JP2011055172A - Optical communication system and optical communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication system evading an invalid band allocation in the declaration of a threshold and a buffer amount when allocating a plurality of wavelengths, a plurality of core wires or bands of different priorities by a simultaneous declaration for the declaration for performing a plurality of allocations from an OLT to an ONU. <P>SOLUTION: In the optical communication system, the optical transmitter of a subscriber side device is equipped with: a threshold setting unit for defining a number equal to or larger than the smaller one of the maximum number of wavelengths allocatable to one declaration of the same optical transmitter and a value for which 1 is subtracted from the number of optical transmitters to be an allocation object in the same allocation cycle as the number of thresholds, and setting a value for which the maximum value of allocatable transmission permissions is added to the value of the boundary of a declaration frame declared corresponding to the threshold of the preceding stage as the threshold; and a declaration unit for declaring the boundary and total buffer length of a data frame equal to or lower than the set threshold and closest to the threshold, respectively. <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 inexpensive SiGe-BiCMOS process conventionally used in a high-speed access network, an intensity modulation-direct detection method is assumed. Due to constraints, the upper limit of the total 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. OLT (Optical Line Terminal) is required to have optical transmitters / receivers corresponding to the number of optical subscriber unit ONUs. 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.

  Furthermore, a GE-PON system that realizes optical fiber access section communication at 1 Gbps is known (see Non-Patent Document 3). Such a GE-PON can realize a gigabit FTTH service by transmitting a variable-length frame, and can solve the problem of an increase in cost due to the total bandwidth expansion.

"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 Institute), 2009 IEICE General Conference, Communication Lectures Collection 2, p. 426 "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 “Technology Basic Course [GE-PON Technology] 3rd DBA Function”, Noriyuki Ota et al., NTT Technology Journal 2005.10, pp. 65-70

  By the way, in the GE-PON system that transmits variable-length frames, in order to suppress invalid bandwidth allocation that cannot be used for allocation and transmitted in units of frames without dividing the frames, the allocated information amount and the frame breaks are matched. At the same time, a method of declaring the boundary of the data frame that is not more than a preset threshold and is closest to the threshold and the total buffer amount has been adopted. On the other hand, since this reporting method is proposed for transmitting traffic having a single wavelength, a core, and the same priority, a plurality of wavelengths or a plurality of cores are suppressed while suppressing invalid band allocation by a single report. Alternatively, it has been difficult to allocate bandwidth to multi-priority traffic.

  In addition, when the preset threshold value is simply expanded to a plurality of values, there is a problem that invalid allocation that cannot be used for allocation occurs. For example, the threshold is an integral multiple of 1542 bytes of the maximum data length, the guaranteed value for data allocation to each wavelength in each allocation period is 1542 bytes for data below the threshold, and the frame stored in the buffer is 88 bytes , 1475 bytes, 1521 bytes. Consider a case where the first threshold value is set to 1542 bytes and the second threshold value is set to 3084 bytes with a fixed threshold value of 1542 bytes, which is a guaranteed value of transmission permission to each wavelength in each allocation period. For the maximum frame edge below the first threshold, the frame edge of the second frame is 1563 bytes, which is a combination of 88 bytes and 1475 bytes. Since this value exceeds the first threshold, the declared value corresponding to the first threshold is 88 bytes, which is the frame end of the first frame.

  The maximum frame edge below the second threshold is 3084 bytes when 88 bytes, 1475 bytes, and 1521 bytes are combined. The declared value corresponding to the second threshold is 3084 bytes, which is the frame end of the third frame. The allocation corresponding to the report value is 2996 bytes obtained by subtracting the report value (88 bytes) corresponding to the first threshold value from the report value (3084 bytes) corresponding to the second threshold value. From the above, the allocation to the wavelength corresponding to the declared value of the first threshold (wavelength 1) is 88 bytes, and the allocation of the wavelength corresponding to the declared value of the second threshold (wavelength 2) is 2996. However, since 2996 bytes exceed 1542 bytes, which is a value that guarantees data allocation to the wavelength in each allocation period, the amount of information to be allocated cannot be matched with a frame break, and invalid allocation is avoided. I couldn't.

  In addition, when allocating bandwidths of classes with different priorities to simultaneous declarations, traffic of lower priority classes of the same optical transmitter with the remaining allocated bandwidth of higher priority classes is not preferentially used. A problem arises when fair assignment is made with priority class traffic for all transmitters. In other words, the remaining bandwidth in the class that should be allocated to other optical transmitters in the higher priority class is used for traffic in the lower priority class of the same optical transmitter. Does not match. The priority refers to the order of band allocation. When traffic is aggregated again at the destination device and priority processing is performed according to the original priority in the event of congestion, there is a high risk of being discarded because the low priority class uses the bandwidth of the high priority class. This is not preferable because the allocated bandwidth is discarded.

  Accordingly, the present invention provides an optical communication system and an optical communication method applicable to a PON in order to solve the above-described problems, and a plurality of wavelengths, a plurality of core wires, or a priority for a declaration for making a plurality of assignments from an OLT to an ONU. To provide an optical communication system and an optical communication method capable of avoiding invalid bandwidth allocation due to threshold value and buffer amount reporting and the accompanying shortage of allocation when performing allocation of different bandwidths simultaneously. And

  In order to achieve the above object, an optical communication system according to a first aspect of the present invention shares a time domain and a plurality of wavelength domains between a plurality of subscriber-side apparatuses and one station-side apparatus, and is a passive optical branch circuit. An optical communication system that transmits and receives signal light using the optical transmitter, wherein the optical transmitter of the subscriber side device can allocate the maximum number of wavelengths that can be allocated to one declaration of the same optical transmitter and the same allocation period Can be assigned to the boundary value of the reporting frame declared in accordance with the preceding threshold value, with the smaller number or more of the values obtained by subtracting 1 from the number of optical transmitters to be assigned as the threshold number. A threshold setting unit that sets a value obtained by adding a maximum value of transmission permission as a threshold, and a reporting unit that reports a boundary of a data frame that is equal to or less than the set threshold and a total buffer length. And

  An optical communication system according to a first aspect of the present invention includes an optical multiplexer / demultiplexer in which an optical receiver of the station side device demultiplexes signal light for each wavelength and outputs demultiplexed signal light, and the optical multiplexing / demultiplexing It is preferable to provide a plurality of light receivers that respectively receive the demultiplexed signal light from the receiver.

