JP3755761B2

JP3755761B2 - Wavelength multiplexing communication system using wavelength selection mechanism

Info

Publication number: JP3755761B2
Application number: JP2002082445A
Authority: JP
Inventors: 英明井上; 克己村上; 明浩大▲高▼; 守康塩沢
Original assignee: Nippon Telegraph and Telephone Corp
Current assignee: Nippon Telegraph and Telephone Corp
Priority date: 2002-03-25
Filing date: 2002-03-25
Publication date: 2006-03-15
Anticipated expiration: 2022-03-25
Also published as: JP2003283465A

Description

【０００１】
【発明の属する技術分野】
本発明は、波長多重通信技術に関する波長多重通信システムであり、波長選択機構を用いたものである。
【０００２】
【従来の技術】
従来の技術を用いた波長多重（Wave-length Division Multiplexing:ＷＤＭ）通信システムを図１３に示す。
図１３に示すように、従来のＷＤＭ通信システムでは、アクセス系に用いられる場合には、ユーザ毎に上り及び下り方向の通信に異なる波長を割り当てることにより、通信を行う。
【０００３】
即ち、複数のユーザ側通信装置Ａ，Ｂ，Ｃ，Ｄと一つのセンタ側通信装置１０との間で通信を行う通信システムにおいて、各ユーザ側通信装置Ａ〜Ｄからセンタ側通信装置１０への通信及び、センタ側通信装置１０から各ユーザ側通信装置Ａ〜Ｄへの通信は、各々異なる波長λ２，４，６，８及びλ１，３，５，７を用いる。
【０００４】
このような波長多重技術を用いた通信システムは、各波長λ１，３，５，７及びλ２，４，６，８の通信信号を分離するために、図に示すようにＷＤＭフィルタ２０と呼ばれる１対多の波長分岐結合素子が必要である。
このＷＤＭフィルタ２０は、該当ユーザ側通信装置Ａ〜Ｄに割り当てられた受信用の波長λ１，３，５又は７のみを該当ユーザ側通信装置Ａ〜Ｄと接続された光ファイバヘ透過し、また該当ユーザ側通信装置Ａ，Ｂ，Ｃ又はＤに割り当てられた送信用波長λ２，４，６又は８のみを、該当ユーザ側通信装置Ａ，Ｂ，Ｃ又はＤと接続された光ファイバから、センタ側通信装置１０に接続された光ファイバヘ透過する機能を有する。
【０００５】
このＷＤＭフィルタ２０は、複数のユーザ側通信装置Ａ〜Ｄが共用で使用するために、ユーザ側通信設備が設置される複数の建物に近い電柱の上に設置される。
このため、ユーザ側通信装置Ａ〜Ｄの変更などで、割り当て波長に変更が発生した場合には、電柱の上に設置されたＷＤＭフィルタ２０を交換する必要が生じ、作業を迅速に行うことができず、また、ＷＤＭフィルタ２０の交換時に現在通信中のユーザの通信も切れてしまうといった問題があった。
【０００６】
また、パッシブ・オプティカル・ネットワーク（ＰＯＮ）形態のシステムを使用してサービスを展開している地域に、このような波長多重技術を用いたシステムを導入する場合には、既に電柱の上に設置された未使用の光スプリッタがあったとしても、それを使用することができず、あらたにＷＤＭフィルタ２０を柱上に設置しなければならず、設備使用の効率の点からも問題があった。
【０００７】
【発明が解決しようとする課題】
従来のＷＤＭ通信システムにおいて、通常の作業に適さない場所にＷＤＭフィルタ２０があるため、交換作業などを迅速に行うことができないといった問題があった。
即ち、従来のＷＤＭ通信システムでは、各ユーザ毎に光信号の波長を割り当てているため、各ユーザ毎に所定波長の信号を送出するユーザ側通信装置Ａ〜Ｄ及び屋外の電柱に波長合分波フィルタを設置する必要があり、ユーザの移転等により設置場所の変更があった場合、ユーザ側通信装置Ａ〜Ｄを取り替える必要があったと共に、電柱に設置された波長選択フィルタも使用波長の変更等が発生した場合、その都度、フィルタを交換する必要があったため、交換コストがかかっていた。
【０００８】
更に、従来のＷＤＭ通信システムにおいては、システムのアップグレードやユーザ側通信装置Ａ〜Ｄの変更に伴う波長割り当ての変更において、複数のユーザで共用しているＷＤＭフィルタ２０の交換が必要となり、交換時に通信中のユーザの通信が断になってしまうといった問題があった。
更に、ユーザに波長を割り当てる場合、波長毎にユーザ側通信装置が必要であるといった問題があった。
更に、従来の通信システムにおいてはユーザ毎にユーザ側通信装置は特定の波長に対し装置が必要であるため、設置場所が変更になった場合、装置を取り替える必要があるといった問題があった。
また、波長毎にユーザ管理を行う必要があるといった問題があった。
【０００９】
【課題を解決するための手段】
上記課題を解決する本発明の請求項１に係る波長多重通信システムは、複数のユーザ側通信装置と一つのセンタ側通信装置との間で通信を行う通信システムにおいて、各前記ユーザ側通信装置からセンタ側通信装置への通信及び、前記センタ側通信装置から各前記ユーザ側通信装置への通信は、各々異なる波長を用い、前記ユーザ側通信装置と前記センタ側通信装置は光ファイバを多対１に分岐結合する光スプリッタを介して光ファイバで接続され、前記光スプリッタと各前記ユーザ側通信装置との間の伝送路に、該当ユーザ側通信装置に割り当てられた通信用の波長を選択的に透過するための波長選択機構部を有し、各前記ユーザ側通信装置内では、前記通信用の波長のうちの該当ユーザ側通信装置に割り当てられた上り信号用の波長を折り返すことを特徴とする。
