JP2008061149A

JP2008061149A - Optical communication system

Info

Publication number: JP2008061149A
Application number: JP2006238438A
Authority: JP
Inventors: Manabu Yoshino; 學吉野; Norimoto Miki; 準基三鬼
Original assignee: Nippon Telegraph and Telephone Corp
Current assignee: Nippon Telegraph and Telephone Corp
Priority date: 2006-09-04
Filing date: 2006-09-04
Publication date: 2008-03-13
Anticipated expiration: 2026-09-04
Also published as: JP4641013B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication system for improving a code error rate, and for reducing code length or the number of use of optical chips configuring an optical signal, and for increasing the multiplex number. <P>SOLUTION: An optical communication system 100 is provided with: a light transmitter 10 for transmitting an optical signal coded according to predetermined codes, and configured of a plurality of optical chips; and a light receive 20 for receiving the optical signal, and for decoding each of the optical chips configuring the optical signal as plus or minus according to codes as the object of decoding, wherein the light receiver 20 detects the optical chips configuring the optical signal with which disturbing rays of light are mixed not as the object of decoding, and detects the optical chips for improving the balance of the total sum of strength after decoding of the optical chips when decoding the optical signal coded according to the codes not the object of decoding not as the object of decoding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、符号化した光信号を送受信する光ＣＤＭ（ＣｏｄｅＤｉｖｉｓｉｏｎＭｕｌｔｉｐｌｅｘ）方式の光通信システムに関する。 The present invention relates to an optical CDM (Code Division Multiplex) optical communication system that transmits and receives an encoded optical signal.

既設の光通信システムに影響を与えずに、既設の光通信システムに新たに光通信システムを追加する方法として、光ＣＤＭ方式が有望視されている。光ＣＤＭ方式では、広帯域の光周波数幅又は時間幅に拡散符号に従って光信号を拡散することで、その符号化利得により、既設の光通信システムに影響を与えない弱い強度の光信号で通信することが可能となるためである。 The optical CDM system is promising as a method for newly adding an optical communication system to an existing optical communication system without affecting the existing optical communication system. In the optical CDM system, an optical signal is spread in accordance with a spread code over a wide-band optical frequency width or time width, and communication is performed with a weak intensity optical signal that does not affect an existing optical communication system due to the coding gain. This is because it becomes possible.

ここで、消光比８〜１２ｄＢと想定される既設の光通信システムに影響を与えない光信号の強度レベルは、その数％と十分小さなものが要求される。従って、既設の光通信システムにおいて伝送する光信号の強度は、追加する光ＣＤＭ方式の光通信システムにおいて伝送する光信号の強度と比較して極めて大きい。そのため、光ＣＤＭ方式の光通信システムにとっては既設の光通信システムにおいて伝送する光信号が妨害光として作用する。このような妨害光に対する十分な符号化利得の確保は、光周波数帯域幅の拡大を要するため、光伝送路における波長分散に起因する信号波形の劣化により制限される問題がある。また、光検波器が飽和する問題がある。 Here, the intensity level of the optical signal that does not affect the existing optical communication system assumed to have an extinction ratio of 8 to 12 dB is required to be as small as several percent. Therefore, the intensity of the optical signal transmitted in the existing optical communication system is extremely large as compared with the intensity of the optical signal transmitted in the added optical CDM optical communication system. Therefore, for an optical CDM optical communication system, an optical signal transmitted in the existing optical communication system acts as interference light. Ensuring sufficient coding gain for such interference light requires expansion of the optical frequency bandwidth, and thus has a problem that it is limited by signal waveform deterioration caused by chromatic dispersion in the optical transmission line. In addition, there is a problem that the optical detector is saturated.

このような問題を解決する方法として、光信号を構成する各光チップに入力される光の強度を一定の値で制限するハードリミッタの技術がある（例えば、特許文献１及び非特許文献１を参照。）。 As a method for solving such a problem, there is a hard limiter technique that limits the intensity of light input to each optical chip constituting an optical signal with a constant value (for example, Patent Document 1 and Non-Patent Document 1). reference.).

特開平１１−１８６９８４号公報JP-A-11-186984 ＥｘｐｅｒｉｍｅｎｔａｌＤｅｍｏｎｓｔｒａｔｉｏｎｏｆＭｕｌｔｉｐｌｅ−ＷａｖｅｌｅｎｇｔｈＨａｒｄ−ＬｉｍｉｔｉｎｇＲｅｃｅｉｖｅｒｆｏｒＲｅｄｕｃｉｎｇＭＡＩＮｏｉｓｅｉｎａ２−ＤＴｉｍｅ−ＷａｖｅｌｅｎｇｔｈＯＣＤＭＡＳｙｓｔｅｍ（Ｐ．Ｅｂｒａｈｉｍｉ他、ＥＣＯＣ２００３Ｔｈ１．５．３）Experimental Demonstration of Multiple-Wavelength Hard-Limiting Receiver for Reducing MAI Noise in a 2-D Time-Wavelength OCDMA System, et al. (C.Eb.

しかし、符号間干渉を十分に抑制できるバイポーラ符号及び擬似バイポーラ符号を用いる場合、符号間干渉を抑制するためのハードリミッタによる抑制の下限は、符号化された光信号を構成する光チップ毎に使用中の全光信号の入力の総和がある光チップに到達しうる最大の強度となる。互いに直交する符号化系列に属する符号で符号化した一群の光信号をすべて用いる場合、あるチップに到達しうる最大の光チップ数と、符号が合致する復号器で復号した時の光信号を構成する光チップ数とが略等しい。そのため、妨害光の影響を軽減するためにハードリミッタによる抑制の下限をさげると、多重数が制限される問題がある。 However, when using bipolar codes and pseudo-bipolar codes that can sufficiently suppress intersymbol interference, the lower limit of suppression by the hard limiter for suppressing intersymbol interference is used for each optical chip that constitutes the encoded optical signal. The total sum of all optical signal inputs is the maximum intensity that can reach the optical chip. When all of a group of optical signals encoded with codes belonging to mutually orthogonal encoded sequences are used, the maximum number of optical chips that can reach a certain chip and the optical signal when decoded by a decoder that matches the code are configured. The number of optical chips to be performed is approximately equal. Therefore, if the lower limit of suppression by the hard limiter is reduced in order to reduce the influence of interference light, there is a problem that the number of multiplexing is limited.

また、妨害光を受信する光チップを復号対象としない方法が推測されるが、この方法は以下に示す問題がある。ここで、擬似バイポーラ符号として用いられるＭ系列符号に従って符号化した光信号を例に説明する。符号長をＬ（＝２ｋ＋１）とすると、送信側で光を送信して受信側でプラスとして取り扱う光チップはｋ＋１で、送信側で光を送信せず受信側でマイナスとして取り扱う光チップはｋとなる。符号の特性から復号器の符号に合致する符号で符号化した光信号を構成する光チップは、全てプラスとして加算される。また、復号器の符号に合致しない符号で符号化した光信号を構成する光チップは、受信側でプラスとマイナスとで半分ずつ加算されることで相殺され、符号間干渉が無くなる。 In addition, a method that does not target an optical chip that receives interference light as a decoding target is estimated, but this method has the following problems. Here, an optical signal encoded according to an M-sequence code used as a pseudo bipolar code will be described as an example. If the code length is L (= 2k + 1), the optical chip that transmits light on the transmitting side and handles it as positive on the receiving side is k + 1, and the optical chip that does not transmit light on the transmitting side and handles it as negative on the receiving side is k. Become. All optical chips constituting an optical signal encoded with a code that matches the code of the decoder are added as a plus. Further, the optical chips constituting the optical signal encoded with a code that does not match the code of the decoder are offset by adding half each plus and minus on the receiving side, and there is no intersymbol interference.

しかし、妨害光が混入した１チップを復号対象としないと復号器の符号に合致しない符号で符号化した光信号を構成する光チップが相殺されなくなるため、符号間干渉が発生する。図８に、光信号を７チップＭ系列とした場合の、使用光信号数と残留干渉チップ数との関係を示す。ここで、残留干渉チップ数とは、復号対象としない符号で符号化した光信号を構成する光チップで相殺されない光チップの数とする。図８には、破線が残留干渉チップ数の最大値、実線が残留干渉チップ数の平均値及び点線が残留干渉チップ数の最小値を示す。図８に示すように、残留干渉チップ数は、光信号を符号化した符号の特性から、確率的には、使用光信号数の半分であるが、通信中の光信号を符号化した符号と妨害光の混入した光チップ（以後、「妨害光が混入した光チップ」を「妨害光混入チップ」と記す。）との関係により、使用光信号数又はｋ＋１の大きい方が上限となる。従って、許容できる残留干渉チップ数が多重数の上限となる問題がある。 However, if one chip mixed with interfering light is not targeted for decoding, the optical chips constituting the optical signal encoded with a code that does not match the code of the decoder will not cancel out, causing intersymbol interference. FIG. 8 shows the relationship between the number of used optical signals and the number of residual interference chips when the optical signal is a 7-chip M series. Here, the number of residual interference chips is the number of optical chips that are not canceled out by the optical chips constituting the optical signal encoded with a code that is not to be decoded. In FIG. 8, the broken line indicates the maximum value of the number of residual interference chips, the solid line indicates the average value of the number of residual interference chips, and the dotted line indicates the minimum value of the number of residual interference chips. As shown in FIG. 8, the number of residual interference chips is stochastically half of the number of optical signals used from the characteristics of the code that encodes the optical signal. Depending on the relationship with the optical chip mixed with interfering light (hereinafter, “optical chip mixed with interfering light” will be referred to as “interfering light mixed chip”), the larger the number of used optical signals or k + 1 becomes the upper limit. Therefore, there is a problem that the allowable number of residual interference chips becomes the upper limit of the number of multiplexing.

