JP6285885B2 - Transceiver design apparatus, transceiver design method, and transceiver design program - Google Patents

Description

  The present invention relates to a transceiver design apparatus, a transceiver design method, and a transceiver design program for optimizing the specifications of a transceiver included in an optical communication apparatus.

  Due to the explosive increase in communication traffic in recent years, optical communication systems are required to have higher speed. In addition, high economic efficiency is also required at the same time to ensure a high speed and not to increase the service provision price as compared with the prior art.

  In an optical communication system, particularly in an access network that provides a network connection function to a plurality of users, it is a big problem to ensure economy while ensuring high speed. PON (Passive Optical Network) is an example of an optical communication system that can achieve both high speed and low cost. FIG. 1 shows a simplified PON model. The PON is a network based on the modulation of an optical signal using an optical fiber, and can construct a communication service with a wider bandwidth than a network using a conventional metal wiring. In PON, only optical branching by an optical splitter (optical branching device) placed in the middle of an optical fiber line is performed per station side device (OLT: Optical Line Terminal) accommodated in an equipment center (OLT accommodating station). Thus, a plurality of ONUs (Optical Network Units), that is, a plurality of users can be accommodated. For this reason, PON can be said to be a network with excellent economic efficiency.

  In constructing such a PON system, it is extremely important to perform user accommodation design efficiently and economically. For example, Patent Document 1 states that an optical splitter arrangement design method that can accommodate a user most efficiently can be realized by applying a special area division algorithm. However, the OLT and ONU are each equipped with an optical transceiver that is necessary for the physical interface of optical communication. However, in this document, there is no detailed description about this, and it is possible to design by simply defining the distance that can be accommodated by the user. This is just an assertion that it is not a more realistic design method.

  On the other hand, Patent Document 2 claims that it is possible to design an operation of the management target area by simplifying the operation of the management target area by accessing the information database of the optical receiving apparatus, that is, it is possible to guarantee the economic efficiency when operating the PON system. However, in this document, the registration name of the optical receiver, the address of the optical receiver, the area to which the optical receiver belongs, the subscriber information of the optical receiver, only the database containing the control information of the optical receiver, A description of an optical transceiver that is a physical interface of an optical receiver is missing.

  Therefore, there is no prior art in consideration of the characteristics of the optical transceiver in the system design method for improving the economic efficiency of the PON system.

  An optical stage component of an optical transceiver (hereinafter referred to as “transceiver”) is simply composed of two elements: an output laser for transmitting an optical signal and a light receiving photodiode for receiving the optical signal. The intensity of the optical signal output from the output laser is expressed as output power, and the lower limit value of the intensity of the optical signal that can be received by the photodiode is expressed by the minimum light receiving sensitivity. That is, if the specifications of the transceiver required in the PON system are arranged, it can be basically expressed by four parameters of the output power and minimum light receiving sensitivity of the OLT transceiver and the output power and minimum light receiving sensitivity of the ONU transceiver.

  The difference between the output power and reception sensitivity of the opposing transceivers between the OLT and the ONU is defined as the optical budget. The optical budget is defined by both the upstream budget (ONU to OLT direction) and the downstream budget (OLT to ONU direction) when wavelength multiplexing is performed according to the upper and lower communication directions such as GE-PON and 10G-EPON. The If the optical budget for either the upper or lower or both is insufficient, the optical power necessary for communication between the OLT and the ONU is insufficient, and bit error rate deterioration and link down occur, and the specified communication quality cannot be ensured. Therefore, in order to provide a fair PON system service to each user, all the accommodated users must be designed to satisfy the optical budget.

  The IEEE standard (IEEE Std. 802.3-2012) sets the upper and lower limits of transmission power and minimum light receiving sensitivity, and the corresponding transmission distance. In an ideal PON system, this optical budget regulation must be observed. If so, communication quality does not deteriorate (see, for example, Non-Patent Document 1). However, in an actual PON system, there are cases where it is desired to accommodate users longer than the distance specified by the IEEE standard, or when it is desired to introduce new equipment although optical loss increases. Therefore, assuming a case other than the IEEE standard, it is necessary to optimize the desired transceiver specification in advance while considering the line condition, and to estimate the user-accommodable distance and the loss allowed for the line in advance. It is extremely important in the design and construction of PON systems.

  However, the output power and minimum light receiving sensitivity of actual OLT and ONU transceivers are distributed with an average value at the time of manufacturing and manufacturing variations. At this time, if the specification of the transceiver to be manufactured is set excessively, it is possible to suppress the occurrence of a user having a budget shortage, while the cost required for manufacturing increases dramatically. For example, when it is desired to set the output of the output laser from +0 dBm or more to +2 dBm or more, under the condition that the manufacturing laser output center value / standard deviation is +0 dBm / 1 dB, the yield of a laser having an output of +2 dBm or more is that of +0 dBm or more. Compared to 1/20 or less (when normal distribution is assumed). In other words, if the manufacturing process is not improved and the yield reduction is simply passed on to the cost, the cost will increase more than 20 times at the maximum. On the other hand, if the manufacturing process is changed and the laser output center value is increased to +2 dBm, the entire manufacturing line such as manufacturing conditions, process control, inspection items, and test methods will fluctuate, and in some cases, the manufacturing yield will be affected. May give. This leads to higher investment costs.

  Therefore, not only does the optical budget not be insufficient for all users accommodated, but also the appropriate manufacturing specifications so as not to become excessive specifications, the output laser of the OLT transceiver, the photodiode, and the output laser of the ONU transceiver In addition, after optimizing the four manufacturing distributions of the photodiodes, it is necessary to set the accommodation distance of the user who can be secured.

