JP5378899B2 - Optical communication system and optical communication method - Google Patents

Description

  The present invention relates to an optical communication system and an optical communication method using a wavelength division multiplexing technique or a path multiplexing technique.

  PON (Passive Optical Network) is known as an optical network for realizing an economical high-speed access network. The PON assumes an inexpensive SiGe-BiCMOS process, intensity modulation-direct detection, and time division multiplexing (TDM) similar to those conventionally used for access. Is considered an upper limit.

  Therefore, in order to further increase the speed and capacity, a technique of applying wavelength division multiplexing (WDM) or route (core line) multiplexing to user multiplexing has been considered. However, since the technology using wavelength division multiplexing uses a different wavelength for each user, it is necessary to renew the ONU (Optical Network Unit) which is a user side device, and to assign and control the number of wavelengths corresponding to the number of users. Since an optical transmitter / receiver for the number of users is required for OLT (Optical Line Terminal), there is a problem of an increase in cost. In addition, the technique using route (core wire) multiplexing requires an optical transmitter / receiver and a route corresponding to the route (core wire), which causes a problem of cost increase.

  In response to this problem, as a total bandwidth expansion method for expanding the total bandwidth that can be allocated to the entire user, ONUs under the OLT are classified into a plurality of groups, wavelength division multiplexing is performed between the groups, and time division multiplexing is performed within the group (non- There is a WDM / TDM-PON system (see Non-Patent Documents 2 and 3) that dynamically changes the belonging group of an ONU. These have solved the problem of the cost increase accompanying expansion of the total bandwidth by sharing the wavelength among a plurality of ONUs. In addition, there is a method (see Non-Patent Document 4) in which a backup route (core wire) for a redundant configuration is also used as an active route (core wire). This method solves the problem of an increase in cost due to the expansion of the total bandwidth by utilizing a redundant route (core wire).

“Outline of G-PON System and Future Development”, Fujitsu. July 2006 (VOL.57, No.4) p360-365http: // img. jp. fujitsu. com / downloads / jp / jmag / vol57-4 / paper04. pdf (searched on February 5, 2009) “A 10-Gbit / s CMOS Burst-Mode Clock and Data Recovery IC for a WDM / TDM-PON Access Network”. Kimura et al. LEOS 2004 09 NOVEMBER 2004. TuR1 "A proposal for total bandwidth expansion WDM / TDM-PON and dynamic wavelength band allocation", Manabu Yoshino, Kazutaka Hara, Hirotaka Nakamura, Shunji Kimura, Naoto Yoshimoto, Kiyomi Kumozaki (Nippon Telegraph and Telephone Corporation, Access Service) System Research Laboratories), 2009 IEICE General Conference, Communication Lectures 2, 426 pages. "Examination of cooperative operation with ATM-PON protection system and dynamic bandwidth allocation", Toshikazu Yoshida, Hiroaki Mukai, Mitsuka Iwasaki, Yoshihiro Asashiba, Hiroshi Ichibanase, Tetsuya Yokoya, May 2001 CS system research IEICE technical report vol. 101 (53): CS2001-21, pp. 25-30

  However, when the ONUs are distributed and accommodated in a plurality of wavelengths or routes, there is a problem that unfairness occurs in the band (allocated band) allocated to the user depending on the accommodation method. In particular, each ONU is almost fixedly accommodated in one wavelength or route in order to reduce invalid allocation of allocated bandwidth by fragmentation, reduce switching, and partially sleep state of multiple transceivers for energy saving. When it is done, it becomes awkward. For example, when there are a plurality of groups accommodating ONUs, and one group has a small number of allocated ONUs or a small number of ONUs requesting bandwidth, the ONUs allocated to the group generally have the maximum contracted bandwidth. Can be used. When the other group has a large number of allocated ONUs or a large number of ONUs requesting a bandwidth, the ONU allocated to the group cannot substantially use the contractual maximum bandwidth. Therefore, the available bandwidth differs depending on the allocated group, which is unfair. For example, it is assumed that a plurality of wavelengths are two wavelengths and the number of ONUs to be accommodated is three. In this case, 1 ONU is accommodated in one wavelength and 2 ONUs are accommodated in the other wavelength. When the total allocated bandwidth for each wavelength is the same, the allocated bandwidth to the ONU accommodated by only 1 ONU per wavelength is twice the allocated bandwidth for the ONU accommodated by 2 ONU per wavelength, and fairness cannot be realized.

  In order to solve the above-described problems, the present invention provides an optical communication that expands the total band by accommodating a plurality of ONUs divided into a plurality of wavelengths, paths, or combinations thereof while ensuring fairness of the allocated band. It is an object to provide a system and an optical communication method.

