dynamic wavelength band allocation circuit includes:
A value obtained by multiplying the average value of the upstream signal band of one wavelength by a constant multiplied by the standard deviation of the upstream signal band of the wavelength, or the average value of the downstream signal band of one wavelength and the downstream signal band of the wavelength When the value obtained by multiplying the standard deviation by a constant exceeds the maximum signal bandwidth of the wavelength, select one of the subscriber devices that use the wavelength as the wavelength switching candidate and use it for the wavelength switching candidate. A wavelength different from the congested wavelength among the possible wavelengths is assigned.

An optical subscriber system according to the present invention includes:
An optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology,
The station side device includes a dynamic wavelength band allocation circuit that allocates a wavelength to the subscriber device in response to a request from the subscriber device for each predetermined wavelength switching period,
The dynamic wavelength band allocation circuit includes:
Either one of the wavelengths used for the upstream signal is discarded due to congestion, or the value obtained by multiplying the average value of the upstream signal band of one wavelength by the standard deviation of the upstream signal band of the wavelength and the constant is added. At least one of exceeding the maximum signal bandwidth of the wavelength, or
Either one of the wavelengths used for the downlink signal is discarded due to congestion, or a value obtained by multiplying the average value of the downlink signal band of one wavelength by the standard deviation of the downlink signal band of the wavelength and a constant is added. If at least one of the maximum signal bandwidth of the wavelength has been exceeded,
One of the subscriber apparatuses using the wavelength is selected as a wavelength switching candidate, and a wavelength different from the congested wavelength among the usable wavelengths is assigned to the wavelength switching candidate.

In the optical subscriber system according to the present invention,
The dynamic wavelength band allocation circuit includes:
When the wavelength that has the maximum uplink average surplus bandwidth among the assignable wavelengths is selected and the uplink average surplus bandwidth of the wavelength is larger than the uplink average use bandwidth of the wavelength switching candidate, the wavelength is designated as the uplink signal. Assign to the requested wavelength switching candidate,
When the wavelength that has the maximum downlink average surplus bandwidth among the assignable wavelengths is selected and the downlink average surplus bandwidth of the wavelength is larger than the downlink average use bandwidth of the wavelength switching candidate, the wavelength is designated as the downlink signal. You may allocate with respect to the said wavelength switching candidate to request.

In the optical subscriber system according to the present invention,
The dynamic wavelength band allocation circuit includes:
The wavelength having the maximum uplink average surplus bandwidth among the assignable wavelengths is selected, the uplink average surplus bandwidth of the wavelength is larger than the uplink average use bandwidth of the wavelength switching candidate, and the downlink average surplus bandwidth of the wavelength is If the wavelength switching candidate is larger than the downlink average use band, the wavelength is assigned to the wavelength switching candidate that requests an uplink signal,
A wavelength having the maximum downlink average surplus bandwidth among the assignable wavelengths is selected, the uplink average surplus bandwidth of the wavelength is larger than the uplink average use bandwidth of the wavelength switching candidate, and the downlink average surplus bandwidth of the wavelength is If the wavelength switching candidate is larger than the average downlink use band, the wavelength may be assigned to the wavelength switching candidate that requests a downlink signal.

The dynamic wavelength band allocation method according to the present invention includes:
In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the wavelength is set according to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation method for allocating to a device, comprising:
When signal loss due to congestion occurs at any wavelength used for upstream or downstream signals, one of the subscriber devices using the wavelength can be selected as a wavelength switching candidate and can be used for the wavelength switching candidate. Of the wavelengths, a wavelength different from the wavelength at which congestion occurs is assigned.

The dynamic wavelength band allocation method according to the present invention includes:
In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the wavelength is set according to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation method for allocating to a device, comprising:
A value obtained by multiplying the average value of the upstream signal band of one wavelength by a constant multiplied by the standard deviation of the upstream signal band of the wavelength, or the average value of the downstream signal band of one wavelength and the downstream signal band of the wavelength When the value obtained by multiplying the standard deviation by a constant exceeds the maximum signal bandwidth of the wavelength, select one of the subscriber devices that use the wavelength as the wavelength switching candidate and use it for the wavelength switching candidate. A wavelength different from the congested wavelength among the possible wavelengths is assigned.

The dynamic wavelength band allocation method according to the present invention includes:
In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the wavelength is set according to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation method for allocating to a device, comprising:
Either one of the wavelengths used for the upstream signal is discarded due to congestion, or the value obtained by multiplying the average value of the upstream signal band of one wavelength by the standard deviation of the upstream signal band of the wavelength and the constant is added. At least one of exceeding the maximum signal bandwidth of the wavelength, or
Either one of the wavelengths used for the downlink signal is discarded due to congestion, or a value obtained by multiplying the average value of the downlink signal band of one wavelength by the standard deviation of the downlink signal band of the wavelength and a constant is added. If at least one of the maximum signal bandwidth of the wavelength has been exceeded,
One of the subscriber apparatuses using the wavelength is selected as a wavelength switching candidate, and a wavelength different from the congested wavelength among the usable wavelengths is assigned to the wavelength switching candidate.

The dynamic wavelength band allocation program according to the present invention is:
In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the station-side device responds to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation program for allocating a wavelength to the subscriber unit,
When signal loss due to congestion occurs at any wavelength used for the uplink signal or downlink signal, the station side device selects any of the subscriber devices using the wavelength as the wavelength switching candidate, and the wavelength switching candidate On the other hand, assign a wavelength different from the congested wavelength among the usable wavelengths,
A dynamic wavelength band allocation program for causing a computer to execute a dynamic wavelength band allocation procedure.

The dynamic wavelength band allocation program according to the present invention is:
In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the station-side device responds to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation program for allocating a wavelength to the subscriber unit,
The station side device adds an average value of the upstream signal band of one wavelength to the standard deviation of the upstream signal band of the wavelength multiplied by a constant, or an average value of the downstream signal band of one wavelength, When the value obtained by multiplying the standard deviation of the downstream signal band of the wavelength by a constant exceeds the maximum signal band of the wavelength, select one of the subscriber devices using the wavelength as a wavelength switching candidate, Assign a wavelength that is different from the congested wavelength among the usable wavelengths to the switch candidate.
A dynamic wavelength band allocation program for causing a computer to execute a dynamic wavelength band allocation procedure.

The dynamic wavelength band allocation program according to the present invention is:
In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the station-side device responds to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation program for allocating a wavelength to the subscriber unit,
Either the station side device causes signal discard due to congestion at any wavelength used for the upstream signal, or the average value of the upstream signal band of one wavelength is multiplied by a constant to the standard deviation of the upstream signal band of the wavelength. Or the added value exceeds the maximum signal bandwidth of the wavelength, or
Either one of the wavelengths used for the downlink signal is discarded due to congestion, or a value obtained by multiplying the average value of the downlink signal band of one wavelength by the standard deviation of the downlink signal band of the wavelength and a constant is added. If at least one of the maximum signal bandwidth of the wavelength has been exceeded,
Select one of the subscriber devices using the wavelength as a wavelength switching candidate, and assign a wavelength different from the congested wavelength among the usable wavelengths to the wavelength switching candidate.
A dynamic wavelength band allocation program for causing a computer to execute a dynamic wavelength band allocation procedure.