"Optical network design support system and program", Japanese Patent No. 538548 "Optical receiver management program, optical receiver manager, and optical transmission system", Japanese Patent No. 5308174

Naoto Yoshimoto, “Future Outlook for Optical Access Technology”, IEICE Transactions B, Vol. J96-B, no. 3, pp. 233-242, 2013.

  However, it is difficult to determine an appropriate manufacturing specification for a transceiver in an actual PON system. This is because an actual PON system has a very large number of parameters required for analysis.

  First, the user accommodation situation accommodated in the PON system, that is, the distance from the OLT accommodation station and the user accommodation distribution must be considered. For users close to the OLT accommodation station, the optical budget may be small because the line loss is small, and for users far from the OLT accommodation station, the optical budget must be large because the line loss is large. Therefore, when ONU transceivers having specifications with a certain degree of variation are randomly accommodated, the affected range has a certain dependency on the accommodation distribution of users.

  In addition, in order to determine an appropriate manufacturing specification of the transceiver, it is necessary to consider the variation of the optical lines constituting the PON system. In an actual optical line, a certain error occurs due to the number of fusion points when the optical line is laid and variations in the laying distance. In other words, in addition to the above-described user accommodation distribution, it is necessary to consider that variation in line loss is superimposed on each user accommodated in each OLT.

  In accordance with the viewpoint of ensuring the fairness of the PON system, it is necessary to design an appropriate transceiver specification for all users taking all these effects into consideration and to set the user-accommodable distance. However, the scale of computation explodes for each of a large number of users nationwide, because it is necessary to perform multidimensional analysis as it is when applying the case of random application with manufacturing variations with specifications of OLT transceiver and ONU transceiver. Increase.

  As described above, in order to provide a high-quality communication service that does not have a shortage of budget for all users accommodated in an actual PON system, the optimal production distribution of OLT and ONU transceivers is accommodated by users. There is a problem that it is necessary to complete the analysis within a finite time while considering the distribution and the line loss variation.

  Accordingly, the present invention provides a transceiver design apparatus, a transceiver design method, and a transceiver design apparatus capable of proposing an optimum manufacturing specification of a transceiver of an optical communication device within a finite time in consideration of user accommodation distribution and line loss variation, in order to solve the above-described problems. An object is to provide a transceiver design program.

  In order to achieve the above object, a transceiver design device, a transceiver design method, and a transceiver design program according to the present invention calculate a budget distribution based on a minimum light receiving sensitivity and output power of a random number generated in a predetermined manufacturing distribution range. Calculate the cumulative budget shortage probability distribution according to the distance between the optical communication devices by adding the line loss distribution and the user distribution for each distance to the budget distribution, and the number of budget shortage users at the desired distance is within the allowable level We decided to determine the transceiver manufacturing specifications so that

Specifically, the transceiver design apparatus according to the present invention is:
Based on the manufacturing distribution of the minimum light receiving sensitivity and the optical output power of the transceiver included in the optical communication device, the generated values of the minimum light receiving sensitivity and the optical output power for the transceiver N (N is a integer greater than or equal to 2) are generated and generated. Calculating an optical budget between transceivers based on the generated value within a predetermined standard among the generated values, and calculating an optical budget distribution from a plurality of the optical budgets;
An optical budget less than an arbitrary value at an arbitrary point based on a line loss distribution representing a line loss from one optical communication device to an arbitrary point on the optical communication system and the optical budget distribution calculated by the optical budget distribution calculation unit Is a convolution calculation unit that calculates the cumulative number of optical budget shortage users who are short of the light budget at an arbitrary point by integrating with the user distribution representing the arrangement position of the optical communication device in the optical communication system. When,
The cumulative light budget shortage user number at an arbitrary point is compared with a predetermined allowable level value, and the manufacturing distribution given to the light budget distribution calculation unit when the cumulative light budget shortage user number is less than the allowable level value If the number of accumulated light budget deficient users is equal to or greater than the allowable level value and the number of calculations of the accumulated light budget deficient users is equal to or less than a specified number, change at least a part of the production distribution. An optimization unit for the light budget distribution calculation unit;
Is provided.

Further, the transceiver design method according to the present invention includes:
Based on the manufacturing distribution of the minimum light receiving sensitivity and the optical output power of the transceiver included in the optical communication device, the generated values of the minimum light receiving sensitivity and the optical output power for the transceiver N (N is a integer greater than or equal to 2) are generated and generated. An optical budget distribution calculation procedure for calculating an optical budget between transceivers based on the generated value within a predetermined standard among the generated values, and calculating an optical budget distribution from a plurality of the optical budgets;
An optical budget less than an arbitrary value at an arbitrary point based on a line loss distribution representing a line loss from one optical communication device to an arbitrary point on the optical communication system and the optical budget distribution calculated by the optical budget distribution calculation procedure A convolution calculation procedure for calculating the cumulative number of users who have insufficient optical budget at an arbitrary point by integrating with the user distribution representing the arrangement position of the optical communication device in the optical communication system. When,
The cumulative light budget insufficiency user number at a given point is compared with a predetermined allowable level value, and if the cumulative light budget insufficiency user number is less than the allowable level value, the manufacturing distribution given in the optical budget distribution calculation procedure If the number of accumulated light budget deficient users is equal to or greater than the allowable level value and the number of calculations of the accumulated light budget deficient users is equal to or less than a specified number, change at least a part of the production distribution. An optimization procedure for calculating the light budget distribution;
I do.

  The present invention provides an algorithm capable of designing the manufacturing specifications of the OLT transceiver and the ONU transceiver described in the above problem in a short time and accurately. The present invention has the following two features.