  In order to achieve the above object, the optical communication system and the optical communication method according to the present invention reduce the number of users accommodated in a wavelength or route accommodating users with a small ratio of the allocated bandwidth to the required bandwidth or guaranteed bandwidth. In addition, the fairness of the allocated bandwidth among users is realized by performing an operation to increase the number of users accommodated in the wavelength or route accommodating the user having a large ratio of the allocated bandwidth to the requested bandwidth or the guaranteed bandwidth.

  Specifically, an optical communication system according to the present invention includes a plurality of transmitters allocated to a plurality of groups, a receiver that receives a signal from the transmitter for each of the plurality of groups, and a transmitter from the transmitter. A transmission path for coupling a signal to the receiver, a guaranteed bandwidth guaranteed by the transmitter, or an allocation ratio of an allocated bandwidth allocated to a requested bandwidth requested by the transmitter; And a controller that issues a group designation instruction for designating a group to be allocated to the transmitter so that the allocation ratios are equal.

  The plurality of groups may be a plurality of wavelengths, a plurality of paths, or a combination thereof. That is, the optical communication system according to the present invention outputs an optical signal of one wavelength among a plurality of selectable wavelengths, or a plurality of transmissions that output an optical signal to one of the selectable paths. A receiver for receiving an optical signal from the transmitter for each of the plurality of wavelengths or a plurality of paths, and wavelength division multiplexing, time division multiplexing, path multiplexing and time division of the optical signal from the transmitter. Multiplexing, or one or a plurality of optical transmission lines coupled to the receiver in a multiplexing scheme combining wavelength division multiplexing, time division multiplexing, path multiplexing, and time division multiplexing, and a guaranteed bandwidth guaranteed by the transmitter, or the Monitors the allocation ratio of the allocated bandwidth to the requested bandwidth requested by the transmitter, and the wavelength and path allocated to the transmitter so that the allocation ratio of each of the transmitters becomes equal Specify a combination of wavelength and path And a control unit, the issue group designation instruction that.

  The optical communication method according to the present invention is an optical communication method of an optical communication system in which signals from a plurality of transmitters allocated to a plurality of groups are combined with a receiver for each group, which is guaranteed by the transmitter. The allocation ratio of the allocated band allocated to the guaranteed band or the requested band requested by the transmitter is monitored, and allocated to the transmitter so that the allocation ratio of each of the transmitters becomes equal. A group designation instruction for designating a group is issued.

  The plurality of groups may be a plurality of wavelengths, a plurality of paths, or a combination thereof. That is, the optical communication method according to the present invention outputs an optical signal having one wavelength out of a plurality of selectable wavelengths or outputs a plurality of transmissions outputting an optical signal in one of the selectable paths. The optical signal from the receiver is coupled to the receiver by wavelength division multiplexing and time division multiplexing, path multiplexing and time division multiplexing, or wavelength division multiplexing and a combination of time division multiplexing, path multiplexing and time division multiplexing. An optical communication method of an optical communication system, wherein an allocation ratio of an allocated band allocated to a guaranteed band guaranteed by the transmitter or a requested band requested by the transmitter is monitored, and each of the transmitters A group designation instruction for designating a wavelength, a route, or a combination of a wavelength and a route is issued to the transmitter so that the allocation ratio is uniform.

  The optical communication system and the optical communication method according to the present invention monitor the allocation ratio of transmitters possessed by a user, and signals transmitted by each transmitter so that the allocation ratios of the respective transmitters are equal even during communication. Dynamically change the wavelength of light. Therefore, the present invention can provide an optical communication system and an optical communication method for expanding the total bandwidth by distributing and accommodating a plurality of users to a plurality of transceivers while ensuring fairness of the allocated bandwidth.

  The controller of the optical communication system according to the present invention provides a loss band that is a band lost due to a communication interruption that occurs when the transmitter performs wavelength or path switching based on the group designation instruction before switching the wavelength or path. Alternatively, it is preferable to additionally assign the transmitter after wavelength or path switching. Further, the optical communication method according to the present invention provides a loss band that is a band lost due to a communication interruption that occurs when the transmitter performs wavelength or path switching based on the group designation instruction. Alternatively, it is preferable to additionally assign the transmitter after the route is switched.

  When switching the wavelength of a transmitter or a route, a communication interruption time occurs. If the wavelength or the route is frequently switched, the integrated amount of communication interruption time increases and the allocated bandwidth is affected. In the present invention, when the buffer overflow is negligible and the communication interruption time falls within the delay fluctuation that does not hinder traffic control, the band of the communication interruption time associated with the switching of the wavelength or route can be compensated. Even when the communication interruption time associated with the path switching occurs, the fairness of the allocated bandwidth of each transmitter can be ensured.

  The transmitter of the optical communication system according to the present invention may estimate the required bandwidth based on a communication amount in a past certain period. In the optical communication method according to the present invention, the required bandwidth can be estimated based on a communication amount of the transmitter for a certain period in the past. Since the allocated bandwidth is determined based on the actual amount of communication, the fairness of the allocated bandwidth can be further maintained.