  According to the present invention, in an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, in response to a request from the subscriber device for each predetermined wavelength switching period, In the dynamic wavelength band allocation method for allocating wavelengths to subscriber devices, it is possible to detect or predict congestion of traffic passing through the OSU 12 and switch wavelengths appropriately.

It is a block diagram which shows an example of the wavelength variable type WDM / TDM-PON system relevant to this invention. It is a block diagram which shows an example of the buffer of the demultiplexing part relevant to this invention. The block diagram which shows an example of ONU in the wavelength variable type WDM / TDM-PON system relevant to this invention is shown. The band allocation period and wavelength switching sequence example in Embodiment 1 are shown. 2 shows a bandwidth allocation flowchart (overall) in the first embodiment. The wavelength switching judgment flowchart (DWA calculation) in Embodiment 1 is shown. List of parameters in the dynamic wavelength band allocation flowchart of the present invention 10 shows a bandwidth allocation flowchart (DWA calculation) in the second embodiment. 10 shows a bandwidth allocation flowchart (DWA calculation) in the third embodiment. 10 shows a bandwidth allocation flowchart (DWA calculation) in the fourth embodiment. 10 shows a bandwidth allocation flowchart (DWA calculation) in the fifth embodiment. 10 shows a bandwidth allocation flowchart (DWA calculation) in the sixth embodiment. 10 shows a bandwidth allocation flowchart (DWA calculation) in the seventh embodiment. 10 is a bandwidth allocation flowchart (DWA calculation) in the eighth embodiment. FIG. 18 shows a bandwidth allocation flowchart (corresponding to steps S178 and S179 in FIG. 13) in the ninth embodiment.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
In this embodiment, the DWABA calculation unit 114 shown in FIG. 1 monitors the frame discard in the previous DWA cycle in the DWA calculation in which the wavelength switching is interrupted, and if the frame discard occurs, it is considered that congestion has occurred. The ONU 92 to which the discarded OSU 12 belongs is moved to another OSU 12, that is, wavelength switching is performed.

The operation of this embodiment will be described.
FIG. 4 shows the period of the dynamic wavelength band allocation operation used in the first embodiment of the present invention. In the present embodiment, assuming that the time required for wavelength switching of the ONU 92 or the wavelength tunable optical transceiver 25 is longer than the DBA cycle, the cycle for performing DBA calculation and band allocation is divided from the cycle for performing wavelength allocation calculation. ing. The time of the l-th DWA cycle of dynamic wavelength allocation is T_dwa_l, and the time of the k-th cycle of dynamic bandwidth allocation is T_dba_k. T_dwa_l is set to a plurality of DBA cycle times. In the example of FIG. 4, the 3DBA cycle is a 1DWA cycle.

The ONU 92 belonging to each OSU 12 performs communication using wavelengths λ1 _{d, u to} λmd _{, u} that are fixedly assigned to each OSU 12. In the embodiment of FIG. 4, it is assumed that ONU1, ONU2, and ONUh communicate using λ1d _{, u} of OSU1 in periods T_dwa_l-1 and T_dba_k-1. Each ONU 92 that receives the Gate signals g1_k-1 to gh_k-1 transmitted from the OSU1 first transmits the Report signals rep1_k to reph_k to the OLT 91 according to the transmission time and duration of the Report signal and the upstream signal included in each Gate signal. . Further, uplink signals d1_k-1 to dh_k-1 are transmitted.

  The dynamic wavelength band allocation circuit 11 of the OLT 91 that has received the report signal of the period T_dwa_l and the period T_dba_k has a band allocated to each ONU 92 from the band requested by the report signal during the period described as DBA and DWA calculation in FIG. Calculate the wavelength. The calculation of whether to switch the wavelength is performed based on the DBA calculation described later with reference to FIG. For the ONU 92 calculated not to switch the wavelength, the bandwidth allocation calculation result according to an arbitrary DBA calculation method to be described later with reference to FIG. 5 is described in the Gate signal, and the ONU 92 is instructed. Also, in the DBA cycle that is not the head of the DWA cycle, only the DBA calculation in FIG. 5 described later is performed, and the DWA calculation related to wavelength switching is not performed.

In this embodiment, the wavelength of ONUh is changed from λ1 _{d, u} to λ2 _{d, u as} a result of calculation, and is described as an example of changing to belong to OSU2. In this case, the OLT 91 that has performed the allocation calculation transmits the transmission time and duration of the Report signal and the uplink signal in the T_dba_k cycle in g1_k to gh-1_k of the Gate signal excluding gh_l. Thereafter, for ONU1 to ONUh-1, an uplink signal can be transmitted based on the operation of the DBA described so far.

  FIG. 5 shows an overall flowchart of the dynamic wavelength band allocation algorithm in the present invention. This flowchart is performed at the DBA calculation timing for each DBA cycle. Here, the DBA cycle at the start of the flowchart is set to k.

  First, DBA calculation is performed in each OSU 12 (S101). The DWBA calculation unit 114 closes to the ONUs 92 belonging to each OSU 12, and does not cause interference due to overlapping of signals transmitted from request sources in the reception unit of the OSU 12 according to the band requested by those Report signals. As described above, the upstream band or time slot in the next cycle k + 1 is assigned to the ONU 92 belonging to each OSU 12 in the cycle k, and the transmission start time and transmission duration of the upstream signal of each ONU 92 are calculated. This calculation also allocates a fair bandwidth for each request source in one OSU 12. The above calculation is called DBA calculation.

Next, it is determined whether the DBA cycle k corresponds to the head of the DWA cycle l (S102). If it is the head of the DWA cycle (Yes in S102), the DWA calculation is performed (S103), and the wavelength created as a result A Gate frame for wavelength switching is created based on the list L _sw (k) of the switching ONU 92 (S104). In each element of L _sw (k) for performing wavelength switching, an ONU number for performing wavelength switching and an OSU number as a switching destination are described in pairs. If it is not the head of the DWA cycle (No in S102), the DWA calculation and the step of creating a Gate frame for wavelength switching by DWA are not performed.

Next, a Gate frame is created based on the DBA calculation result (S105). At this time, for the ONU 92 described in the list L _sw (k) for performing wavelength switching, priority is given to creating a Gate frame for wavelength switching, and a Gate frame based on the DBA calculation result is not created. Alternatively, the Gate frame for switching the wavelength and the Gate frame describing the contents designated by the DBA calculation may be unified into one Gate frame. Finally, the created Gate frame is transmitted (S106).

  In this embodiment, assuming that the wavelength switching time is longer than the DBA cycle, the DWA calculation cycle is described as a plurality of DBA cycles. However, when the time required for wavelength switching is sufficiently shorter than one DBA cycle, the DWA calculation can be calculated at the same timing as the DBA calculation. In this case, since it is not necessary to determine whether the DBA cycle k is the head of the DWA cycle 1, the first branch determination (S102) in FIG. 5 can be omitted.

  Details of the DBA calculation of this embodiment other than the following conditions are not specified. In the DBA calculation, an uplink bandwidth of period k + 1 is allocated according to the bandwidth requirement amount of the ONU 92 belonging to one OSU 12 so far. However, when the total amount of bandwidth requests of the ONUs 92 belonging to the OSU 12 exceeds the bandwidth that can be allocated in one DBA cycle, it is assumed that calculation means for ensuring the fairness and priority of bandwidth allocation distribution is provided.