(Feature 1)
The present invention is characterized in that the Monte Carlo method is used in determining the specifications of the transceiver. The Monte Carlo method is a numerical calculation method in which a certain parameter is randomly generated, a desired result obtained when the parameter is used is calculated a plurality of times, and finally the calculation accuracy is improved by statistical processing. The Monte Carlo method has the advantage that the calculation is always completed within a finite time by setting the number of calculation trials to a finite number. According to the present invention, the production distribution of the output laser and photodiode of the transceiver of one optical communication device and the output laser and photodiode of the other optical communication device is randomly generated, and the budget is insufficient in that case. Can be easily estimated. This makes it possible to confirm whether or not the transceiver manufacturing distribution given by calculation is appropriate.

(Feature 2)
The present invention is characterized in that the Monte Carlo method is used only for the specification of the transceiver, and the convolution calculation is performed after the discretization process without applying the Monte Carlo method for the user accommodation distribution and the line loss variation. It is also possible to apply the Monte Carlo method described in the feature 1 to the user accommodation distribution and the line loss variation, but in that case, one random user generated distribution for one set of random numbers generated. Since one line loss variation corresponds, it is necessary to make the number of trials sufficiently large in order to cover all patterns, and the calculation time becomes long. On the other hand, the Monte Carlo method is used only for determining the manufacturing distribution of the transceiver, that is, the budget distribution, and then the probability that the other optical communication device (user) is included with respect to the distance from one optical communication device, and the line variation. If the user who runs out of the budget is convolved and calculated, the user-accommodable distance can be calculated while ensuring high calculation accuracy with a small number of trials.

  Therefore, the present invention can provide a transceiver design device and a transceiver design method capable of proposing an optimum manufacturing specification of a transceiver of an optical communication device within a finite time while considering a user accommodation distribution and a line loss variation.

  In the transceiver design apparatus and transceiver design method according to the present invention, the optical communication system is a PON, the optical communication apparatus is an OLT or an ONU constituting the PON, and the arbitrary point is a distance from the OLT. It is characterized by. The present invention can be applied to a PON.

  In the transceiver design device and the transceiver design method according to the present invention, the line loss distribution is such that a line loss from the optical communication device to the arbitrary point is different from a line loss in the optical communication device from the arbitrary point. And The present invention makes it possible to design a more accurate transceiver by considering a loss difference in the communication direction of the communication system.

  A transceiver design program according to the present invention causes a computer to execute the transceiver design method. The transceiver design apparatus and transceiver design method of the present invention can be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.

  By adopting the Monte Carlo method of the feature 1, the device budget distribution can be expressed without taking into account the complicated manufacturing distribution of the OLT / ONU transceiver, and as a result, the calculation can be completed within a finite time.

  Further, the feature 2 can ensure high calculation accuracy with a small number of trials, and the overall calculation time can be shortened.

  By combining these two features, it is possible to calculate the optimum transceiver manufacturing distribution for ensuring the user accommodation distance in a given line condition / user distribution in a short time and with high accuracy. If this calculation result is applied to the production line, it becomes possible to efficiently produce transceivers that are not over-spec, and measures can be taken to improve profitability.

  Accordingly, the present invention provides a transceiver design apparatus, a transceiver design method, and a transceiver design program capable of proposing an optimum manufacturing specification of a transceiver of an optical communication device within a finite time while considering a user accommodation distribution and a line loss variation. Can do.

It is a figure explaining the model of the simplified PON. It is a figure explaining the transceiver design apparatus based on this invention. It is a figure explaining the transceiver design method based on this invention. It is an example of the distribution of the output power and the minimum light receiving sensitivity of the transceiver in which random numbers are generated according to the normal distribution in the transceiver design method according to the present invention. It is an example of the budget distribution which performed the Monte Carlo simulation by the transceiver design method which concerns on this invention. , It is an example of track conditions. It is an example of user distribution. It is a figure explaining the image of the accumulation budget shortage probability distribution computed with the transceiver design method concerning the present invention. It is a figure explaining the accumulation budget shortage probability distribution computed with the transceiver design method concerning the present invention. It is a figure explaining the accumulation budget shortage probability distribution computed with the transceiver design method concerning the present invention. It is a list of parameters used in a calculation example of the transceiver design method according to the present invention.

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

FIG. 2 is a diagram for explaining the transceiver design apparatus of the present embodiment. The transceiver design apparatus of this embodiment is
Based on the manufacturing distribution of the minimum light receiving sensitivity and the optical output power of the transceiver included in the optical communication device, the generated values of the minimum light receiving sensitivity and the optical output power for the transceiver N (N is a integer greater than or equal to 2) are generated and generated. Calculating an optical budget between transceivers based on the generated value within a predetermined standard among the generated values, and calculating an optical budget distribution from a plurality of the optical budgets;
An optical budget less than an arbitrary value at an arbitrary point based on a line loss distribution representing a line loss from one optical communication device to an arbitrary point on the optical communication system and the optical budget distribution calculated by the optical budget distribution calculation unit 12. Is a convolution calculation unit that calculates the cumulative number of optical budget shortage users who are short of the light budget at an arbitrary point by integrating with the user distribution representing the arrangement position of the optical communication device in the optical communication system. 13 and
The cumulative light budget insufficiency number of users at an arbitrary point is compared with a predetermined allowable level value, and if the cumulative light budget insufficiency user number is less than the allowable level value, the manufacturing distribution given to the optical budget distribution calculation unit 12 If the number of accumulated light budget deficient users is equal to or greater than the allowable level and the number of calculations for the accumulated light budget deficient users is equal to or less than a specified number, at least part of the production distribution is changed to An optimization unit 14 to be provided to the budget distribution calculation unit 12,
Is provided.