  The controller of the optical communication system according to the present invention may issue the wavelength or route designation instruction only to the transmitter having the allocation ratio of less than 1. Further, the optical communication method according to the present invention can issue the wavelength or route designation instruction only to the transmitter having the allocation ratio of less than 1. Disadvantages such as communication disconnection due to a change in the wavelength or route to which the transmitter belongs are reduced, and the amount of operation at the controller is also reduced.

  The controller of the optical communication system according to the present invention can ensure the guaranteed bandwidth of the transmitter when issuing a wavelength designation instruction to the wavelength or route selected by the transmitter for which the guaranteed bandwidth is set. It is desirable to give the wavelength or route designation instruction to the other transmitters when it is confirmed. The optical communication method according to the present invention secures the guaranteed bandwidth of the transmitter when a wavelength or route designation instruction is issued to the wavelength or route selected by the transmitter for which the guaranteed bandwidth is set. It is desirable to give the wavelength or route designation instruction to the other transmitters when it can be confirmed. Even when a guaranteed bandwidth is set for a transmitter other than the transmitter whose wavelength or route is to be switched, the guaranteed bandwidth of the transmitter can be secured.

  The present invention can provide an optical communication system and an optical communication method for expanding the total bandwidth by distributing and accommodating a plurality of users in a plurality of groups while ensuring fairness of the allocated bandwidth.

It is a conceptual diagram explaining the optical communication system which concerns on this invention. It is a figure explaining the mixed signal light after combining the signal light from the transmitter of the optical communication system which concerns on this invention. It is the result of having calculated the allocation band in case the 2 wavelengths are shared by 32 transmitters in the optical communication system which concerns on this invention. It is a figure explaining the mixed signal light after combining the signal light from the transmitter of the optical communication system which concerns on this invention. (A) is a case where wavelength allocation is performed without considering the wavelength switching time, and (b) is a case where wavelength allocation is performed considering the wavelength switching time. It is a conceptual diagram explaining the optical communication system which concerns on this invention. It is a conceptual diagram explaining the optical communication system which concerns on this invention.

  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)
FIG. 1 is a conceptual diagram illustrating an optical communication system according to the present embodiment. In this embodiment, they are grouped for each wavelength. The optical communication system includes a transmitter (11A, 11B, 11C), an optical transmission line 31, a receiver 21, and a controller (not shown). The transmitter (11A, 11B, 11C) is owned by each user, and outputs an optical signal of one wavelength among a plurality of selectable wavelengths. The receiver 21 receives an optical signal from the transmitter (11A, 11B, 11C) for each of a plurality of wavelengths. The optical transmission line 31 couples the optical signal from the transmitter (11A, 11B, 11C) to the receiver 21 by wavelength division multiplexing and time division multiplexing.

  The controller monitors the allocation ratio of the allocated band allocated to the guaranteed band guaranteed by the transmitter (11A, 11B, 11C) or the requested band requested by the transmitter, and the allocation ratio of each transmitter. A wavelength designation instruction for designating the wavelength is issued to the transmitters (11A, 11B, 11C) so that.

  The transmitter (11A, 11B, 11C) outputs signal light at one wavelength selected from two wavelengths (λ1, λ2). The transmitter 11A transmits signal light of wavelength λ1 in the transmittable region (L51, L52). Send. The transmitter 11B transmits the signal light having the wavelength λ2 in the transmittable region L53, subsequently performs wavelength switching, and transmits the signal light having the wavelength λ1 in the transmittable region L54. The transmitter 11C transmits the signal light having the wavelength λ2 in the transmittable region (L55, L56). In FIG. 1, the transmittable areas (L51 to L56) are communication wavelength areas given to the transmitter in the vertical direction and the communicable time given to the transmitter in the horizontal direction.

  The optical transmission line 31 combines the signal light from the transmitters (11 A, 11 B, 11 C) and couples it to the receiver 21. Here, as will be described later, since the receiver 21 demultiplexes the light with the optical multiplexer / demultiplexer 42 and individually receives the wavelengths with the light receivers (43a, 43b), it can simultaneously receive the signal light with different wavelengths. The optical signals of the same wavelength cannot be received simultaneously. Therefore, the controller issues a wavelength designation instruction to switch wavelengths to the transmitters (11A, 11B, and 11C) or designates a transmittable time so that signal light of the same wavelength does not arrive at the receiver at the same time.

  Referring to FIG. 1, at time t1, the controller instructs the transmitter 11A to output the signal light having the wavelength λ1, instructs the transmitter 11B to output the signal light having the wavelength λ2, and transmits the signal to the transmitter 11C. Instructs to stop sending light. The controller instructs the transmitter 11A to stop transmitting the signal light at time t2, instructs the transmitter 11B to output the signal light switched from the wavelength λ1 to the wavelength λ2, and instructs the transmitter 11C to output the wavelength λ2. Instruct to output the signal light. Further, the controller instructs the transmitter 11A to output the signal light having the wavelength λ1 at time t3, instructs the transmitter 11B to stop sending the signal light, and sends the signal light having the wavelength λ2 to the transmitter 11C. Instruct to output. Here, when the transmission distance from the transmitter to the receiver is different, the controller adjusts the interval between the signal lights so that they do not overlap when combined. When the signal light is composed of frames, the controller adjusts the frame interval.

