JP2011061480A - Optical communication system, and optical communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication system for distributing a plurality of users into a plurality of groups, storing the users, and extending a total band, while securing fairness in assigned bands, and to provide an optical communication method. <P>SOLUTION: In the optical communication system, a time domain and a plurality of wavelength areas are shared between a plurality of ONU-A to C (11-1-A to C) and an OLT (21-1), so as to exchange signal light by using a passive light branching circuit. The OLT (21-1) monitors the wavelength and time assigned to the optical transmitters A to C (10-1-A to C) of the ONU-A to C (11-1-A to C), calculates the average values of the assignment bands by each one of the optical transmitters A to C (10-1-A to C), calculates the ratio of the average values among the optical transmitters A to C (10-1-A to C), and determines the wavelength and time to be assigned to the optical transmitters of ONU-A to C (11-1-A to C), so as to allow the ratio of the average values to be within a predetermined fixed range. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical communication system that accommodates a plurality of optical transmitters in a plurality of groups, and more particularly to an optical communication system and an optical communication method using a wavelength division multiplexing technique or a core line multiplexing technique.

  PON (Passive Optical Network) is known as an optical network for realizing an economical high-speed access network. Assuming that time division multiplexing (TDM) technology is applied to PON using an intensity modulation-direct detection method using an inexpensive SiGe-BiCMOS process conventionally used in high-speed access networks, Due to restrictions, the upper limit of the bandwidth is considered to be 10 Gbps.

  Therefore, in order to further increase the speed, it has been considered to apply wavelength division multiplexing (WDM) or core multiplexing to multiplex signals for each user. However, since different wavelengths are used for each user when WDM is applied, wavelength allocation and wavelength control according to the number of ONUs (Optical Network Units) that are optical subscriber-side devices are required. An optical transmitter / receiver corresponding to the number of optical subscriber side devices ONU is also required for OLT (Optical Line Terminal). These require renewal of the existing optical subscriber side device ONU and the station side device OLT. Further, when the core wire multiplexing is applied, the core wires and the number of optical transmitters / receivers corresponding to the core wires are necessary, and any increase in cost cannot be avoided.

  To solve this problem, as a total bandwidth expansion method for expanding the total bandwidth that can be allocated to the entire optical subscriber unit ONU, the optical subscriber unit ONUs are grouped into a plurality of groups, and the WDM and the groups are inter-grouped. There is a WDM / TDM-PON system (see, for example, Non-Patent Document 1) that applies TDM. This is because the wavelength is shared by a plurality of optical subscriber unit ONUs, thereby minimizing the cost increase associated with the total bandwidth expansion. In addition, there is a method of using a spare core wire for a redundant configuration as an active core wire (see, for example, Non-Patent Document 2). This minimizes the cost increase associated with the expansion of the total bandwidth by utilizing the spare core wire.

"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 ATM-PON protection method and cooperative operation with dynamic bandwidth allocation", Toshikazu Yoshida, Hiroaki Mukai, Mitsuka Iwasaki, Yoshihiro Asashiba, Hiroshi Ichibanse, Tetsuya Yokoya, May 2001 CS System Study Group Electronic Information 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 core wires, there is a problem that unfairness occurs in a band (allocated band) allocated to the ONU depending on how the ONUs are accommodated. In particular, each ONU is almost fixedly accommodated in one wavelength or core line in order to reduce invalid allocation of allocated bandwidth by fragmentation, reduce switching, and partially sleep state of multiple transceivers for energy saving. It becomes awkward when it is.

  For example, if there are multiple groups that accommodate users, and one group has a small number of assigned users or only a few users requesting communication bandwidth, the users assigned to that group are generally the largest in the contract. Bandwidth can be used. When the other group has a large number of assigned users or a large number of users requesting a communication band, the user allocated to the group cannot generally use the contracted maximum band.

  FIG. 6 shows an example of a conventional assignment method to ONUs. Assume that the number of wavelengths or core wires is 2, and the number of ONUs to be accommodated is 3. In this case, one ONU (ONU-C) is accommodated in one wavelength or core wire, and two ONUs (ONU-A, B) are accommodated in the other wavelength or core wire. When the total allocated bandwidth for each wavelength or core is equal, the allocated bandwidth to the ONU (ONU-C) of group 1 accommodated by only one ONU per wavelength is the group 2 accommodated by two ONUs per wavelength. The bandwidth allocated to ONUs (ONU-A, B) is doubled and fairness cannot be realized. In this way, the available bandwidth differs depending on the allocated group, which is unfair.

  In addition, when providing services that increase the number of wavelengths by paying additional costs when only some users wish to increase the allocated bandwidth, users who have not paid the additional cost will also be able to increase the allocated bandwidth. There is a possibility that allocated bandwidths between users who have utility or pay additional costs may differ, and fairness in providing services cannot be ensured. For example, it is assumed that the number of wavelengths or core wires is 2 and the number of users to be accommodated is 32. Here, when the bandwidth is not congested, both the extra user and the normal user can be allocated up to the maximum bandwidth, and it is fair that the ratio between the extra user who requires the bandwidth and the normal user is 2: 1 when the bandwidth is congested. .