FIG. 3 is a flowchart showing a processing procedure of a transceiver design method performed by the transceiver design apparatus of the present embodiment. The transceiver design method of this embodiment is
The optical budget distribution calculation unit 12 determines the minimum light reception sensitivity and light output power of the transceiver N (N is a finite integer of 2 or more) based on the manufacturing distribution of the minimum light reception sensitivity and light output power of the transceiver included in the optical communication device. An optical budget distribution calculating procedure for generating a generated value, calculating an optical budget between transceivers based on the generated value within a predetermined standard among the generated generated values, and calculating an optical budget distribution from a plurality of the optical budgets S101,
The convolution calculation unit 13 at an arbitrary point based on the line loss distribution representing the line loss from one optical communication device to an arbitrary point on the optical communication system and the optical budget distribution calculated in the optical budget distribution calculation procedure. The number of accumulated light budget shortage users who find the probability of occurrence of an optical budget below an arbitrary value and become short of the optical budget at an arbitrary point by integrating with the user distribution representing the arrangement position of the optical communication device in the optical communication system A convolution calculation procedure S102 for calculating
The optimization unit 14 compares the cumulative light budget shortage user number at a given point with a predetermined allowable level value. If the cumulative light budget shortage user number is less than the allowable level value, the light budget distribution calculation procedure S101 is performed. If the given production distribution is an optimum production standard, the cumulative light budget shortage user count is not less than the allowable level, and the cumulative light budget shortage user count is not more than a specified number, at least a part of the production distribution An optimization procedure which is given to the light budget distribution calculation procedure S101 by changing
I do.

  In this embodiment, the optical communication system is a PON, the optical communication apparatus is an OLT or an ONU constituting the PON, and the arbitrary point is a distance from the OLT.

[Parameters used in calculation]
The parameters used in the calculation are shown below. The subscript i takes two values, up and down, but in principle, it can be generalized to 2 or more in the case of wavelength multiplexing. The subscript j represents the jth generated parameter of all trials performed N times. X is a distance from the OLT accommodation station.

(1) Solution R (x) [people] to be finally obtained: cumulative budget shortage probability distribution (cumulative budget shortage number of users at point x)
(2) Desired transceiver manufacturing distribution (parameters to be optimized, manufacturing standards)
μ _{p, i} [dBm]: Average value of transceiver output power in manufacturing (i = down for OLT, i = up for ONU)
σ _{p, i} [dBm]: Variation in output power of transceiver (i = down for OLT, i = up for ONU)
μ _{s, i} [dBm]: average value for manufacturing the minimum light receiving sensitivity of the transceiver (i = up for OLT, i = down for ONU)
σ _{s, i} [dBm]: manufacturing variation of minimum light receiving sensitivity of transceiver (i = up for OLT, i = down for ONU)
(3) Specified parameters required for calculation (parameters that need to be given in advance)
P _{min, i} [dBm]: Lower limit value of transceiver output power in specification (OL = i = down, ONU i = up)
P _{max, i} [dBm]: Upper limit value of output power of transceiver according to specifications (i = down for OLT, i = up for ONU)
S _{min, i} [dBm]: Lower limit value of minimum light receiving sensitivity of transceiver according to specifications (i = down for OLT, i = up for ONU)
S _{max, i} [dBm]: Upper limit value OLT of minimum light receiving sensitivity of transceiver on specifications (OL = i = down, ONU i = up)
Λ _i (x) [dB]: Average line loss value from the OLT accommodating station at point x σ _{Λ, i} (x) [dB]: Variation in line loss at point x (line loss at point x in normal distribution) (The probability that the measured value falls into Λ _i (x) ± σ _{Λ, i} (x) is 68.2%)
U (x) [person]: Number of users accommodated at point x (4) Parameters required in the calculation process (parameters that do not need to be given in advance)
P _ij [dBm]: Output power of transceiver of j-th trial (i = down for OLT, i = up for ONU)
S _ij [dBm]: Minimum light receiving sensitivity of the j-th transceiver (i = up for OLT, i = down for ONU)
B _ij [dB]: Up / down budget D _{p, i} (P _i ) of the number of trials j times: Occurrence probability D _{s, i} (S _i ) of the output power P _i : Occurrence probability D _b of the minimum light receiving sensitivity S _{i , I} (B _i ): Probability of occurrence of budget B _i C _{b, i} (x, B _i ): Cumulative occurrence probability of budget B _{i at} point x (probability of occurrence of budget less than B _i )
C _b (x): Cumulative occurrence probability that satisfies all i, that is, the upper and lower budgets at the point x

  In order to derive the cumulative budget deficient number of users at point x, which is the final solution desired in (1) above, the parameters required in the calculation are the transceiver manufacturing distribution (4 parameters) desired in (2) above, And the parameters (7 parameters) required for the calculation of (3) above. The parameters required in the calculation process (4) are the minimum required parameters when mounted on a computer.

  In the present embodiment, for simplification, i takes up or down. Therefore, each subscripted parameter has two values. If both GE-PON and 10G-EPON coexist, the upper and lower sides of each must be taken into account, so i becomes four.

[Conditions for calculation]
The transceiver manufacturing distribution and line loss distribution follow a lognormal distribution. This does not mean that the power or loss of light is expressed as a normal distribution when expressed in watts, but indicates that the decibel value when the logarithm is taken follows a normal distribution. However, since the manufacturing distribution can be arbitrarily set in principle, the manufacturing distribution can be calculated by reflecting an arbitrary manufacturing distribution followed by a transceiver manufactured in an arbitrary manufacturing line.