図９に、符号長とＱ値との関係を示す。なお、図９は、符号長Ｌと同じ数のＬ個の光信号を多重化した場合の図であり、図９の矢印は、Ｑ値が６．０３であることを示す（但し、符号誤り率が１０^−９のとき。）。Ｑ値は、影響を明確にするため、符号間干渉の残留のみを雑音とした。図９の矢印に示すように、符号誤り率１０^−９に要するＱ値は、略６であるので、この残留干渉による影響を抑制するためには、符号長１２７以上が必要である。 FIG. 9 shows the relationship between the code length and the Q value. FIG. 9 is a diagram in the case where L optical signals having the same number as the code length L are multiplexed, and the arrow in FIG. 9 indicates that the Q value is 6.03 (provided that the code error When the rate is ^10-9 .) In order to clarify the influence of the Q value, only the residual intersymbol interference is regarded as noise. As indicated by the arrow in FIG. 9, the Q value required for the code error rate 10 ⁻⁹ is approximately 6, and therefore a code length of 127 or more is necessary to suppress the influence of this residual interference.

本発明は、前記課題を解決するため、妨害光信号存在下での符号誤り率の向上、符号長或いは光信号を構成する使用中の光チップの数の縮小及び多重数の増大を可能とする光通信システムを提供することを目的とする。 In order to solve the above problems, the present invention makes it possible to improve the code error rate in the presence of an interfering optical signal, reduce the code length or the number of optical chips in use constituting the optical signal, and increase the number of multiplexing. An object is to provide an optical communication system.

上記目的を達成するために、第１発明に係る光通信システムは、光受信器が、妨害光が混入した光信号を構成する光チップを検出して復号対象とせず、かつ、復号対象としない符号で符号化した光信号を復号した光チップの復号後の強度の総和の均衡が改善する光チップを復号対象としないことを特徴とする。 In order to achieve the above object, in the optical communication system according to the first aspect of the present invention, the optical receiver detects the optical chip constituting the optical signal mixed with interfering light and does not set it as a decoding target, and does not set it as a decoding target. An optical chip in which the balance of the sum of intensity after decoding of the optical chip obtained by decoding the optical signal encoded with the code is not targeted for decoding.

具体的には、第１発明に係る光通信システムは、所定の符号に従って符号化され、複数の光チップで構成される光信号を送信する光送信器と、前記光信号を受信し、前記光信号を構成する前記光チップをそれぞれ復号対象とする前記符号に従ってプラス又はマイナスとして復号する光受信器と、を備える光通信システムであって、前記符号は、前記光信号を、前記光信号の符号化に用いた前記符号を復号対象として復号する前記光受信器で受信して復号すると、復号した前記光チップの復号後の強度の総和がプラス又はマイナスの所定の閾値以上となり、及び、前記光信号を、前記光信号の符号化に用いていない前記符号を復号対象として復号する前記光受信器で受信して復号すると、復号した前記光チップの復号後の強度の総和が略均衡し、前記光受信器は、妨害光が混入した前記光信号を構成する前記光チップを検出して復号対象とせず、かつ、復号対象としない前記符号で符号化した前記光信号を復号した前記光チップの復号後の強度の総和の均衡が改善する前記光チップを復号対象としない、ことを特徴とする。 Specifically, an optical communication system according to a first aspect of the present invention is an optical transmitter that transmits an optical signal that is encoded according to a predetermined code and includes a plurality of optical chips, and that receives the optical signal and transmits the optical signal. An optical communication system comprising: an optical receiver that decodes each of the optical chips constituting a signal as plus or minus according to the code to be decoded, wherein the code is a code of the optical signal. When the optical receiver that decodes the code used for conversion as a decoding target receives and decodes, the sum of the decoded optical chips after decoding is equal to or greater than a predetermined threshold value of plus or minus, and the optical When a signal is received and decoded by the optical receiver that decodes the code not used for encoding the optical signal as a decoding target, the sum of the decoded intensity of the decoded optical chips is substantially balanced. The optical receiver detects the optical chip constituting the optical signal mixed with interfering light and does not set it as a decoding target, and decodes the optical signal encoded with the code not set as a decoding target. The optical chip whose balance of the sum of the strengths after decoding is improved is not targeted for decoding.

上記光通信システムは、妨害光混入時に復号化が不能となる事態を改善し、符号間干渉の残留を抑制することができる。従って、符号誤り率の向上、符号長或いは光信号を構成する光チップの数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。 The above optical communication system can improve the situation in which decoding becomes impossible when interfering light is mixed, and can suppress residual intersymbol interference. Therefore, it is possible to provide an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips constituting an optical signal, and increase the number of multiplexing.

前記光信号を、前記光信号の符号化に用いていない前記符号を復号対象として復号する前記光受信器は、復号対象としない前記符号で符号化した前記光信号を構成する前記光チップでプラスとして復号される前記光チップとマイナスとして復号される前記光チップとの復号後の強度の総和が０となる前記光チップを復号対象としないことが好ましい。 The optical receiver that decodes the optical signal with the code not used for encoding the optical signal as a decoding target is added by the optical chip constituting the optical signal encoded with the code that is not the decoding target. It is preferable that the optical chip in which the sum of the intensities after decoding of the optical chip to be decoded as negative and the optical chip to be decoded as negative is 0 is not targeted for decoding.

上記光通信システムは、符号間干渉を最小にすることができる。 The optical communication system can minimize intersymbol interference.

上記目的を達成するために、第２発明に係る光通信システムは、光送信器が、妨害光が混入した光信号を構成する光チップを検出して、同一の符号に対応する複数の光信号の相対応する光チップから妨害光が混入していない光チップをそれぞれ同数選択して復号対象とすることを特徴とする。 In order to achieve the above object, an optical communication system according to a second aspect of the present invention is that an optical transmitter detects an optical chip constituting an optical signal mixed with interfering light, and a plurality of optical signals corresponding to the same code The same number of optical chips that do not contain interfering light are selected from the corresponding optical chips, and are selected as decoding targets.

具体的には、第２発明に係る光通信システムは、所定の符号に従って符号化され、複数の光チップで構成される光信号を送信する光送信器と、前記光信号を受信し、前記光信号を構成する前記光チップをそれぞれ復号対象とする前記符号に従ってプラス又はマイナスとして復号する光受信器と、を備える光通信システムであって、前記所定の符号は、複数のチップから構成され、前記光信号は、前記所定の符号を構成する前記チップに対応する前記光チップから構成され、かつ、前記所定の符号を構成する少なくとも１の前記チップに対応する前記光チップが複数あり、前記符号は、前記光信号を、前記光信号の符号化に用いた前記符号を復号対象として復号する前記光受信器で受信して復号すると、復号した前記光チップの復号後の強度の総和がプラス又はマイナスの所定の閾値以上となり、及び、前記光信号を、前記光信号の符号化に用いていない前記符号を復号対象として復号する前記光受信器で受信して復号すると、復号した前記光チップの復号後の強度の総和が略均衡し、前記光受信器は、妨害光が混入した前記光信号を構成する前記光チップを検出して、同一の前記符号に対応する複数の前記光信号の相対応する前記光チップから前記妨害光が混入していない前記光チップをそれぞれ同数選択して復号対象とする、ことを特徴とする。 Specifically, an optical communication system according to a second invention is encoded according to a predetermined code and transmits an optical signal composed of a plurality of optical chips, receives the optical signal, and transmits the optical signal. An optical receiver that decodes each of the optical chips constituting the signal as a plus or minus according to the code to be decoded, wherein the predetermined code comprises a plurality of chips, The optical signal is composed of the optical chip corresponding to the chip constituting the predetermined code, and there are a plurality of the optical chips corresponding to at least one of the chips constituting the predetermined code. When the optical signal is received and decoded by the optical receiver that decodes the code used for encoding the optical signal as a decoding target, the intensity of the decoded optical chip after decoding is When the sum is equal to or greater than a predetermined threshold of plus or minus and the optical signal is received and decoded by the optical receiver that decodes the code not used for encoding the optical signal as a decoding target, decoding is performed. The sum of the intensity of the optical chips after decoding is substantially balanced, and the optical receiver detects the optical chips constituting the optical signal mixed with interfering light, and a plurality of the codes corresponding to the same code The same number of the optical chips that are not mixed with the interfering light are selected from the optical chips corresponding to the optical signals, and are selected as decoding targets.

上記光通信システムは、妨害光混入時に復号化が不能となる事態を回避し、符号間干渉の残留を発生させない。従って、符号誤り率の向上、符号長或いは光信号を構成する光チップの使用数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。さらに、第１発明に係る光通信システムと比べて、復号対象とする符号で符号化された光信号の復号後の強度を同一に保つことができる。 The above optical communication system avoids a situation in which decoding becomes impossible when interfering light is mixed, and does not cause residual intersymbol interference. Accordingly, it is possible to provide an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips that constitute an optical signal, and increase the number of multiplexing. Furthermore, compared with the optical communication system according to the first invention, the intensity after decoding of an optical signal encoded with a code to be decoded can be kept the same.

前記光送信器は、所定の同一の前記符号に従って符号化された前記複数の光チップで構成される前記光信号を複数連結して送信し、前記複数の光信号を構成する前記光チップは、時間領域及び光周波数領域の少なくとも一方が異なることが好ましい。 The optical transmitter concatenates and transmits a plurality of the optical signals composed of the plurality of optical chips encoded according to a predetermined same code, and the optical chips constituting the plurality of optical signals are: It is preferable that at least one of the time domain and the optical frequency domain is different.

上記目的を達成するために、第３発明に係る光通信システムは、光送信器が、妨害光が混入した光信号を構成する光チップを検出して復号対象とせず、妨害光が混入した光チップに相当し、かつ、妨害光が混入していない予備の光チップの送信を光受信器に指示し、妨害光が混入した光チップの代わりに指示に従って送信された予備の光チップを復号対象に含めることを特徴とする。 In order to achieve the above object, an optical communication system according to a third aspect of the present invention is an optical communication system in which an optical transmitter detects an optical chip constituting an optical signal mixed with disturbing light and does not set it as a decoding target. Instructs the optical receiver to transmit a spare optical chip that is equivalent to a chip and does not contain interfering light, and decodes the spare optical chip transmitted according to the instruction instead of the optical chip containing interfering light It is characterized by including.