  An optical communication system according to a second aspect of the present invention shares a time domain and a plurality of core wires between a plurality of 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 optical transmitter of the subscriber side apparatus can allocate the maximum number of core wires that can be assigned to one declaration of the same optical transmitter and the optical transmitter to be assigned in the same allocation cycle. The maximum number of transmission permission that can be assigned is added to the value of the boundary of the declaration frame declared according to the previous threshold value. A threshold value setting unit that sets a value as a threshold value, and a reporting unit that reports a boundary of a data frame that is equal to or smaller than the set threshold value and the total buffer length are provided.

  In the optical communication system according to the second aspect of the present invention, it is preferable that the optical receiver of the station side device includes a plurality of light receivers that receive the signal light for each core wire.

  An optical communication system according to a third aspect of the present invention is an optical communication in which a plurality of subscriber side devices and one station side device share a time domain and a core wire, and transmit and receive signal light using a passive optical branch circuit. In the system, the optical transmitter of the subscriber-side apparatus can assign the maximum number of classes with different priorities that can be assigned to one declaration of the same optical transmitter, and the optical transmission to be assigned in the same assignment cycle. The maximum number of transmission permission that can be assigned to the boundary value of the declaration frame declared according to the previous threshold is set to the number of thresholds that is the smaller of the number obtained by subtracting 1 from the number of machines. A threshold setting unit that sets the added value as a threshold value, and a reporting unit that reports the boundary of the data frame that is equal to or less than the set threshold value and the total buffer length, respectively.

  According to a fourth aspect of the present invention, there is provided an optical communication method in which a plurality of subscriber-side devices and one station-side device share a time region and a plurality of wavelength regions, and transmit and receive signal light using a passive optical branch circuit. In this optical communication method, the maximum number of wavelengths that the optical transmitter of the subscriber side apparatus can allocate to one declaration of the same optical transmitter and the optical transmitter to be allocated in the same allocation cycle The number of thresholds is equal to or greater than the smaller value of 1 minus one, and the threshold is added to the value of the boundary of the reporting frame declared according to the previous threshold, and the maximum value of transmission permission that can be assigned is added. The threshold value is set as a threshold value, and the boundary of the data frame closest to the threshold value and the total buffer length is reported below the set threshold value.

  An optical communication method according to a fifth aspect of the present invention shares a time domain and a plurality of core wires between a plurality of subscriber-side devices and a single station-side device, and transmits and receives signal light using a passive optical branch circuit. In the optical communication method, the optical transmitter of the subscriber-side apparatus can allocate the maximum number of core wires that can be allocated to one declaration of the same optical transmitter and the optical transmitter to be allocated in the same allocation cycle. The maximum number of transmission permission that can be assigned is added to the value of the boundary of the declaration frame declared according to the previous threshold value. A value is set as a threshold value, and the boundary of the data frame closest to the threshold value and less than the set threshold value and the total buffer length are reported.

  According to a sixth aspect of the present invention, there is provided an optical communication method in which a plurality of subscriber side devices and one station side device share a time domain and a wavelength domain, and transmit and receive signal light using a passive optical branch circuit. In the communication method, the optical transmitter of the subscriber-side device can assign the maximum number of classes with different priorities that can be assigned to one declaration of the same optical transmitter, and the optical to be assigned in the same assignment cycle. The maximum number of transmission permissions that can be assigned to the value of the border of the reporting frame declared according to the previous threshold value, with the smaller number or more of the values obtained by subtracting 1 from the number of transmitters as the threshold number. A value obtained by adding is set as a threshold value, and the boundary of the data frame closest to the threshold value and the total buffer length is reported below each set threshold value.

  In the optical communication system according to the present invention, the optical transmitter of the subscriber side apparatus has a threshold of the number of bands to which a bandwidth is allocated in one declaration as a declaration, up to the maximum frame end below the threshold and the transmission buffer capacity. Declare the amount of data. Therefore, it distributes and accommodates the traffic of a plurality of users to each of a plurality of wavelengths, core lines, or priorities for one declaration of the same optical transmitter, and avoids invalid bandwidth allocation and insufficient allocation accompanying it, An optical communication system that can expand the total bandwidth and is optimal for PON.

  Further, the optical communication method according to the present invention distributes and accommodates a plurality of user traffics to each of a plurality of wavelengths, core lines or priorities for one declaration of the same optical transmitter, and allocates an invalid band. This is an optical communication method that is optimal for PON and can extend the total bandwidth.

1 is a schematic configuration diagram of an optical communication system according to a first embodiment of the present invention. It is the figure which showed the example which allocated the zone | band by the time division multiplexing system for every wavelength. It is the schematic diagram which showed the threshold value setting at the time of using the optical communication system which concerns on 1st Embodiment, and the report corresponding to the said threshold value. It is the schematic diagram which showed the threshold value setting piled up fixed and the report corresponding to the said threshold value. It is the figure which showed the relationship between the report of a front | former stage, and the maximum value of a self-report. It is a schematic block diagram of the optical communication system which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the optical communication system which concerns on 3rd Embodiment of this invention. It is the figure which showed the example which allocated the band by the time division multiplexing system for every priority.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment. Moreover, the same code | symbol was attached | subjected to the same apparatus and the same member.

(First embodiment)
(1) Configuration of optical communication system:
FIG. 1 is a schematic configuration diagram of an optical communication system 1 according to the first embodiment. The optical communication system 1 according to the present embodiment is applied to a PON (Passive Optical Network) that transmits and receives signal light by sharing a time domain and a plurality of wavelength domains between a plurality of subscriber-side apparatuses and a single station-side apparatus. The optical communication system 1 includes six optical transmitters 2 (optical transmitters A, B, C, D, E, and F), an optical receiver 3, an optical transmission line 4, and a controller (not shown) as a basic configuration. In the following figures including FIG. 1, the subscriber side optical device (ONU) has the optical transmitter 2, but the subscriber side optical device is not shown. Similarly, the station side device (OLT) has the optical receiver 3, but the station side device is not shown.

  The optical transmitter 2 (optical transmitter A, B, C, D, E, F) of the subscriber unit is owned by each user, and outputs signal light of one wavelength among a plurality of selectable wavelengths. To do. The six optical transmitters 2 output signal light so that they do not overlap each other at different times with respect to the three wavelengths (λ1, λ2, λ3). This is not the case when the signal light can be transmitted by overlapping the input signal with respect to a plurality of wavelengths separately for each frame.)

  A controller (not shown) is provided for each wavelength such as λ1, λ2, and λ3 in accordance with the declared values reported from the optical transmitter 2 to the optical transmitter 2 (optical transmitters A, B, C, D, E, and F). In the time division multiplexing method, a bandwidth is allocated with transmission permission. FIG. 2 is a diagram showing an example in which a band is assigned by the time division multiplexing method for each wavelength of λ1, λ2, and λ3 when the optical receiver 3 receives the band.