  All parameters are independent trials. For example, it is assumed that an arbitrary operation such as preferentially assigning an ONU transceiver with a large budget to a distant place where the line loss is large (when x is large) is not performed. Based on this assumption, the budget distribution, line loss distribution, and user distribution can be handled as independent variables, and the calculation can be simplified.

[Summary of calculation]
The calculation for determining the number of budget-deficient users R (x) at the point x is performed in three stages. The budget distribution is obtained by the Monte Carlo method using the manufacturing distribution given as the first stage. As a second stage, the number of budget-deficient users R (x) at the point x is obtained based on the obtained budget distribution, line loss distribution, and user distribution. As a third step, the transceiver manufacturing distribution may be optimized so that R (x) is sufficiently small within the range desired to be provided by the assumed service. That is, the transceiver manufacturing distribution (manufacturing specifications) may be optimized so that the number of users that fall within the allowable level is less than a certain probability.

[Budget distribution calculation procedure]
First, random numbers are generated for the specifications of the OLT transceiver and the ONU transceiver, and the distribution of the upper and lower budgets is calculated based on the desired transceiver specifications. The concept is shown in FIG. Let N be the number of random numbers generated at this time, that is, the number of transceivers to be tried. The calculation time becomes longer as N increases, but the calculation result approaches an analytical solution, that is, an exact solution obtained mathematically without using random numbers. On the other hand, if N is small, the calculation time is shortened, but the calculation result deviates from the analysis result. If an appropriate N is specified at this time, the calculation is always completed within a finite time, and a result that the calculation accuracy substantially coincides with the analytical solution can be obtained. An appropriate setting method for N is to set N large if the variation in transceiver specifications or line loss is large, and to set N small if the variation is small. In the case of realistic manufacturing conditions and line conditions, a calculation result with almost desired calculation accuracy can be obtained if N is approximately 10,000 or more.

First, the initial transceiver manufacturing distribution (μ _{p, i} , σ _{p, i} , μ _{s, i} , σ _{s, i} ) is input to the parameter input unit 11. This may be input by an operator or may be introduced from another device using a communication function. Further, the budget distribution calculation unit 12 takes out the upper limit value and lower limit value (P _{min, i} , P _{max, i} , S _{min, i} , S _{max, i} ) of the output power of the transceiver and the minimum light receiving sensitivity from the transceiver specification DB 16. .

この正規分布は実際のトランシーバ作製の際の製造分布を模擬するが、実際の製造分布に応じて自由に分布を設定することができる。 The budget distribution calculation unit 12 calculates the budget distribution as follows using the transceiver manufacturing distribution.
Transceiver spec generation distributions D _{p, i} (P _ij ) and D _{s, i} (S _ij ) are generated in random numbers so that they follow a normal distribution in decibel display values.

Although this normal distribution simulates the manufacturing distribution at the time of actual transceiver fabrication, the distribution can be freely set according to the actual manufacturing distribution.

の条件を満たし、かつ、生起確率が１となるための正規化条件として、

を満たす必要がある。 However, since P _{i, j} and S _{i, j} must all comply with the specifications, transceivers with specifications that deviate from the upper and lower limits in the standard are not mixed.

As a normalization condition for satisfying the above condition and having an occurrence probability of 1,

It is necessary to satisfy.

図５に概念を示す。この上下バジェットを試行回数分算出し、統計を取ることでバジェットの分布、すなわちＰ_ｉｊと−Ｓ_ｉｊの重ね合わせ分布が求まる。ある任意のバジェットＢ_ｉが発生する確率Ｄ_ｂ，ｉ（Ｂ_ｉ）は、理想的にはＢ_ｉｊを用いて下式で算出することができる。

ここでδ（ｘ）は以下の挙動を示す。

Next, the upper and lower budget B _ij is calculated from the following equation from P _ij and S _ij generated by random numbers.

The concept is shown in FIG. By calculating the upper and lower budgets for the number of trials and taking statistics, the distribution of the budget, that is, the superimposed distribution of P _ij and -S _ij is obtained. The probability D _{b, i} (B _i ) that a certain arbitrary budget B _i is generated can be calculated by the following equation using B _ij ideally.

Here, δ (x) exhibits the following behavior.

ここで、δ’（ｘ）は以下の挙動を示す。

However, since the number of trials N is finite on an actual computer, δ (x) cannot be introduced. Therefore, a method of setting a budget interval having a finite width of ε and counting B _ij included therein, that is, B _ij is discretized with a granularity of ε and mounted. That is, the probability that an arbitrary budget B _i is included in the interval of ± ε / 2 is expressed by the following equation.

Here, δ ′ (x) exhibits the following behavior.

In other words, a section having an appropriate budget width ε may be set, and D _{b, i} (B _i ) may be calculated from the number of points where the budget of B _ij is included in the section. In order to return an ideal budget distribution, the interval ε, ie the resolution ε, must be close to the limit of zero. In this case, for example, if the value of ε is 0.1 dB, that is, if the calculation accuracy of the budget is 0.1 dB or less, the calculation can be completed in a short time while ensuring a calculation accuracy with no practical problem. Can be made.

[Convolution calculation procedure]
Next, the convolution calculator 13 calculates the budget distribution D _{b, i} (B _i ), the line loss variation (Λ _i (x), σ _{Λ, i} (x)) extracted from the user DB 17, and the user accommodation distribution U ( x) is used to calculate the cumulative budget shortage user count R (x) as follows.
Using the upper and lower budget distributions D _{b, i} (B _i ) derived in the light budget distribution calculation procedure, the probability that the user accommodated at the point x satisfies the budget B _i , that is, the cumulative occurrence probability C _{b, i} (x , B _i ). Since there is a line loss in the optical communication system, when x is small, that is, when the distance between the OLT and the ONU is not far, the budget is satisfied even when B _i is small, but the budget is increased as x increases for the same B _i. The probability of satisfaction decreases.