  At this time, for example, when all of the initial premium users are shifted to the expansion side in an attempt to ensure fairness among the premium users, the allocated bandwidth of the user who has not paid the additional cost increases and becomes unfair. When all users are requesting the maximum bandwidth, it is as follows in the form of (number of extra users, extra user bandwidth, conventional user allocated bandwidth). (0, 0, 1/32), (1, 1, 1/31), (2, 1/2, 1/30), (3, 1/3, 1/29), ..., (16, 1 / 16, 1/16), ...

  That is, when the additional user becomes 16 users, the conventional user also becomes the same bandwidth allocation as the additional user due to the survivor's profit, which is unfair to the user who paid the additional cost. In addition, although the maximum bandwidth is generated at the time of non-congestion, in the initial stage when there are few additional users, only the additional cost of allocation at most is paid, but there is an unfair feeling in the sense that there is an allocation of 30 times.

  In order to solve the above-described problems, the present invention provides an optical communication system and an optical communication method for extending a total bandwidth by distributing and accommodating a plurality of users into a plurality of groups while ensuring fairness of the allocated bandwidth. For the purpose.

  In order to achieve the above object, the optical communication system and the optical communication method of the present invention allocate the bandwidth so that the average value of the allocated bandwidth is within a predetermined allocated bandwidth ratio, thereby ensuring fairness of the allocated bandwidth between users. It was decided to realize.

  Specifically, the optical communication system of the present invention shares a time region and a plurality of wavelength regions between a plurality of optical subscriber-side devices and a single station-side device, and transmits signal light using a passive optical branch circuit. An optical communication system for transmitting and receiving, wherein the station side device monitors the wavelength and time assigned to the optical transmitter of the optical subscriber side device and calculates an average value of the allocated bandwidth for each of the optical transmitters. When the ratio of the average values between the optical transmitters is calculated and the ratio of the average values exceeds a predetermined range, the wavelength or time allocated to the optical transmitter having the high average value is reduced. .

  The station side apparatus allocates the allocated band to each optical transmitter so that the ratio of the average values of the allocated bands of the respective optical transmitters is within a predetermined range. Thereby, fairness of the allocated bandwidth between users can be realized.

  Specifically, the optical communication system of the present invention shares a time domain and a plurality of core wires between a plurality of optical subscriber side devices and one station side device, and transmits and receives signal light using a passive optical branch circuit. In the optical communication system, the station side device monitors the core line and time assigned to the optical transmitter of the optical subscriber side device, calculates the average value of the allocated bandwidth for each optical transmitter, When the ratio of the average values between the optical transmitters exceeds a predetermined range, the core or time allocated to the optical transmitter having a high average value is reduced.

  The station side apparatus allocates the allocated band to each optical transmitter so that the ratio of the average values of the allocated bands of the respective optical transmitters is within a predetermined range. Thereby, fairness of the allocated bandwidth between users can be realized.

  In the optical communication system of the present invention, it is preferable that the station side apparatus calculates the average value between the optical transmitters requesting bandwidth allocation exceeding a predetermined guaranteed bandwidth.

  Specifically, the optical communication method of the present invention shares a time domain and a plurality of wavelength domains between a plurality of optical subscriber-side devices and a single station-side device, and transmits signal light using a passive optical branch circuit. An optical communication method for transmitting and receiving, wherein the station side device monitors the wavelength and time assigned to the optical transmitter of the optical subscriber side device and calculates an average value of the allocated bandwidth for each of the optical transmitters. When the ratio of the average values between the optical transmitters exceeds a predetermined range, the wavelength or time allocated to the optical transmitter having a high average value is reduced.

  The station side apparatus allocates the allocated band to each optical transmitter so that the ratio of the average values of the allocated bands of the respective optical transmitters is within a predetermined range. Thereby, fairness of the allocated bandwidth between users can be realized.

  Specifically, the optical communication method of the present invention shares a time domain and a plurality of core wires between a plurality of optical subscriber side devices and one station side device, and transmits and receives signal light using a passive optical branch circuit. In the optical communication method, the station side device monitors the core line and time assigned to the optical transmitter of the optical subscriber side device, calculates an average value of the allocated bandwidth for each optical transmitter, When the ratio of the average values between the optical transmitters exceeds a predetermined range, the core or time allocated to the optical transmitter having a high average value is reduced.

  The station side apparatus allocates the allocated band to each optical transmitter so that the ratio of the average values of the allocated bands of the respective optical transmitters is within a predetermined range. Thereby, fairness of the allocated bandwidth between users can be realized.

  In the optical communication method of the present invention, it is preferable that the station side device calculates the average value between the optical transmitters requesting bandwidth allocation exceeding a predetermined guaranteed bandwidth.