  Further, the optical receiver 3 of the station side device includes an optical multiplexer / demultiplexer 31 for demultiplexing light from an optical transmission line 4 to be described later for each wavelength and outputting a demultiplexed signal light, and an optical multiplexer / demultiplexer 31. And a plurality of light receivers 32 (three light receivers A, B, and C in the present embodiment) that respectively receive the demultiplexed signal light from the light receivers 32. For example, a wavelength filter or the like can be applied as the optical multiplexer / demultiplexer 31, and a photodiode or the like can be used as the light receiver 32 (light receivers A, B, and C), for example. The optical receiver 3 receives signal light from the optical transmitter 2 (optical transmitters A, B, C, D, E, and F) for each of a plurality of wavelengths. The optical multiplexer / demultiplexer 31 demultiplexes the mixed signal light as shown in FIG. 1 into a wavelength λ1, a wavelength λ2, and a wavelength λ3, and couples them to the light receivers 32 (light receivers A, B, and C), respectively. The light receiver 32 outputs the received signal light as an electrical signal.

  The optical transmission line 4 combines the signal light from the optical transmitter 2 (optical transmitters A, B, C, D, E, and F) by wavelength division multiplexing and time division multiplexing and couples to the optical receiver 3. . Here, the optical receiver 3 can simultaneously receive the signal light of different wavelengths, but cannot receive the signal light of the same wavelength at the same time, so that the signal light of the same wavelength does not arrive at the optical receiver 3 at the same time. A controller (not shown) designates a communicable time for the optical transmitter 2.

  Furthermore, when the optical transmitter 2 cannot transmit signal light due to temporal overlap with a plurality of wavelengths, as shown in FIG. 2, the controller (not shown) controls the same optical transmitter 2 for different wavelengths. Thus, the time during which transmission is permitted includes the time required for switching the wavelength transmitted by the optical transmitter 2, and the communicable time is specified so as not to overlap each other. The time required for switching the wavelength includes a difference in transmission time for each wavelength. That is, when switching from a wavelength having a long transmission time to a short wavelength, a transmission time difference is added to the time required for switching, and in the opposite case, it is reduced. Further, since the controller cannot receive the signal light from a plurality of optical transmitters at the same wavelength at the same time, it does not overlap at the optical receiver 3 in consideration of the difference in transmission time at each wavelength for each optical transmitter. The communication possible time is specified in.

(2) Report:
The optical transmitter 2 constituting the optical communication system 1 according to the present embodiment has a maximum wavelength that a threshold setting unit (not shown) arranged in the optical transmitter can assign to one declaration of the same optical transmitter. Declaration frame in which the threshold number is equal to or greater than the smaller of the number and the value obtained by subtracting 1 from the number of optical transmitters 2 to be allocated in the same allocation cycle, and the threshold is declared according to the previous threshold A value obtained by adding the maximum value of the transmission permission that can be assigned to the value of the boundary between the values is set as the threshold value. Also, a reporting unit (not shown) reports the boundary of the data frame closest to the threshold value and the total buffer length from the set threshold value. As described above, the smaller number of the maximum number of wavelengths that can be assigned to one declaration of the same optical transmitter and the value obtained by subtracting 1 from the number of optical transmitters 2 to be assigned in the same allocation period. It has the above threshold value, and declares the data amount up to the maximum frame end below the threshold value and the transmission buffer capacity.

  The lower limit of the number related to the number of optical transmitters 2 in the threshold is derived from the current multiple request method of GE-PON. The lower limit setting will be described below. Usually, in the multiple request method, the frame end value including the IFG and preamble is used to declare the end value of the frame below a predetermined threshold and the end value (total buffer length) of all frames. Note that if the value at the end of all frames is less than or equal to the predetermined threshold, both values match. The purpose of this reporting method is to reduce invalid allocation, which occurs because the transmission permission does not match the end of the frame, to at most one frame length per allocation cycle. Make the following assignments using the declared value.

-When the total sum of all optical transmitter (ONU) declarations falls within the transmission permission for one allocation cycle:
All-optical transmitters (ONUs) are assigned with the end values of all frames. Invalid allocation is almost zero and there is an unallocated bandwidth. Here, “nearly zero” means that the allocation is in units of TQ, and therefore, there is an invalid bandwidth allocation corresponding to a fraction when it does not match an integer multiple of TQ.

・ When the total sum of all optical transmitter (ONU) declarations greatly exceeds the transmission permission for one allocation period:
All but one of the optical transmitters (ONUs) to be allocated within one allocation period are allocated with the end value of the frame below the threshold, and the remaining bandwidth is equal to or less than the end value of all the frames of the optical transmitter (ONU). To assign to one optical transmitter (ONU). The invalid bandwidth allocation due to the frame length not matching is only allocation to the ONU to which the remaining bandwidth is allocated.

When the sum of all optical transmitter (ONU) declarations slightly exceeds the transmission permission for one allocation period:
All but one of the optical transmitters (ONUs) to be allocated within one allocation period are allocated with the end value of the frame below the threshold value or the end value of all frames, and the remaining bandwidth is allocated to one optical transmitter (ONU). . The invalid bandwidth allocation due to the frame length not matching is only allocation to the ONU to which the remaining bandwidth is allocated.

  Considering the above allocation, among the optical transmitters (ONUs) allocated in one allocation cycle, the value of the end of the frame below a predetermined threshold is 1 from the optical transmitter (ONU) allocated in one allocation cycle at the maximum. Only a reduced number is used. Here, when the end of the total frame length matches the value of the end of the frame that is equal to or smaller than the predetermined threshold, it is considered that the value of the end of the frame that is equal to or smaller than the predetermined threshold is not used. For this reason, the number of thresholds is set to be equal to or greater than the number obtained by subtracting 1 from the optical transmitter (ONU) allocated in one allocation cycle.

  As is clear from the premise of setting the number of thresholds, when not declaring the end value (total buffer length) of all frames, the wavelength of the wavelength that can be assigned to one report of the same optical transmitter Obviously, the maximum number is equal to or larger than the smaller one of the number of optical transmitters 2 to be allocated in the same allocation period. The lower limit of the number of thresholds is the same for the following embodiments of the present invention.