【００１０】
上記課題を解決する本発明の請求項２に係る波長多重通信システムは、請求項１において、前記光スプリッタと各前記波長選択機構部の間の伝送路が１芯の光ファイバであり、前記波長選択機構部と前記ユーザ側通信装置との間の伝送路が２芯の光ファイバであり、前記波長選択機構部は、前記光スプリッタから前記ユーザ側通信装置へ向かう方向の光信号のうち、予め定められた波長の光のみを前記ユーザ側通信装置と接続された一方の光ファイバに通過し、前記波長選択機構部と前記ユーザ側通信装置と接続された前記光ファイバとは異なる光ファイバから前記波長選択機構部に入力した光信号のうち前記波長とは異なる予め定められた波長の光のみを前記光スプリッタと接続された光ファイバに透過することを特徴とする。
【００１１】
上記課題を解決する本発明の請求項３に係る波長多重通信システムは、請求項１において、前記光スプリッタと各前記ユーザ側通信装置との間の伝送路が２芯の光ファイバであり、前記光スプリッタと前記ユーザ側通信装置の間の各々の光ファイバに前記波長選択機構部が接続され、前記波長選択機構部は、前記通信システム内部で重複がないように定められた特定の波長の光のみを透過する波長フィルタであることを特徴とする。
【００１２】
上記課題を解決する本発明の請求項４に係る波長多重通信システムは、複数のユーザ側通信装置と一つのセンタ側通信装置との間で通信を行う通信システムにおいて、各前記ユーザ側通信装置からセンタ側通信装置への通信及び、前記センタ側通信装置から各前記ユーザ側通信装置への通信は、各々異なる波長を用い、前記ユーザ側通信装置と前記センタ側通信装置は光ファイバを多対１に分岐結合する光スプリッタを介して光ファイバで接続され、前記光スプリッタと各前記ユーザ側通信装置との間の伝送路に、該当ユーザ側通信装置に割り当てられた通信用の波長を選択的に透過するための波長選択機構部を有すること、前記光スプリッタと各前記波長選択機構部の間の伝送路が１芯の光ファイバであり、前記波長選択機構部と前記ユーザ側通信装置との間の伝送路が２芯の光ファイバであり、前記ユーザ側通信装置の発光素子が、回折格子を用いたブラッグ反射により発光する波長が決まるブラッグ反射型半導体レーザであって、半導体素子と回折格子が分離して設置されており、前記半導体素子は前記ユーザ側通信装置内に設置され、前記回折格子は前記波長選択機構部に設置され、前記波長選択機構部は、前記光スプリッタから前記ユーザ側通信装置へ向かう方向の光信号のうち、予め定められた波長の光のみを前記ユーザ側通信装置と接続された前記回折格子が設置されていない方の光ファイバに通過することを特徴とする。
【００１３】
上記課題を解決する本発明の請求項５に係る波長多重通信システムは、請求項１において、前記光スプリッタと各前記ユーザ側通信装置との間の伝送路が１芯の光ファイバであり、前記波長選択機構部は、予め定められた波長範囲の光のみを透過し、それ以外の波長の光を透過せず、各前記ユーザ側通信装置は、各々接続された前記波長選択機構部が透過可能な２種類の波長の異なる光を用いて前記センタ側通信装置と通信を行うことを特徴とする。
【００１４】
上記課題を解決する本発明の請求項６に係る波長多重通信システムは、請求項１，２，３又は５のいずれかに記載した前記センタ側通信装置は、各前記ユーザ側通信装置から前記センタ側通信装置への通信及び、前記センタ側通信装置から各前記ユーザ側通信装置への通信で使用している前記波長とは異なる波長の光を用い、すべての前記ユーザ側通信装置へ向けて放送形式で信号を送信し、前記波長選択機構部は、該当する前記ユーザ側通信装置が前記センタ側通信装置との間の前記通信に用いている２つの波長のほかに、前記放送形式で送信された信号の波長をも通過することにより、前記放送形式の信号をすべての前記ユーザ側通信装置で受信することを特徴とする。
【００１５】
上記課題を解決する本発明の請求項７に係る波長多重通信システムは、請求項１，２，３，５又は６のいずれかに記載した前記波長選択機構部は、光ファイバを接続する光終端箱に収容されることを特徴とする。
【００１６】
上記課題を解決する本発明の請求項８に係る波長多重通信システムは、請求項７に記載された前記光終端箱は、屋外光ケーブルと構内光ケーブルを接続する光終端箱であることを特徴とする。
【００１７】
【発明の実施の形態】
本発明の実施の形態を図１及び図２に示す。
図１及び図２に示すように、本発明は、複数のユーザ側通信装置Ａ〜Ｄと一つのセンタ側通信装置１０との間で通信を行う通信システムであり、ユーザ側通信装置Ａ〜Ｄとセンタ側通信装置１０の間は光ファイバで接続されると共にこの光ファイバを多対１に分岐結合する光スプリッタ３０が介設されている。
【００１８】
ここで、図１では、各ユーザ側通信装置Ａ〜Ｄからセンタ側通信装置１０への上がり方向への通信は波長λ２，４，６，８を用い、センタ側通信装置１０から各ユーザ側通信装置Ａ〜Ｄへの下り方向への通信は波長λ１，３，５，７を用いる。
また、図２では、各ユーザ側通信装置Ａ〜Ｄからセンタ側通信装置１０への上がり方向への通信は波長λ２，４，６，８を用い、センタ側通信装置１０から各ユーザ側通信装置Ａ〜Ｄへの下り方向への通信は波長λ１，２，３，４，５，６，７，８を用いる。
【００１９】
各ユーザ側通信装置Ａ〜Ｄと光終端箱５０との間の伝送路の何れかの箇所（図中破線で囲んで示す）には波長選択機構部４０が配置されている。
この波長選択機構部４０は、該当ユーザ側通信装置Ａ〜Ｄに割り当てられた通信用の波長を選択的に透過するための装置である。具体的には、通信システム内部で重複がないように定められた特定の波長の光のみを透過する波長フィルタである。
【００２０】
ここで、図１に示す波長選択機構部４０は、下り方向への通信に割り当てられた波長λ１をユーザ側通信装置Ａへ、波長λ３をユーザ側通信装置Ｂへ、波長λ５をユーザ側通信装置Ｃへ、波長λ７をユーザ側通信装置Ｄへ透過する。