具体的には、第３発明に係る光通信システムは、所定の符号に従って符号化された複数の光チップ及び指示に従って送信する予備の前記光チップで構成される光信号を送信する光送信器と、前記光信号を受信し、前記光信号を構成する前記光チップをそれぞれ復号対象とする前記符号に従ってプラス又はマイナスとして復号する光受信器と、を備える光通信システムであって、前記符号は、前記光信号を、前記光信号の符号化に用いた前記符号を復号対象として復号する前記光受信器で受信して復号すると、復号した前記光チップの復号後の強度の総和がプラス又はマイナスの所定の閾値以上となり、及び、前記光信号を、前記光信号の符号化に用いていない前記符号を復号対象として復号する前記光受信器で受信して復号すると、復号した前記光チップの復号後の強度の総和が略均衡し、前記光受信器は、妨害光が混入した前記光信号を構成する前記光チップを検出して復号対象とせず、前記妨害光が混入した前記光チップに相当し、かつ、前記妨害光が混入していない前記予備の光チップの送信を前記光受信器に指示し、前記妨害光が混入した前記光チップの代わりに前記指示に従って送信された前記予備の光チップを復号対象に含める、ことを特徴とする。 Specifically, an optical communication system according to a third aspect of the present invention includes an optical transmitter that transmits an optical signal composed of a plurality of optical chips encoded according to a predetermined code and the spare optical chip that transmits according to an instruction. An optical receiver that receives the optical signal and decodes the optical chip constituting the optical signal as plus or minus according to the code to be decoded, respectively, wherein the code is When the optical signal is received and decoded by the optical receiver that decodes the code used for encoding the optical signal as a decoding target, the sum of the intensity of the decoded optical chip after decoding is plus or minus. When the optical signal is received and decoded by the optical receiver that decodes the optical signal that is not used for encoding the optical signal as a decoding target, the decoding is performed. The sum of the intensity of the optical chips after decoding is substantially balanced, and the optical receiver detects the optical chip constituting the optical signal mixed with interfering light and does not set it as a decoding target, and the interfering light is mixed. Instructs the optical receiver to transmit the spare optical chip that corresponds to the optical chip and does not contain the interfering light, and is transmitted according to the instruction instead of the optical chip in which the interfering light is mixed. The spare optical chip is included in the decoding target.

上記光通信システムは、妨害光混入時に復号が不能となる事態を回避し、符号間干渉の残留を発生させない。従って、符号誤り率の向上、符号長或いは光信号を構成する光チップの使用数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。さらに、上記光通信システムは、符号化に用いた符号の各チップに対応するそれぞれ複数の光チップによって冗長化していないので、少ない光チップ数で同様の効果が得られる。 The above optical communication system avoids a situation in which decoding becomes impossible when interfering light is mixed, and does not cause residual intersymbol interference. Accordingly, it is possible to provide an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips that constitute an optical signal, and increase the number of multiplexing. Furthermore, since the optical communication system is not made redundant by a plurality of optical chips corresponding to each chip of the code used for encoding, the same effect can be obtained with a small number of optical chips.

前記光送信器及び前記光受信器は、前記光信号の符号化に用いた前記符号を復号対象として復号する前記光受信器で受信して復号すると、一方がプラス及び他方がマイナスとして復号される前記光チップの組み合わせ、かつ、前記光信号の符号化に用いていない前記符号を復号対象として復号する前記光受信器で受信して復号すると、両方ともプラス又はマイナスとなる前記光チップの組み合わせがある前記光信号を、送受信することが好ましい。 When the optical transmitter and the optical receiver receive and decode the code used for encoding the optical signal as a decoding target and decode it, one is decoded as positive and the other as negative. When the optical receiver that decodes the combination of the optical chips and the code that is not used for encoding the optical signal as a decoding target is received and decoded, the combination of the optical chips that is both positive or negative is It is preferable to transmit and receive a certain optical signal.

上記光通信システムは、符号間干渉の残留をより抑制することができる。 The optical communication system can further suppress residual intersymbol interference.

本発明は、符号誤り率の向上、符号長或いは光信号を構成する光チップの使用数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。 The present invention can provide an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips constituting an optical signal, and increase the number of multiplexed signals.

添付の図面を参照して本発明の実施の形態を説明する。以下に説明する実施の形態は本発明の構成の例であり、本発明は、以下の実施の形態に制限されるものではない。また、同一部材及び同一部位には同一符号を付した。 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 member and the same site | part.

（第１実施形態）
図１を用いて、第１実施形態に係る光通信システムの例について説明する。図１に、光通信システム１００の概略図を示した。光通信システム１００は、所定の符号に従って符号化され、複数の光チップで構成される光信号を送信する光送信器１０と、光信号を受信し、光信号を構成する光チップをそれぞれ復号対象とする符号に従ってプラス又はマイナスとして復号する光受信器２０と、を備える光通信システム１００であって、符号は、光信号を、光信号の符号化に用いた符号を復号対象として復号する光受信器２０で受信して復号すると、復号した光チップの復号後の強度の総和がプラス又はマイナスの所定の閾値以上となり、及び、光信号を、光信号の符号化に用いていない符号を復号対象として復号する光受信器２０で受信して復号すると、復号した光チップの復号後の強度の総和が略均衡し、光受信器２０は、妨害光が混入した光信号を構成する光チップを検出して復号対象とせず、かつ、復号対象としない符号で符号化した光信号を復号した光チップの復号後の強度の総和の均衡が改善する光チップを復号対象としない、ことを特徴とする。 (First embodiment)
An example of the optical communication system according to the first embodiment will be described with reference to FIG. FIG. 1 shows a schematic diagram of an optical communication system 100. The optical communication system 100 includes an optical transmitter 10 that transmits an optical signal that is encoded according to a predetermined code and includes a plurality of optical chips, and an optical chip that receives the optical signal and configures the optical signal. And an optical receiver 20 that decodes the optical signal as plus or minus according to the code, wherein the code is an optical receiver that decodes the optical signal using the code used for encoding the optical signal as a decoding target. When the receiver 20 receives and decodes, the sum of the intensity of the decoded optical chip after decoding is equal to or greater than a predetermined positive or negative threshold, and a code that is not used to encode the optical signal is to be decoded. As a result, the sum of the intensity of the decoded optical chips after the decoding is substantially balanced, and the optical receiver 20 configures an optical chip that constitutes an optical signal mixed with interfering light. The optical chip that is detected and not subject to decoding, and the balance of the sum of the intensity of the optical chips after decoding the optical signal encoded with the code that is not subject to decoding is not subject to decoding. To do.

光通信システム１００は、例えば、ＰＯＮ（ＰａｓｓｉｖｅＯｐｔｉｃａｌＮｅｔｗｏｒｋ）であり、３個の光送信器１０ａ，１０ｂ，１０ｃ、光スプリッタ６０ａ並びに３個の光受信器２０ａ，２０ｂ，２０ｃ及び光スプリッタ６０ｂからなる光受信器２０を備える。光スプリッタ６０ａは、光送信器１０ａ，１０ｂ，１０ｃに接続される。光伝送媒体５０としては、例えば、光ファイバ又は光導波路がある。 The optical communication system 100 is, for example, a PON (Passive Optical Network), and includes three optical transmitters 10a, 10b, 10c, an optical splitter 60a, three optical receivers 20a, 20b, 20c, and an optical splitter 60b. An optical receiver 20 is provided. The optical splitter 60a is connected to the optical transmitters 10a, 10b, and 10c. Examples of the optical transmission medium 50 include an optical fiber and an optical waveguide.

図１に示すように、光受信器２０ａ，２０ｂ，２０ｃは、光伝送媒体５０の一部を共有する。光ＣＤＭ方式では、光受信器２０ａ，２０ｂ，２０ｃは、それぞれが有する符号と同一の符号で符号化された受信対象の光信号のみ復号化が可能であり、それぞれが有する符号と異なる符号で符号化された受信対象以外の光信号を受信しても復号化できない。よって、光伝送媒体５０の一部の共有が可能となり、光通信システム１００は、ＰＯＮに適する。なお、図１には示していないが、光通信システム１００は、１個の光送信器１０と１個の光受信器２０とを備えても良い。 As shown in FIG. 1, the optical receivers 20 a, 20 b, and 20 c share a part of the optical transmission medium 50. In the optical CDM system, the optical receivers 20a, 20b, and 20c can decode only the optical signal to be received that is encoded with the same code as each of the codes. Even if an optical signal other than the reception target is received, it cannot be decoded. Therefore, a part of the optical transmission medium 50 can be shared, and the optical communication system 100 is suitable for PON. Although not shown in FIG. 1, the optical communication system 100 may include one optical transmitter 10 and one optical receiver 20.

図２を用いて、光送信器１０について説明する。図２に、光送信器１０の概略図を示した。光送信器１０は、例えば、光を出力する光源１２、光源１２が出力した光をデータに基づいて変調して変調信号光を出力する変調器１４及び変調器１４から出力される変調信号光を光信号９０に変換して出力する符号器１６を有する。 The optical transmitter 10 will be described with reference to FIG. FIG. 2 shows a schematic diagram of the optical transmitter 10. The optical transmitter 10 includes, for example, a light source 12 that outputs light, a modulator 14 that modulates light output from the light source 12 based on data and outputs modulated signal light, and a modulated signal light output from the modulator 14. It has an encoder 16 that converts it into an optical signal 90 and outputs it.

光送信器１０は、例えば、送信するデータの値がマーク又はスペースのときに符号化に用いた符号を構成するチップの値が１であるチップに対応する光チップで構成される光信号９０を送信する。なお、各光信号９０の符号化に用いる符号として符号を構成するチップの値が１と０と或いは１と−１との数が平衡するアダマール符号を用いる場合は、伝送するデータの値がマーク及びスペースのそれぞれに対して符号化に用いる符号を構成するチップの値が１のチップに対応する光チップで構成される光信号９０、符号化に用いる符号を構成するチップの値が０のチップに対応する光チップで構成される光信号９０を送信する場合であっても妨害光の混入がないために、ある光チップを復号対象としない以前には符号間干渉が発生しない。 For example, when the value of data to be transmitted is a mark or a space, the optical transmitter 10 generates an optical signal 90 composed of an optical chip corresponding to a chip whose value of a chip constituting a code used for encoding is 1. Send. When a Hadamard code in which the number of chips constituting the code is 1 and 0 or the number of 1 and -1 is balanced is used as a code used for encoding each optical signal 90, the value of data to be transmitted is a mark. And an optical signal 90 composed of an optical chip corresponding to a chip having a code value of 1 for coding and a chip having a value of 0 for a code used for coding. Even when an optical signal 90 composed of an optical chip corresponding to is transmitted, no interfering light is mixed, so that no intersymbol interference occurs before a certain optical chip is not subject to decoding.