Here, regarding the setting of the threshold value, the threshold value Tn in the n-th stage (n = 1 to N: N is the number of threshold values) can be expressed by Expression (1).
_Tn = _Mn + Rn _-1 (1)

Here, the maximum frame end value that does not exceed the threshold value T _n of the n-th stage is defined as a declared value R _n corresponding to the threshold value T _n (where R ₀ = 0). M _n is the maximum amount of data that can be guaranteed by the transmission permission corresponding to the report corresponding to the threshold value T _n (the maximum frame length that can be reported taking into account the IFG and preamble), and is set in advance. The However, the setting of the maximum data amount may be changed in a timely manner according to the congestion state on the receiver side and the number of stages and the reporting cycle. The threshold value T _n of the n-th stage is changed by the report value R _n-1 corresponding to the threshold value T _n-1 of the n-1 stage for each report. As shown in the equation, the value is determined by adding the maximum data amount M _n that can be declared to the declared value R _n−1 .

  Next, an optical communication method implemented using the optical communication system 1 according to the present embodiment shown in FIG. 1 will be described. When determining the number of thresholds, the maximum number of wavelengths that can be assigned to one declaration of the same optical transmitter 2 (for example, optical transmitter A) is 3 from the description of FIG. Since the value obtained by subtracting 1 from the number of optical transmitters 2 (six) is 5, the number of threshold values may be three or more, which is the smaller number.

  The maximum amount of data that can be reported for each report (maximum value of data allocation to each wavelength in each allocation period) is 1542 bytes, which is the maximum frame length plus IFG (Inter Frame Gap) and preamble. The frame length stored in the buffer is a frame length including IFG and preamble, and is 88, 1475, and 1521 bytes in order from the top.

  FIG. 3 is a schematic diagram illustrating threshold setting and reporting corresponding to the threshold when the optical communication system 1 according to the present embodiment is used. As shown in FIG. 3, when the optical communication system according to the present embodiment is used, the first threshold is 1542 bytes, and the declared value for the first threshold is 88 bytes. The second threshold value is a value obtained by adding the maximum data amount that can be declared by the declaration corresponding to the second threshold value to the declaration of the first threshold value, that is, 1630 bytes obtained by adding 1542 bytes to 88 bytes. For this reason, the declared value corresponding to the second threshold is 1563 (= 88 + 1475) bytes. The request corresponding to the second declaration value is 1475 bytes obtained by subtracting the declaration value of the first threshold value, which is the previous threshold value, from the declaration value of 1563 bytes of the second threshold value, and the declaration value of the first threshold value, 88 bytes. Become. Similarly, the next threshold value is 3105 (= 1563 + 1542) bytes, and the declared value corresponding to the threshold value is 3084 (= 1563 + 1521 = 88 + 1475 + 1521) bytes. The request corresponding to the third declared value is 1521 bytes obtained by subtracting the declared value 1563 bytes of the second threshold, which is the previous declared value, from the declared value 3084 bytes of the third threshold, which is the current declared value. Become.

  The total buffer length is the total amount of data stored in the buffer. In the example described here, the total amount of data is 3084 bytes, and the declared value for the final threshold (the declared value for the third threshold). This is the same as 3084 bytes. If there is a frame that exceeds the final threshold with a frame length that takes into account the IFG and preamble, the value is greater than the declared value for the final threshold. For example, if the frame length in consideration of IFG and preamble and the frame length accumulated in the buffer is 88, 1475, 1521, 1000, it will be 4084 bytes, and if it is 88, 1475, 1521, 1000, 500, It is 4584 bytes.

  From this result, the allocation corresponding to the first declared value (for example, allocation to the transmitter A and the wavelength λ1) is 88 bytes, and the allocation corresponding to the next reported value (for example, allocation to the transmitter A and the wavelength λ2). Is 1475 bytes, and the allocation corresponding to the next declared value (for example, allocation to the transmitter A and the wavelength λ3) is 1521 bytes, and allocation can be performed without invalid bandwidth allocation.

  Here, the allocation corresponding to each declaration value is calculated from the declaration value at the current stage minus the declaration value at the previous stage. In the above example, the allocation corresponding to the first declaration value (for example, transmitter A, wavelength (assignment to λ1) is 88 bytes (= 88-0) bytes), and the assignment corresponding to the next declared value (eg, assignment to transmitter A, wavelength λ2) is 1475 bytes (= 1563-88) bytes, The allocation corresponding to the declared value (for example, allocation to transmitter A, wavelength λ3) is calculated as 1521 bytes (= 3084-1563) bytes. Further, in the present embodiment, the frame boundary value is reported as the declared value, but the difference from the frame boundary value reported in the previous stage may be used as the declared value. In the example, the declared value (difference from the border value of the frame declared in the previous stage) is 88 bytes, 1475 bytes, and 1521 bytes, respectively.

When the difference R _n −R _n−1 (= ΔR _n ) from the border value of the frame reported in the previous stage is to be reported, the threshold value T _{n in the} nth stage (n = 1 to N: N is a threshold value) Equation (1) indicating (number) can be expressed as the following equation (2).
_Tn = _Mn + Rn _-1
= M _n + ΣΔR _i (2)

Here, Σ is the sum up to n−1 regarding i, and ΔR _i is the difference R _i −R _{i−1 from} the value of the border of the frame declared in the previous stage. The respective threshold values are as follows, and it is understood that the threshold values are the same as when the reporting value Rn is reported.
T ₁ = M ₁ + ΣΔR _i = 1542 + 0 = 1542
T ₂ = M ₂ + ΣΔR _i = 1542 + 88 = 1630
T ₃ = M ₃ + ΣΔR _i = 1542 + 88 + 1475 = 3105
The same applies to the second and third embodiments described later.

  In addition, the example at the time of performing the fixed threshold value setting which is a prior art is demonstrated as a comparison. FIG. 4 is a schematic diagram showing fixed threshold values and report values corresponding to the threshold values. As shown in FIG. 4, in the case of a fixed threshold setting, the maximum amount of data that can be reported by the first threshold and the second threshold is 1542 bytes and 3084 bytes, respectively. The declared values are 88 bytes and 3084 bytes. Therefore, the request corresponding to the second declared value is obtained by subtracting the declared value of 3084 bytes of the second threshold value, which is the current declared value, from the declared value of 88 bytes of the first threshold value, which is the previous value. It exceeds 1542 bytes that can be guaranteed. For this reason, it can be seen that allocation with a small invalid allocation due to a mismatch between the frame breaks and the amount of information to be allocated cannot be performed using the declared value with the fixed threshold setting. This is because with a fixed threshold setting, a value obtained by subtracting the reported value from the maximum amount of data that can be reported in the previous stage may be added to the reported value of the previous stage.