また、図２に示す波長選択機構部４０は、下り方向への通信に割り当てられた波長λ１，２をユーザ側通信装置Ａへ、波長λ３，４をユーザ側通信装置Ｂへ、波長λ５，６をユーザ側通信装置Ｃへ、波長λ７，８をユーザ側通信装置Ｄへ透過する。
【００２１】
本発明では、従来は一つのＷＤＭフィルタ２０で実現していた、伝送路を分岐する機能とそれぞれのユーザ側通信装置Ａ〜Ｄに必要な波長を選択する選択機能を分離し、共用部分である伝送路を分岐する機能部分の変更を行わずに、各ユーザ側通信装置Ａ〜Ｄに割り当てる波長の変更を可能とした。
更に、ユーザ側通信装置Ａ〜Ｄの発光素子として、回折格子を用いたブラッグ反射により発光する波長が決まるブラッグ反射型半導体レーザを用いれば、この半導体素子と回折格子を分離して設置することができる。
【００２２】
このように、本発明では、図１に示すように、半導体素子をユーザ側通信装置Ａ〜Ｄ内に設置し、ファイバグレーティングなどで構成した回折格子は波長選択機構部４０に設置することを可能とし、また、図２に示すように、個々のユーザ側通信装置Ａ〜Ｄに波長依存性を持たない構造等によりユーザ側通信装置Ａ〜Ｄに波長依存性をなくすと共に、従来、電柱に設置していた波長合分波フィルタを各ユーザ側近傍に設置することにより、上記課題を解決したものである。
【００２３】
【実施例】
〔実施例１〕
本発明の第１の実施例を図３及び図４に示す。
本実施例の通信システムにおいては、センタ側通信装置１０からの各波長信号をセンタ側通信装置１０内の光波長合分波フィルタ（図示省略）を介し、１芯の光ファイバで伝送し、伝送路上のユーザ近傍に設けた波長選択機構部４０からユーザ側通信装置Ａ〜Ｄまでを１芯の光ファイバで構成し、波長選択機構部４０により、各ユーザ側通信装置Ａ〜Ｄに特定の２波長信号を送出する。
【００２４】
各ユーザ側通信装置Ａ〜Ｄからは２波長のうちの１波長をユーザ側通信装置Ａ〜Ｄで受信し、残る１波長はユーザ側通信装置Ａ〜Ｄ内で折り返し、センタ側通信装置１０へ送出される。
このとき、ユーザ側通信装置Ａ〜Ｄ内で半導体光アンプなどを用いて、折り返した光波長について増幅を行うことにより変調を行い、上り方向の信号を該当波長の光に乗せて送信する。
【００２５】
各ユーザ側通信装置Ａ〜Ｄから送出された各波長信号は、伝送路上のユーザ近傍の波長選択機構部４０を介し、１芯の光ファイバ伝送路を経由しセンタ側通信装置１０へ到達する。
センタ側では到達した信号は再度、波長選択機構部４０を介し、各信号毎に該当ユーザに振り分けられる。
波長選択機構部４０は、図３に示すように、屋外光ケーブルと構内光ケーブルを接続するための光終端箱５０内部に実装しても良く、また、図４に示すように、ユーザ側通信装置Ａ〜Ｄと光ファイバを接続する光コネクタに実装しても良い。
【００２６】
本実施例では、波長選択機構部４０を容易に交換が可能なユーザ近傍に配置し、また、ユーザ側の装置としては、従来の通信方式に比べ、ユーザ側通信装置Ａ〜Ｄでの波長依存性が不要となると共に、ユーザ毎に波長選択機構部４０が設けられることから、電柱での交換作業をなくすことが可能となり、低コスト化が実現可能となる。
例えば、ユーザの引越しや他の波長が各ユーザ毎に必要になった場合など、該当ユーザヘ割り当てられる波長が変更になったとしても、サービス提供者がその波長に対応した波長選択機構部４０を交換することにより、ユーザはこれまで使用していた通信機器をそのまま使用することが可能である。
【００２７】
〔実施例２〕
本発明の第２の実施例を図５及び図６に示す。
本実施例の通信システムにおいては、センタ側通信装置１０からの各波長信号をセンタ側通信装置１０内の光波長合分波フィルタを介し、１芯の光ファイバで伝送し、伝送路上のユーザ近傍に設けた波長選択機構部４０からユーザ側通信装置Ａ〜Ｄまでを２芯の光ファイバで構成し、波長選択機構部４０により、各ユーザ側通信装置Ａ〜Ｄに特定の２波長信号を送出する。
【００２８】
各ユーザ側通信装置Ａ〜Ｄからは２波長のうちの１波長をユーザ側通信装置Ａ〜Ｄで受信し、残る１波長はユーザ側通信装置Ａ〜Ｄ内で折り返し、センタ側通信装置１０へ送出される。
実施例１の場合と同様に、折り返す波長の光は、ユーザ側通信装置Ａ〜Ｄ内で半導体光アンプなどを用いて増幅を行うことにより変調を行い、上り方向の信号を該当波長の光に乗せて送信する。
【００２９】
各ユーザ側通信装置Ａ〜Ｄから送出された各波長信号は、伝送路上のユーザ近傍の波長選択機構部４０を介し、１芯の光ファイバ伝送路を経由しセンタ側通信装置１０へ到達する。
センタ側では到達した信号は再度、光波長合分波フィルタを介し、各信号毎に該当ユーザに振り分けられる。
波長選択機構部４０は、図５に示すように、屋外光ケーブルと構内光ケーブルを接続するための光終端箱５０内部に実装しても良く、図６に示すように、ユーザ側通信装置Ａ〜Ｄと光ファイバを接続する光コネクタに実装しても良い。
【００３０】
本実施例では、実施例１に比べ、波長選択機構部４０からユーザ側通信装置Ａ〜Ｄまでを２芯の光ファイバで伝送することにより、波長選択機構部４０の波長合波機構の削減が図られる。
即ち、ユーザ側通信装置Ａ〜Ｄでは、物理的に異なるファイバ上において受信信号を受信し、送信信号を送信するために、受信信号と送信信号及び送信信号の反射光の間の分離を行う機構が不要となる。
【００３１】
また、本実施例では、波長選択機構部４０は容易に交換が可能なユーザ近傍に配置され、ユーザ側の装置としては、従来の通信方式に比べ、ユーザ側通信装置Ａ〜Ｄでの波長依存性が不要となると共に、ユーザ毎に波長選択機構部４０が設けられることから、電柱での交換作業をなくすことが可能となり、低コスト化が実現可能となる。