  The above inventions can be combined as much as possible.

  According to the present invention, it is possible to provide an optical communication system and an optical communication method that realize fairness of allocated bandwidth between users by allocating so that an average value of allocated bandwidth is within a predetermined allocated bandwidth ratio. Can do.

1 is a schematic configuration diagram illustrating an example of an optical communication system according to a first embodiment. An example of a time chart of signal light from an optical transmitter at point X is shown. An example of a bandwidth allocation method is shown. FIG. 5 is a schematic configuration diagram illustrating an example of an optical communication system according to a second embodiment. An example of a time chart of signal light from an optical transmitter at point X is shown. An example of a conventional bandwidth allocation method is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are embodiments 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 schematic configuration diagram illustrating an example of an optical communication system according to the present embodiment. The optical communication system according to the present embodiment includes ONU-A (11-1-A), ONU-B (11-1-B), and ONU-C (11-1-C) as a plurality of optical subscriber side devices. ), An OLT (21-1) as a station side device, and an optical splitter 12 as a passive optical branching circuit.

  The optical communication system according to the present embodiment uses the optical splitter 12 by sharing a time domain and a plurality of wavelength domains between the ONU-A to C (11-1-A to C) and the OLT (21-1). To transmit and receive signal light. The optical communication system is typically applied to a PON, for example, but a passive tree other than the PON can also be applied.

  The optical communication system according to the present embodiment includes a controller (not shown) and executes the optical communication method according to the present embodiment. The controller (not shown) monitors the wavelength and time assigned to the optical transmitters A to C (10-1-A to C) and monitors each of the optical transmitters A to C (10-1-A to C). The average value of the allocated bandwidth is calculated. Then, an average value ratio between the optical transmitters A to C (10-1-A to C) is calculated, and the optical transmitters A to C are set so that the average value ratio falls within a predetermined range. The wavelength and time allocated to C (10-1-A to C) are determined. Hereinafter, the optical communication system and the optical communication method according to the present embodiment will be specifically described.

  The controller (not shown) is connected to a position where the communication states of the optical transmitters A to C (10-1-A to C) can be monitored. For example, it is connected to the optical transmission line with the OLT (21-1) via the optical splitter 12. A controller (not shown) is arrange | positioned at OLT (21-1), for example.

  The ONU-A (11-1-A) includes an optical transmitter A (10-1-A). The same applies to ONU-B (11-1-B) and ONU-C (11-1-C). The OLT (21-1) includes an optical multiplexer / demultiplexer (25), a light receiver a (22-1-a), and a light receiver b (22-1-b). The optical multiplexer / demultiplexer (25) is, for example, a wavelength filter. The light receivers a and b (22-1-a and b) are, for example, photodiodes. Here, an optical receiver mounted on the ONU-A to C (11-1-A to C) and an optical transmitter mounted on the OLT (21-1) are omitted.

  ONU-A to C (11-1-A to C) are installed in the subscriber's house. The optical transmitters A to C (10-1-A to C) output signal light having an allocated wavelength. The assigned wavelength is one of a plurality of selectable wavelengths. The output signal light is transmitted through the optical fiber and is coupled by the optical splitter (12). The optical transmission line couples the signal light from the optical transmitters A to C (10-1-A to C) to the optical receiver (20-1) by wavelength division multiplexing and time division multiplexing. The optical multiplexer / demultiplexer (25) demultiplexes and outputs the signal light from the optical transmission path for each wavelength. The light receivers a and b (22-1-a, b) respectively receive the signal light from the optical multiplexer / demultiplexer (25). Accordingly, the optical receiver (20-1) receives the signal light from the optical transmitters A to C (10-1-A to C) for each of a plurality of wavelengths.

  A controller (not shown) assigns a wavelength and a time at which signal light can be transmitted to the optical transmitters A to C (10-1-A to C). For example, the optical transmitters A to C (10-1-A to C) output signal light at a predetermined one wavelength assigned from two wavelengths (λ1, λ2). In this way, the controller (not shown) assigns the wavelength and time to the optical transmitters A to C (10-1-A to C), whereby the allocated band is determined.

  FIG. 2 shows an example of a time chart of signal light from the optical transmitter at point X. The vertical direction is the transmission wavelength region given to the optical transmitters A to C, and the horizontal direction shows the transmission allocation time given to the optical transmitters A to C. The optical transmitter A transmits the signal light of wavelength λ1 in the allocated time region from time t1 to time t2. The optical transmitter B transmits the signal light having the wavelength λ1 in the allocated time region from time t2 to time t3. The optical transmitter C transmits the signal light of wavelength λ2 in the allocated time region from time t1 to time t2. As described above, the optical communication system shown in FIG. 1 performs the wavelength division multiplexing and the time division multiplexing on the signal light from the optical transmitters A to C (10-1-A to C) to perform the optical receiver (20-1). ).