図３に、光受信器２０の第１形態の概略図を示す。図３に示すように、光受信器２０は、例えば、復号器３０及び選択器４０を有する。復号器３０は、光周波数チップ毎に光チップを分波させる分波器３２、符号のチップの値が１及び０である光チップをそれぞれ合波する合波器３４ａ，３４ｂ及び分波されたチップであって光信号９０を符号化した符号のチップで「１１１００１０」の１に相当するチップをプラスとして、かつ、０に相当するチップをマイナスとして、それぞれ光検波の後に加える差動光検波器３６を有する。 FIG. 3 shows a schematic diagram of the first form of the optical receiver 20. As illustrated in FIG. 3, the optical receiver 20 includes, for example, a decoder 30 and a selector 40. The decoder 30 includes a demultiplexer 32 that demultiplexes the optical chip for each optical frequency chip, a demultiplexer 34a and 34b that multiplexes the optical chips whose code chip values are 1 and 0, and demultiplexed. A differential optical detector that is added after the optical detection, with a chip corresponding to 1 of “1110010” as a plus and a chip corresponding to 0 as a minus, which is a chip that encodes the optical signal 90. 36.

なお、光受信器２０が「１１１００１０」の７チップからなるＭ系列の光周波数領域で符号化した光信号９０を受信する例で説明するが、この光信号９０に限定されず、異なる符号長の符号で符号化した光信号９０又は異なる符号系列であるアダマール符号等を用いて符号化した光信号９０であっても良い。また、符号化に用いた符号のチップの順序と光チップの光周波数軸上の順序とが異なっていても良い。 Note that an example in which the optical receiver 20 receives an optical signal 90 encoded in an M-sequence optical frequency domain composed of 7 chips of “1110010” will be described. However, the optical receiver 20 is not limited to this optical signal 90 and has different code lengths. It may be an optical signal 90 encoded with a code or an optical signal 90 encoded using a Hadamard code which is a different code sequence. Further, the order of the chips of the codes used for encoding may be different from the order of the optical chips on the optical frequency axis.

分波器３２には、光信号９０が入力される。分波器３２としては、例えば、ＡＷＧ（ＡｒｒａｙｅｄＷａｖｅｇｕｉｄｅＧｒａｔｉｎｇ）、ラティスフィルタ、ＦＩＲ（ＦｉｎｉｔｅＩｍｐｕｌｓｅＲｅｓｐｏｎｓｅ）フィルタ、マッハツェンダーフィルタ又は誘電体多層膜フィルタがあり、光信号９０に適合した光フィルタであれば制限されない。なお、図３において、復号器３０は、光周波数領域で拡散した場合であるが、時間領域で拡散、時間と光周波数との２次元領域で拡散又は位相領域で拡散しても良い。時間領域で拡散した場合であれば、例えば、分波器３２は、時間領域の符号に対応する遅延を付与する遅延器と光スプリッタとを有しても良い（図３には図示していない。）。時間と光周波数との２次元領域で拡散した場合であれば、例えば、分波器３２は、所定の光周波数チップに所定の遅延を付与するために、光周波数に依存するＡＷＧと遅延線とを有しても良い（図３には図示していない。）。また、分波器３２は、ＦＢＧ（ＦｉｂｅｒＢｒａｇｇＧｒａｔｉｎｇ）によって反射させて所定の光周波数チップに所定の遅延をあたえるものであっても良い（図３には図示していない。）。 An optical signal 90 is input to the duplexer 32. Examples of the demultiplexer 32 include an AWG (Arrayed Waveguide Grating), a lattice filter, an FIR (Finite Impulse Response) filter, a Mach-Zehnder filter, or a dielectric multilayer filter, and any optical filter that is suitable for the optical signal 90 can be used. Not limited. In FIG. 3, the decoder 30 is spread in the optical frequency domain, but may be spread in the time domain, spread in the two-dimensional area of time and optical frequency, or spread in the phase domain. In the case of spreading in the time domain, for example, the duplexer 32 may include a delay unit that adds a delay corresponding to the code in the time domain and an optical splitter (not shown in FIG. 3). .) In the case of spreading in a two-dimensional region of time and optical frequency, for example, the demultiplexer 32 includes an AWG and a delay line depending on the optical frequency in order to give a predetermined delay to a predetermined optical frequency chip. (Not shown in FIG. 3). Further, the duplexer 32 may be one that is reflected by FBG (Fiber Bragg Grating) and gives a predetermined delay to a predetermined optical frequency chip (not shown in FIG. 3).

選択器４０は、例えば、符号情報９２及び妨害光情報９４に基づいて切り替えを指示する指示器４２及び所定のチップを復号対象としない切替器４４を有する。 The selector 40 includes, for example, an indicator 42 that instructs switching based on the code information 92 and the interference light information 94 and a switch 44 that does not target a predetermined chip.

図４に、光受信器２１の第２形態の概略図を示す。図３と図４との差異は、選択器４０の配置及び合波器３４ａ，３４ｂと差動光検波器３６との代わりに合成器３８と光検波器群３７とを有することである。図３の光受信器２０は、差動光検波器３６の前に選択器４０を有するため、光検波器２つと一方の出力から他方の出力を減算する合成器からなる差動光検波器３６が１つで良い。一方、図４の光受信器２１は、選択器４０で選択するチップの数だけ、ここでは、７個の光検波器からなる光検波器群３７が必要となる。また、図３に示すような差動光検波器３６の前に選択器４０を有する構成であっても、図４に示すように選択器４０で選択するチップの数だけ光検波器と、符号のチップの値が１に相当するチップをプラスとし、符号のチップの値が０に相当するチップをマイナスとして加減算する合成器３８と、を有しても良い。 FIG. 4 shows a schematic diagram of the second form of the optical receiver 21. The difference between FIG. 3 and FIG. 4 is that the selector 40 is arranged, and that a combiner 38 and an optical detector group 37 are provided instead of the multiplexers 34 a and 34 b and the differential optical detector 36. Since the optical receiver 20 in FIG. 3 includes a selector 40 in front of the differential optical detector 36, the differential optical detector 36 includes two optical detectors and a synthesizer that subtracts the other output from one output. One is enough. On the other hand, the optical receiver 21 of FIG. 4 requires the optical detector group 37 including seven optical detectors as many as the number of chips selected by the selector 40. Further, even in the configuration having the selector 40 in front of the differential optical detector 36 as shown in FIG. 3, as many optical detectors and codes as the number of chips selected by the selector 40 as shown in FIG. And a synthesizer 38 that adds and subtracts a chip corresponding to a chip value of 1 as a plus and a chip corresponding to a sign chip value of 0 as a minus.

図４に示すように、光チップ毎に検波した後に電気的手段の加減算で復号する場合、光チップ毎に検波した出力を光信号９０を符号化する符号間で分岐させ、それぞれの符号に応じて加減算する合成器３８を有しても良い。これによって、光処理を異なる符号で符号化した光信号９０間で共有できる効果がある。 As shown in FIG. 4, when decoding is performed by adding / subtracting electrical means after detection for each optical chip, the output detected for each optical chip is branched between the codes for encoding the optical signal 90, and according to the respective codes. It is also possible to have a synthesizer 38 for adding and subtracting. This has the effect that the optical processing can be shared between the optical signals 90 encoded with different codes.

なお、選択器４０は、ＯＮ／ＯＦＦの切り換えができるスイッチでも良く、増倍率を略０から所定値の間で変更できる増幅器でも良い。さらに、図４の光受信器２１において、選択器４０は、光検波器群３７を構成する各光検波器のそれぞれの光検波のＯＮ／ＯＦＦで代用しても良く、ＡＰＤ（ＡｖａｌａｎｃｈｅＰｈｏｔｏＤｉｏｄｅ）の場合はその増倍率を変更することによって代用しても良い。時間領域の拡散においてゲートスイッチの開閉で復号対象となるチップを選択する場合は、ゲートスイッチを選択器４０のスイッチとして流用しても良い。積分等の電気処理により光信号９０を光検波した後に処理する場合は、電気処理の過程で該当するチップを復号対象としないことで選択器４０を置き変えても良い。また、コヒーレント検波する場合は、局発光の停止、位相又は周波数を所定の値からずらすことで選択器４０を置き換えても良い。さらに、光受信器２０，２１は、出力を識別する識別器及び分散補償器を必要に応じて備えても良い（図３及び図４には示していない。）。 The selector 40 may be a switch that can be switched ON / OFF, or an amplifier that can change the multiplication factor between approximately 0 and a predetermined value. Further, in the optical receiver 21 of FIG. 4, the selector 40 may be substituted by ON / OFF of the respective optical detectors of the optical detectors constituting the optical detector group 37, and an APD (Avalanche Photo Diode). In this case, it may be substituted by changing the multiplication factor. When the chip to be decoded is selected by opening and closing the gate switch in the time domain diffusion, the gate switch may be used as a switch of the selector 40. When the optical signal 90 is processed after optical detection by electrical processing such as integration, the selector 40 may be replaced by not setting the corresponding chip as a decoding target in the electrical processing. In the case of coherent detection, the selector 40 may be replaced by stopping local light emission, shifting the phase or frequency from a predetermined value. Further, the optical receivers 20 and 21 may include an identifier for identifying the output and a dispersion compensator as necessary (not shown in FIGS. 3 and 4).