例えば、ユーザの引越しや他の波長が各ユーザ毎に必要になった場合など、該当ユーザヘ割り当てられる波長が変更になったとしても、サービス提供者がその波長に対応した波長選択機構部４０を交換することにより、ユーザはこれまで使用していた通信機器をそのまま使用することが可能である。
【００３２】
〔実施例３〕
本発明の第３の実施例を図７及び図８に示す。
前述の実施例１、２では、センタ側通信装置１０から発信された特定の２波長のうち、１波長をユーザ側通信装置Ａ〜Ｄで折り返し、ユーザ側通信装置Ａ〜Ｄの発信波長として使用していたが、本実施例では、センタ側通信装置１０からは特定の１波長のみをユーザ側通信装置Ａ〜Ｄで受信し、ユーザ側通信装置Ａ〜Ｄからの発信波長については、回折格子部をそれぞれ、ユーザ側通信装置Ａ〜Ｄと波長選択機構部４０の間に設け、回折格子部により特定の波長を発信するものである。
【００３３】
本実施例の通信システムにおいては、センタ側通信装置１０からの各波長信号をセンタ側通信装置１０内の光波長合分波フィルタを介し、１芯の光ファイバで伝送し、伝送路上のユーザ近傍に設けた波長選択機構部４０からユーザ側通信装置Ａ〜Ｄまでを２芯の光ファイバで構成し、波長選択機構部４０により、各ユーザ側通信装置Ａ〜Ｄに特定の１波長信号を送出する。
各ユーザ側通信装置Ａ〜Ｄは、発光素子として回折格子を用いたブラッグ反射により発光する波長が決まるブラッグ反射型半導体レーザを用い、この半導体素子と回折格子が分離して設置される。
【００３４】
即ち、半導体素子（ＳＯＡ;Semiconductor Optical Amplifier）をユーザ側通信装置Ａ〜Ｄ内に設置し、ファイバグレーティング機構６０などで構成した回折格子をユーザ側通信装置Ａ〜Ｄと波長選択機構部４０の間に設けたものである。そのため、回折格子部において、特定の波長をユーザ側通信装置Ａ〜Ｄ内のＳＯＡへ反射することにより、ユーザ側通信装置Ａ〜Ｄから発信し、各ユーザ側通信装置Ａ〜Ｄから送出された各波長信号は伝送路上のユーザ近傍の波長選択機構部４０を介し、１芯の光ファイバ伝送路を経由しセンタ側通信装置１０へ到達する。
【００３５】
センタ側では到達した信号は再度、波長選択機構部４０を介し、各信号毎に該当ユーザに振り分けられる。
波長選択機構部４０は、図７に示すように、屋外光ケーブルと構内光ケーブルを接続するための光終端箱５０内部に実装しても良く、図８に示すように、ユーザ側通信装置Ａ〜Ｄと光ファイバを接続する光コネクタに実装しても良い。
【００３６】
本実施例では前述した実施例で述べたような、センタ側通信装置１０にユーザ宅内で光を折り返すための発信用レーザを搭載する必要がなくなる。
本実施例では、波長選択機構部４０を容易に交換が可能なユーザ近傍に配置し、ユーザ側の装置としては、従来の通信方式に比べ、ユーザ側通信装置Ａ〜Ｄでの波長依存性が不要となると共に、ユーザ毎に波長選択機構部４０が設けられることから、電柱での交換作業をなくすことが可能となり、低コスト化が実現可能となる。
例えば、ユーザの引越しや他の波長が各ユーザ毎に必要になった場合など、該当ユーザヘ割り当てられる波長が変更になったとしても、サービス提供者がその波長に対応した波長選択機構部４０を交換することにより、ユーザはこれまで使用していた通信機器をそのまま使用することが可能である。
【００３７】
〔実施例４〕
本発明の第４の実施例を図９及び図１０に示す。
上記実施例１〜３では、各ユーザ側通信装置Ａ〜Ｄが各々センタ側通信装置１０と個別に通信する場合について説明を行ったが、本実施例では、更にセンタ側通信装置１０から放送形式の信号を送信し、全てのユーザ側通信装置Ａ〜Ｄで受信する通信システムに関するものである。
【００３８】
また、各ユーザ側通信装置Ａ〜Ｄと各々センタ側通信装置１０との個別の通信については、実施例１〜３のいずれの方法であっても用いることが可能である。
ここで、センタ側通信装置１０は、各ユーザ側通信装置Ａ〜Ｄが各々センタ側通信装置１０と個別に通信に使用している波長λ１〜λ８とは異なる波長λ９を用いて、下り方向に放送形式の通信信号を送信する。
各ユーザ側通信装置Ａ〜Ｄに接続された波長選択機構部４０は、該当ユーザ側通信装置Ａ〜Ｄが各々センタ側通信装置１０と個別に通信に用いる波長λ１及びλ２及び、下り方向に放送形式の通信信号で用いる波長λ９を透過する。
【００３９】
この結果、ユーザ側通信装置Ａ〜Ｄ側では、放送形式の通信信号をも受信することが可能となる。
図９に示すように、個別の通信と放送形式の通信の両方を一つのユーザ側通信装置Ａで行うこともでき、図１０に示すように、個別の通信と放送形式の通信を別々のユーザ側通信装置Ａ，Ａ’で行うことも可能である。
本実施例では、波長選択機構部４０を容易に交換が可能なユーザ近傍に配置し、ユーザ側の装置としては、従来の通信方式に比べ、ユーザ側通信装置Ａ〜Ｄでの波長依存性が不要となると共に、ユーザ毎に波長選択機構部４０が設けられることから、電柱での交換作業をなくすことが可能となり、低コスト化が実現可能となる。
【００４０】
例えば、ユーザの引越しや他の波長が各ユーザ毎に必要になった場合など、該当ユーザヘ割り当てられる波長が変更になったとしても、サービス提供者がその波長に対応した波長選択機構部４０を交換することにより、ユーザはこれまで使用していた通信機器をそのまま使用することが可能である。
また、従来のＷＤＭシステムにおいては、放送型の通信を個別通信に多重することができなかったが、本実施例においては、光分岐素子として波長依存性のない光スプリッタ３０を用いることにより、放送型の通信も可能となった。
【００４１】
〔実施例５〕
本発明の第５の実施例を図１１及び図１２に示す。
本実施例の通信システムにおいては、センタ側装置からの各波長信号をセンタ側装置内の光波長合分波フィルタを介し、１芯の光ファイバで伝送し、伝送路上の光スプリッタ３０からユーザ側通信装置Ａ〜Ｄまでを２芯の光ファイバで構成し、２芯各々の光ファイバに対し、波長選択機構部４０を設け、各ユーザ側通信装置Ａ〜Ｄに特定の２波長を送出する。