  At this time, the controller ensures that the bandwidth allocated to the optical transmitters A and B (10-1-A, B) having the wavelength λ1 and the optical transmitter C (10-1-C) having the wavelength λ2 is fair. The bandwidth allocated to the optical transmitter C (10-1-C) having the wavelength λ2 is suppressed. As a result, the bandwidth is equally allocated to any of the optical transmitters A to C (10-1-A to C) between the times t1 and t3.

  The optical multiplexer / demultiplexer (25) demultiplexes the signal light into the wavelengths λ1 and λ2, and couples them to the light receivers a and b (22-1-a, b), respectively. The light receivers a and b (22-1-a and b) respectively output the received signal light as electric signals.

  The optical receiver (20-1) can simultaneously receive signal lights of different wavelengths, but cannot simultaneously receive signal lights of the same wavelength. Therefore, the controller (not shown) communicates with the optical transmitters A to C (10-1-A to C) so that the signal light with the same wavelength does not reach the optical receiver (20-1) at the same time. It is necessary to allocate possible time.

  For this reason, the controller instructs the optical transmitter A (10-1-A) to output the signal light having the wavelength λ1 at time t1, and instructs the optical transmitter B (10-1-B) to output the signal having the wavelength λ1. An instruction is given to stop the transmission of light, and an instruction is given to the optical transmitter C (10-1-C) to output the signal light of wavelength λ2. The controller instructs the optical transmitter A (10-1-A) to stop sending the signal light at time t2, and outputs the signal light having the wavelength λ1 to the optical transmitter B (10-1-B). And instruct the optical transmitter C (10-1-C) to stop sending the signal light.

  When the transmission distances from the optical transmitters A to C (10-1-A to C) to the optical receiver (20-1) are different, the controller sets the time between the signal lights so as not to overlap when they are combined. Adjust the interval. When the signal light is composed of frames, the controller adjusts the frame interval.

  The controller is configured so that the bandwidth allocated to the optical transmitters A and B (10-1-A, B) belonging to the wavelength λ1 and the optical transmitter C (10-1-C) belonging to the wavelength λ2 is fair. The allocated bandwidth of the optical transmitter C (10-1-C) belonging to the wavelength λ2 is suppressed. In other words, the present optical communication system is a basic value of the allocated bandwidth so that the allocated bandwidth is within a certain range regardless of the accommodated wavelength, for example, the ratio of the guaranteed bandwidth to the guaranteed bandwidth ratio. For example, the controller performs an operation to suppress excessive allocation to accommodated users accommodated in wavelengths where the total guaranteed bandwidth is small, thereby realizing fairness of allocated bandwidth between users regardless of the accommodated wavelengths. Yes.

  As a method for such allocation, for example, the controller monitors the wavelength and time allocated to the optical transmitters A to C (10-1-A to C), and the optical transmitters A to C (10-1). The average value of the allocated bands for each of (A to C) is calculated, and the ratio of the average values among the optical transmitters A to C (10-1-A to C) is calculated. Then, the controller determines the wavelength and time to be assigned to the optical transmitters A to C (10-1-A to C) so that the ratio of the average values falls within a predetermined range.

  For this purpose, the controller retains the history of the allocated bandwidth assigned to the requested bandwidth requested to the optical transmitters A to C (10-1-A to C), and compares the retained history. . Then, the bandwidth allocated to the optical transmitters A to C (10-1-A to C) is determined so that the bandwidth allocated falls within a predetermined ratio range.

  For example, the controller includes a history holding unit that holds the history of both the allocated bandwidth or the requested bandwidth and the allocated bandwidth for each user, a comparison unit that compares the history held by the history holding unit, and a comparison value of the comparison unit. Accordingly, a suppression unit is included that suppresses allocation to a user who is allocated excessively for a predetermined time or allocated bandwidth. As for the history, the communication history may be a history in a window for a certain period of time in the past, may be a history of a sliding window for a certain period of time, or may be a history based on an average such as an exponential average or a weighted average. .

  Then, the controller sets the upper limit of the allocation to the user as the maximum bandwidth until the average value of the allocated bandwidth exceeds a predetermined ratio, and until the average value returns to the predetermined ratio after exceeding, Processing is performed such that the upper limit of allocation is set to a guaranteed bandwidth that guarantees allocation.

  Here, the predetermined range can be arbitrarily set. For example, the certain range is the ratio of the guaranteed bandwidth. When the guaranteed bandwidth of the optical transmitters A to C (10-1-A to C) is 1: 1: 1, a predetermined range is set to 1: 1: 1. In this case, the allocated bandwidths of all-optical transmitters A to C (10-1-A to C) can be equalized. If the ratios of the guaranteed bands differ because the priorities of the optical transmitters A to C (10-1-A to C) are different, the ratio of the guaranteed bands is set. Thereby, the fairness of the allocated bandwidth according to the priority can be realized. Here, the fixed range is illustrated as a single set of values. However, when the deviation from the uniform allocation band is allowed, for example, if the maximum allocation value is allowed up to twice that, the allocation Allocated bandwidth to the lowest optical transmitter: Allocated bandwidth = 1: 1 to 1: 2 to the largest allocated optical transmitter is a predetermined fixed range.