以下、光受信器２０，２１の動作について説明する。光受信器２０，２１は、例えば、以下の動作を行なう。
（１）妨害光の混入により復号が困難となる場合、妨害光が混入したチップを復号対象としない
（２）さらに、妨害光が混入したチップ以外のチップを復号対象としないことで、復号対象以外の符号で符号化した光信号でプラス及びマイナスとして扱うチップの復号後の強度の総和の均衡が改善する場合、妨害光が混入したチップ以外のチップであって復号後の強度の総和の均衡が改善するチップを復号対象としない Hereinafter, the operation of the optical receivers 20 and 21 will be described. For example, the optical receivers 20 and 21 perform the following operations.
(1) When decoding becomes difficult due to mixing of interfering light, a chip mixed with interfering light is not set as a decoding target. (2) Furthermore, a chip other than a chip mixed with interfering light is not set as a decoding target. If the balance of the sum of the intensity after decoding of the chips treated as plus and minus in the optical signal encoded with a code other than is improved, the balance of the sum of the intensity after decoding is a chip other than the chip mixed with interfering light Does not target chips that improve

図５に、光信号を符号化した符号を構成するチップの値が１のチップに妨害光が混入した場合の例として「１１１００１０」の符号の第１のチップに混入した例の残留干渉チップ数を示す。図５（ａ）は、妨害光混入チップのみ復号対象とせず、図５（ｂ）〜（ｄ）は、妨害光混入チップと、妨害光混入チップ以外のチップであって妨害光混入チップの逆の値を有するチップ、すなわち、それぞれ第４チップ、第５チップ又は第７チップを復号対象としない場合である。また、図６に、光信号を構成するチップの値が０のチップに妨害光が混入した場合の例として「１１１００１０」の符号の第７のチップに混入した例の残留干渉チップ数を示す。図６（ａ）は、妨害光混入チップのみ復号対象とせず、図６（ｂ）〜（ｅ）は、妨害光混入チップと、妨害光混入チップ以外のチップであって妨害光混入チップの逆の値を有するチップ、すなわち、それぞれ第２チップ、第３ップ、第６チップ又は第１チップを復号対象としない場合である。例えば、妨害光混入チップの値が１であれば、妨害光混入チップの逆の値を有するチップの値は０となり、妨害光混入チップの値が０であれば、妨害光混入チップの逆の値を有するチップの値は１となる。 FIG. 5 shows the number of residual interference chips in an example in which interference light is mixed into a chip whose value of a chip constituting a code obtained by encoding an optical signal is 1 and mixed in the first chip of the code “1110010”. Indicates. FIG. 5A shows only the jamming light mixed chip as a decoding target. FIGS. 5B to 5D show the jamming light mixed chip and a chip other than the jamming light mixed chip, which is the reverse of the jamming light mixed chip. This is a case where the chip having the value of i.e., the fourth chip, the fifth chip, or the seventh chip is not set as a decoding target. FIG. 6 shows the number of residual interference chips in an example in which interference light is mixed into a chip whose optical signal value is 0 and mixed in a seventh chip having a code of “1110010”. FIG. 6A shows only the jamming light mixed chip as a decoding target. FIGS. 6B to 6E show the jamming light mixed chip and a chip other than the jamming light mixed chip, which is the reverse of the jamming light mixed chip. In other words, the second chip, the third chip, the sixth chip, or the first chip are not targeted for decoding. For example, if the value of the interfering light mixed chip is 1, the value of the chip having the opposite value of the interfering light mixed chip is 0, and if the value of the interfering light mixed chip is 0, the reverse of the interfering light mixed chip. The value of a chip having a value is 1.

ここで、復号対象チップの行の下向き矢印は、当該チップを復号に用いないことを意味する。プラス記号又はマイナス記号は、それぞれ符号で加算又は減算を行なうチップであることを意味する。他光信号１〜６の１と０との値は、それぞれ復号対象以外の符号を構成するチップの値である。他光信号１〜６の残留干渉チップ数の列の値は、その符号による光信号によるプラス又はマイナス付きの残留干渉チップ数である。自光信号の残留干渉チップ数の列の値は、他光信号１〜６の残留干渉チップ数の総和である。なお、残留干渉チップ数の値が０のものを網掛けで示した。 Here, the downward arrow in the row of the decoding target chip means that the chip is not used for decoding. A plus sign or a minus sign means a chip that performs addition or subtraction by a sign, respectively. The values 1 and 0 of the other optical signals 1 to 6 are values of chips that constitute codes other than the decoding target. The value of the column of the number of residual interference chips of the other optical signals 1 to 6 is the number of residual interference chips with plus or minus due to the optical signal by the sign. The value of the column of the number of remaining interference chips of the own optical signal is the sum of the number of remaining interference chips of the other optical signals 1 to 6. A residual interference chip number of 0 is shown by shading.

第１実施形態に係る光通信システムでは、光送信器及び光受信器は、光信号の符号化に用いた符号を復号対象として復号する光受信器で受信して復号すると、一方がプラス及び他方がマイナスとして復号される光チップの組み合わせ、かつ、光信号の符号化に用いていない符号を復号対象として復号する光受信器で受信して復号すると、両方ともプラス又はマイナスとなる光チップの組み合わせがある符号系列で符号化した光信号を、送受信することが好ましい。このとき、妨害光混入チップを含み、復号対象の光信号を符号化した符号を構成するチップの値が０と１となる組み合わせの中から通信中の復号対象以外の光信号を符号化した符号を構成するチップの値が０と０又は１と１となる組み合わせとなる光信号が最も多いチップを選択することがより好ましい。妨害光混入チップが復号側で１、すなわち、加算として扱う光チップと、妨害光混入チップが復号側で０、すなわち、減算として扱う光チップと、に入力する復号対象以外の光信号を符号化した符号を構成するチップの値が１と１となる組み合わせである場合、以下のようになる。加算として扱う光チップに１が入力され、減算として扱う光チップに１が入力され、加算として扱う光チップの値と減算として扱う光チップの値との和が０となり、均衡する。また、妨害光混入チップが復号側で１、すなわち、加算として扱う光チップと、妨害光混入チップが復号側で０、すなわち、減算として扱う光チップと、に入力する復号対象以外の光信号を符号化した符号を構成するチップの値が０と０となる組み合わせである場合、以下のようになる。加算として扱う光チップに０が入力され、減算として扱う光チップに０が入力され、加算として扱う光チップの値と減算として扱う光チップの値との和が０となり、均衡する。よって、第１実施形態に係る光通信システムは、符号間干渉の残留をより抑制することができる。なお、復号から除外すると光チップに対応する復号対象以外の光信号を符号化した符号を構成するチップの値が０と１又は１と０となる組み合わせの通信中の光信号の数だけ、残留干渉チップ数が積みあがる。 In the optical communication system according to the first embodiment, when an optical transmitter and an optical receiver receive and decode an optical receiver that decodes a code used for encoding an optical signal as a decoding target, one is plus and the other is Is a combination of optical chips that are decoded as negative, and a combination of optical chips that are both positive or negative when received and decoded by an optical receiver that decodes a code that is not used to encode an optical signal as a decoding target. It is preferable to transmit and receive an optical signal encoded with a certain code sequence. At this time, a code including an interfering light mixed chip and encoding an optical signal other than the decoding target being communicated from among combinations in which the values of the chips constituting the code obtained by encoding the optical signal to be decoded are 0 and 1 It is more preferable to select a chip that has the largest number of optical signals in a combination in which the values of the chips that make up 0 are 0 and 0 or 1 and 1. The optical signal other than the target to be decoded is input to the optical chip whose interference light mixing chip is 1 on the decoding side, that is, the optical chip that is treated as addition, and the optical chip that is processing the interference light mixing chip is 0 on the decoding side, that is, the optical chip In the case of a combination in which the values of the chips constituting the codes are 1 and 1, the following is obtained. 1 is input to the optical chip handled as addition, 1 is input to the optical chip handled as subtraction, and the sum of the value of the optical chip handled as addition and the value of the optical chip handled as subtraction becomes 0, which is balanced. Also, optical signals other than those to be decoded that are input to the interfering light mixed chip 1 on the decoding side, that is, an optical chip that is handled as addition, and the interfering light mixed chip is 0 on the decoding side, that is, an optical chip that is handled as subtraction. In the case of a combination in which the values of the chips constituting the encoded code are 0 and 0, the result is as follows. 0 is input to the optical chip handled as addition, 0 is input to the optical chip handled as subtraction, and the sum of the value of the optical chip handled as addition and the value of the optical chip handled as subtraction becomes 0, which is balanced. Therefore, the optical communication system according to the first embodiment can further suppress residual intersymbol interference. In addition, if excluded from decoding, the remaining number of optical signals in communication of a combination in which the value of the chip constituting the code obtained by encoding the optical signal other than the decoding target corresponding to the optical chip is 0 and 1 or 1 and 0 will remain. Increases the number of interference chips.

第１実施形態に係る光通信システムでは、光信号を、光信号の符号化に用いていない符号を復号対象として復号する光受信器は、復号対象としない符号で符号化した光信号を構成する光チップでプラスとして復号される光チップとマイナスとして復号される光チップとの復号後の強度の総和が０となる光チップを復号対象としないことが好ましい。上記のような好ましい組み合わせ、すなわち、妨害光混入チップと加減算が逆の光チップから１光チップを選択して復号対象から除外することで残留干渉が低減できる場合、その光チップを復号対象としないことで、符号間干渉を最小にすることができる。 In the optical communication system according to the first embodiment, an optical receiver that decodes an optical signal using a code that is not used for encoding the optical signal as a decoding target configures an optical signal that is encoded using a code that is not a decoding target. It is preferable that an optical chip whose sum of intensity after decoding of an optical chip decoded as plus by an optical chip and an optical chip decoded as minus is 0 is not targeted for decoding. When the residual interference can be reduced by selecting one optical chip out of the optical chips having the opposite combination of the interference light mixed chip and the addition / subtraction in the preferred combination as described above and excluding it from the decoding target, the optical chip is not set as the decoding target. Thus, intersymbol interference can be minimized.