ただしｅｒｆは誤差関数であり、以下の式で表される。

ただし上式はｉ＝ｕｐ，ｄｏｗｎそれぞれの場合におけるバジェット満足確率である。実際のＰＯＮシステムでは上下でバジェットを満たす必要がある。すなわち、上りバジェット、および下りバジェットを同時に満たす確率を、全てのバジェットで足しあわせる必要が有ることから、最終的に点ｘでのバジェット満足確率Ｃ_ｂ（ｘ）は以下のように計算される。

ｉをｕｐ，ｄｏｗｎの２通りではなく、ｉ＝０，・・・，ｋ−１としてｋ次元の波長を持つ系で一般化すると以下のように定式化できる。

上式において、ＧＥ−ＰＯＮの際にはｉ＝ｕｐ，ｄｏｗｎの２通りとすればよい。１０Ｇ−ＥＰＯＮとのデュアルレートで設計するために、ｉ＝１０Ｇ ｕｐ，１０Ｇ ｄｏｗｎ，１Ｇ ｕｐ，１Ｇ ｄｏｗｎの４通りとしてもよく、設計には柔軟性がある。 For example, given line conditions as shown in FIG. 6, that is, line loss average value Λ _i (x) [dB] from the OLT accommodating station at point x, and line loss variation σ _{Λ, i at} point x (X) Consider [dB]. In this case, the cumulative occurrence probability C _{b, i} (B _i ) satisfying an arbitrary optical budget B _i on the line can be statistically expressed by the following equation. Here, Λ _i (x) may be the same value at the upper and lower wavelengths, or may be devised to relax any of the specifications of the transceiver by applying different values for the upper and lower wavelengths.

However, erf is an error function and is expressed by the following equation.

However, the above equation is the budget satisfaction probability in each case of i = up and down. In an actual PON system, it is necessary to satisfy the budget at the top and bottom. That is, since it is necessary to add the probability of satisfying the uplink budget and the downlink budget simultaneously for all the budgets, the budget satisfaction probability C _b (x) at the point x is finally calculated as follows.

When i is generalized in a system having k-dimensional wavelengths as i = 0,..., k−1 instead of two types of up and down, it can be formulated as follows.

In the above equation, in the case of GE-PON, i = up and down may be used. In order to design at a dual rate with 10G-EPON, four types of i = 10G up, 10G down, 1G up, and 1G down may be used, and the design is flexible.

以上の方法により、任意のトランシーバスペックでのＲ（ｘ）が導出される。横軸をＯＬＴからの距離ｘ、縦軸をＲ（ｘ）とした累積バジェット不足確率分布のイメージを図８に示す。 Finally, by multiplying the user distribution U (x) as shown in FIG. 7 accommodated on the track, the distribution of users who will be under budget can be calculated as follows.

By the above method, R (x) in an arbitrary transceiver specification is derived. FIG. 8 shows an image of the cumulative budget shortage probability distribution in which the horizontal axis represents the distance x from the OLT and the vertical axis represents R (x).

[Optimization procedure]
The optimization unit 14 compares the cumulative budget shortage probability distribution with the allowable level value required for the optical communication system, and optimizes the transceiver manufacturing specifications as follows.
In order to obtain the manufacturing specifications of the transceiver that can sufficiently reduce R (L) at the position x = L, the optimization unit 14 sets the optical budget distribution calculation calculation unit 12 so that R (L) is smaller than the allowable level. A part or all of the manufacturing distribution (μp _{, i} , σp _{, i} , _{μs, i} , σs _{, i} ) of the given transceiver is changed, and the optical budget distribution calculation procedure and the convolution calculation procedure are repeatedly performed. Then, the manufacturing distribution when R (L) becomes smaller than the allowable level value is output as the manufacturing specification of the transceiver. Note that it is possible to avoid infinite calculation by limiting the number of repetitions. In addition, R (x) for the number of repetitions is acquired in advance, and R (x) of the production distribution that satisfies the allowable level and satisfies the acceptable level is determined as the production specification of the transceiver. May be.

  In this way, by repeating the light budget distribution calculation procedure, the convolution calculation procedure, and the optimization procedure, the transceiver manufacturing specifications can be calculated in a short time and with high accuracy.

A specific example of optimization will be described with reference to FIG. It is assumed that the allowable level can only be guaranteed up to a distance L in the current manufacturing distribution. When the communication system wants to allow the distance L ′, the optimization unit 14 changes some or all values of the manufacturing distribution, and calculates R (x) again in the budget distribution calculation unit 12 and the convolution calculation unit 13. Let By repeating this, a manufacturing distribution (μ ′ _{p, i} , σ ′ _{p, i} , μ ′ _{s, i} , σ ′ _{s, i} ) in which R (L) is less than the allowable level value is obtained. The acceptable level depends on the content of the access service you want to provide, but if you set it to 1 or less (1 ppm or less) for 1 million users, the PON system will indicate that almost all users will not run out of budget. Can be built.

  By feeding back the calculation results to the transceiver manufacturing line, it will be possible to efficiently produce transceivers that are not over-specs in line with the user's capacity, improving profitability in both transceiver design and PON system design. You will be able to take measures.