  For the optical transmitters A to C (10-1-A to C), a guaranteed band or a light that is a band that must be allocated to each of the optical transmitters A to C (10-1-A to C). There may be a case where one or both of the maximum bandwidths, which are the upper bandwidths of the allocation to each of the transmitters A to C (10-1-A to C), are set. In addition, the bandwidth allocated to the optical transmitters A to C (10-1-A to C) is allocated according to the required bandwidth required by the optical transmitters A to C (10-1-A to C). The requested bandwidth is the amount of information waiting to be transmitted and the transmission stored in the optical transmitters A to C (10-1-A to C) declared by the optical transmitters A to C (10-1-A to C). It is decided according to the amount of information in the past and past communication history. The communication history may be a history in a window for a fixed time in the past, a history of a sliding window for a fixed time, or a history based on an average such as an exponential average or a weighted average.

FIG. 3 shows an example of the bandwidth allocation method. A case where the predetermined range is a one-to-one constant value will be described. In this case, initially, the optical transmitter A uses the maximum bandwidth, and the optical transmitter C uses the intermediate bandwidth between the maximum bandwidth and the guaranteed bandwidth. When the predetermined time ΔT ₁ elapses, the average value of the allocated bandwidth of the optical transmitter A at the time ΔT ₁ exceeds a certain range (constant value), and the bandwidth allocated to the optical transmitter A becomes excessive. At this point, the wavelength band assigned to the optical transmitter A is reduced to the guaranteed band.

When the predetermined time ΔT ₂ elapses, the average value of the allocated bands between the optical transmitter A and the optical transmitter C at the time ΔT ₁ and the time ΔT ₂ becomes the same. At this time t3, the same band is allocated to the optical transmitter A and the optical transmitter C. As a result, the ratio of the average values of the allocated bands of the optical transmitter A and the optical transmitter C can be set to 1: 1, which is a predetermined range (fixed value), and the fairness of the band can be maintained. After the average value of the allocated bandwidth between the optical transmitter A and the optical transmitter C becomes the same, both the maximum bandwidth and the guaranteed bandwidth are alternately allocated so that the time average value of the allocated bandwidth becomes the same. It may be assigned.

  Although FIG. 3 shows an example of the optical transmitter A and the optical transmitter C, the optical transmitter A may be a group composed of a plurality of optical transmitters. The same applies to the optical transmitter B and the optical transmitter C. In this case, when the ratio of the average values of the allocated bands allocated to one group exceeds a predetermined range, the time allocated to the group having a high average value is reduced.

  In order to perform such processing, at the time of processing, the controller, at least for a predetermined time, except for a user who does not request bandwidth allocation, the allocated bandwidth has a predetermined ratio between users who request bandwidth allocation. The allocated bandwidth is determined so as to be within the range. This is because bandwidth allocation cannot be performed unless all users request the allocated bandwidth unless the allocated bandwidth is within a predetermined ratio range between users requesting bandwidth allocation. If the bandwidth requirement for all users can be roughly categorized as either requiring more than the guaranteed bandwidth or not requiring it at all, if the allocated bandwidth is within a predetermined ratio range between users requesting bandwidth allocation Good.

  Furthermore, when there are many users who request only a small amount of bandwidth less than the guaranteed bandwidth, the allocated bandwidth is determined so that the allocated bandwidth is within a predetermined ratio range between users whose requested bandwidth is equal to or greater than the allocated bandwidth. For example, the controller calculates an average value between optical transmitters that request bandwidth allocation exceeding a predetermined guaranteed bandwidth. Thereby, when there is a user who requests only a small amount of bandwidth below the guaranteed bandwidth, it is possible to prevent the allocated bandwidth from being suppressed by the bandwidth of the user having the minimum required bandwidth.

  If the objective is to suppress only the profits of survivors of conventional users with low guaranteed bandwidth, the average value of conventional users exceeded a predetermined ratio with respect to the average value of premium users who have a required bandwidth that exceeds the allocated bandwidth. Sometimes, it is also possible to suppress the conventional user assignment.

  As described above, the controller holds the history of the requested bandwidth and the allocated bandwidth requested for each of the optical transmitters A to C (10-1-A to C), compares the retained history, and is over-allocated. By suppressing the bandwidth allocated to the existing optical transmitter, the bandwidth allocated to the optical transmitters A to C (10-1-A to C) is determined so that the allocated bandwidth falls within a predetermined ratio range.

  The present invention is characterized in that the average bandwidth allocated between users requesting bandwidth allocation is equal in time average. This is advantageous in terms of fairness and efficiency compared to the case where the average bandwidth is a fixed value.