なお、妨害光混入チップのみを復号対象としない場合は、妨害光混入チップが復号側で１、すなわち、加算として扱う光チップである場合は、復号対象以外の符号で符号化した光信号の各残留干渉チップ数は非正の値となり、妨害光混入チップが復号側で０、すなわち、減算として扱う光チップである場合は、残留干渉チップ数は非負の値をとる。また、複数の光チップを復号対象としない場合は、残留干渉チップ数は正及び負の値をとる。 If only the interfering light mixed chip is not to be decoded, the interfering light mixed chip is 1 on the decoding side, that is, if it is an optical chip handled as addition, each optical signal encoded with a code other than the decoding target The number of residual interference chips is a non-positive value. When the interference light mixed chip is 0 on the decoding side, that is, an optical chip handled as subtraction, the number of residual interference chips takes a non-negative value. Further, when a plurality of optical chips are not targeted for decoding, the number of residual interference chips takes positive and negative values.

以上説明したように通信中の光信号と、光信号と復号対象としない光チップとによる残留干渉の組み合わせに関する情報を用いて、光受信器は、復号対象以外の符号で符号化した各光信号で、復号器におけるプラスの光チップ数とマイナスの光チップ数との不均衡が最小となる光チップの組み合わせを復号対象としない。ここで、光チップの組み合わせには、妨害光の強度が無視できる程度に低い場合には妨害光混入チップを復号対象から除外しない組み合わせ、妨害光混入チップのみを復号対象としない組み合わせ、及び、妨害光混入チップ以外の光チップも含めて復号対象としない組み合わせがある。 As described above, the optical receiver uses the information regarding the combination of the optical signal being communicated and the residual interference between the optical signal and the optical chip not to be decoded, so that the optical receiver encodes each optical signal encoded with a code other than the decoding target. Therefore, the combination of optical chips that minimizes the imbalance between the number of plus optical chips and the number of minus optical chips in the decoder is not targeted for decoding. Here, in the combination of optical chips, when the intensity of the interference light is low enough to be ignored, the combination that does not exclude the interference light mixed chip from the decoding target, the combination that does not include only the interference light mixed chip, and the interference There are combinations that are not targeted for decoding, including optical chips other than light-mixed chips.

図７に、第１実施形態に係る光通信システムの使用光信号数と残留干渉チップ数との関係を示す。ここで、光信号は、７チップＭ系列である。図７には、破線が残留干渉チップ数の最大値、実線が残留干渉チップ数の平均値及び点線が残留干渉チップ数の最小値を示す。図８と比較して、使用光信号数が少ない場合には、残留干渉チップ数は、略半分となっている。このようにして、第１実施形態に係る光通信システムは、妨害光混入による復号化が不能となる事態を改善し、その際に発生しうる符号間干渉の残留を抑制することができる。従って、符号誤り率の向上、符号長或いは光信号を構成する光チップの数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。 FIG. 7 shows the relationship between the number of used optical signals and the number of residual interference chips in the optical communication system according to the first embodiment. Here, the optical signal is a 7-chip M series. In FIG. 7, the broken line indicates the maximum value of the remaining interference chips, the solid line indicates the average value of the remaining interference chips, and the dotted line indicates the minimum value of the remaining interference chips. Compared with FIG. 8, when the number of used optical signals is small, the number of residual interference chips is approximately half. In this way, the optical communication system according to the first embodiment can improve the situation in which decoding due to interfering light mixing becomes impossible, and can suppress residual intersymbol interference that may occur at that time. Therefore, it is possible to provide an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips constituting an optical signal, and increase the number of multiplexing.

なお、上記では、１光チップに妨害光が混入した例で説明したが、複数の光チップに妨害光が混入した場合も同様に処理することができる。また、送信するデータの値がマーク又はスペースのときに光信号を符号化した符号を構成するチップの値が１の光チップのみを送信する場合を例として説明したが、以下の場合のようにしても良い。光信号を符号化した符号を構成するチップの値が１のチップと、光信号を符号化した符号を構成するチップの値が０であれば−１として復号されるチップと、を送信し、それぞれに１と−１とを乗じて復号化しても良い。すなわち、妨害光混入チップを含み、復号対象の光信号を符号化した符号を構成するチップの値が０と１となる組み合わせの中から通信中の復号対象以外の光信号を符号化した符号を構成するチップの値が０と０又は１と１となる組み合わせとなる光信号が最も多い光チップを選択する。言い換えれば、妨害光混入チップを含み、復号対象の光信号を符号化した符号を構成するチップの値が１と−１となる組み合わせの中から通信中の復号対象以外の光信号を符号化した符号を構成するチップの値が−１と−１又は１と１として復号される光チップの組み合わせとなる光信号が最も多い光チップを選択する。ここで、バイポーラ符号のとる値として１及び−１を例として説明したが、例えば、０及びπであっても良く、受信時に加減算により受信対象以外の光信号による出力が０となり、均衡すれば良い。また、バイポーラ符号のとる値が、例えば、０、π／２、π及び３π／２の４値であっても良い。更に、光チップの強度が略等しいことを前提に説明したが、複数の光チップ同士の組み合わせで均衡している場合は、それぞれを１つの光チップのように処理すれば同様である。 In the above description, an example in which interference light is mixed in one optical chip has been described. However, the same processing can be performed when interference light is mixed in a plurality of optical chips. Further, the case has been described as an example in which only the optical chip having the value of the chip constituting the code that encodes the optical signal is transmitted when the value of the data to be transmitted is a mark or space, but as in the following case May be. Transmitting a chip whose value of a chip constituting a code obtained by encoding an optical signal is 1 and a chip which is decoded as -1 if the value of a chip constituting a code obtained by encoding an optical signal is 0; Each may be multiplied by 1 and −1 for decoding. That is, a code that includes an interfering light mixed chip and encodes an optical signal other than the decoding target being communicated from among combinations in which the values of the chips that constitute the code that encodes the optical signal to be decoded are 0 and 1 An optical chip having the largest number of optical signals in a combination in which the values of the constituent chips are 0 and 0 or 1 and 1 is selected. In other words, an optical signal other than the decoding target in communication is encoded from among the combinations in which the value of the chip that includes the interfering light mixed chip and the code that encodes the optical signal to be decoded is 1 and −1. An optical chip having the largest number of optical signals that is a combination of optical chips decoded with the value of the chip constituting the code being -1 and -1 or 1 and 1 is selected. Here, 1 and −1 have been described as examples of the values taken by the bipolar code, but may be 0 and π, for example, and may be 0 and π at the time of reception. good. Further, the value taken by the bipolar code may be, for example, four values of 0, π / 2, π, and 3π / 2. Further, the description has been made on the premise that the optical chips have substantially the same strength. However, when the optical chips are balanced by a combination of a plurality of optical chips, the same applies if each is processed as one optical chip.

（第２実施形態）
第２実施形態に係る光通信システムは、所定の符号に従って符号化され、複数の光チップで構成される光信号を送信する光送信器と、光信号を受信し、光信号を構成する光チップをそれぞれ復号対象とする符号に従ってプラス又はマイナスとして復号する光受信器と、を備える光通信システムであって、所定の符号は、複数のチップから構成され、光信号は、所定の符号を構成するチップに対応する光チップから構成され、かつ、所定の符号を構成する少なくとも１のチップに対応する光チップが複数あり、符号は、光信号を、光信号の符号化に用いた符号を復号対象として復号する光受信器で受信して復号すると、復号した光チップの復号後の強度の総和がプラス又はマイナスの所定の閾値以上となり、及び、光信号を、光信号の符号化に用いていない符号を復号対象として復号する光受信器で受信して復号すると、復号した光チップの復号後の強度の総和が略均衡し、光受信器は、妨害光が混入した光信号を構成する光チップを検出して、同一の符号に対応する複数の光信号の相対応する光チップから妨害光が混入していない光チップをそれぞれ同数選択して復号対象とする、ことを特徴とする。 (Second Embodiment)
An optical communication system according to the second embodiment includes an optical transmitter that transmits an optical signal that is encoded according to a predetermined code and includes a plurality of optical chips, and an optical chip that receives the optical signal and configures the optical signal. And an optical receiver that decodes each of the signals as plus or minus according to a code to be decoded, wherein the predetermined code is composed of a plurality of chips, and the optical signal constitutes the predetermined code There are a plurality of optical chips that are made up of optical chips corresponding to the chips and that correspond to at least one chip constituting a predetermined code, and the code is an object to be decoded. As a result, the sum of the intensity of the decoded optical chip after decoding is equal to or greater than a predetermined threshold value of plus or minus, and the optical signal is encoded into the optical signal. When an unrecognized code is received and decoded by an optical receiver that decodes it as a decoding target, the sum of the intensity of the decoded optical chips after decoding is substantially balanced, and the optical receiver constitutes an optical signal mixed with disturbing light An optical chip is detected, and the same number of optical chips not interfering with interfering light are selected from the corresponding optical chips of a plurality of optical signals corresponding to the same code, and set as decoding targets.

第２実施形態に係る光通信システムは、第１実施形態に係る光通信システムとは選択器の動作が異なる。光送信器は、光信号を符号化した符号を構成する各チップに対応した複数の光チップを送信する。 The optical communication system according to the second embodiment differs from the optical communication system according to the first embodiment in the operation of the selector. The optical transmitter transmits a plurality of optical chips corresponding to each chip constituting a code obtained by encoding an optical signal.