【００４２】
各ユーザ側通信装置Ａ〜Ｄからは２波長のうちの１波長をユーザ側装置で受信し、残る１波長はユーザ側通信装置Ａ〜Ｄ内で折り返し、センタ側通信装置１０へ送出される。
実施例１の場合と同様に、折り返す波長の光は、ユーザ側装置内で半導体光アンプなどを用いて増幅を行うことにより変調を行い、上り方向の信号を該当波長の光に乗せて送信する。
【００４３】
各ユーザ側装置から送出された各波長信号は伝送路上のユーザ近傍の波長選択機構部４０を介し、伝送路上の柱上に設置された光スプリッタ３０まで各々の光ファイバで伝送し、光スプリッタ３０を通過し、１芯の光ファイバ伝送路を経由しセンタ側装置へ到達する。
センタ側では到達した信号は再度、光波長合分波フィルタを介し、各信号毎に該当ユーザに振り分けられる。
波長選択機構部４０は、図１１に示すように、屋外光ケーブルと構内光ケーブルを接続するための光終端箱５０内部に実装しても良く、図１２に示すように、ユーザ側通信装置Ａ〜Ｄと光ファイバを接続する光コネクタに実装しても良い。
【００４４】
本実施例では、実施例１に比ベ、光スプリッタ３０からユーザ側通信装置Ａ〜Ｄまでを２芯の光ファイバで伝送することにより、波長選択機構部４０の波長合分波機構の削減が図られる。
即ち、波長選択機構部４０及びユーザ側通信装置Ａ〜Ｄでは、物理的に異なるファイバ上において受信信号を受信し、送信信号を送信するために、受信信号と送信信号及び送信信号の反射光の間の分離を行う機構が不要となる。
【００４５】
また、容易に交換が可能なユーザ近傍に波長選択機構部４０を持たせ、ユーザ側の装置としては、従来の通信方式に比べ、ユーザ側装置での波長依存性が不要となるとともに、ユーザ毎に波長選択機構部４０が設けられることから、電柱での交換作業をなくすことが可能となり、低コスト化が実現可能となる。
例えば、ユーザの引越しや他の波長が各ユーザ毎に必要になった場合など、該当ユーザへ割り当てられる波長が変更になったとしても、サービス提供者がその波長に対応した波長選択機構部４０を交換することにより、ユーザはこれまで使用していた通信機器をそのまま使用することが可能である。
【００４６】
このように説明したように本発明は、通信センタとユーザ間をそれぞれ異なる波長で通信する波長多重の光通信ネットワークにおいて、光を分岐結合する光スプリッタ３０とユーザ個別の波長を選択する波長選択機構部４０を有することを特徴とした波長多重通信システムである。
従って、本発明によれば、ユーザは、ユーザ側通信装置Ａ〜Ｄの種別を意識する必要なく自装置を転居先でも利用できると共に、サービス提供事業者もユーザ端末種別を管理する必要がないため、サービスの低コスト化が可能になる。
更に、設備交換コストやネットワークの信頼性も併せて改善されるものである。
【００４７】
【発明の効果】
以上、説明したように、本発明によれば、以下の４つの効果を奏する。
（１）端末利用者がユーザ側通信装置の種別を意識する必要がなく、ユーザが移転した場合でも装置交換が不要となり、サービス提供側においてもユーザ端末種別の管理が不要となる。このため、サービスの低コスト化が可能となる。
（２）波長選択機構部を電柱ではなく、ユーザ近傍に設けることにより、ユーザ毎に使用する波長を変更したい場合や全く別の波長を使用する場合にユーザ毎の波長選択機構部を交換することにより対応するため、交換コスト等が削減でき、低コスト化が実現できる。
（３）パッシブ・オプティカル・ネットワーク形態のシステムと違い、特定のユーザ側通信装置の故障等による、伝送路上の同一光ファイバ１芯を共有している他のユーザの通信を妨害したり、ネットワーク側に対し通信障害を与える恐れがなくなり、ユーザ及びネットワークの信頼性向上が図られる。
（４）将来、多くのサービスに波長割当が行われた場合、伝送路上の機器を交換することなく、ユーザ側の波長選択機構部の交換で対処できることから交換コストの削減が図られる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る波長多重通信システムの概念図である。
【図２】本発明の実施の形態に係る波長多重通信システムの概念図である。
【図３】本発明の第１の実施例に係る波長多重通信システムの概念図である。
【図４】本発明の第１の実施例に係る波長多重通信システムの概念図である。
【図５】本発明の第２の実施例に係る波長多重通信システムの概念図である。
【図６】本発明の第２の実施例に係る波長多重通信システムの概念図である。
【図７】本発明の第３の実施例に係る波長多重通信システムの概念図である。
【図８】本発明の第３の実施例に係る波長多重通信システムの概念図である。
【図９】本発明の第４の実施例に係る波長多重通信システムの概念図である。
【図１０】本発明の第４の実施例に係る波長多重通信システムの概念図である。
【図１１】本発明の第５の実施例に係る波長多重通信システムの概念図である。
【図１２】本発明の第５の実施例に係る波長多重通信システムの概念図である。
【図１３】従来の技術を用いた波長多重通信システムの概念図である。
【符号の説明】
１０センタ側通信装置
２０ＷＤＭフィルタ
３０光スプリッタ
４０波長選択機構部
５０光終端箱
６０ファイバグレーティング機構
Ａ，Ａ’，Ｂ，Ｃ，Ｄユーザ側通信装置[0001]
BACKGROUND OF THE INVENTION
The present invention is a wavelength division multiplexing communication system related to wavelength division multiplexing technology, and uses a wavelength selection mechanism.