FIG. 6 shows details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of the present invention shown in S103 of FIG. A list of parameters used in the flowchart of the invention is shown in FIG. In each OSUn, a parameter dn _{, u} (l) indicating a result of measuring whether or not the upstream traffic of the OSUn (n = 1 to m) of the period 1 is discarded, and the upstream surplus bandwidth Q _n of each OSUn in the period k _{, U} (k) are constantly measured. The measurement method of d _{n, u} (l) is not particularly specified. For example, the occurrence of discard in the upstream buffer of the ONU 92 may be notified to the OLT 91 and detected by the notification.

In the procedure of S107 in FIG. 6, those parameters of the period l-1 and the period k-1 are acquired, and the maximum value Q _{ave_numax, u} between the average value Q _{ave_n, u} (k−1) of the surplus band and the OSU 12 is _acquired. (K-1) (however, the OSU number having the maximum value is set to nu _max ) is calculated.
Next, it is determined for each OSU 12 whether uplink traffic is discarded in the previous DWA cycle 1-1. The procedure for confirming each OSU 12 is shown in S108, S111, and S112.
In step S109, dn _{, u} (l-1) becomes 1, that is, the OSU 12 in which the upstream traffic is discarded in the period l-1 is determined, and in step S110, the wavelength switching for moving the traffic by the wavelength switching is performed. Candidate ONUs 92 are selected from the ONUs 92 belonging to OSUn. The selection of the ONU 92 may be any ONU 92 belonging to OSUn, and is not specified. The ONU 92 that has been discarded may be targeted, or the ONU 92 that maximizes the fairness of the load between the OSUs 12 may be used. However, the switching destination OSU 12 is set to OSUnu _max having the maximum surplus bandwidth.
The list L _sw (k) is a list having a pair of the wavelength switching ONU number and the switching destination OSU number in the DBA cycle k, and the ONU 92 determined to generate the wavelength switching in step S110 is added to this L _sw (k). Is done.
When the presence or absence of wavelength switching is determined for all the OSU1 to OSUm in step S112, the DWA calculation ends.

In this embodiment, it shows about the up, and u is used for the subscript. However, by replacing all the subscripts with d, the present embodiment can be similarly applied to the downlink. The measurement method of d _{n, d} (l-1) is not particularly specified, but for example, it may be monitored whether the ONU buffer 132 is discarded in the demultiplexing unit 13 of FIG.

  It is also possible to operate both the upstream and downstream DWA flowcharts of this embodiment independently for upstream and downstream. In this case, an uplink signal wavelength and a downlink signal wavelength of the switching destination are specified for the Gate signal for switching the wavelength. As a result, the upstream destination OSU 12 and the OSU 12 that transmits the downstream signal may be different for a certain ONU 92.

  In the example related to downlink, discard due to congestion occurs in the ONU buffer 132 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU buffer 132. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to the present embodiment, the following effects can be expected.
In the present embodiment, wavelength switching is performed when traffic is discarded due to congestion occurring in the DWA cycle 1-1. If traffic congestion continues, discard due to buffer overflow or the like occurs. When the discard is detected, the wavelength is switched, and the ONU 92 belonging to the OSU 12 in which the congestion has occurred moves to the OSU 12 having the smallest load, so that it is possible to distribute the traffic load.

  Further, in this embodiment, until the discard in the DWA cycle l-1 is detected and the wavelength switching is performed in the DWA cycle l, the dynamic bandwidth allocation by the DBA is performed for the upstream embodiment, and the multiplexing is performed for the downstream embodiment. Downlink traffic priority and fair control are performed by SEL control in the separation unit 13. Therefore, at least 2DWA cycles are required until the wavelength state is switched by DWA and the congestion state is resolved. However, while the congestion state continues, the downlink priority and fair control of the OSA 12 DBA and the demultiplexing unit 13 are performed. Done. In the present embodiment, it is unavoidable that signal discard due to congestion occurs. However, according to fair control and priority control within the upper limit of the upstream or downstream bandwidth of the OSU 12, priority and fairness of limited bandwidth are Can be maintained.

(Embodiment 2)
In this embodiment, in the DWA calculation that breaks the wavelength switching, the traffic statistics information of the OSU 12 before the previous DWA cycle, that is, the average value and the dispersion value are used to predict the frame discard due to congestion, and the frame discard is predicted. The ONU 92 to which the OSU 12 belongs is moved to another OSU 12, that is, wavelength switching is performed.

  The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG.

FIG. 8 shows the details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of this embodiment shown in S103 of FIG. In each OSUn, the upstream signal bands Q _{n, u} (k) and _{An, u} (k) and the upstream surplus band Q _{n, u} (k) of each OSUn in the period k are constantly measured.

ただし、Ｃ_ｎ，ｕはＯＳＵｎに割当て可能な上り最大信号帯域、α_ｕはＯＳＵｎの平均帯域の変動の大きさのリスクを表す定係数である。 In step S113 of FIG. 8, those parameters in the period k−1 are acquired, the average value A _ave — _{n, u} (k−1) of the signal band, the standard deviation σ _{An, u} (k−1), and the average of the surplus band The maximum value Q _{ave_numax, u} (k−1) between the value Q _ave — _{n, u} (k−1) and the OSU (where the OSU number that takes the maximum value is set to nu _max ) is calculated. Next, for each OSU, the following formula in the previous DBA cycle k−1 is evaluated.

Here, C _{n, u} is a maximum uplink signal band that can be assigned to OSUn, and α _u is a constant coefficient that represents a risk of the magnitude of fluctuation of the average band of OSUn.

If the expression (1) is true in step S115, it is determined that there is a possibility that discard due to exceeding the maximum signal band in the upstream traffic of OSUn may occur, and in step S116, the ONU 92 that moves the traffic by wavelength switching Is selected from ONU 92 belonging to OSUn. The ONU 92 may be selected as long as it is an ONU belonging to OSUn, and is not specified. The ONU 92 that generates the maximum traffic may be targeted, or the ONU 92 that maximizes the fairness of the load between the OSUs 12 may be used. However, the switching destination OSU 12 is set to OSUnu _max having the maximum surplus bandwidth. The list L _sw (k) is a list having a pair of the wavelength switching ONU number and the switching destination OSU number in the DBA cycle k, and the ONU 92 determined to generate the wavelength switching in step S116 is added to this L _sw (k). Is done. If it is determined in step S118 that all the OSU1 to OSUm have wavelength switching, the DWA calculation ends.

ただし、０＜α_ｕ＜１である。 Another formula (2) can also be introduced as a judgment formula of formula (1).

However, 0 <α _u <1.

  In this embodiment, it shows about the up, and u is used for the subscript. However, by replacing all the subscripts with d, the present embodiment can be similarly applied to the downlink. It is also possible to operate both the upstream and downstream DWA flowcharts of this embodiment independently for upstream and downstream. In this case, an uplink signal wavelength and a downlink signal wavelength of the switching destination are specified for the Gate signal for switching the wavelength. As a result, the upstream destination OSU 12 and the OSU 12 that transmits the downstream signal may be different for a certain ONU 92.