  FIG. 2 is a diagram illustrating the mixed signal light after the signal lights from the transmitters (11A, 11B, and 11C) are multiplexed. The horizontal axis is time, and the vertical axis is wavelength or band. As described above, the optical communication system according to the present embodiment couples the signal light from the transmitters (11A, 11B, and 11C) to the receiver 21 by performing wavelength division multiplexing and time division multiplexing.

  The receiver 21 demultiplexes the light from the optical transmission path 31 for each wavelength and outputs a demultiplexed signal light, and a plurality of demultiplexed signal lights from the optical multi / demultiplexer 42, respectively. Light receivers (43a, 43b). The optical multiplexer / demultiplexer 42 is, for example, a wavelength filter. The light receivers (43a, 43b) are, for example, photodiodes. The optical multiplexer / demultiplexer 42 demultiplexes the mixed signal light as shown in FIG. 2 into the wavelength λ1 and the wavelength λ2, and couples them to the light receivers (43a, 43b), respectively. The light receivers (43a, 43b) each output the received signal light as an electrical signal.

  In FIG. 1, three transmitters and two wavelengths are illustrated, but the number of transmitters may be increased or decreased, and the number of wavelengths to be wavelength division multiplexed may be three or more. In FIG. 1, one receiver receives a wavelength division multiplexed signal, but a plurality of receivers may be provided. Further, the optical communication system may be a bidirectional communication system.

  As described above, in this optical communication system, the controller allocates a wavelength and a time at which signal light can be transmitted to the transmitters (11A, 11B, and 11C). The communication amount that can be communicated with the wavelength and time allocated to the transmitter by the controller in this way will be described below as an allocated band.

  Here, there is a case where a guaranteed bandwidth, which is a bandwidth that must be guaranteed, is set in the transmitter (11A, 11B, 11C). The transmitters (11A, 11B, 11C) also have a required bandwidth that is a bandwidth necessary for communication. For example, the requested bandwidth may be determined according to past communication history. The communication history may be a history of a window at a fixed time interval in the past, a history of a sliding window for a fixed time, or a history based on a weighted average.

  The controller monitors the allocation ratio, which is the ratio of the allocated bandwidth to the guaranteed bandwidth or the required bandwidth, for each transmitter. For example, the controller searches for a transmitter with the smallest allocation ratio and a transmitter with the largest allocation ratio, and for the transmitter with the smallest allocation ratio, the transmitter with the largest allocation ratio from the currently used wavelength. A wavelength designation instruction is issued to switch to the wavelength being used.

  Here, even when the guaranteed bandwidth is not set as an absolute amount, when a bandwidth that can be shared between transmitters is allocated at a predetermined ratio (for example, 1: 1: 1), the bandwidth that can be shared x the corresponding transmitter The operation of the present embodiment may be performed with the sum of the ratio of ÷ the ratio of all transmitters as an effective guaranteed bandwidth.

  In addition, when the ratio of the allocated bandwidth to the guaranteed bandwidth is used, the comparison of the allocation ratios described above may be limited to only a transmitter having a required bandwidth larger than the allocated bandwidth. By doing so, it is possible to suppress a malfunction that is caused by trying to increase the allocation ratio even though the allocation ratio of the transmitter having a small required bandwidth is generated because the requested bandwidth is small rather than congestion.

  The allocation ratio may be compared with respect to a band that is fixedly allocated without depending on the required band, or a band that is obtained by reducing the allocated band for the priority class. In such a case, fairness of only the bandwidth allocated in a best effort manner can be realized.

  In the optical communication system of FIG. 1, the controller changes the transmitters belonging to the respective wavelengths in a timely manner so that the assigned wavelengths to the transmitters belonging to the wavelength λ1 and the transmitters belonging to the wavelength λ2 are fair. As a result, as shown in FIG. 2, the bandwidths are equally allocated to all the transmitters between the times t1 and t3.

  In other words, this optical communication system reduces the number of accommodated users of the wavelength transceivers accommodating users with a small allocation ratio and reduces the number of accommodated users of the wavelength transceivers accommodating users with a large allocation ratio. The fairness of the allocated bandwidth between users is realized by performing increasing operations with the controller.

  For example, in a system in which traffic is concentrated at the start time of 8:30 on weekdays morning, the controller occupies one wave for the transmitter 11A for that time on Monday and one wave for that time on Tuesday for the transmitter 11B. The wavelength allocation is controlled so that the transmitter 11C occupies one wave during that time on Wednesday. That is, in the case where congestion occurs only for a specific time, the controller performs control so that the wavelength allocation history of each transmitter at the time of congestion becomes equal between weeks or months. In particular, when the wavelength switching time is long, it is desirable that the history of wavelength assignment be fair in the time of congestion in the range of 1 day, 1 week, 1 month, or 1 year. In addition, although the equality within a short time is shown here, it is desirable to equalize over a long time.