  FIG. 5 is a diagram showing the relationship between the previous report value and the maximum value of the self report value. In FIG. 5, a solid line indicates a threshold setting when the optical communication system 1 according to the present embodiment is used, and a broken line indicates a threshold setting when the maximum data amount that can be reported is fixedly accumulated. As shown in FIG. 5, in the threshold setting when the optical communication system according to the present embodiment is used, the reporting value corresponding to each threshold is always suppressed to the maximum data amount that can be reported regardless of the reporting value in the previous stage. Can be confirmed. On the other hand, with the fixed threshold setting, it can be confirmed that there is a possibility that the maximum data amount that can be reported may be exceeded when the previous report value is 88 to 1541 bytes. Note that the maximum value of excess in such a setting is a value obtained by subtracting the minimum frame length from the maximum frame length.

  A typical example of this optical communication system is application to PON. In addition to PON, it can also be applied to passive trees. The same applies to the embodiments of the present invention described below.

  As described above, the optical communication system 1 according to the present embodiment is a one-time declaration, and a declaration for making a plurality of allocations from the OLT to the ONU. There are thresholds for the number of bands to be allocated, and the amount of data up to the maximum frame end below the threshold and the transmission buffer capacity is reported. Therefore, it is possible to allocate a plurality of users to a plurality of transmitters / receivers for each of a plurality of wavelengths for one declaration of the same optical transmitter, avoid invalid bandwidth allocation, and extend the total bandwidth. The optical communication system 1 that is optimal for PON can be provided.

(Second Embodiment)
(1) Configuration of optical communication system:
FIG. 6 is a schematic configuration diagram of the optical communication system 1 according to the second embodiment. The optical communication system 1 according to the first embodiment shown in FIG. 1 distributes and accommodates each optical transmitter into a plurality of wavelengths, whereas the optical communication system 1 according to the present embodiment includes each optical transmitter. Is different in that it is distributed and accommodated in a plurality of core wires.

  In the following description, parts that are the same as or substantially the same as those already described in the first embodiment are denoted by common reference numerals and description thereof is omitted.

  An optical communication system 1 according to the present embodiment shown in FIG. 6 is an optical communication system 1 applied to a PON, similar to the first embodiment described above, and includes six optical transmitters 2 (optical transmitters A, B, and C). , D, E, and F), an optical receiver 3, three optical transmission lines 41, 42, and 43 and a controller (not shown) as a basic configuration.

  The optical transmitter 2 (optical transmitter A, B, C, D, E, F) of the subscriber side device is owned by each user, and the signal light of one core wire among a plurality of selectable core wires is received. Output. The six optical transmitters 2 output signal light so that they do not overlap each other at different times with respect to the three core wires (H1, H2, H3) (in this case, each optical transmitter 2 This is not the case if the input signal can be sent separately for each frame and transmitted over multiple core wires in time.)

  A controller (not shown), for example, when the wavelength is replaced with a core wire in accordance with the reported value reported from the optical transmitter 2 to the optical transmitter 2 (optical transmitters A, B, C, D, E, F) As shown in FIG. 2, a bandwidth is allocated by time division multiplexing for each core wire.

  Further, the optical receiver 3 of the station side device has a plurality of light receivers 32 (three light receivers A, B, and C in the present embodiment) that respectively receive light from an optical transmission path 4 to be described later for each core wire. . For example, a photodiode or the like can be used as the light receiver 32 (light receivers A, B, and C). The optical receiver 3 receives signal light from the optical transmitter 2 (optical transmitters A, B, C, D, E, and F) for each of a plurality of core wires. The light receiver 32 outputs the received signal light as an electrical signal.

  The optical transmission line 4 time-division-multiplexes the signal light from the optical transmitter 2 (optical transmitters A, B, C, D, E, and F) and couples it to the optical receiver 3 for each core wire. Here, the optical receiver 3 can simultaneously receive the signal light of different core wires, but cannot receive the signal light of the same core wire at the same time, so that the signal light of the same core wire does not arrive at the receiver at the same time. The controller that does not specify the communicable time for the optical transmitter 2. The correspondence to the time required for switching the core wire and the transmission time difference for each core wire is the same as in the first embodiment.

(2) Report:
In the optical transmitter 2 constituting the optical communication system 1 according to the present embodiment, the maximum number of core wires that a threshold setting unit (not shown) arranged in the optical transmitter can assign to one declaration of the same optical transmitter. Declaration frame in which the threshold number is equal to or larger than the smaller number of the number and the value obtained by subtracting 1 from the number of optical transmitters 2 to be allocated in the same allocation cycle, and the threshold value is declared according to the previous threshold value A value obtained by adding the maximum value of the transmission permission that can be assigned to the value of the boundary between the values is set as the threshold value. Further, a notifying unit (not shown) reports the boundary of the data frame and the total buffer length that are not more than the set threshold values and are closest to the threshold values from the set threshold values. In this way, there are thresholds for the number of bands to be allocated in one report, and the amount of data up to the maximum frame end below the threshold and the transmission buffer capacity is reported respectively.

As for the lower limit of the number of thresholds and the setting of the thresholds, the threshold value T _{n of the} n-th stage (n = 1 to N: N is the number of thresholds) can be expressed by Equation (1), as in the first embodiment. Since the contents are the same, the description is omitted.

  Next, an optical communication method implemented using the optical communication system 1 according to this embodiment shown in FIG. 6 will be described. In determining the number of thresholds, the maximum number of core wires that can be assigned to one declaration of the same optical transmitter (for example, optical transmitter A) is 3, as shown in FIG. Since the value obtained by subtracting 1 from the number of optical transmitters 2 (six) is 5, the number of threshold values may be three or more, which is the smaller number.

  Then, the maximum amount of data that can be reported for each report (the maximum value of data allocation to each core wire in each allocation cycle) is set to the maximum frame length in the same way as in the first embodiment, and the IFG (Inter Frame Gap: frame interval time). ) And a preamble are added to 1542 bytes, and the frame length stored in the buffer is a frame length including IFG and preamble, and is 88, 1475, and 1521 bytes in order from the top.

  When the optical communication system according to the present embodiment is used, as shown in FIG. 3 described above, the first threshold value is 1542 bytes, and the declared value for the first threshold value is 88 bytes. The second threshold value is a value obtained by adding the maximum data amount that can be declared by the declaration corresponding to the second threshold value to the declared value of the first threshold value, that is, 1630 bytes obtained by adding 1542 bytes to 88 bytes.