[0002]
[Prior art]
A wavelength division multiplexing (WDM) communication system using a conventional technique is shown in FIG.
As shown in FIG. 13, in a conventional WDM communication system, when used in an access system, communication is performed by assigning different wavelengths to uplink and downlink communications for each user.
[0003]
That is, in a communication system that performs communication between a plurality of user-side communication devices A, B, C, and D and one center-side communication device 10, each user-side communication device A to D communicates with the center-side communication device 10. Communication and communication from the center side communication device 10 to each of the user side communication devices A to D use different wavelengths λ2, 4, 6, 8 and λ1, 3, 5, 7, respectively.
[0004]
A communication system using such a wavelength multiplexing technique is called a WDM filter 20 as shown in FIG. 1 in order to separate communication signals of wavelengths λ1, 3, 5, 7 and λ2, 4, 6, 8. A many-to-many wavelength branching and coupling element is required.
The WDM filter 20 transmits only the reception wavelength λ1, 3, 5, or 7 assigned to the corresponding user side communication devices A to D to the optical fiber connected to the corresponding user side communication devices A to D. Only the transmission wavelength λ2, 4, 6 or 8 assigned to the user side communication device A, B, C or D is transferred from the optical fiber connected to the user side communication device A, B, C or D to the center side. It has a function of transmitting through an optical fiber connected to the communication device 10.
[0005]
The WDM filter 20 is installed on a power pole close to a plurality of buildings where user-side communication facilities are installed in order to be shared by a plurality of user-side communication apparatuses A to D.
For this reason, when a change occurs in the allocated wavelength due to a change in the user side communication devices A to D, it is necessary to replace the WDM filter 20 installed on the utility pole, and the work can be performed quickly. In addition, there is a problem that communication with the user who is currently communicating is interrupted when the WDM filter 20 is replaced.
[0006]
In addition, when a system using such a wavelength multiplexing technology is introduced in an area where a service is developed using a passive optical network (PON) system, it is already installed on a power pole. Even if there is an unused optical splitter, it cannot be used, and the WDM filter 20 must be newly installed on the pillar, which causes a problem in terms of the efficiency of equipment use.
[0007]
[Problems to be solved by the invention]
In the conventional WDM communication system, since the WDM filter 20 is located in a place that is not suitable for normal work, there is a problem that replacement work or the like cannot be performed quickly.
That is, in the conventional WDM communication system, since the wavelength of the optical signal is assigned to each user, wavelength multiplexing / demultiplexing is performed on the user side communication devices A to D that transmit a signal of a predetermined wavelength for each user and the outdoor utility pole. When it is necessary to install a filter and the installation location is changed due to the transfer of a user, etc., it is necessary to replace the user side communication devices A to D, and the wavelength selection filter installed on the utility pole also changes the wavelength used. In such a case, it was necessary to replace the filter each time, so that replacement costs were incurred.
[0008]
Further, in the conventional WDM communication system, when the wavelength allocation is changed due to the system upgrade or the change of the user side communication devices A to D, it is necessary to replace the WDM filter 20 shared by a plurality of users. There was a problem that the communication of the user during communication was interrupted.
Furthermore, when assigning a wavelength to a user, there is a problem that a user-side communication device is required for each wavelength.
Further, in the conventional communication system, since the user side communication device is required for each user for a specific wavelength, there is a problem that the device needs to be replaced when the installation location is changed.
In addition, there is a problem that it is necessary to perform user management for each wavelength.
[0009]
[Means for Solving the Problems]
A wavelength division multiplexing communication system according to claim 1 of the present invention that solves the above problem is a communication system that performs communication between a plurality of user side communication devices and one center side communication device. Communication to the center-side communication device and communication from the center-side communication device to each user-side communication device use different wavelengths, and the user-side communication device and the center-side communication device have many-to-one optical fibers. Are connected by an optical fiber via an optical splitter that branches and couples to the transmission path between the optical splitter and each user-side communication device, and selectively uses the communication wavelength assigned to the user-side communication device. Has a wavelength selection mechanism for transmission In each user-side communication device, the uplink signal wavelength assigned to the user-side communication device among the communication wavelengths is turned back. It is characterized by that.
[0010]
A wavelength division multiplexing communication system according to a second aspect of the present invention for solving the above-mentioned problem is the wavelength division multiplexing communication system according to the first aspect, wherein a transmission line between the optical splitter and each of the wavelength selection mechanism units is a single-core optical fiber. The transmission path between the selection mechanism unit and the user-side communication device is a two-core optical fiber, and the wavelength selection mechanism unit is preliminarily selected among optical signals in a direction from the optical splitter toward the user-side communication device. Only light of a predetermined wavelength passes through one optical fiber connected to the user side communication device, and the optical fiber connected to the wavelength selection mechanism unit and the user side communication device is different from the optical fiber. Of the optical signal input to the wavelength selection mechanism, only light having a predetermined wavelength different from the wavelength is transmitted through the optical fiber connected to the optical splitter.