  For example, when the average bandwidth is fixed to the guaranteed bandwidth, the maximum bandwidth does not appear even if no group is congested. In that case, since the maximum bandwidth is almost not output, the utilization efficiency of the apparatus is reduced meaninglessly. If the average bandwidth is set to be equal to or greater than the guaranteed bandwidth and the maximum available bandwidth is equal to the total guaranteed bandwidth of the group, a congested group, especially on access lines where the number of users sharing the bandwidth is small and the statistical multiplexing effect cannot be expected Then, the average bandwidth is not reached. For this reason, the allocated bandwidth of the non-congested group is reduced as compared with the case where there is no limit, but the unfairness between the groups remains.

  In the present embodiment, a single request bandwidth and an allocation bandwidth are shown for each user, but different allocation methods may be used for a plurality of request bandwidths and allocation bandwidths. For example, a band that is fixedly allocated to each user may be separately provided, and only the band excluding the band may be allocated in the present embodiment.

  In FIG. 1, three optical transmitters A to C (10-1-A to C) and two wavelengths are illustrated, but the number of optical transmitters A to C (10-1-A to C) is illustrated. The number of wavelengths to be wavelength-division multiplexed may be 3 or more. In FIG. 1, one optical receiver (20-1) side receives a wavelength division multiplexed signal, but there are a plurality of optical receivers (20-1) that respectively receive the wavelength division multiplexed signals. May be. Further, the optical communication system may be a bidirectional communication system. In the above description, the single optical transmitters A to C (10-1-A to C) communicate with only a single wavelength at the same time, but simultaneously communicate using a plurality of wavelengths. The same applies to

(Embodiment 2)
FIG. 4 is a conceptual diagram illustrating the optical communication system of the present embodiment. The difference between the present optical communication system and the optical communication system of FIG. 1 is that each optical transmitter is distributed and accommodated in a plurality of core wires instead of being distributed and accommodated in a plurality of wavelengths.

  The optical communication system according to the present embodiment shares the time domain and a plurality of core wires between the ONU-A to C (11-1-A to C) and the OLT (21-1), and uses the optical splitter 12. Transmit and receive signal light. The optical communication system is typically applied to a PON, for example, but a passive tree other than the PON can also be applied.

  The optical communication system according to the present embodiment includes a controller (not shown) and executes the optical communication method according to the present embodiment. The controller (not shown) is configured so that the OLT (21-2) monitors the core wires and times assigned to the optical transmitters A to C (10-2-A to C) and the optical transmitters A to C (10 The average value of the allocated bandwidth for each of (-2-A to C) is calculated. Then, the ratio of the average values between the optical transmitters A to C (10-2-A to C) is calculated, and the optical ratio is set so that the ratio of the average values is a constant value within a predetermined range. The core line and time allocated to the transmitters A to C (10-2-A to C) are determined. Hereinafter, the optical communication system and the optical communication method according to the present embodiment will be specifically described.

  The controller (not shown) is connected to a position where the communication states of the optical transmitters A to C (10-2-A to C) can be monitored. For example, it is connected to the optical transmission line with the OLT (21-2) via the optical splitter 12. A controller (not shown) is arrange | positioned at OLT (21-2), for example.

  The ONU-A (11-2-A) includes an optical transmitter A (10-2-A). The same applies to ONU-B (11-2-B) and ONU-C (11-2-C). The OLT (21-2) includes a light receiver a (22-2a) and a light receiver b (22-2b). The light receivers a and b (22-2a and b) are, for example, photodiodes. Here, an optical receiver mounted on the ONU-A to C (11-2-A to C) and an optical transmitter mounted on the OLT (21-2) are omitted.

  ONU-A to C (11-2-A to C) are installed in the subscriber's house. The optical transmitters A to C (10-2-A to C) output signal light to one of the selectable core wires. The assigned core wire is one core wire among a plurality of selectable core wires. The output signal light is transmitted through the optical fiber and is coupled by the optical splitter (12). The optical transmission line couples the signal light from the optical transmitters A to C (10-2-A to C) to the optical receiver (20-2) by performing core line multiplexing and time division multiplexing.

  The optical receiver (20-2) includes a plurality of light receivers a and b (22-2-a and b) that receive light from the optical transmission path for each core wire. The light receivers a and b (22-2a and b) are, for example, photodiodes. The light receivers a and b (22-2a and b) respectively output the received signal light as electric signals. As described above, the optical communication system according to the present embodiment is configured such that the signal light from the optical transmitters A to C (10-2-A to C) is subjected to the core line multiplexing and the time division multiplexing to the optical receiver (20-2). To join.

  The controller is the same if the wavelength in the first embodiment is read as the core wire. A controller (not shown) allocates a core wire and time capable of transmitting signal light to the optical transmitters A to C (10-2-A to C). For example, the optical transmitters A to C (10-2-A to C) output signal light using a predetermined single core line assigned from the two core lines (H1, H2). As described above, the controller (not shown) assigns the core wire and time to the optical transmitters A to C (10-2-A to C), thereby determining the allocation band.