  The controller may issue a wavelength designation instruction only to a transmitter having an allocation ratio of less than 1. For example, when the allocation ratio of all transmitters (11A, 11B, 11C) is 1 or more, all transmitters satisfy the guaranteed bandwidth and the required bandwidth. In this case, even if there is a transmitter having the smallest bandwidth ratio, wavelength switching is not performed. It is possible to prevent the bandwidth from being lowered due to the communication interruption of the transmitter accompanying the wavelength switching, and to reduce the operation amount at the controller.

  In addition, when issuing a designation instruction for the wavelength selected by the transmitter for which the guaranteed bandwidth is set, the controller can confirm that the guaranteed bandwidth of the transmitter for which the guaranteed bandwidth is set can be secured. A wavelength designation instruction may be issued to another transmitter. For example, the case where the transmitter 11A has a guaranteed bandwidth, the allocation ratio of the transmitter 11A is the maximum, and the allocation ratio of the transmitter 11B is the minimum will be described. When the controller 11B switches the wavelength λ2 currently used by the transmitter 11B to the wavelength λ1 used by the transmitter 11A, the controller 11A causes the guaranteed bandwidth to be reduced due to communication interruption or switching congestion at the switching time. Whether or not can be maintained. As a result, if the transmitter 11A cannot maintain the guaranteed bandwidth, the controller does not issue a wavelength designation instruction to the transmitter 11B. On the other hand, if the transmitter 11A can maintain the guaranteed bandwidth as a result of the calculation, the controller issues a wavelength designation instruction to the transmitter 11B. Thereby, the transmitter 11A can ensure the guaranteed bandwidth. Here, whether or not the guaranteed bandwidth can be maintained may be calculated in consideration of addition of allocation shown in an embodiment described later. Note that ensuring the guaranteed bandwidth means that the average value of the amount of data that can be transmitted in a predetermined observation time (for example, 1 second) has reached the guaranteed bandwidth.

  FIG. 3 shows the result of calculating the allocated bandwidth when two wavelengths are shared by 32 transmitters. In the figure, the horizontal axis represents the number of transmitting transmitters, and the vertical axis represents the allocated bandwidth in the transmitting transmitters. A black square is a calculation result of the optical communication system in which the static wavelength arrangement described in Non-Patent Document 1 and Non-Patent Document 2 is performed. A white circle is a calculation result of the optical communication system in which dynamic wavelength allocation described in Non-Patent Document 3 is performed. In the optical communication system described in Non-Patent Document 3, the allocation ratio of each transmitter is not controlled to be equal. A solid line is a calculation result of the optical communication system of the present embodiment. As shown in FIG. 3, the allocated bandwidth is fair in the optical communication system of this embodiment.

  Here, the explanation will be supplemented with respect to FIG. The transmission band of each transmitter described in FIG. 3 is 10 Gbit / s. Since it is an object of the present invention to realize fairness of the allocated bandwidth in the worst condition, the point plotted in FIG. 3 is the allocated bandwidth in the worst condition.

  In the case of the static wavelength arrangement of Non-Patent Document 1 in which the wavelength used by the user is fixedly assigned (black square), the worst condition is that a single wavelength is shared by all users in communication. In other words, this worst condition is a situation where the transmitter in communication is biased to one wavelength. In this case, a band of 20 Gbit / s at two wavelengths is not allocated to all users in communication, but a band of 10 Gbit / s of one wavelength is allocated to all users in communication. That is, under the worst condition of static wavelength arrangement, a value obtained by dividing 10 Gbit / s by the number of users is an allocated band.

  On the other hand, in the case of the dynamic wavelength arrangement (white circle) of Non-Patent Document 3, active users using a band during communication are equally assigned to each wavelength. The dynamic wavelength arrangement of Non-Patent Document 3 is switched so that the transmitter in communication is equal to both wavelengths. When the number of users in communication is divisible by the number of available wavelengths, the dynamic wavelength allocation can obtain the ideal value of the allocated band. However, when the number of users in communication is not divisible by the number of wavelengths that can be used (here, 2) (that is, the number of users in communication is an odd number), the dynamic wavelength allocation of Non-Patent Document 3 is a surplus user that cannot be divided. The allocated bandwidth at the wavelength on the side of taking over decreases. For example, in the case of 5 users, one wavelength is used by 3 users and the other wavelength is used by 2 users. In this case, the wavelength on the side where one wavelength is shared by three users is the worst condition, and 3.3G per user is the allocated bandwidth. On the other hand, when it is divisible (when the number of users in communication is an even number), it is an ideal state, and the allocated bandwidth is fair. The values are plotted in FIG.