According to the present embodiment, the following effects can be expected.
In the present embodiment, wavelength switching is performed by predicting the occurrence of congestion in the DWA cycle 1-1. Before discarding due to buffer overflow or the like, the OSU 12 having a high possibility of congestion is selected and wavelength switching is performed. The prediction of the occurrence of congestion may be the case of equation (1) using the average value and standard deviation of the traffic of the OSU 12, or the equation (2) using only the average value. Since the flow rate of traffic changes from moment to moment, it is possible to improve the prediction accuracy considering the fluctuation risk by the average value and standard deviation which are statistics. On the other hand, when it is difficult to carry out the calculation up to the standard deviation, the formula (2) can be applied. This indicates that the wavelength switching execution determination is performed when the average traffic value of the OSU 12 exceeds a certain percentage of the maximum bandwidth of the OSU 12, and can be determined relatively easily.
Furthermore, in this embodiment, since the ONU 92 belonging to the OSU 12 where congestion may occur is moved to the OSU 12 with the smallest load, it is possible to distribute traffic efficiently.

(Embodiment 3)
Embodiment 3 of the present invention uses Embodiment 1 and Embodiment 2 in combination. By combining Embodiment 1 and Embodiment 2, congestion can be detected more reliably.

The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG.
The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

FIG. 9 shows details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of this embodiment shown in S103 of FIG. Parameters dn _{, u} (l) Upstream signal bandwidth of each OSUn indicating the result of measuring whether or not the upstream traffic of the OSUn (n = 1 to m) of the period 1 (el) is discarded in each OSUn dn _{, u} (l) The uplink surplus band dn _{, u} (l) is constantly measured.

In step S119 of FIG. 9, those parameters for the period _1-1 and the period k-1 are acquired, and the average value A _ave — _{n, u} (k−1) of the signal band and the standard deviation σ _{An, u} (k−1). , and calculates the surplus bandwidth of the average value _{Q ave_n, u (k-1} ) and the maximum value _{Q Ave_numax} between OSU12, u (k-1) ( where a _{nu max} the OSU number having the maximum value).
Next, in step S121, it is determined whether or not uplink traffic is discarded in the OSUn of the previous DWA cycle 1-1. When the discard has occurred (Yes in S121), the process proceeds to step S123 for selecting the switching ONU 92 and the switching destination OSU 12 as in the first and second embodiments.
When the discard has not occurred (No in S121), the formula (1) of the second embodiment is evaluated as the procedure S122. If the expression (1) is true in step S122, it is determined that there is a possibility that discard due to exceeding the maximum signal band in the upstream traffic of OSUn may occur, and the switching ONU, It progresses to procedure S123 which selects switching destination OSU.
The selection of the ONU 92 in step S123 is not particularly specified as long as it is the ONU 92 belonging to OSUn as in the first and second embodiments. The ONU generating the maximum traffic may be the target, or the ONU 92 that maximizes the fairness of the load between the OSUs 12 may be used. However, the OSU to be switched to is OSUnu _max having the maximum surplus bandwidth. The list L _sw (k) is a list having a pair of the wavelength switching ONU number and the switching destination OSU number in the DBA cycle k, and the ONU 92 determined to generate wavelength switching in step S123 is added to this L _sw (k). Is done.
If it is determined in step S125 whether or not wavelength switching has been performed for all of the OSU1 to OSUm, the DWA calculation is terminated.
Further, the expression (2) can also be introduced as the determination expression of the procedure S122 as in the second embodiment.

In this embodiment, it shows about the up, and u is used for the subscript. However, by replacing all the subscripts with d, the present embodiment can be similarly applied to the downlink. The measurement method of d _{n, d} (l−1) is not particularly specified, but for example, it may be monitored whether the ONU buffer 133 is discarded in the demultiplexing unit 13 of FIG.

  It is also possible to operate both the upstream and downstream DWA flowcharts of this embodiment independently for upstream and downstream. In this case, an uplink signal wavelength and a downlink signal wavelength of the switching destination are specified for the Gate signal for switching the wavelength. As a result, the upstream destination OSU 12 and the OSU 12 that transmits the downstream signal may be different for a certain ONU 92.

  In the example related to downlink, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, in addition to the first and second embodiments, the following effects can be further expected.
In the second embodiment, the average value and the standard deviation value of OSU traffic are used to predict the occurrence of congestion. On the other hand, the average value and the standard deviation value are calculated using measured values of a plurality of cycles ( _Nq cycle described in FIG. 7). Depending on the value of N _q , it is difficult to predict congestion using Equations (1) and (2) for sudden traffic changes that occur within the calculation interval. In other words, when traffic suddenly increases within the calculation interval, congestion may occur without satisfying the determination formulas (1) and (2). Therefore, by combining with the method used in the first embodiment, the present embodiment normally calculates the calculation interval N that is unpredictable while predicting congestion in the equation (1) or (2) and performing load distribution. It is possible to detect the congestion caused by a sudden increase in traffic shorter than _q and perform load distribution, and to realize load distribution that avoids congestion more reliably.

(Embodiment 4)
In the fourth embodiment of the present invention, in addition to the first embodiment, the switching determination is made after confirming whether the switching destination OSU 12 has a free band equal to or higher than the average band of the switching ONU 92.
The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG. The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

FIG. 10 shows details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of this embodiment shown in S103 of FIG. In the present embodiment, the same parameters as in the first embodiment are constantly measured, and the upstream traffic volume S _u (j, k) of ONUj (j = 1 to h) is measured every period k.

In step S126 of FIG. 10, first, in addition to the parameter calculation of step S107 of FIG. 6 of the first embodiment, the average value S _{ave — u} (j, k) of the upstream traffic amount of ONUj (j = 1 to h) is calculated. The procedure for determining whether or not the upstream traffic is discarded for each ONU in the period 1-1 is the same as that in the first embodiment. The difference from the first embodiment is steps S129 to S134 in FIG.

  In step S129, the ONU 92 whose wavelength is switched is selected from the OSUn determined that the upstream signal discarding has occurred in the period 1-1. One of them is called ONUj. The method for selecting the ONU 92 is the same as the procedure S110 of the first embodiment.

Next, when the average bandwidth S _{ave_u} (j, k) of the selected ONUj is smaller than the surplus bandwidth Q _{ave_numax, u} (k−1) of the OSUnu _max that is the switching destination OSU 12 in step S130 (Yes in S130). Since it is determined that the bandwidth after switching of ONUj is sufficient for OSUnu _max , ONUj is added to the switching list L _sw (k) as in step S110 of the first embodiment (S131). When wavelength switching occurs, Q _{ave_numax, u} (k−1) is reduced by the average bandwidth of _{ONUj. Therefore,} S _{ave_u} (j, k) is subtracted from Q _{ave_numax, u} (k−1) in step S132. . Since Q _{ave_numax, u} (k−1) changes, nu _max is updated in step S133.
If it is not determined in step S130 that the bandwidth after ONUj switching is sufficient for OSUnu _max (No in S130), ONUj switching is not performed.

Next, in step S134, it is determined whether there is a surplus bandwidth for all ONUs 92 selected in step S129, that is, whether step S130 has been performed. If all have been performed, the process proceeds to step S135, and there is an ONU 92 that has not yet been performed. For example, the process returns to step S130 for the ONU 92 and the subsequent steps are repeated.
When the above procedure is performed for OSU1 to OSUm, the DWA calculation is completed.

In this embodiment, it shows about the up, and u is used for the subscript. However, by replacing all the subscripts with d, the present embodiment can be similarly applied to the downlink. The measurement method of _{dn, d} (l-1) is not particularly specified, but for example, it may be monitored whether the ONU buffer 133 is discarded in the demultiplexing unit 131 of FIG.