  FIG. 5 shows an example of a time chart of signal light from the optical transmitter at point X. The vertical direction is the core line given to the optical transmitters A to C, and the horizontal direction shows the transmission allocation time given to the optical transmitters A to C. The optical transmitter A transmits the signal light of the core wire H1 in the allocated time region from time t1 to time t2. The optical transmitter B transmits the signal light of the core wire H1 in the allocated time region from time t2 to time t3. The optical transmitter C transmits the signal light of the core wire H2 in the allocated time region from time t1 to time t2. As described above, the optical communication system shown in FIG. 4 is an optical receiver (20-2) in which signal light from the optical transmitters A to C (10-2-A to C) is subjected to core line multiplexing and time division multiplexing. To join.

  At this time, the controller ensures that the bandwidth allocated to the optical transmitters A and B (10-2-A, B) of the core wire H1 and the optical transmitter C (10-2-C) of the core wire H2 is fair. The allocated bandwidth of the optical transmitter C (10-2-C) of the core wire H2 is suppressed. As a result, every optical transmitter is evenly allocated a band between times t1 and t3.

  The optical transmitters A to C (10-2-A to C) output signal light using a predetermined one core wire assigned from the two core wires (H1, H2). The optical transmitter A transmits the signal light in the transmittable area through the core wire H1. The optical transmitter B transmits the signal light of the core wire H1 in the transmittable area. The optical transmitter C transmits the signal light of the core wire H2 in the transmittable area.

  The optical transmission line combines the signal light from the optical transmitters A to C (10-2-A to C) and couples it to the optical receiver (20-2). Here, although signal light of different core wires can be received simultaneously, signal light of the same core wire cannot be received simultaneously. Therefore, the controller designates the communicable time to the optical transmitters A to C (10-2-A to C) so that the signal light of the same core wire does not reach the optical receiver (20-2) at the same time. .

  Therefore, the controller instructs the optical transmitter A to output the signal light of the core wire H1 at the time t1, instructs the optical transmitter B to stop sending the signal light of the core wire H1, and transmits the optical transmitter C. Is instructed to output the signal light of the core wire H2. The controller instructs the optical transmitter A to stop sending the signal light at time t2, instructs the optical transmitter B to output the signal light of the core wire H1, and sends the signal light to the optical transmitter C. Instruct to stop.

  When the transmission distance from the optical transmitter to the optical receiver (20-2) 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 controller suppresses the allocated bandwidth of the optical transmitter C belonging to the core H2 so that the allocated bandwidth to the optical transmitters A and B belonging to the core H1 and the optical transmitter C belonging to the core H2 is fair. . In other words, the present optical communication system is a basic value of the allocated bandwidth such that the allocated bandwidth is within a certain range regardless of the core wire accommodated, for example, the ratio of the guaranteed bandwidth. For example, the controller performs an operation to suppress over-allocation to accommodated users accommodated in core wires with a small sum of guaranteed bandwidths, thereby realizing fairness of allocated bandwidth between users regardless of the accommodated core wires. Yes.

  As a method of such allocation, for example, the controller monitors the cores and times allocated to the optical transmitters A to C (10-2-A to C) and monitors the optical transmitters A to C (10-2). The average value of the allocated bandwidth for each of (A to C) is calculated. Then, an average value ratio between the optical transmitters A to C (10-2-A to C) is calculated, and the optical transmitters A to C are set so that the average value ratio falls within a predetermined range. The core line and time allocated to C (10-2-A to C) are determined.

  For this purpose, the controller holds the history of the allocated bandwidth allocated to the requested bandwidth requested to the optical transmitters A to C (10-2-A to C), and compares the held history. By suppressing the bandwidth allocated to the excessively allocated optical transmitter, the bandwidth to the optical transmitters A to C (10-2-A to C) is adjusted so that the allocated bandwidth falls within a predetermined ratio range. Determine the allocated bandwidth.

  The controller includes, for example, a history holding unit that holds the history of both the allocated bandwidth or the requested bandwidth and the allocated bandwidth for each user, a comparison unit that compares the history held by the history holding unit, and a comparison value of the comparison unit. Accordingly, a suppression unit is included that suppresses allocation to a user who is allocated excessively for a predetermined time or allocated bandwidth. As for the history, the communication history may be a history in a window for a certain period of time in the past, may be a history of a sliding window for a certain period of time, or may be a history based on an average such as an exponential average or a weighted average. .

  Then, the controller sets the upper limit of the allocation to the user as the maximum bandwidth until the average value of the allocated bandwidth exceeds a predetermined ratio, and until the average value returns to the predetermined ratio after exceeding, Processing is performed such that the upper limit of allocation is set to a guaranteed bandwidth that guarantees allocation. The functions and operations of the controller are as described in the first embodiment.