  In the optical communication system according to the present embodiment in which the allocation ratios of the transmitters are controlled to be equal, the allocation bandwidth for the user with the lowest allocation bandwidth is 10 Gbit / s, with the upper limit being 10 Gbit / s, and a total of 20 Gbit for 10 Gbit / s. This is a value (solid line in the figure) obtained by dividing / s by the number of users in communication. That is, the optical communication system of the present embodiment can always obtain the ideal state of the allocated band of the optical communication system of Non-Patent Document 3.

(Embodiment 2)
In the optical communication system of the present embodiment, wavelength allocation may be performed in consideration of wavelength switching time. The difference between the present optical communication system and the optical communication system according to the first embodiment is that the controller equalizes the allocated bandwidth of each transmitter in consideration of the communication interruption time associated with the wavelength change. The controller additionally allocates a loss band, which is a band lost due to a communication interruption that occurs when the transmitter performs wavelength switching, to the transmitter before or after wavelength switching based on the wavelength designation instruction.

  When the wavelength is switched, a communication interruption time that cannot be performed by the transmitter occurs. FIG. 5 shows an image of this embodiment. In the present embodiment, a band corresponding to the communication interruption time (gap between L53 and L54) accompanying wavelength switching is added as the additional band 27. In the image of this figure, an additional band is assigned both before and after switching, but it may be either before or after switching. FIG. 5 is an image, and the vertical width (bandwidth) of L53 and L54 is partially enlarged, but the PON that allocates the entire bandwidth of the transmission path to any transmitter for each wavelength at the moment instant. In the system, as shown in FIG. 4B described later, since the vertical width is constant, the allocation time is added (= expanded in the time axis direction).

  In FIG. 4A, this communication interruption time is shown as a switching time (2TQ (time-quanta)). In FIG. 4A, the allocated bandwidth of the transmitter 11B is reduced. For this reason, if the wavelength is frequently switched, the allocated bandwidth of the transmitter decreases. Therefore, the present optical communication system additionally allocates the lost band lost due to the communication interruption time associated with the wavelength change to the transmitter to be switched before or after switching.

  Here, the addition of the missing band means that the wavelength allocation times of the transmitter 11A, the transmitter 11B, and the transmitter 11C are made equal. Specifically, as shown in FIG. 4B, the controller sets the time of the transmittable area L51 to 12TQ, the time of the transmittable area L52 to 8TQ, and the time of the transmittable area (L53 to L56) to 10TQ. Thus, wavelength allocation is performed for each transmitter. The transmission time of all transmitters is allocated in units of 20 TQ.

  For example, if the current transmission band is Bi and the communication interruption time is Ti, the missing band is BiTi, and only BiTi is allocated as the additional band 27. This will be further described with reference to FIG. The wavelength switching target is the transmitter 11B. In consideration of the fact that many bands other than the transmitter 11B (transmitter 11A) have been allocated until then at the wavelength λ1 after wavelength switching, it is desirable to allocate the additional band 27 to the transmitter 11B at the wavelength λ1 after wavelength switching. . However, even if the additional band 27 is allocated at the wavelength λ2 before wavelength switching, the allocated band becomes larger after the transmitter 11B performs wavelength switching except for the transmitter 11B (transmitter 11C). The ratio does not decrease.

  When a guaranteed band is set for a transmitter (11A, 11C) other than the transmitter 11B, the controller allocates an additional band 27 to the transmitter 11B so that the guaranteed band can be secured. Specifically, the controller adds the additional band 27 to the wavelength λ2 before the wavelength switching or the wavelength λ1 after the wavelength switching in order to maintain the guaranteed band of the transmitter (11A, 11C). Consider.

Furthermore, it is desirable that the controller suppresses the frequency of wavelength switching to a frequency that can ensure the guaranteed bandwidth of the transmitter for which the guaranteed bandwidth is set. In the present embodiment, when the buffer overflow can be ignored and the communication interruption time falls within the delay fluctuation that does not hinder traffic control, the bandwidth of the communication interruption time associated with the switching of the wavelength or the route can be compensated. Even when the communication interruption time associated with the route switching occurs, the fairness of the allocated bandwidth of each transmitter can be ensured.
(Embodiment 3)

  In this embodiment, each route is grouped. FIG. 6 is a conceptual diagram illustrating the optical communication system of the present embodiment. The optical communication system includes a transmitter (11A, 11B, 11C), a route (31-1, 31-2), a receiver 21, and a controller (not shown). The transmitter (11A, 11B, 11C) is owned by each user, and outputs an optical signal to one of a plurality of selectable routes. The receiver 21 receives an optical signal from the transmitter (11A, 11B, 11C) for each of a plurality of wavelengths. The optical transmission line 31 couples the optical signal from the transmitter (11A, 11B, 11C) to the receiver 21 by wavelength division multiplexing and time division multiplexing.