  It is also possible to operate both the upstream and downstream DWA flowcharts of this embodiment independently for upstream and downstream. In this case, an uplink signal wavelength and a downlink signal wavelength of the switching destination are specified for the Gate signal for switching the wavelength. As a result, the upstream destination OSU 12 and the OSU 12 that transmits the downstream signal may be different for a certain ONU 92.

  In the example related to downlink, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, the following effects can be expected in addition to the first embodiment.
In the first embodiment, it is not determined whether or not the switching destination OSUnu _max has a surplus bandwidth sufficient for the switching ONUj to newly use the bandwidth by wavelength switching. Therefore, by switching the wavelength of ONUj, the congestion of OSUn is resolved, but conversely, there is a possibility that new congestion occurs in OSUnu _max . In the present embodiment, whether or not a new congestion occurs in the switching destination OSU 12 after switching is confirmed in step S130, and wavelength switching is performed by confirming that no congestion occurs immediately in the switching destination OSU 12. Thus, it is possible to suppress the occurrence of new congestion due to wavelength switching.

  In addition, even if congestion occurs, wavelength switching is not performed, that is, there is a possibility that congestion will continue in OSUn determined as No in step S130. However, for the upstream embodiment, dynamic bandwidth allocation by DBA is performed, and for the downstream embodiment, downlink traffic priority and fair control are performed by the SEL control in the demultiplexing unit 13, so that the upstream or downstream bandwidth of the OSU is controlled. In accordance with fair control and priority control within the upper limit, priority and fairness of limited bandwidth can be maintained.

(Embodiment 5)
In the fifth embodiment of the present invention, the procedure for making a switching determination after confirming whether or not the switching destination OSU 12 has a free bandwidth equal to or higher than the average bandwidth of the switching ONU 92 is added to the second embodiment. It is a thing.

The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG.
The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

FIG. 11 shows the details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of this embodiment shown in S103 of FIG. In this embodiment, step S128 of FIG. 10 in the fourth embodiment is modified so that the formula (1) or the formula (2) in the second embodiment can be applied. Therefore, the parameters to be constantly measured are the same parameters as in the second embodiment, and the upstream traffic volume S _u (j, k) of ONUj (j = 1 to h) is measured every period k. In addition to the parameters similar to those in step S113 in FIG. 7 of the second embodiment, the parameters calculated in step S137 are calculated as the average value S _{ave — u} (j, k) of the upstream traffic volume of ONUj (j = 1 to h). To do. Other procedures are the same as those in the fourth embodiment.

In this embodiment, it shows about the up, and u is used for the subscript. However, by replacing all the subscripts with d, the present embodiment can be similarly applied to the downlink. The measurement method of d _{n, d} (l−1) is not particularly specified, but for example, it may be monitored whether the ONU buffer 133 is discarded in the demultiplexing unit 13 of FIG.

  It is also possible to operate both the upstream and downstream DWA flowcharts of this embodiment independently for upstream and downstream. In this case, an uplink signal wavelength and a downlink signal wavelength of the switching destination are specified for the Gate signal for switching the wavelength. As a result, the upstream destination OSU 12 and the OSU 12 that transmits the downstream signal may be different for a certain ONU 92.

  In the embodiment relating to downlink, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, the following effects can be expected in addition to the second embodiment.
In the second embodiment, it is not determined whether the switching ONUj has a surplus band that can newly use a band by wavelength switching in the switching destination OSUnu _max . Therefore, by switching the wavelength of ONUj, the congestion of OSUn is resolved, but conversely, there is a possibility that new congestion occurs in OSUnu _max . In this embodiment, whether or not a new congestion occurs in the switching destination OSU 12 after switching is confirmed in step S141, and wavelength switching is performed after confirming that no congestion occurs immediately in the switching destination OSU 12. Thus, it is possible to suppress the occurrence of new congestion due to wavelength switching.

  Also, even if congestion occurs, wavelength switching is not performed, that is, congestion may continue in OSUn determined as No in step S141. However, for the upstream embodiment, dynamic bandwidth allocation by DBA is performed, and for the downstream embodiment, downlink traffic priority and fair control are performed by the SEL control in the demultiplexing unit 13, so that the upstream or downstream bandwidth of the OSU 12 is controlled. In accordance with fair control and priority control within the upper limit, priority and fairness of limited bandwidth can be maintained.

(Embodiment 6)
The sixth embodiment of the present invention implements the procedure for making a switching determination after confirming whether the switching destination OSU 12 has a free band equal to or higher than the average band of the switching ONU 92, in addition to the fourth and fifth embodiments. This is in addition to Form 3.

  The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG. The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

FIG. 12 shows the details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of this embodiment shown in S103 of FIG. In the present embodiment, steps S121 and S122 in the third embodiment are applied to the step S128 in FIG. 10 in the fourth embodiment. Therefore, the parameters to be constantly measured are the same parameters as in the third embodiment, and the upstream traffic volume S _u (j, k) of ONUj (j = 1 to h) is measured every period k. In addition to the same parameters as those in step S119 in FIG. 7 of the third embodiment, the parameters calculated in step S148 are the average values S _{ave — u} (j, k) of the ONUj (j = 1 to h) uplink traffic volume. To do. Other procedures are the same as those in the fourth and fifth embodiments.

In this embodiment, it shows about the up, and u is used for the subscript. However, by replacing all the subscripts with d, the present embodiment can be similarly applied to the downlink. The measurement method of d _{n, d} (l−1) is not particularly specified, but for example, it may be monitored whether the ONU buffer 133 is discarded in the demultiplexing unit 13 of FIG.

  It is also possible to operate both the upstream and downstream DWA flowcharts of this embodiment independently for upstream and downstream. In this case, an uplink signal wavelength and a downlink signal wavelength of the switching destination are specified for the Gate signal for switching the wavelength. As a result, the upstream destination OSU 12 and the OSU 12 that transmits the downstream signal may be different for a certain ONU 92.

  In the example related to downlink, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, the following effects can be expected in addition to the third embodiment.
In the third embodiment, it is not determined whether or not there is a surplus bandwidth that the switching ONUj uses a new bandwidth by wavelength switching in the switching destination OSUnu _max . Therefore, by switching the wavelength of ONUj, the congestion of OSUn is resolved, but conversely, there is a possibility that new congestion occurs in OSUnu _max . In this embodiment, it is confirmed in step S153 whether or not new congestion occurs in the switching destination OSU 12 after switching, and wavelength switching is performed by confirming that congestion does not occur immediately in the switching destination OSU 12. Thus, it is possible to suppress the occurrence of new congestion due to wavelength switching.

  In addition, even if congestion occurs, wavelength switching is not performed, that is, congestion may continue in OSUn determined as No in step S153. However, for the upstream embodiment, dynamic bandwidth allocation by DBA is performed, and for the downstream embodiment, downlink traffic priority and fair control are performed by the SEL control in the demultiplexing unit 13, so that the upstream or downstream bandwidth of the OSU 12 is controlled. In accordance with fair control and priority control within the upper limit, priority and fairness of limited bandwidth can be maintained.

(Embodiment 7)
In the seventh embodiment of the present invention, in the fourth embodiment, both upstream and downstream congestion is detected, and after checking the surplus bandwidth after wavelength switching, wavelength switching determination is performed.