第２実施形態に係る光通信システムでは、光送信器は、所定の同一の符号に従って符号化された複数の光チップで構成される光信号を複数連結して送信し、複数の光信号を構成する光チップは、時間領域及び光周波数領域の少なくとも一方が異なることが好ましい。光送信器は、例えば、光信号を符号化する符号として「１１１００１０」を用いるのであれば、同一の符号を繰り返し使用して２個連結した「１１１００１０１１１００１０」に対応して符号化した光チップからなる光信号を送信する。なお、符号のチップの順のままで連結しているが、光受信器と光送信器で対応が一致すれば順番を入れ替えても良い。光受信器は、２個連結した符号「１１１００１０１１１００１０」から連結前の１符号「１１１００１０」のそれぞれに対応する１光チップを選択して復号に用いる。この選択の際に、妨害光混入チップを復号対象としない。ここで、ビートノイズやショットノイズの最小化のために使用する光チップの数を最小化するように、符号の各チップに対応して１つの光チップを選択するとした。なお、連結前の１光信号のそれぞれに対応する１光チップを選択するとしたが、復号に用いる光チップの数が同じであれば良いので、妨害光が混入していない場合には、２光チップを用いて復号しても良い。 In the optical communication system according to the second embodiment, the optical transmitter concatenates and transmits a plurality of optical signals composed of a plurality of optical chips encoded according to a predetermined same code, thereby configuring a plurality of optical signals. It is preferable that the optical chip to be used is different in at least one of the time domain and the optical frequency domain. For example, if “1110010” is used as a code for encoding an optical signal, the optical transmitter is composed of an optical chip that is encoded corresponding to “11100101110010” in which two identical codes are connected. Send an optical signal. In addition, although it has connected in the order of the code | symbol chip | tip, if a correspondence corresponds with an optical receiver and an optical transmitter, you may replace an order. The optical receiver selects one optical chip corresponding to each of the one code “1110010” before the concatenation from the two concatenated codes “11100101110010” and uses it for decoding. At the time of this selection, the interference light mixed chip is not targeted for decoding. Here, one optical chip is selected corresponding to each chip of the code so as to minimize the number of optical chips used for minimizing beat noise and shot noise. Although one optical chip corresponding to each optical signal before connection is selected, it is sufficient if the number of optical chips used for decoding is the same. You may decode using a chip | tip.

以下に、符号化に用いる１つの符号に対して３つの光信号を連結した光信号を用いた例で示す。符号化に用いる符号を構成するチップをＣ１，Ｃ２，Ｃ３，Ｃ４とする。連結前の光信号ａ，ｂ，ｃはそれぞれ光チップｆ１ａ，ｆ２ａ，ｆ３ａ，ｆ４ａ，ｆ１ｂ，ｆ２ｂ，ｆ３ｂ，ｆ４ｂ，ｆ１ｃ，ｆ２ｃ，ｆ３ｃ，ｆ４ｃから構成する。妨害光が混入していない場合、各符号を構成するチップに対してそれぞれ同数の光チップを選択して復号する。同数であるので、３チップ、２チップ及び１チップずつのいずれを選択しても良い。符号化利得の最大化の観点からは、妨害光が混入していない場合は、３チップが望ましい。妨害光混入の光チップがｆ１ａとｆ２ｂである場合、各符号を構成するチップに対応する妨害光が混入していない光信号を構成する光チップは、２チップ以上であるので、各符号を構成するチップに対してそれぞれ同数の光信号を構成する光チップから２チップ又は１チップを選択する。妨害光混入の光チップがｆ１ａとｆ２ｂである場合、符号を構成するチップＣ１に対応する光チップで妨害光が混入していないのはｆ１ｃのみなので符号を構成する各チップに対応する妨害光が混入していない光チップをそれぞれ１チップ選択すれば良い。 Hereinafter, an example in which an optical signal obtained by concatenating three optical signals to one code used for encoding will be described. Assume that the chips constituting the code used for encoding are C1, C2, C3, and C4. The optical signals a, b, and c before connection are formed of optical chips f1a, f2a, f3a, f4a, f1b, f2b, f3b, f4b, f1c, f2c, f3c, and f4c, respectively. If the interfering light is not mixed, the same number of optical chips are selected and decoded for the chips constituting each code. Since the number is the same, any of three chips, two chips, and one chip may be selected. From the viewpoint of maximizing the coding gain, three chips are desirable when no interfering light is mixed. When the interfering light-mixed optical chips are f1a and f2b, since there are two or more optical chips that constitute the optical signal that does not contain interfering light corresponding to the chips constituting each code, each code is configured. Two chips or one chip is selected from the optical chips constituting the same number of optical signals with respect to each chip to be performed. When the interfering light-mixed optical chips are f1a and f2b, the optical chip corresponding to the chip C1 constituting the code is only f1c in which no interfering light is mixed, so the interfering light corresponding to each chip constituting the code is present. One chip may be selected for each optical chip that is not mixed.

光受信器は、複数の光チップに妨害光が混入した場合には、各光信号の光チップから妨害光が混入していない光チップを符号化に用いた符号の各チップに対応する光チップと同数選択することが好ましい。このようにして、本願第２実施形態に係る光通信システムは、妨害光混入時の復号化が不能となる事態を回避し、符号間干渉の残留を発生させない。従って、符号誤り率の向上、符号長或いは光信号を構成する光チップの使用数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。 The optical receiver, when interference light is mixed in a plurality of optical chips, is an optical chip corresponding to each chip of the code used for encoding the optical chip in which the interference light is not mixed from the optical chip of each optical signal It is preferable to select the same number. In this way, the optical communication system according to the second embodiment of the present application avoids the situation where decoding becomes impossible when interfering light is mixed, and does not cause residual intersymbol interference. Accordingly, it is possible to provide an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips that constitute an optical signal, and increase the number of multiplexing.

なお、第２実施形態に係る光通信システムは、第１実施形態に係る光通信システムの機能を備えても良い。すなわち、第２実施形態に係る光通信システムは、妨害光が混入した光チップ以外の光チップを復号対象としないことで、受信対象以外の光信号でプラスとマイナスとして扱う光チップの復号後の強度の総和の均衡が改善する場合に、妨害光が混入した光チップ以外の光チップであって復号後の強度の総和の均衡が改善する光チップを復号対象としない機能を備えても良い。第２実施形態に係る光通信システムは、上記の機能を備えることで、光信号を符号化した符号の特定のチップに対応する全光チップに妨害光が混入していない場合は残留干渉チップ数がなく、全光チップに混入している場合にも残留干渉を低減する効果がある。 The optical communication system according to the second embodiment may have the function of the optical communication system according to the first embodiment. That is, in the optical communication system according to the second embodiment, the optical chip other than the optical chip mixed with the disturbing light is not set as the decoding target, so that the optical chip after the decoding of the optical chip that is treated as plus and minus by the optical signal other than the receiving target is performed. When the intensity sum balance is improved, an optical chip other than the optical chip in which the interference light is mixed and an optical chip that improves the intensity sum balance after decoding may be provided as a decoding target. The optical communication system according to the second embodiment has the above-described function, so that when all the optical chips corresponding to the specific chip of the code obtained by encoding the optical signal are not mixed with interference light, the number of residual interference chips There is also an effect of reducing residual interference even when it is mixed in all optical chips.

（第３実施形態）
第３実施形態に係る光通信システムは、所定の符号に従って符号化された複数の光チップ及び指示に従って送信する予備の前記光チップで構成される光信号を送信する光送信器と、光信号を受信し、光信号を構成する光チップをそれぞれ復号対象とする符号に従ってプラス又はマイナスとして復号する光受信器と、を備える光通信システムであって、符号は、光信号を、光信号の符号化に用いた符号を復号対象として復号する光受信器で受信して復号すると、復号した光チップの復号後の強度の総和がプラス又はマイナスの所定の閾値以上となり、及び、光信号を、光信号の符号化に用いていない符号を復号対象として復号する光受信器で受信して復号すると、復号した光チップの復号後の強度の総和が略均衡し、光受信器は、妨害光が混入した光信号を構成する光チップを検出して復号対象とせず、妨害光が混入した光チップに相当し、かつ、妨害光が混入していない予備の光チップの送信を光受信器に指示し、妨害光が混入した光チップの代わりに指示に従って送信された予備の光チップを復号対象に含める、ことを特徴とする。 (Third embodiment)
An optical communication system according to the third embodiment includes an optical transmitter that transmits an optical signal including a plurality of optical chips encoded according to a predetermined code and a spare optical chip that transmits according to an instruction, and an optical signal. An optical communication system comprising: an optical receiver that receives and decodes an optical chip constituting an optical signal as plus or minus according to a code to be decoded, wherein the code is an encoding of the optical signal. When the optical receiver that decodes the code used for decoding as a decoding target receives and decodes, the sum of the intensity of the decoded optical chip after decoding becomes a positive or negative predetermined threshold or more, and the optical signal is converted into the optical signal. When a code that is not used for encoding is received and decoded by an optical receiver that decodes as a decoding target, the sum of the decoded optical chips after decoding is substantially balanced, and the optical receiver is mixed with interfering light. The optical receiver composing the optical signal is not detected and is not subject to decoding, and corresponds to an optical chip mixed with interfering light, and the optical receiver is instructed to transmit a spare optical chip that does not include interfering light. The spare optical chip transmitted according to the instruction is included in the decoding target instead of the optical chip mixed with the interference light.

第３実施形態に係る光通信システムは、第２実施形態に係る光通信システムを改良したものである。また、第３実施形態に係る光通信システムは、妨害光が混入するまでは、予備チップは復号に用いない。妨害光が混入した場合、妨害光混入チップを復号対象としないことは、第１及び第２実施形態に係る光通信システムと同様である。従って、第３実施形態に係る光通信システムは、符号誤り率の向上、符号長或いは光信号を構成する光チップの使用数の縮小及び多重数の増大を可能とする光通信システムを提供することができる。さらに、第３実施形態に係る光通信システムは、光受信器と光送信器とが協調した処理を行なうことで、予備チップを必要なときのみ送受信するので、第２実施形態に係る光通信システムと同様に残留干渉チップがなく、光信号を構成する光チップの数を第２実施形態に係る光通信システムより低減できる。 The optical communication system according to the third embodiment is an improvement of the optical communication system according to the second embodiment. In the optical communication system according to the third embodiment, the spare chip is not used for decoding until interference light is mixed. As in the optical communication systems according to the first and second embodiments, when interference light is mixed, the interference light mixed chip is not set as a decoding target. Therefore, the optical communication system according to the third embodiment provides an optical communication system that can improve the code error rate, reduce the code length or the number of optical chips used in an optical signal, and increase the number of multiplexing. Can do. Furthermore, the optical communication system according to the third embodiment transmits and receives a spare chip only when necessary by performing coordinated processing between the optical receiver and the optical transmitter. Therefore, the optical communication system according to the second embodiment. Similarly to the above, there is no residual interference chip, and the number of optical chips constituting the optical signal can be reduced compared to the optical communication system according to the second embodiment.