  The controller monitors the allocation ratio of the allocated band allocated to the guaranteed band guaranteed by the transmitter (11A, 11B, 11C) or the requested band requested by the transmitter, and the allocation ratio of each transmitter. To the transmitters (11A, 11B, 11C) so as to specify a route.

  The transmitters (11A, 11B, 11C) output signal light in one route assigned from the two routes (31-1, 31-2). The transmitter 11A transmits the signal light in the transmittable area (L51, L52) along the route 31-1. The transmitter 11B transmits the signal light of the route 31-2 in the transmittable region L53, subsequently performs route switching, and transmits the signal light of the route 31-1 in the transmittable region L54. The transmitter 11C transmits the signal light of the route 31-2 in the transmittable area (L55, L56). In FIG. 1, transmission possible areas (L11 to L16) are paths given to the transmitter in the vertical direction, and communication possible times given to the transmitter in the horizontal direction. That is, if the wavelength is read as a route, it is the same as FIG.

  The paths (31-1, 31-2) combine the signal lights from the transmitters (11A, 11B, 11C) and couple them to the receiver 21, respectively. Here, since the receiver 21 includes a light receiver (43a, 43b) for each route as will be described later, it is possible to simultaneously receive the signal light of different routes, but to simultaneously receive the light signal of the same route. I can't. Therefore, the controller issues a route designation instruction to switch the route to the transmitters (11A, 11B, 11C) or designates a transmittable time so that the signal light of the same route does not reach the receiver at the same time. To do.

  Referring to FIG. 6, the controller instructs the transmitter 11A to output signal light on the route 31-1 at time t1, and instructs the transmitter 11B to output signal light on the route 31-2. Instruct the transmitter 11C to stop sending the signal light. The controller instructs the transmitter 11A to stop sending the signal light at time t2, instructs the transmitter 11B to output the signal light switched from the path 31-1 to the path 31-2, The transmitter 11C is instructed to output the signal light of the route 31-2. Further, the controller instructs the transmitter 11A to output the signal light of the route 31-1 at time t3, instructs the transmitter 11B to stop sending the signal light, and instructs the transmitter 11C to have the wavelength λ2. Instruct to output signal light. Here, when the transmission distance from the transmitter to the receiver is different, the controller adjusts the interval between the signal lights so that they do not overlap when combined. When the signal light is composed of frames, the controller adjusts the frame interval.

  The mixed signal light of the optical communication system of FIG. 6 is obtained by combining the signal light from the transmitters (11A, 11B, 11C) by combining the wavelength of the vertical axis in FIG. The description can be made in the same manner as in the first embodiment. As described above, the optical communication system according to the present embodiment couples the signal light from the transmitters (11A, 11B, and 11C) to the receiver 21 through path multiplexing and time division multiplexing.

  The receiver 21 includes a plurality of light receivers (43a, 43b) that receive light from the routes (31-1, 31-2) for each route. The light receivers (43a, 43b) are, for example, photodiodes. The light receivers (43a, 43b) each output the received signal light as an electrical signal.

  In FIG. 6, three transmitters and two routes are illustrated, but the number of transmitters may be increased or decreased, and the number of routes to be multiplexed may be three or more. In FIG. 6, one receiver side receives a route multiplexed signal, but there may be a plurality of receivers. Further, the optical communication system may be a bidirectional communication system.

The operation of the controller can be similarly explained by replacing the wavelength of the operation of the controller shown in the first and second embodiments of the present invention with a route.
In the first and second embodiments, bands are allocated fairly regardless of wavelength groups, and in this embodiment, bands are allocated fairly regardless of route groups. However, a group in which wavelengths and paths are combined is transmitted. The system may be shared by machines, and in this case, the bandwidth is allocated fairly regardless of the group combining the wavelength and the route.

  The present invention can also be applied to, for example, a plurality of lines that are link-aggregated if a set of a plurality of transmitters and light receivers is a transmitter and a receiver for each wavelength.

11A, 11B, 11C: Transmitter 21: Receiver 27: Additional band 31: Optical transmission path 31-1, 31-2: Path 42: Optical multiplexer / demultiplexer 43a, 43b: Light receivers L51, L52, L53, L54 , L55, L56: Transmission possible area

Claims (12)