  For this reason, the declared value corresponding to the second threshold is 1563 (= 88 + 1475) bytes. The request corresponding to the second declaration value is 1475 bytes obtained by subtracting the declaration value of the first threshold value, which is the previous threshold value, from the declaration value of 1563 bytes of the second threshold value, and the declaration value of the first threshold value, 88 bytes. Become. Similarly, the next threshold value is 3105 (= 1563 + 1542) bytes, and the declared value corresponding to the threshold value is 3084 (= 1563 + 1521 = 88 + 1475 + 1521) bytes. The request corresponding to the third declared value is 1521 bytes obtained by subtracting the declared value 1563 bytes of the second threshold, which is the previous declared value, from the declared value 3084 bytes of the third threshold, which is the current declared value. Become. As described in the first embodiment, the total buffer length is the total amount of data stored in the buffer. In the example described here, the total data amount is 3084 bytes, This is the same as 3084 bytes, which is the reporting value for the threshold (the reporting value for the third threshold).

  If there is a frame that exceeds the final threshold with a frame length that takes into account the IFG and preamble, the value is greater than the declared value for the final threshold. For example, if the frame length in consideration of IFG and preamble and the frame length accumulated in the buffer is 88, 1475, 1521, 1000, it will be 4084 bytes, and if it is 88, 1475, 1521, 1000, 500, It is 4584 bytes.

  From this result, the allocation corresponding to the first declared value (for example, allocation to the transmitter A and the core H1) is 88 bytes, and the allocation corresponding to the next declared value (for example, allocation to the transmitter A and the core H2). Is 1475 bytes, and the allocation corresponding to the next declared value (for example, allocation to the transmitter A and the core H3) is 1521 bytes, and allocation can be performed so that there is no invalid bandwidth allocation.

Here, as described in the first embodiment, the allocation corresponding to each reported value is calculated from the reported value at the current stage minus the reported value at the previous stage. Also, when the difference from the border value of the frame reported in the previous stage is used as the declared value, the threshold value T _{n in the} nth stage (n = 1 to N: N is the number of threshold values) as in the first embodiment described above. Can be expressed by equation (2), and the contents are the same, and thus the description thereof is omitted.

  In addition, you may combine this embodiment and 1st Embodiment. In that case, the lower limit of the threshold value may be read as the product of the number of core wires and the number of wavelengths.

  As described above, the optical communication system 1 according to the present embodiment is a one-time declaration, and a declaration for making a plurality of allocations from the OLT to the ONU. There are thresholds for the number of bands to be allocated, and the amount of data up to the maximum frame end below the threshold and the transmission buffer capacity is reported respectively. Therefore, it is possible to allocate a plurality of users to a plurality of transmitters / receivers in each of a plurality of core wires for one declaration of the same optical transmitter, avoid invalid band allocation, and extend the total band. The optical communication system 1 that is optimal for PON can be provided.

(Third embodiment)
(1) Configuration of optical communication system:
FIG. 7 is a schematic configuration diagram of an optical communication system 1 according to the third embodiment. The optical communication system 1 according to the first embodiment shown in FIG. 1 distributes and accommodates each optical transmitter into a plurality of wavelengths, and the optical communication system 1 according to the second embodiment shown in FIG. Whereas each optical transmitter is distributed and accommodated in a plurality of core wires, the optical communication system 1 according to the present embodiment has only one wavelength or only one core wire, and prioritizes each optical transmitter over the same optical transmitter. It is different in that a plurality of transmission permissions are given as classes having different degrees.

  In the following description, parts that are the same as or substantially the same as those already described in the first embodiment are denoted by common reference numerals and description thereof is omitted.

  An optical communication system 1 according to this embodiment shown in FIG. 7 is an optical communication system 1 applied to a PON, similar to the first and second embodiments described above, and includes six optical transmitters 2 (optical transmitters). A, B, C, D, E, and F), an optical receiver 3, an optical transmission line 4, and a controller (not shown) are provided as basic components.

  The optical transmitters 2 (optical transmitters A, B, C, D, E, and F) of the subscriber side devices are owned by each user, and output a plurality of classes of signals having different priorities. The six optical transmitters 2 output signal light so as not to overlap each other at different times.

  As shown in FIG. 8, for example, as shown in FIG. 8, the controller (not shown) is in accordance with the declaration value declared from the optical transmitter 2 with respect to the optical transmitter 2 (optical transmitters A, B, C, D, E, F). Bandwidth is allocated by time division multiplexing for each priority. FIG. 8 is a diagram illustrating an example in which a bandwidth is allocated by the time division multiplexing method for each priority (first priority, second priority, and third priority). In FIG. 8, as in FIG. 2, the order of transmission permission is different for each priority, but unlike the first and second embodiments, transmission is performed sequentially to a single receiver. Therefore, there is no fear that transmission permission between wavelengths and between core wires overlaps, and it is not necessary to change the order of permission for transmission.

  Further, the optical receiver 3 of the station side device has a light receiver 32 that receives light from an optical transmission path 4 to be described later. As the light receiver 32, for example, a photodiode or the like can be used. The optical receiver 3 receives signal light from the optical transmitter 2 (optical transmitters A, B, C, D, E, and F). The light receiver 32 outputs the received signal light as an electrical signal.

  The optical transmission line 4 time-division-multiplexes the signal light from the optical transmitter 2 (optical transmitters A, B, C, D, E, and F) and couples it to the receiver. The optical transmission path couples signal light from the transmitters A, B, C, D, E, and F to the optical receiver 3. Here, since the optical receiver 3 cannot receive the signal light at the same time, a controller (not shown) can communicate with the optical transmitter 2 so that the signal light does not reach the optical receiver 3 at the same time. It is specified.

(2) Report:
In the optical transmitter 2 constituting the optical communication system 1 according to the present embodiment, the threshold setting unit (not shown) arranged in the optical transmitter has a priority that can be assigned to one declaration of the same optical transmitter. The maximum number of different classes (the number of priorities to be considered) and the value obtained by subtracting 1 from the number of optical transmitters 2 to be allocated in the same allocation period are set as the number of thresholds, whichever is smaller. The threshold value is set as a threshold value obtained by adding the maximum value of the transmission permission that can be allocated to the boundary value of the reporting frame declared in accordance with the preceding threshold value. Further, a notifying unit (not shown) reports the boundary of the data frame and the total buffer length that are not more than the set threshold values and are closest to the threshold values from the set threshold values. In this way, the maximum number of classes with different priorities that can be assigned to one declaration of the same optical transmitter (the number of priorities to be considered) and the optical transmitters 2 to be assigned in the same assignment cycle. The threshold is equal to or greater than the smaller one of the values obtained by subtracting 1 from the number, and the data amount up to the maximum frame end below the threshold and the transmission buffer capacity is reported.

  Regarding the setting of the threshold value, the threshold value Tn of the n-th stage (n = 1 to N: N is the number of threshold values) can be expressed by equation (1), as in the first and second embodiments described above. Since the same applies to FIG.