[0011]
The wavelength division multiplexing communication system according to a third aspect of the present invention for solving the above-mentioned problem is the wavelength division multiplexing communication system according to the first aspect, wherein the transmission path between the optical splitter and each of the user side communication devices is a two-core optical fiber, The wavelength selection mechanism is connected to each optical fiber between the optical splitter and the user-side communication device, and the wavelength selection mechanism is configured to transmit light of a specific wavelength determined so as not to overlap within the communication system. It is a wavelength filter that transmits only the light.
[0012]
A wavelength division multiplexing communication system according to claim 4 of the present invention for solving the above-described problem is provided. In a communication system that performs communication between a plurality of user-side communication devices and one center-side communication device, communication from each user-side communication device to the center-side communication device, and from the center-side communication device to each user-side The communication to the communication device uses different wavelengths, and the user-side communication device and the center-side communication device are connected by an optical fiber via an optical splitter that branches and couples optical fibers in a many-to-one relationship, Having a wavelength selection mechanism for selectively transmitting a wavelength for communication assigned to the user side communication device in a transmission path between each of the user side communication devices; The transmission path between the optical splitter and each wavelength selection mechanism is a one-core optical fiber, and the transmission path between the wavelength selection mechanism and the user side communication device is a two-core optical fiber, The light emitting element of the user side communication device is a Bragg reflection type semiconductor laser in which the wavelength to be emitted is determined by Bragg reflection using a diffraction grating, and the semiconductor element and the diffraction grating are separately installed, and the semiconductor element is It is installed in the user side communication device, the diffraction grating is installed in the wavelength selection mechanism unit, and the wavelength selection mechanism unit is predetermined among optical signals in a direction from the optical splitter to the user side communication device. Only the light of the specified wavelength passes through the optical fiber on which the diffraction grating connected to the user-side communication device is not installed.
[0013]
A wavelength division multiplexing communication system according to a fifth aspect of the present invention for solving the above-described problem is the wavelength division multiplexing communication system according to the first aspect, wherein a transmission path between the optical splitter and each of the user side communication devices is a single-core optical fiber, The wavelength selection mechanism transmits only light in a predetermined wavelength range, does not transmit light of other wavelengths, and each user-side communication device can transmit the connected wavelength selection mechanism Communication with the center side communication apparatus is performed using two types of light having different wavelengths.
[0014]
A wavelength division multiplexing communication system according to a sixth aspect of the present invention for solving the above-mentioned problems is the first, second, and second aspects. Three The center side communication device described in any one of 5 is used for communication from each user side communication device to the center side communication device and communication from the center side communication device to each user side communication device. A signal having a wavelength different from the wavelength of the light is transmitted to all the user-side communication devices in a broadcast format, and the wavelength selection mechanism unit is configured so that the corresponding user-side communication device transmits the center-side communication. In addition to the two wavelengths used for the communication with the device, the signal of the broadcast format is received by all the user-side communication devices by passing the wavelength of the signal transmitted in the broadcast format. It is characterized by doing.
[0015]
A wavelength division multiplexing communication system according to a seventh aspect of the present invention for solving the above-mentioned problems is provided by the first, second and third aspects. , 5 Alternatively, the wavelength selection mechanism described in any one of 6 is housed in an optical terminal box that connects optical fibers.
[0016]
A wavelength division multiplexing communication system according to an eighth aspect of the present invention for solving the above-mentioned problems is characterized in that the optical termination box according to the seventh aspect is an optical termination box for connecting an outdoor optical cable and a local optical cable. .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention is shown in FIGS.
As shown in FIGS. 1 and 2, the present invention is a communication system that performs communication between a plurality of user side communication devices A to D and one center side communication device 10, and the user side communication devices A to D. The center side communication device 10 is connected by an optical fiber, and an optical splitter 30 for branching and coupling the optical fiber to many-to-one is interposed.
[0018]
Here, in FIG. 1, the upward communication from each user-side communication device A to D to the center-side communication device 10 uses wavelengths λ2, 4, 6, and 8, and the center-side communication device 10 communicates with each user-side communication. Wavelengths λ1, 3, 5, and 7 are used for communication in the downstream direction to the devices A to D.
In FIG. 2, the upward communication from each user side communication device A to D to the center side communication device 10 uses wavelengths λ2, 4, 6, 8, and the center side communication device 10 to each user side communication device. Wavelengths λ1, 2, 3, 4, 5, 6, 7, and 8 are used for communication in the downstream direction from A to D.
[0019]
A wavelength selection mechanism unit 40 is disposed at any location (enclosed by a broken line in the figure) between transmission paths between the user side communication apparatuses A to D and the optical termination box 50.
The wavelength selection mechanism unit 40 is a device for selectively transmitting the communication wavelength assigned to the corresponding user side communication devices A to D. Specifically, it is a wavelength filter that transmits only light of a specific wavelength determined so as not to overlap within the communication system.
[0020]
Here, the wavelength selection mechanism unit 40 shown in FIG. 1 sets the wavelength λ1 assigned to the downlink communication to the user side communication device A, the wavelength λ3 to the user side communication device B, and the wavelength λ5 to the user side communication device. The wavelength λ7 is transmitted to the user side communication device D to C.
Also, the wavelength selection mechanism unit 40 shown in FIG. 2 transmits wavelengths λ1 and λ2 assigned to downstream communication to the user-side communication device A, wavelengths λ3 and 4 to the user-side communication device B, and wavelengths λ5 and 6 Is transmitted to the user side communication apparatus C, and the wavelengths λ7 and 8 are transmitted to the user side communication apparatus D.
[0021]
In the present invention, the function of branching the transmission path and the selection function of selecting the wavelength required for each user side communication device A to D, which has been conventionally realized by one WDM filter 20, are separated and shared. The wavelength allocated to each of the user side communication devices A to D can be changed without changing the functional part that branches the transmission path.