The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG. The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

  FIG. 13 shows details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of this embodiment shown in S103 of FIG. In this embodiment, both uplink and downlink parameters are used. Therefore, the parameters to be measured always measure both the subscripts u and d of the parameters in the fourth embodiment. Further, parameters used for the algorithm are calculated in step S160. The parameters are parameters obtained by changing the subscript of the parameter in step S126 to d in addition to the parameter in step S126 in the fourth embodiment.

  Next, it is determined whether congestion has occurred for each OSU. Procedures S161, S174, and S175 are procedures for repeating OSU1 to OSUm for that purpose. Next, in steps S162 and S163, it is determined whether or not traffic is discarded on either the upstream or downstream side of OSUn. When discarding occurs on either the upstream side or the downstream side, the ONU 92 to be switched is selected in step S164 as in the fourth embodiment.

For ONUj which was selected as a target of switching, in step S165, uplink surplus bandwidth _{Q Ave_numax} of _{OSUnu max, u (k-1} ) uplink average band _{S ave_u (j, k-1} ) of ONUj than large and _{OSUnu max} When the surplus bandwidth Q _{ave_numax, d} (k−1) of the downstream is larger than the average downstream bandwidth S _{ave_d} (j, k−1) of the ONUj, that is, a margin for using the average bandwidth of the ONUj for both upstream and downstream of the OSUnu _max If there is (Yes in S165), ONUj is added to the list L _sw (k) as the switching destination OSUnu _{max in} step S167. Further, similarly to the procedures S132 and S133 of the fourth embodiment and FIG. 10, Q _{ave_numax, u} (k−1) and Q _{ave_numax are transferred} to the surplus bandwidth of the OSUnu _max after the ONUj switching in the procedure S168 of FIG. _{, D} (k−1) is updated, and nu _max is updated in step S169.

Even when there is no OSUnu _max surplus band in step S165 (No in S165), there is a possibility that there is an OSUnmax _max band. If it is judged No in Step S165, the following steps S166 is, _{OSUnd max} downlink of surplus bandwidth _{Q ave_ndmax,} from d (k-1) is ONUj downlink average bandwidth _{S ave_d (j, k-1} ) large and _{OSUnd max} upstream of surplus bandwidth _{Q ave_ndmax, u (k-1} ) uplink average band _{S ave_u (j, k-1} ) is greater than the ONUj, i.e. the average bandwidth of ONUj also up even downlink _{OSUnd max} Determine whether you can afford to use. If step S166 is Yes, ONUj is added to the list L _sw (k) as the switching destination OSUnd _max in step S170. Further, similarly to the procedures S132 and S133 of the fourth embodiment and FIG. 10, Q _{ave_ndmax, u} (k−1) and Q _{ave_ndmax} are transferred to the uplink / downstream surplus bandwidth of the OSUud _max after the ONUj is switched in the procedure S171 of FIG. _{, D} (k−1) is updated, and nd _max is updated in step S172. If No in step S166, it is assumed that there is no surplus bandwidth in other OSUs 12, and wavelength switching is not performed.

  In step S173, as in step S134 of the fourth embodiment and FIG. 10, it is determined whether there is a surplus bandwidth for all the ONUs 92 selected in step S164, that is, whether step S165 has been performed, and if all have been performed, the process proceeds to step S174. If there is an ONU 92 that has not yet been implemented, the process returns to step S165 for that ONU 92 and the subsequent steps are repeated. When the above procedure is performed for OSU1 to OSUm, the DWA calculation is completed.

  In the embodiment related to downlink, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit of FIG. This is because the downstream signal rate for the OSU coming from the relay network is larger than the rate at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, the following effects can be expected in addition to the fourth embodiment.
In the embodiment 4, the determination of switching ONUj, and determine whether there is a surplus bandwidth of the downlink of the uplink or the switching destination _{OSUnd max} of switching destination _{OSUnu max} in step S130. At this time, even if the wavelength switching is performed based on the determination based on the upstream traffic, the excessive traffic in the downstream of the switching destination OSUnu _max is small, and congestion may be caused by the downstream traffic of the ONUj. Alternatively, even if wavelength switching is performed based on the downlink traffic, the excess traffic of the uplink of the switching destination OSUnd _max is small, and congestion may be caused by the ONUj uplink traffic. However, in this embodiment, since the switching destination OSUnu _max or the switching destination OSUnd _max is confirmed to have a surplus bandwidth that can be used on both upstream and downstream of the switching ONUj, the wavelength switching is performed. The wavelength of the ONU 92 can be switched without causing congestion in the OSU 12.

  Further, even if congestion occurs, wavelength switching is not performed, that is, congestion may continue in OSUn determined as No in step S165 or S166. However, for the upstream embodiment, dynamic bandwidth allocation by DBA is performed, and for the downstream embodiment, downlink traffic priority and fair control are performed by the SEL control in the demultiplexing unit 13, so that the upstream or downstream bandwidth of the OSU 12 is controlled. In accordance with fair control and priority control within the upper limit, priority and fairness of limited bandwidth can be maintained.

(Embodiment 8)
In the eighth embodiment of the present invention, in the same way as the seventh embodiment, both upstream and downstream congestion in the fifth embodiment is detected, and after checking the surplus bandwidth after wavelength switching, wavelength switching determination is performed. .

The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG.
The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

  FIG. 14 shows the details of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of the present embodiment shown in S103 of FIG. In this embodiment, both uplink and downlink parameters are used. Therefore, the parameters to be measured always measure both the subscripts u and d of the parameters in the fifth embodiment. Further, parameters used for the algorithm are calculated in step S176, and the parameters are parameters obtained by changing the subscript of the parameter in step S137 to d in addition to the parameter in step S137 in the fifth embodiment.

  Next, it is determined whether each OSU 12 is congested. Procedures S177, S190, and S191 are procedures for repeating OSU1 to OSUm for that purpose. Next, in steps S178 and S179, it is determined whether traffic discard is predicted on either the upstream or downstream of OSUn. The determination formula is the same as the formula (1) in the second embodiment with respect to step S178. Step S179 is an expression obtained by changing the suffix u of the expression (1) in the second embodiment to d. When the answer is Yes in either step S178 or S179, the ONU 92 to be switched is selected in step S180 as in the fifth embodiment.

Thereafter, steps S180 to S189 are the same as steps S164 to S173 of the seventh embodiment. If both of the determination formulas in steps S178 and S179 are No, the process proceeds to step S190 without performing wavelength switching.
Also, the expression (2) can be applied as in the second embodiment as the determination expression in step S178. Further, as in the second embodiment, an equation in which the subscript u in equation (2) is replaced with d can be applied as the determination equation in step S179.

  In the embodiment relating to downlink, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, the following effects can be expected in addition to the fifth embodiment.
In the embodiment 5, the determination of switching ONUj, and determine whether there is a surplus bandwidth of the downlink of the uplink or the switching destination _{OSUnd max} of switching destination _{OSUnu max} in step S141. At this time, even if the wavelength switching is performed based on the determination based on the upstream traffic, the excessive traffic in the downstream of the switching destination OSUnu _max is small, and congestion may be caused by the downstream traffic of the ONUj. Alternatively, even if wavelength switching is performed based on the downlink traffic, the excess traffic of the uplink of the switching destination OSUnd _max is small, and congestion may be caused by the ONUj uplink traffic. However, in this embodiment, since the switching destination OSUnu _max or the switching destination OSUnd _max is confirmed to have a surplus bandwidth that can be used on both upstream and downstream of the switching ONUj, the wavelength switching is performed. The wavelength of the ONU 92 can be switched without causing congestion in the OSU 12.