  Next, an optical communication method implemented using the optical communication system 1 according to this embodiment shown in FIG. 7 will be described. In determining the number of thresholds, the maximum number of classes with different priorities that can be assigned to one declaration of the same optical transmitter (for example, optical transmitter A) is 3 based on FIGS. 7 and 8 and the above description. Since the value obtained by subtracting 1 from the number of optical transmitters 2 (six) to be allocated in the same allocation cycle is 5, the number of threshold values may be three or more, which is the smaller number. .

  Then, the maximum amount of data that can be reported for each report (the maximum value of data allocation to each core wire in each allocation cycle) is set to the maximum frame length in the same way as in the first and second embodiments described above. Gap: frame interval time) and 1542 bytes added to the preamble, and the frame length stored in the buffer is the frame length including IFG and preamble, and is 88, 1475, and 1521 bytes in order from the top.

  When the optical communication system according to the present embodiment is used, as shown in FIG. 3 described above, the first threshold value is 1542 bytes, and the declared value for the first threshold value is 88 bytes. The second threshold value is a value obtained by adding the maximum data amount that can be declared by the declaration corresponding to the second threshold value to the declared value of the first threshold value, that is, 1630 bytes obtained by adding 1542 bytes to 88 bytes.

  For this reason, the declared value corresponding to the second threshold is 1563 (= 88 + 1475) bytes. The request corresponding to the second declaration value is 1475 bytes obtained by subtracting the declaration value of the first threshold value, which is the previous threshold value, from the declaration value of 1563 bytes of the second threshold value, and the declaration value of the first threshold value, 88 bytes. Become. Similarly, the next threshold value is 3105 (= 1563 + 1542) bytes, and the declared value corresponding to the threshold value is 3084 (= 1563 + 1521 = 88 + 1475 + 1521) bytes. The request corresponding to the third declared value is 1521 bytes obtained by subtracting the declared value 1563 bytes of the second threshold, which is the previous declared value, from the declared value 3084 bytes of the third threshold, which is the current declared value. Become. As described in the first and second embodiments, the total buffer length is the total amount of data stored in the buffer. In the example described here, the total amount of data is 3084 bytes. It is the same.

  If there is a frame that exceeds the final threshold with a frame length that takes into account the IFG and preamble, the value is greater than the declared value for the final threshold. For example, if the frame length in consideration of IFG and preamble and the frame length accumulated in the buffer is 88, 1475, 1521, 1000, it will be 4084 bytes, and if it is 88, 1475, 1521, 1000, 500, It is 4584 bytes.

  From this result, the allocation corresponding to the first declared value (for example, transmitter A, allocation in the first priority class) is 88 bytes, and the allocation corresponding to the next declared value (for example, transmitter A, first priority). Allocation in the priority class of 2) is 1475 bytes, the allocation corresponding to the next declared value (eg, allocation in the transmitter A, the third priority class) is 1541 bytes, and there is no invalid bandwidth allocation. Can be assigned as

Here, as described in the first embodiment, the allocation corresponding to each reported value is calculated from the reported value at the current stage minus the reported value at the previous stage. Also, when the difference from the border value of the frame reported in the previous stage is used as the declared value, the threshold value T _{n in the} nth stage (n = 1 to N: N is the number of threshold values) as in the first embodiment described above. Can be expressed by equation (2), and the contents are the same, and thus the description thereof is omitted.

  Then, in the declaration in the optical communication system 1 of the present embodiment, when allocating bands corresponding to classes with different priorities, the remainder of the allocated bandwidth of the higher priority classes is assigned to the lower priority class of the same optical transmitter. It will be explained by using the above example that the traffic of the priority class of all the optical transmitters 2 can be allocated fairly without being preferentially used.

  The allocated bandwidth is the amount of transmission data per hour, and the threshold is set so that the amount of transmission data per time does not exceed the bandwidth that can be allocated to the ONU. Here, the threshold value is set with 1542 bytes as the data amount in one allocation to the first priority class and the second priority class.

  In the threshold value setting in which the thresholds are fixedly accumulated according to the prior art, the allocation in the first priority class is 88 bytes, and the allocation in the second priority class is 2996 bytes. On the other hand, the allocation to the second priority class exceeds 1542 bytes, which is the upper limit of the data amount in one allocation to the second priority class. This is an excess that occurs because the amount of data to be used in the allocation in the priority class is used in the second priority class. In this case, the low-priority class traffic of the same optical transmitter uses the bandwidth of the high-priority class traffic against the allocation policy, but such traffic is aggregated again at the transmission destination device (system). If the priority processing is performed according to the original priority at the time of congestion, the lower priority class uses the bandwidth of the higher priority class and is often discarded. Since it is discarded, it is not preferable. In addition, when data to be discarded due to policy violation is transmitted in the transmission destination device, the allocated bandwidth is wasted, and the use efficiency of the device is degraded.

  On the other hand, in the threshold setting in the optical communication system 1 of this embodiment, the allocation in the first priority class is 88 bytes, and the allocation in the second priority class is 1475 bytes. The allocation to the second priority class does not exceed 1542 bytes which is the upper limit value of the data amount in one allocation to the second priority class. This is because the amount of data that should be used for allocation in the first priority class is not used in the second priority class. In this case, the lower priority class traffic of the same optical transmitter does not use the higher priority class traffic bandwidth against the allocation policy. Even when the priority processing is performed according to the original priority, since the lower priority class does not use the bandwidth of the higher priority class, it is rarely discarded. For this reason, in the optical communication system 1 of the present embodiment, allocation of invalid bands is avoided, and the utilization efficiency of the device (system) is not deteriorated.

  In addition, you may combine this embodiment and 1st and 2nd embodiment. In this case, the lower limit of the threshold value may be read as the product of the number of cores, the number of wavelengths, and the number of priorities.

  Examples of combinations of the present embodiment and the first embodiment are as follows. The first priority class that accommodates traffic with a low allowance for disconnection time, such as telephone traffic, all accommodates the same wavelength, and uses the remaining bandwidth not used in the first priority class and the bandwidth of other wavelengths. This mode is used for class 2 or lower priority traffic.

  As described above, in the optical communication system 1 according to the present embodiment, as a declaration for making a plurality of allocations from the OLT to the ONUs in a single declaration, the declaration is made in a single request because of multiple allocations. There are thresholds for the number of bands to be allocated, and the amount of data up to the maximum frame end below the threshold and the transmission buffer capacity is reported respectively. Therefore, the traffic of a plurality of users is distributed and accommodated in each of a plurality of classes having different priorities for one declaration of the same optical transmitter, thereby avoiding invalid bandwidth allocation and extending the total bandwidth. Therefore, the optical communication system 1 that is optimal for PON can be provided.