  In the present embodiment, the method of calculating the manufacturing specifications of the transceiver by the transceiver design apparatus having the configuration of FIG. 2 has been described. The transceiver design apparatus can also be realized by causing a computer to execute a transceiver design program. By causing the computer to execute the transceiver design program, the CPU performs operations of the budget distribution calculation unit 12, the convolution calculation unit 13, and the optimization unit 14. The storage unit such as the hard disk of the computer inputs the upper and lower limits of the output power of the transceiver and the minimum light receiving sensitivity, the line loss variation and the user accommodation distribution, so that the storage unit can receive the transceiver specification DB 16 and the user. It functions as DB17. Then, the transceiver manufacturing distribution and allowable level values can be input from the console unit of the computer, and a monitor, a printer, or the like functions as the result output unit 15.

[Calculation example]
Here, in the transceiver having the specification conforming to the actual GE-PON (PX10), calculation of R (x) when the parameter is changed, and determination of the manufacturing specification of the transceiver capable of extending the system based on the calculation A method will be described. The values in FIG. 11 are used as parameters. Assuming that ONUs have already been introduced, the manufacturing distribution of ONU transceivers is unchanged, and the manufacturing specifications of OLT transceivers are optimized.

FIG. 9 shows a case where the manufacturing distribution of the minimum light receiving sensitivity of the OLT transceiver is constant at μ _{s, u} = −26.0 dBm, σ _{s, u} = 1.0 dBm, and the manufacturing distribution of the output power of the OLT transceiver is changed. It is a figure which shows the accumulation budget deficient user number R (x) per million with respect to the distance x [km] from OLT.
(A) μ _{p, d} = −2.0 dBm,
(B) μ _{p, d} = + 0.0 dBm,
(C) μ _{p, d} = + 2.0 dBm
In each graph, σ _{p, d} = 2.0 dB (solid line), 1.0 dB (long broken line), and 0.5 dB (broken line).

For example, when it is desired to design a service so that a budget shortage occurs with only one user per million or less as an allowable level, (a) μ _{p, d} = −2.0 dBm with low OLT output is related to σ _{p, d} . The distance is about 4 km. On the other hand, in (b) μ _{p, d} = + 0.0 dBm and (c) μ _{p, d} = + 2.0 dBm, the smaller the σ _{p, d} , the longer the user accomodable distance. In particular, in (c) μ _{p, d} = + 2.0 dBm, the user accommodable distance can be extended to 7.5 km for both σ _{p, d} = 1.0 dB and 0.5 dB. At this time, the cumulative budget shortage user number R (x) has almost no difference even if the individual difference variation of the output power of the OLT transceiver is 1.0 dB or 0.5 dB. In other words, if the output power of the OLT transceiver is set to μ _{p, d} = + 2.0 dBm, even if the individual difference variation of the output power of the OLT transceiver is 1.0 dB or less, the cumulative budget shortage user number R (x) is affected. Therefore, the individual difference variation of the output power of the OLT transceiver can be allowed up to 1.0 dB.

Conversely, FIG. 10 shows that the manufacturing distribution of the output power of the OLT transceiver is fixed at μ _{p, d} = + 0.0 dBm, σ _{p, d} = 1.0 dBm, and the manufacturing distribution of the minimum light receiving sensitivity of the OLT transceiver is changed. It is a figure which shows the accumulation budget shortage user number R (x) per million with respect to the distance x [km] from OLT in the case. Unlike the result of FIG. 9, the cumulative budget shortage user number R (x) is almost the same regardless of the parameter. That is, if the output distribution of the OLT transceiver is manufactured, the allowable transmission distance can be set to 5.0 km regardless of the manufacturing distribution of the minimum light receiving sensitivity of the OLT transceiver.

This will be described more specifically. The OLT transceiver output power manufacturing distribution in FIG. 10 is the conditions of μ _{p, d} = + 0.0 dBm and σ _{p, d} = 1.0 dB in FIG. 9B, and under this condition, the manufacturing distribution of the minimum light receiving sensitivity of the OLT transceiver. Even if changes, the R (x) curve does not change. That is, even if the OLT transceiver output power manufacturing distribution has a higher specification than that of FIG. 9B, the minimum light reception of the OLT transceiver even under the conditions of μ _{p, d} = + 2.0 dBm and σ _{p, d} = 1.0 dB in FIG. It can be said that there is no change in the R (x) curve irrespective of the sensitivity manufacturing distribution.

As described above, from the results of FIGS. 9 and 10, it can be seen that the transmittable distance with respect to the allowable level in the communication system in this calculation is strongly influenced by the manufacturing parameter of the output power of the OLT transceiver. That is, in the communication system in this calculation, if the manufacturing distribution of the OLT transceiver output power is μ _{p, d} = + 2.0 dBm, σ _{p, d} = 1.0 dB, the transmittable distance for the allowable level is the minimum of the OLT transceiver. Regardless of the manufacturing distribution of the light receiving sensitivity, it can be set to about 7.5 km (see FIG. 9C). Therefore, the transmission distance can be extended by setting the production specifications of the OLT transceiver output power of the OLT transceiver to μ _{p, d} = + 2.0 dBm, σ _{p, d} = 1.0 dB, and the production specification of the minimum light receiving sensitivity can be reduced to μ. _s, d = _-24.0dBm, loosen the σ _s, d = 2.0dB can be achieved economization of a communication system.

[Appendix]
The following describes the transceiver design apparatus of this embodiment.
The transceiver design apparatus of the present embodiment is a user who has insufficient accumulated budget at an arbitrary distance x from a finite number N value (minimum light sensitivity / output power) included in the transceiver distribution (minimum light sensitivity / output power average and variation). The number R (x) is calculated, and a manufacturing distribution in which R (L) at a position of the predetermined distance x = L is equal to or lower than an allowable level is found.