  In addition, even if congestion occurs, wavelength switching is not performed, that is, congestion may continue in OSUn determined as No in steps S178 or S179. However, for the upstream embodiment, dynamic bandwidth allocation by DBA is performed, and for the downstream embodiment, downlink traffic priority and fair control are performed by the SEL control in the demultiplexing unit 13, so that the upstream or downstream bandwidth of the OSU is controlled. In accordance with fair control and priority control within the upper limit, priority and fairness of limited bandwidth can be maintained.

(Embodiment 9)
In the ninth embodiment of the present invention, as in the eighth embodiment, both upstream and downstream congestion in the sixth embodiment is detected, and after checking the surplus bandwidth after wavelength switching, wavelength switching determination is performed. .

  The dynamic wavelength band allocation operation sequence, the cycle, the overall flowchart of the dynamic wavelength band allocation algorithm, and the DBA calculation in this embodiment are the same as those in FIGS. 4, 5, and 6 of the first embodiment. A list of parameters used in the flowchart of the embodiment is also shown in FIG. The DBA calculation conditions of this embodiment are the same as those of the first embodiment.

  The flowchart of the DWA calculation in this embodiment is the same except for steps S176, S178, and S179 in FIG. In the present embodiment, the parameters that are constantly measured are both the parameters that are measured in the seventh embodiment and the parameters that are measured in the eighth embodiment. Further, the parameters calculated in the procedure corresponding to the procedure S176 of FIG. 14 in the eighth embodiment are both the parameters calculated in the procedure S160 of the seventh embodiment and the parameters calculated in the procedure S176 of the eighth embodiment.

  FIG. 15 shows a portion corresponding to steps S178 and S179 in FIG. 14 of the DWA calculation in the allocation flowchart of the dynamic wavelength band allocation algorithm of the present embodiment. Steps S192 and S193 in FIG. 15 correspond to steps S162 and S163 in FIG. 13 of the seventh embodiment, and steps S194 and S195 in FIG. 15 correspond to steps S178 and S179 in FIG. Therefore, in the present embodiment, it is determined whether traffic discard occurs in either the OSUn uplink or downlink, or whether traffic discard is predicted in the OSUn uplink or downlink. As in the eighth embodiment, the discard prediction formula is a formula in which the subscript u in the formula (1) in the second embodiment and the formula (1) in the second embodiment is changed to d.

  Further, in the present embodiment, the formula (2) can be applied as the determination formula in step S194 as in the second embodiment. Further, as in the case of the second embodiment, an equation in which the subscript u in equation (2) is replaced with d can be applied as the determination equation in step S195.

  In the downlink of this embodiment, discard due to congestion occurs in the ONU buffer 133 in the demultiplexing unit 13 of FIG. This is because the downstream signal speed for the OSU 12 coming from the relay network is larger than the speed at which the selector 131 for each OSU 12 reads the signal from the ONU-specific buffer 133. From the occurrence of congestion until the load distribution by DWA calculation and wavelength switching is completed, the SEL control unit 136 or the selector 131 performs inter-user priority control or fair control of the congested traffic.

According to this embodiment, the following effects can be expected in addition to the eighth embodiment.
In the eighth embodiment, the average value and the standard deviation value of the OSU traffic are used for predicting the occurrence of congestion. On the other hand, the average value and the standard deviation value are calculated using measured values of a plurality of cycles ( _Nq cycle described in FIG. 7). Depending on the value of N _q , it is difficult to predict congestion in steps S178 and S179 with respect to sudden upstream and downstream traffic changes that occur within the calculation interval. That is, when the uplink or downlink traffic suddenly increases within the calculation interval, congestion may occur without satisfying the determination formulas of steps S178 and S179. Therefore, by combining with the method used in the seventh embodiment, the present embodiment normally calculates the calculation interval N that is unpredictable while performing load distribution by predicting uplink and downlink congestion in step S194 or step S195. Upstream or downstream congestion caused by a sudden increase in traffic shorter than _q can be detected in steps S192 and S193 to perform load distribution, and load distribution that avoids congestion more reliably can be realized.

  In addition, even if congestion occurs, wavelength switching is not performed, that is, congestion may continue in OSUn determined as No in step S153. However, for the upstream embodiment, dynamic bandwidth allocation by DBA is performed, and for the downstream embodiment, downlink traffic priority and fair control are performed by the SEL control in the demultiplexing unit 13, so that the upstream or downstream bandwidth of the OSU 12 is controlled. In accordance with fair control and priority control within the upper limit, priority and fairness of limited bandwidth can be maintained.

(Embodiment 10)
In the tenth embodiment of the present invention, the parameter used for the DWA calculation in the first to ninth embodiments uses the k-1 DBA cycle information, but uses the kp (p is 2 or more) DBA cycle information. The calculations in steps S17, S113, S119, S126, S137, S148, S160, and S176 in the first to ninth embodiments are started before the pDBA cycle.

  In addition to the first to ninth embodiments, the present embodiment is expected to have the following effects. In general, the shorter the DBA cycle is, the more advantageous is that bandwidth control with high delay and accuracy is possible. According to the present embodiment, the parameter calculation can be started immediately after the DBA calculation before the pDBA cycle in the measurement parameters, averages, and standard deviation parameters used in the first to ninth embodiments. Therefore, it is possible to reduce the load of the DBA calculation according to the first to ninth embodiments, to finish the DBA and DWA calculations at an early stage, and to realize shortening of the DBA cycle.

  The dynamic wavelength band allocation circuit 11 and the OLT 91 according to this embodiment may be realized by causing a computer to execute the dynamic wavelength band allocation program according to the present invention.

  The dynamic wavelength band allocation method, circuit, program, and recording medium recording the same according to the present invention enable automatic avoidance of congestion due to uplink and downlink band allocation in a wavelength tunable WDM / TDM-PON. It is possible to provide a dynamic wavelength band allocation method that enables effective allocation of the total wavelength band to each ONU.

11: Dynamic wavelength band allocation circuit 12: OSU
13: Demultiplexing unit 21: Data receiving unit 22: Up buffer memory 23: Frame transmission control unit 24: Frame assembly transmission unit 25: Wavelength variable optical transmitter / receiver 26: Frame transmission and wavelength control signal reception unit 27: Wavelength switching control unit 28: Destination analysis selection reception unit 29: Downstream buffer memory 30: Data transmission unit 31: Request band signal generation unit 32: Request band calculation unit 91: OLT
92: ONU
111: switching instruction signal generation unit 112: control signal transmission unit 113: request signal reception unit 114: DWBA calculation unit 131: selector 132: buffer 133: ONU buffer 134: multiplexing unit 135: separation unit 136: SEL control unit

Claims (11)

An optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology,
The station side device includes a dynamic wavelength band allocation circuit that allocates a wavelength to the subscriber device in response to a request from the subscriber device for each predetermined wavelength switching period,
The dynamic wavelength band allocation circuit includes:
When signal loss due to congestion occurs at any wavelength used for upstream or downstream signals, one of the subscriber devices using the wavelength can be selected as a wavelength switching candidate and can be used for the wavelength switching candidate. Assign a wavelength that is different from the congested wavelength,
Optical subscriber system. An optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology,
The station side device includes a dynamic wavelength band allocation circuit that allocates a wavelength to the subscriber device in response to a request from the subscriber device for each predetermined wavelength switching period,
The dynamic wavelength band allocation circuit includes:
A value obtained by multiplying the average value of the upstream signal band of one wavelength by a constant multiplied by the standard deviation of the upstream signal band of the wavelength, or the average value of the downstream signal band of one wavelength and the downstream signal band of the wavelength When the value obtained by multiplying the standard deviation by a constant exceeds the maximum signal bandwidth of the wavelength, select one of the subscriber devices that use the wavelength as the wavelength switching candidate and use it for the wavelength switching candidate. Assign a different wavelength than the congested wavelength among the possible wavelengths,
Optical subscriber system. An optical subscriber system in which a plurality of subscriber devices and a single station side device are connected in a PON topology,
The station side device includes a dynamic wavelength band allocation circuit that allocates a wavelength to the subscriber device in response to a request from the subscriber device for each predetermined wavelength switching period,
The dynamic wavelength band allocation circuit includes:
Either one of the wavelengths used for the upstream signal is discarded due to congestion, or the value obtained by multiplying the average value of the upstream signal band of one wavelength by the standard deviation of the upstream signal band of the wavelength and the constant is added. At least one of exceeding the maximum signal bandwidth of the wavelength, or
Either one of the wavelengths used for the downlink signal is discarded due to congestion, or a value obtained by multiplying the average value of the downlink signal band of one wavelength by the standard deviation of the downlink signal band of the wavelength and a constant is added. If at least one of the maximum signal bandwidth of the wavelength has been exceeded,
Select one of the subscriber devices using the wavelength as a wavelength switching candidate, and assign a wavelength different from the congested wavelength among the usable wavelengths to the wavelength switching candidate.
Optical subscriber system. The dynamic wavelength band allocation circuit includes:
When the wavelength that has the maximum uplink average surplus bandwidth among the assignable wavelengths is selected and the uplink average surplus bandwidth of the wavelength is larger than the uplink average use bandwidth of the wavelength switching candidate, the wavelength is designated as the uplink signal. Assign to the requested wavelength switching candidate,
When the wavelength that has the maximum downlink average surplus bandwidth among the assignable wavelengths is selected and the downlink average surplus bandwidth of the wavelength is larger than the downlink average use bandwidth of the wavelength switching candidate, the wavelength is designated as the downlink signal. Assigning to the requested wavelength switching candidate,
The optical subscriber system according to any one of claims 1 to 3. The dynamic wavelength band allocation circuit includes:
The wavelength having the maximum uplink average surplus bandwidth among the assignable wavelengths is selected, the uplink average surplus bandwidth of the wavelength is larger than the uplink average use bandwidth of the wavelength switching candidate, and the downlink average surplus bandwidth of the wavelength is If the wavelength switching candidate is larger than the downlink average use band, the wavelength is assigned to the wavelength switching candidate that requests an uplink signal,
A wavelength having the maximum downlink average surplus bandwidth among the assignable wavelengths is selected, the uplink average surplus bandwidth of the wavelength is larger than the uplink average use bandwidth of the wavelength switching candidate, and the downlink average surplus bandwidth of the wavelength is If the wavelength switching candidate is larger than the downlink average use band, the wavelength is assigned to the wavelength switching candidate that requests a downlink signal,
The optical subscriber system according to any one of claims 1 to 3. In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the wavelength is set according to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation method for allocating to a device, comprising:
When signal loss due to congestion occurs at any wavelength used for upstream or downstream signals, one of the subscriber devices using the wavelength can be selected as a wavelength switching candidate and can be used for the wavelength switching candidate. Assign a wavelength that is different from the congested wavelength,
Dynamic wavelength band allocation method. In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the wavelength is set according to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation method for allocating to a device, comprising:
A value obtained by multiplying the average value of the upstream signal band of one wavelength by a constant multiplied by the standard deviation of the upstream signal band of the wavelength, or the average value of the downstream signal band of one wavelength and the downstream signal band of the wavelength When the value obtained by multiplying the standard deviation by a constant exceeds the maximum signal bandwidth of the wavelength, select one of the subscriber devices that use the wavelength as the wavelength switching candidate and use it for the wavelength switching candidate. Assign a different wavelength than the congested wavelength among the possible wavelengths,
Dynamic wavelength band allocation method. In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the wavelength is set according to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation method for allocating to a device, comprising:
Either one of the wavelengths used for the upstream signal is discarded due to congestion, or the value obtained by multiplying the average value of the upstream signal band of one wavelength by the standard deviation of the upstream signal band of the wavelength and the constant is added. At least one of exceeding the maximum signal bandwidth of the wavelength, or
Either one of the wavelengths used for the downlink signal is discarded due to congestion, or a value obtained by multiplying the average value of the downlink signal band of one wavelength by the standard deviation of the downlink signal band of the wavelength and a constant is added. If at least one of the maximum signal bandwidth of the wavelength has been exceeded,
Select one of the subscriber devices using the wavelength as a wavelength switching candidate, and assign a wavelength different from the congested wavelength among the usable wavelengths to the wavelength switching candidate.
Dynamic wavelength band allocation method. In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the station-side device responds to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation program for allocating a wavelength to the subscriber unit,
When signal loss due to congestion occurs at any wavelength used for the uplink signal or downlink signal, the station side device selects any of the subscriber devices using the wavelength as the wavelength switching candidate, and the wavelength switching candidate On the other hand, assign a wavelength different from the congested wavelength among the usable wavelengths,
A dynamic wavelength band allocation program for causing a computer to execute a dynamic wavelength band allocation procedure. In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the station-side device responds to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation program for allocating a wavelength to the subscriber unit,
The station side device adds an average value of the upstream signal band of one wavelength to the standard deviation of the upstream signal band of the wavelength multiplied by a constant, or an average value of the downstream signal band of one wavelength, When the value obtained by multiplying the standard deviation of the downstream signal band of the wavelength by a constant exceeds the maximum signal band of the wavelength, select one of the subscriber devices using the wavelength as a wavelength switching candidate, Assign a wavelength that is different from the congested wavelength among the usable wavelengths to the switch candidate.
A dynamic wavelength band allocation program for causing a computer to execute a dynamic wavelength band allocation procedure. In an optical subscriber system in which a plurality of subscriber devices and a single station-side device are connected in a PON topology, the station-side device responds to a request from the subscriber device for each predetermined wavelength switching period. A dynamic wavelength band allocation program for allocating a wavelength to the subscriber unit,
Either the station side device causes signal discard due to congestion at any wavelength used for the upstream signal, or the average value of the upstream signal band of one wavelength is multiplied by a constant to the standard deviation of the upstream signal band of the wavelength. Or the added value exceeds the maximum signal bandwidth of the wavelength, or
Either one of the wavelengths used for the downlink signal is discarded due to congestion, or a value obtained by multiplying the average value of the downlink signal band of one wavelength by the standard deviation of the downlink signal band of the wavelength and a constant is added. If at least one of the maximum signal bandwidth of the wavelength has been exceeded,
Select one of the subscriber devices using the wavelength as a wavelength switching candidate, and assign a wavelength different from the congested wavelength among the usable wavelengths to the wavelength switching candidate.
A dynamic wavelength band allocation program for causing a computer to execute a dynamic wavelength band allocation procedure.

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