(Modification of embodiment)
The aspect described above shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment, and has the configuration of the present invention and can achieve the objects and effects. It goes without saying that modifications and improvements within the scope are included in the content of the present invention. Further, the specific structure, shape, and the like in carrying out the present invention are not problematic as other structures, shapes, and the like as long as the objects and effects of the present invention can be achieved. The present invention is not limited to the above-described embodiments, and modifications and improvements within the scope that can achieve the object of the present invention are included in the present invention.

  In the first embodiment described above, the optical communication system 1 according to the present invention is illustrated with six optical transmitters 2 and three wavelengths. However, the number of optical transmitters 2 may be increased or decreased, or wavelength division may be performed. The number of wavelengths to be multiplexed may be 3 or more.

  Similarly, in the second embodiment, the optical communication system 1 according to the present invention is illustrated with six optical transmitters 2 and three core wires, but the number of optical transmitters 2 may be increased or decreased. The number of core wires may also be 3 or more.

  Similarly, in the third embodiment, the optical communication system 1 according to the present invention is illustrated with six optical transmitters 2 and one core wire and one wavelength, but the number of optical transmitters 2 may be increased or decreased. The wavelength may be increased by wavelength division multiplexing, or the number of core wires may be increased to achieve core multiplexing, or both.

  In the above-described embodiment, one optical receiver 3 side receives the wavelength division multiplexed signal in the optical communication system 1, but a plurality of optical receivers 3 may be provided. Furthermore, the optical communication system 1 according to the present invention may be a bidirectional communication system.

  In addition, the specific structure, shape, and the like in the implementation of the present invention may be other structures as long as the object of the present invention can be achieved.

  The present invention can be advantageously used in a technical field related to an optical communication system applied to a PON.

DESCRIPTION OF SYMBOLS 1: Optical communication system 2: Optical transmitter 3: Optical receiver 31: Optical multiplexer / demultiplexer 32: Light receiver 4: Optical transmission path 41: Optical transmission path 42: Optical transmission path 43: Optical transmission path

Claims (8)

An optical communication system that shares a time domain and a plurality of wavelength domains between a plurality of subscriber-side devices and one station-side device, and transmits / receives signal light using a passive optical branch circuit,
A value obtained by subtracting 1 from the maximum number of wavelengths that the optical transmitter of the subscriber-side apparatus can allocate to one declaration of the same optical transmitter and the number of optical transmitters to be allocated in the same allocation period. The smaller number is the number of thresholds,
A threshold value setting unit that sets a value obtained by adding the maximum value of the transmission permission that can be assigned to the boundary value of the reporting frame declared according to the previous threshold value, as the threshold value;
A declaring section for declaring the boundary of the data frame closest to the threshold value and the total buffer length below the set threshold value, respectively;
An optical communication system comprising:   The optical receiver of the station side device demultiplexes the signal light for each wavelength and outputs a demultiplexed signal light, and a plurality of demultiplexed signal lights respectively received from the optical multi / demultiplexer The optical communication system according to claim 1, further comprising a light receiver. An optical communication system that shares a time domain and a plurality of core wires between a plurality of subscriber side devices and one station side device, and transmits and receives signal light using a passive optical branch circuit,
A value obtained by subtracting 1 from the maximum number of core wires that the optical transmitter of the subscriber-side apparatus can allocate to one declaration of the same optical transmitter and the number of optical transmitters to be allocated in the same allocation cycle The number of thresholds is equal to or greater than the smaller one of
A threshold value setting unit that sets a value obtained by adding the maximum value of the transmission permission that can be assigned to the boundary value of the reporting frame declared according to the previous threshold value, as the threshold value;
A declaring section for declaring the boundary of the data frame closest to the threshold value and the total buffer length below the set threshold value, respectively;
An optical communication system comprising:   The optical communication system according to claim 3, wherein the optical receiver of the station side device includes a plurality of light receivers that respectively receive the signal light for each core wire. An optical communication system that shares a time domain and a core wire between a plurality of subscriber-side devices and one station-side device, and transmits and receives signal light using a passive optical branch circuit,
1 from the maximum number of classes with different priorities that the optical transmitter of the subscriber side apparatus can assign to one declaration of the same optical transmitter and the number of optical transmitters to be assigned in the same allocation period. The number of thresholds is equal to or greater than the smaller of the subtracted values,
A threshold value setting unit that sets a value obtained by adding the maximum value of the transmission permission that can be assigned to the boundary value of the reporting frame declared according to the previous threshold value, as the threshold value;
A declaring section for declaring the boundary of the data frame closest to the threshold value and the total buffer length below the set threshold value, respectively;
An optical communication system comprising: An optical communication method for sharing a time domain and a plurality of wavelength domains between a plurality of subscriber-side devices and one station-side device, and transmitting and receiving signal light using a passive optical branch circuit,
A value obtained by subtracting 1 from the maximum number of wavelengths that the optical transmitter of the subscriber-side apparatus can allocate to one declaration of the same optical transmitter and the number of optical transmitters to be allocated in the same allocation period. The number of thresholds is equal to or greater than the smaller one of
The threshold value is set as a threshold value obtained by adding the maximum value of the transmission permission that can be assigned to the boundary value of the declaration frame declared according to the previous threshold value, and the data frame closest to the threshold value below the set threshold value. An optical communication method characterized by declaring the boundary of the data and the total buffer length. 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 subscriber side devices and one station side device,
A value obtained by subtracting 1 from the maximum number of core wires that the optical transmitter of the subscriber-side apparatus can allocate to one declaration of the same optical transmitter and the number of optical transmitters to be allocated in the same allocation cycle The threshold number is set to the number of the smaller one of the threshold values, and the threshold value is set to a value obtained by adding the maximum value of the transmission permission that can be assigned to the boundary value of the reporting frame declared according to the previous threshold value, An optical communication method characterized by declaring a boundary of a data frame and a total buffer length which are not more than a set threshold value and are closest to the threshold value. An optical communication method in which a time domain and a wavelength domain are shared between a plurality of subscriber side apparatuses and one station side apparatus, and signal light is transmitted and received using a passive optical branch circuit,
1 from the maximum number of classes with different priorities that the optical transmitter of the subscriber side apparatus can assign to one declaration of the same optical transmitter and the number of optical transmitters to be assigned in the same allocation period. The number of thresholds is equal to or greater than the smaller of the subtracted values,
The threshold value is set as a threshold value obtained by adding the maximum value of the transmission permission that can be assigned to the boundary value of the declaration frame declared according to the previous threshold value, and the data frame closest to the threshold value below the set threshold value. An optical communication method characterized by declaring the boundary of the data and the total buffer length.

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