Multiple transmitters assigned to multiple groups;
A receiver for receiving a signal from the transmitter for each of the plurality of groups;
A transmission line for coupling the signal from the transmitter to the receiver;
Against the required bandwidth guaranteed bandwidth or that the transmitter requests the transmitter to ensure monitors the ratio a is allocated ratio Allocated allocated bandwidth, smaller the transmission of the allocation ratio than the other of said transmitters An operation to reduce the number of transmitters of the group that accommodates the transmitter and to increase the number of transmitters of the group that accommodates the transmitter having the larger allocation ratio than other transmitters. A controller for issuing a group designation instruction to be performed ;
An optical communication system comprising: A plurality of transmitters that output an optical signal of one of a plurality of selectable wavelengths, or that output an optical signal to one of a plurality of selectable paths;
A receiver for receiving an optical signal from the transmitter for each of the plurality of wavelengths or a plurality of paths;
The receiver in a wavelength division multiplexing and time division multiplexing, a path multiplexing and a time division multiplexing, or a wavelength division multiplexing, a combination of a time division multiplexing, a path multiplexing and a time division multiplexing, for the optical signal from the transmitter. One or more optical transmission lines coupled to
Against the required bandwidth guaranteed bandwidth or that the transmitter requests the transmitter to ensure monitors the ratio a is allocated ratio Allocated allocated bandwidth, smaller the transmission of the allocation ratio than the other of said transmitters Wavelengths and paths accommodating the transmitter, reducing the number of transmitters accommodated from the combination of wavelengths, paths, or combinations of wavelengths and paths, and accommodating the transmitter having a larger allocation ratio than the other transmitters Or a controller for issuing a group designation instruction for performing an operation for increasing the number of transmitters accommodated from a combination of a wavelength and a route ;
An optical communication system comprising:   The controller, based on the group designation instruction, a loss band, which is a band lost due to communication disconnection that occurs when the transmitter switches a wavelength, a path, or a combination of a wavelength and a path. Or before switching the combination of wavelength and path, or after switching the combination of wavelength, path, or combination of wavelength and path, and additionally assigning to the transmitter Optical communication system.   4. The controller according to claim 1, wherein the controller estimates the requested bandwidth based on a communication amount in a past fixed period, and specifies a group allocated to the transmitter according to the estimation. An optical communication system according to claim 1.   5. The controller according to claim 1, wherein the controller issues the group designation instruction so that only the transmitter having the allocation ratio less than a predetermined value has the allocation ratio equal to or higher than a predetermined value. The optical communication system described.   When the controller issues the group designation instruction for the wavelength, route, or combination of wavelength and route selected by the transmitter for which the guaranteed bandwidth is set, the guaranteed bandwidth of the transmitter is secured. The optical communication system according to any one of claims 1 to 5, wherein the group designation instruction is issued to the other transmitters when it can be confirmed. An optical communication method of an optical communication system for combining signals from a plurality of transmitters allocated to a plurality of groups to a receiver for each group,
Against the required bandwidth guaranteed bandwidth or that the transmitter requests the transmitter to ensure monitors the ratio a is allocated ratio Allocated allocated bandwidth, smaller the transmission of the allocation ratio than the other of said transmitters An operation to reduce the number of transmitters of the group that accommodates the transmitter and to increase the number of transmitters of the group that accommodates the transmitter having the larger allocation ratio than other transmitters. An optical communication method of an optical communication system, characterized by issuing a group designation instruction to be performed . Optical signal from a plurality of transmitters that output an optical signal of one of a plurality of selectable wavelengths or output an optical signal to one of a plurality of selectable paths is wavelength division multiplexed and time An optical communication method of an optical communication system that couples to a receiver by division multiplexing, path multiplexing and time division multiplexing, or wavelength division multiplexing and time division multiplexing and path multiplexing and time division multiplexing combined.
Against the required bandwidth guaranteed bandwidth or that the transmitter requests the transmitter to ensure monitors the ratio a is allocated ratio Allocated allocated bandwidth, smaller the transmission of the allocation ratio than the other of said transmitters Wavelengths and paths accommodating the transmitter, reducing the number of transmitters accommodated from the combination of wavelengths, paths, or combinations of wavelengths and paths, and accommodating the transmitter having a larger allocation ratio than the other transmitters Or an optical communication method for an optical communication system, characterized by issuing a group designation instruction for performing an operation for increasing the number of transmitters accommodated from a combination of a wavelength and a route .   Based on the group designation instruction, a loss band, which is a band lost due to communication disconnection that occurs when the transmitter switches the wavelength, the path, or the combination of the wavelength and the path, the wavelength, the path, or the wavelength and the path. 9. The optical communication method according to claim 7, wherein the transmitter is additionally allocated before switching of a combination with a path, or after switching of a combination of a wavelength, a path, or a combination of a wavelength and a path.   The said request | requirement band is estimated based on the traffic of the said transmitter for a fixed period in the past, The group allocated with respect to the said transmitter according to estimation is designated, The any one of Claim 7 to 9 characterized by the above-mentioned. An optical communication method according to claim 1.   The optical communication method according to any one of claims 7 to 10, wherein the group designation instruction is issued so that only the transmitter with the allocation ratio less than a predetermined value has the allocation ratio equal to or greater than a predetermined value. .   When issuing the group designation instruction of the wavelength, route, or combination of wavelength and route selected by the transmitter for which the guaranteed bandwidth is set, it was confirmed that the guaranteed bandwidth of the transmitter could be secured The optical communication method according to any one of claims 7 to 11, wherein the group designation instruction is sometimes issued to another transmitter.

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