なお、第３実施形態に係る光通信システムは、第１実施形態に係る光通信システムの機能を備えても良い。すなわち、第３実施形態に係る光通信システムは、妨害光が混入した光チップ以外の光チップを復号対象としないことで、受信対象以外の光信号でプラスとマイナスとして扱う光チップの復号後の強度の総和の均衡が改善する場合に、妨害光が混入した光チップ以外の光チップであって復号後の強度の総和の均衡が改善する光チップを復号対象としない機能を備えても良い。第３実施形態に係る光通信システムは、上記の機能を備えることで、予備の光チップを超える数の光チップに妨害光が混入している場合にも残留干渉を低減することができる。 Note that the optical communication system according to the third embodiment may include the function of the optical communication system according to the first embodiment. That is, in the optical communication system according to the third embodiment, the optical chip other than the optical chip mixed with the disturbing light is not set as the decoding target, so that the optical chip after the decoding of the optical chip treated as the plus and minus with the optical signal other than the receiving target is performed. When the intensity sum balance is improved, an optical chip other than the optical chip in which the interference light is mixed and an optical chip that improves the intensity sum balance after decoding may be provided as a decoding target. Since the optical communication system according to the third embodiment has the above-described function, it is possible to reduce residual interference even when disturbing light is mixed in the number of optical chips exceeding the number of spare optical chips.

また、第３実施形態に係る光通信システムは、第２実施形態に係る光通信システムの機能を備えても良い。このようにして、光信号を符号化した符号のあるチップに対応する複数の光チップに妨害光が混入している場合の対処が強化できる。また、光受信器から指示があった際、光送信器が送信可能な予備のチップの組み合わせを多く残しておく、いわゆる、予備のチップの使い果たし対策の強化ができる。 Further, the optical communication system according to the third embodiment may have the function of the optical communication system according to the second embodiment. In this way, it is possible to reinforce a countermeasure when interference light is mixed in a plurality of optical chips corresponding to a chip having a code obtained by encoding an optical signal. Further, when there is an instruction from the optical receiver, it is possible to reinforce the countermeasure for so-called spare chip exhaustion, in which many spare chip combinations that can be transmitted by the optical transmitter are left.

第３実施形態に係る光通信システムは、第１及び第２実施形態に係る光通信システムの機能を備えても良い。この場合、第３実施形態に係る光通信システムは、第１及び第２実施形態に係る光通信システムの効果を兼ね備えることができる。 The optical communication system according to the third embodiment may include the functions of the optical communication systems according to the first and second embodiments. In this case, the optical communication system according to the third embodiment can have the effects of the optical communication systems according to the first and second embodiments.

本発明に係る光通信システムは、ＰＯＮをはじめとする光通信網等で利用することができる。 The optical communication system according to the present invention can be used in an optical communication network such as a PON.

第１実施形態に係る光通信システムの概略図である。1 is a schematic diagram of an optical communication system according to a first embodiment. 第１実施形態に係る光送信器の概略図である。It is the schematic of the optical transmitter which concerns on 1st Embodiment. 第１実施形態に係る光受信器の第１形態の概略図である。It is the schematic of the 1st form of the optical receiver which concerns on 1st Embodiment. 第１実施形態に係る光受信器の第２形態の概略図である。It is the schematic of the 2nd form of the optical receiver which concerns on 1st Embodiment. 光信号を構成するチップの値が１のチップに妨害光が混入した場合の残留干渉チップ数を示し、（ａ）は、妨害光混入チップのみ復号対象とせず、（ｂ）〜（ｄ）は、妨害光混入チップと、妨害光混入チップ以外のチップであって妨害光混入チップの逆の値を有するチップと、を復号対象としない場合の図である。The number of residual interfering chips when interfering light is mixed into a chip whose optical signal value is 1 is shown. (A) does not include only interfering light mixed chips, and (b) to (d) FIG. 10 is a diagram in a case where a jamming light mixed chip and a chip other than the jamming light mixed chip and having a value opposite to that of the jamming light mixed chip are not to be decoded. 光信号を構成するチップの値が０のチップに妨害光が混入した場合の残留干渉チップ数を示し、（ａ）は、妨害光混入チップのみ復号対象とせず、（ｂ）〜（ｅ）は、妨害光混入チップと、妨害光混入チップ以外のチップであって妨害光混入チップの逆の値を有するチップと、を復号対象としない場合の図である。The number of residual interference chips when interference light is mixed into a chip whose optical signal value is 0 is shown. (A) does not target only the interference light mixed chips, and (b) to (e) FIG. 10 is a diagram in a case where a jamming light mixed chip and a chip other than the jamming light mixed chip and having a value opposite to that of the jamming light mixed chip are not to be decoded. 第１実施形態に係る光通信システムの使用光信号数と残留干渉チップ数との関係を示した図である。It is the figure which showed the relationship between the use optical signal number of the optical communication system which concerns on 1st Embodiment, and the number of residual interference chips. 従来の光通信システムの使用光信号数と残留干渉チップ数との関係を示した図である。It is the figure which showed the relationship between the use optical signal number of the conventional optical communication system, and the number of residual interference chips. 従来の光通信システムの符号長とＱ値との関係を示した図である。It is the figure which showed the relationship between the code length and Q value of the conventional optical communication system.

Explanation of symbols

１００光通信システム
１０，１０ａ，１０ｂ，１０ｃ光送信器
１２光源
１４変調器
１６符号器
２０，２０ａ、２０ｂ，２０ｃ，２１光受信器
３０復号器
３２分波器
３４ａ，３４ｂ合波器
３６差動光検波器
３７光検波器群
３８合成器
４０選択器
４２指示器
４４切替器
５０光伝送媒体
６０ａ，６０ｂ光スプリッタ
９０光信号
９２符号情報
９４妨害光情報
100 optical communication system 10, 10a, 10b, 10c optical transmitter 12 light source 14 modulator 16 encoder 20, 20a, 20b, 20c, 21 optical receiver 30 decoder 32 demultiplexer 34a, 34b multiplexer 36 differential Optical detector 37 Optical detector group 38 Synthesizer 40 Selector 42 Indicator 44 Switch 50 Optical transmission medium 60a, 60b Optical splitter 90 Optical signal 92 Code information 94 Interference light information

Claims

An optical transmitter that transmits an optical signal that is encoded according to a predetermined code and configured by a plurality of optical chips;
An optical communication system comprising: an optical receiver that receives the optical signal and decodes the optical chip constituting the optical signal as plus or minus according to the code to be decoded, respectively.
When the optical signal is received and decoded by the optical receiver that decodes the code used for encoding the optical signal as a decoding target, the sum of the intensity of the decoded optical chip after decoding is obtained. When the optical signal is received by the optical receiver that decodes the optical signal that is not used for the encoding of the optical signal as a decoding target and is decoded, The total strength after decryption of the chip is approximately balanced,
The optical receiver detects the optical chip constituting the optical signal mixed with interfering light and does not set it as a decoding target, and decodes the optical signal encoded with the code not set as a decoding target. An optical communication system characterized in that the optical chip whose balance of the sum of the strengths after decoding is improved is not targeted for decoding.

The optical receiver that decodes the optical signal with the code not used for encoding the optical signal as a decoding target is added by the optical chip constituting the optical signal encoded with the code that is not the decoding target. 2. The optical communication system according to claim 1, wherein the optical chip having a sum of intensity after decoding of the optical chip decoded as negative and the optical chip decoded negative is not targeted for decoding. .

An optical transmitter that transmits an optical signal that is encoded according to a predetermined code and configured by a plurality of optical chips;
An optical communication system comprising: an optical receiver that receives the optical signal and decodes the optical chip constituting the optical signal as plus or minus according to the code to be decoded, respectively.
The predetermined code is composed of a plurality of chips,
The optical signal is composed of the optical chip corresponding to the chip constituting the predetermined code, and there are a plurality of the optical chips corresponding to at least one of the chips constituting the predetermined code,
When the optical signal is received and decoded by the optical receiver that decodes the code used for encoding the optical signal as a decoding target, the sum of the intensity of the decoded optical chip after decoding is obtained. When the optical signal is received by the optical receiver that decodes the optical signal that is not used for the encoding of the optical signal as a decoding target and is decoded, The total strength after decryption of the chip is approximately balanced,
The optical receiver detects the optical chip constituting the optical signal mixed with interfering light,
An optical communication system, wherein the same number of the optical chips not mixed with the interfering light are selected from the corresponding optical chips of the plurality of optical signals corresponding to the same code as decoding targets. .

The optical transmitter transmits a plurality of the optical signals composed of the plurality of optical chips encoded according to the predetermined same code,
The optical communication system according to claim 3, wherein the optical chips constituting the plurality of optical signals are different in at least one of a time domain and an optical frequency domain.

An optical transmitter for transmitting an optical signal composed of a plurality of optical chips encoded according to a predetermined code and the spare optical chip for transmitting according to an instruction;
An optical communication system comprising: an optical receiver that receives the optical signal and decodes the optical chip constituting the optical signal as plus or minus according to the code to be decoded, respectively.
When the optical signal is received and decoded by the optical receiver that decodes the code used for encoding the optical signal as a decoding target, the sum of the intensity of the decoded optical chip after decoding is obtained. When the optical signal is received by the optical receiver that decodes the optical signal that is not used for the encoding of the optical signal as a decoding target and is decoded, The total strength after decryption of the chip is approximately balanced,
The optical receiver detects the optical chip composing the optical signal mixed with disturbing light and does not subject to decoding, corresponds to the optical chip mixed with the disturbing light, and contains the disturbing light. Instructing the optical receiver to transmit the spare optical chip that is not, and including the spare optical chip transmitted in accordance with the instruction instead of the optical chip mixed with the interfering light as a decoding target. An optical communication system.

When the optical transmitter and the optical receiver receive and decode the code used for encoding the optical signal as a decoding target and decode it, one is decoded as positive and the other as negative. When the optical receiver that decodes the combination of the optical chips and the code that is not used for encoding the optical signal as a decoding target is received and decoded, the combination of the optical chips that is both positive or negative is 6. The optical communication system according to claim 1, wherein the optical signal is transmitted and received.