  Also in the present embodiment, as described in the first embodiment, when there are many users who request only a small amount of bandwidth less than or equal to the guaranteed bandwidth, the allocated bandwidth is within a predetermined ratio range between users whose requested bandwidth is greater than or equal to the allocated bandwidth. The allocated bandwidth is determined so that For example, the controller calculates an average value between optical transmitters that request bandwidth allocation exceeding a predetermined guaranteed bandwidth. Thereby, when there is a user who requests only a small amount of bandwidth below the guaranteed bandwidth, it is possible to prevent the allocated bandwidth from being suppressed by the bandwidth of the user having the minimum required bandwidth.

  As described above, the controller holds the history of the requested bandwidth and the assigned bandwidth requested for each of the optical transmitters A to C (10-2-A to C), compares the retained history, and is over-allocated. By allocating the allocated bandwidth to the existing optical transmitter, the allocated bandwidth to the optical transmitters A to C (10-2-A to C) is determined so that the allocated bandwidth falls within a predetermined ratio range.

  Here, although time division multiplexing is used for each core wire, wavelength division multiplexing and time division multiplexing may be used in each core wire as in the first embodiment. At this time, the controller ensures fairness between the core wires of the core wires.

  In FIG. 4, three optical transmitters and two core wires are illustrated, but the number of optical transmitters may be increased or decreased, and the number of core wires to be multiplexed may be three or more. Further, in FIG. 4, one optical receiver (20-2) side receives the signal multiplexed by the core wire, but there may be a plurality of optical receivers (20-2). Further, the optical communication system may be a bidirectional communication system.

  In the above description, the single optical transmitters A to C (10-2-A to C) are described as examples in which communication is performed using only a single core wire at the same time, but communication is performed using a plurality of core wires at the same time. The same applies to the case where the first embodiment of the present invention is combined with the present embodiment. When assigning, in consideration of the difference in ONU-OLT distance difference, chromatic dispersion, and the difference in transmission time due to the distance difference between the plurality of core wires, the transmission time of the transmitter in the case where simultaneous transmission is not possible, When the signals cannot be received simultaneously, the arrival times of the signals arriving at the receiver are assigned so as not to overlap each other.

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

10-1-A to C, 10-2-A to C: Optical transmitter
11-1-A to C, 11-2-A to C: Optical subscriber unit ONU
12: Optical splitters 20-1, 20-2: Optical receivers 21-1, 21-2: Station side apparatus OLT
22-1-a, 22-2-a: light receiver a
22-1-b, 22-2-b: light receiver b
23: Core wire H1
24: Core wire H2
25: Optical multiplexer / demultiplexer

Claims (6)

An optical communication system that shares a time domain and a plurality of wavelength domains between a plurality of optical subscriber-side devices and a single station-side device, and transmits and receives signal light using a passive optical branch circuit,
The station side device monitors the wavelength and time assigned to the optical transmitter of the optical subscriber side device, calculates the average value of the allocated bandwidth for each optical transmitter, and the average between the optical transmitters An optical communication system that calculates a ratio of values and determines a wavelength and time to be allocated to an optical transmitter of the optical subscriber side apparatus so that the ratio of the average values is within a predetermined range. An optical communication system that shares a time domain and a plurality of core wires between a plurality of optical subscriber side devices and a single station side device, and transmits and receives signal light using a passive optical branch circuit,
The station side device monitors the core line and time assigned to the optical transmitter of the optical subscriber side device, calculates the average value of the allocated bandwidth for each optical transmitter, and the ratio of the average values is predetermined. An optical communication system for determining a core line and a time allocated to an optical transmitter of the optical subscriber side apparatus so as to be within a predetermined range.   3. The optical communication system according to claim 1, wherein the station side device calculates the average value between the optical transmitters requesting bandwidth allocation exceeding a predetermined guaranteed bandwidth. 4. An optical communication method for sharing a time domain and a plurality of wavelength domains between a plurality of optical subscriber side apparatuses and a single station side apparatus, and transmitting and receiving signal light using a passive optical branch circuit,
The station side device monitors the wavelength and time assigned to the optical transmitter of the optical subscriber side device, calculates the average value of the allocated bandwidth for each optical transmitter, and the ratio of the average values is determined in advance. An optical communication method for determining a wavelength and a time to be allocated to an optical transmitter of the optical subscriber side apparatus so as to be within a certain range. An optical communication method for transmitting and receiving signal light using a passive optical branch circuit, sharing a time domain and a plurality of core wires between a plurality of optical subscriber side devices and one station side device,
The station side device monitors the core line and time assigned to the optical transmitter of the optical subscriber side device, calculates the average value of the allocated bandwidth for each optical transmitter, and the ratio of the average values is predetermined. An optical communication method for determining a core line and a time allocated to an optical transmitter of the optical subscriber side apparatus so as to be within a predetermined range.   The optical communication method according to claim 4 or 5, wherein the station side device calculates the average value between the optical transmitters requesting bandwidth allocation exceeding a predetermined guaranteed bandwidth.

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