The specific configuration is as follows.
(1):
In a system design apparatus for ensuring the service quality of a user accommodated in an optical communication system,
The process of calculating the device's budget distribution by generating random numbers for the minimum receiver sensitivity and output power between the communication terminals in the specified value range and manufacturing distribution, and
The process of calculating the cumulative budget shortage probability distribution according to the distance between communication terminals by integrating the line loss distribution, the user distribution for each distance to the budget distribution,
A design apparatus comprising: a calculation process for prolonging a distance that satisfies an allowable level of a budget shortage probability by optimizing a transceiver manufacturing specification from a budget shortage probability distribution for each distance.

(2):
In an optical communication system, in a system design apparatus for ensuring the service quality of a user accommodated in a PON system,
The process of calculating the budget distribution of the device by generating random numbers in the specified range and manufacturing distribution of the upstream and downstream transceiver minimum light sensitivity and output power of the communication terminal in the central office and user,
The process of calculating the cumulative budget shortage probability distribution according to the distance from the central station by integrating the line loss distribution, the user distribution for each distance to the budget distribution,
A design that includes a calculation process for prolonging the distance that satisfies the acceptable level of the budget shortage probability by optimizing the manufacturing specifications of the transceiver on the central office side from the budget shortage probability distribution for each distance Design device that realizes the method.

The transceiver design apparatus of this embodiment has the following effects.
(I) Rather than imposing an excessively strict manufacturing standard (variation standard that lowers the manufacturing yield) on the transceiver in order to ensure the quality of the communication system, find a manufacturing standard that R (L) falls below an acceptable level. be able to.
(II) The calculation time can be shortened by generating a finite number N of minimum light receiving sensitivity and output power values included in the manufacturing distribution.

  In the present embodiment, a design method of an optical communication system for access using a PON system is described as a typical example, but the present invention can also be applied to a long-distance relay network.

11: Parameter input unit 12: Budget distribution calculation unit 13: Convolution calculation unit 14: Optimization unit 15: Result output unit 16: Transceiver specification database (DB)
17: User database (DB)
18: Allowable level input part

Claims (7)

Based on the manufacturing distribution of the minimum light receiving sensitivity and the optical output power of the transceiver included in the optical communication device, the generated values of the minimum light receiving sensitivity and the optical output power for the transceiver N (N is a integer greater than or equal to 2) are generated and generated. Calculating an optical budget between transceivers based on the generated value within a predetermined standard among the generated values, and calculating an optical budget distribution from a plurality of the optical budgets;
An optical budget less than an arbitrary value at an arbitrary point based on a line loss distribution representing a line loss from one optical communication device to an arbitrary point on the optical communication system and the optical budget distribution calculated by the optical budget distribution calculation unit Is a convolution calculation unit that calculates the cumulative number of optical budget shortage users who are short of the light budget at an arbitrary point by integrating with the user distribution representing the arrangement position of the optical communication device in the optical communication system. When,
The cumulative light budget shortage user number at an arbitrary point is compared with a predetermined allowable level value, and the manufacturing distribution given to the light budget distribution calculation unit when the cumulative light budget shortage user number is less than the allowable level value If the number of accumulated light budget deficient users is equal to or greater than the allowable level value and the number of calculations of the accumulated light budget deficient users is equal to or less than a specified number, change at least a part of the production distribution. An optimization unit for the light budget distribution calculation unit;
A transceiver design apparatus comprising:   The optical communication system is a PON (Passive Optical Network), and the optical communication apparatus is a station side apparatus (OLT: Optical Line Terminal) or a subscriber side apparatus (ONU: Optical Network Unit) constituting the PON, The transceiver design apparatus according to claim 1, wherein the arbitrary point is a distance from the OLT.   The line loss distribution used by the convolution calculation unit is different from the line loss from the optical communication device to the arbitrary point and the line loss from the arbitrary point to the optical communication device. The transceiver design device described in 1. Based on the manufacturing distribution of the minimum light receiving sensitivity and the optical output power of the transceiver included in the optical communication device, the generated values of the minimum light receiving sensitivity and the optical output power for the transceiver N (N is a integer greater than or equal to 2) are generated and generated. An optical budget distribution calculation procedure for calculating an optical budget between transceivers based on the generated value within a predetermined standard among the generated values, and calculating an optical budget distribution from a plurality of the optical budgets;
An optical budget less than an arbitrary value at an arbitrary point based on a line loss distribution representing a line loss from one optical communication device to an arbitrary point on the optical communication system and the optical budget distribution calculated by the optical budget distribution calculation procedure A convolution calculation procedure for calculating the cumulative number of users who have insufficient optical budget at an arbitrary point by integrating with the user distribution representing the arrangement position of the optical communication device in the optical communication system. When,
The cumulative light budget insufficiency user number at a given point is compared with a predetermined allowable level value, and if the cumulative light budget insufficiency user number is less than the allowable level value, the manufacturing distribution given in the optical budget distribution calculation procedure If the number of accumulated light budget deficient users is equal to or greater than the allowable level value and the number of calculations of the accumulated light budget deficient users is equal to or less than a specified number, change at least a part of the production distribution. An optimization procedure for calculating the light budget distribution;
Transceiver design method.   The optical communication system is a PON (Passive Optical Network), and the optical communication apparatus is a station side apparatus (OLT: Optical Line Terminal) or a subscriber side apparatus (ONU: Optical Network Unit) constituting the PON, 5. The transceiver design method according to claim 4, wherein the arbitrary point is a distance from the OLT.   6. The line loss distribution used in the convolution calculation procedure is different from a line loss from the optical communication apparatus to the arbitrary point and a line loss from the arbitrary point to the optical communication apparatus. The transceiver design method described in 1.   A transceiver design program for causing a computer to execute the transceiver design method according to claim 4.

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