Furthermore, if a Bragg reflection type semiconductor laser whose wavelength is determined by Bragg reflection using a diffraction grating is used as the light emitting element of the user side communication devices A to D, the semiconductor element and the diffraction grating can be installed separately. it can.
[0022]
As described above, in the present invention, as shown in FIG. 1, it is possible to install the semiconductor element in the user side communication devices A to D, and to install the diffraction grating constituted by the fiber grating or the like in the wavelength selection mechanism unit 40. In addition, as shown in FIG. 2, the user-side communication devices A to D are not dependent on the wavelength due to a structure or the like that does not have the wavelength dependency of the individual user-side communication devices A to D, and is conventionally installed on a utility pole. The above-described problem is solved by installing the wavelength multiplexing / demultiplexing filter in the vicinity of each user side.
[0023]
【Example】
[Example 1]
A first embodiment of the present invention is shown in FIGS.
In the communication system of the present embodiment, each wavelength signal from the center side communication device 10 is transmitted through a single wavelength optical fiber via an optical wavelength multiplexing / demultiplexing filter (not shown) in the center side communication device 10 and transmitted. The wavelength selection mechanism unit 40 provided in the vicinity of the user on the road to the user side communication devices A to D are configured by a single-core optical fiber, and the wavelength selection mechanism unit 40 uses a specific 2 for each user side communication device A to D. Sends wavelength signal.
[0024]
From each of the user side communication devices A to D, one of the two wavelengths is received by the user side communication devices A to D, and the remaining one wavelength is turned back in the user side communication devices A to D and sent to the center side communication device 10. Sent out.
At this time, modulation is performed by amplifying the folded optical wavelength by using a semiconductor optical amplifier or the like in the user side communication apparatuses A to D, and an uplink signal is transmitted on the light of the corresponding wavelength.
[0025]
Each wavelength signal transmitted from each user-side communication device A to D reaches the center-side communication device 10 via the single-core optical fiber transmission line via the wavelength selection mechanism 40 near the user on the transmission line.
On the center side, the arrived signal is again distributed to the corresponding user for each signal via the wavelength selection mechanism 40.
As shown in FIG. 3, the wavelength selection mechanism unit 40 may be mounted inside the optical terminal box 50 for connecting the outdoor optical cable and the indoor optical cable. Also, as shown in FIG. It may be mounted on an optical connector that connects ~ D and an optical fiber.
[0026]
In the present embodiment, the wavelength selection mechanism unit 40 is arranged in the vicinity of a user that can be easily exchanged, and the user side device has a wavelength dependency in the user side communication devices A to D as compared with the conventional communication method. Since the wavelength selection mechanism 40 is provided for each user, it is possible to eliminate the replacement work on the utility pole and to realize cost reduction.
For example, even if the wavelength assigned to the user is changed, such as when a user moves or another wavelength is required for each user, the service provider replaces the wavelength selection mechanism unit 40 corresponding to the wavelength. By doing so, the user can use the communication device used so far as it is.
[0027]
[Example 2]
A second embodiment of the present invention is shown in FIGS.
In the communication system of the present embodiment, each wavelength signal from the center side communication device 10 is transmitted through a single wavelength optical fiber through the optical wavelength multiplexing / demultiplexing filter in the center side communication device 10, and in the vicinity of the user on the transmission line. The wavelength selection mechanism unit 40 to the user-side communication devices A to D provided in FIG. 2 are configured by a two-core optical fiber, and the wavelength selection mechanism unit 40 sends a specific two-wavelength signal to each user-side communication device A to D. To do.
[0028]
From each of the user side communication devices A to D, one of the two wavelengths is received by the user side communication devices A to D, and the remaining one wavelength is turned back in the user side communication devices A to D and sent to the center side communication device 10. Sent out.
Similar to the case of the first embodiment, the light having the wavelength to be turned back is modulated by performing amplification using a semiconductor optical amplifier or the like in the user-side communication devices A to D, and the upstream signal is converted into light of the corresponding wavelength. Send it on board.
[0029]
Each wavelength signal transmitted from each user-side communication device A to D reaches the center-side communication device 10 via the single-core optical fiber transmission line via the wavelength selection mechanism 40 near the user on the transmission line.
On the center side, the arrived signal is again distributed to the corresponding user for each signal through the optical wavelength multiplexing / demultiplexing filter.
As shown in FIG. 5, the wavelength selection mechanism unit 40 may be mounted inside the optical terminal box 50 for connecting the outdoor optical cable and the indoor optical cable. As shown in FIG. And may be mounted on an optical connector that connects the optical fiber.
[0030]
In the present embodiment, the wavelength combining mechanism of the wavelength selecting mechanism section 40 can be reduced by transmitting from the wavelength selecting mechanism section 40 to the user-side communication devices A to D using the two-core optical fiber as compared with the first embodiment. Figured.
That is, in the user side communication apparatuses A to D, a reception signal is received on physically different fibers and a transmission signal is transmitted, and a mechanism for separating the reception signal from the transmission signal and the reflected light of the transmission signal is performed. Is no longer necessary.
[0031]
Further, in the present embodiment, the wavelength selection mechanism unit 40 is arranged in the vicinity of a user that can be easily replaced, and the user side device has a wavelength dependency on the user side communication devices A to D as compared with the conventional communication method. Since the wavelength selection mechanism 40 is provided for each user, it is possible to eliminate the replacement work on the utility pole and to realize cost reduction.
For example, even if the wavelength assigned to the user is changed, such as when a user moves or another wavelength is required for each user, the service provider replaces the wavelength selection mechanism unit 40 corresponding to the wavelength. By doing so, the user can use the communication device used so far as it is.
[0032]
Example 3
A third embodiment of the present invention is shown in FIGS.
In the first and second embodiments described above, one of the two specific wavelengths transmitted from the center side communication device 10 is turned back by the user side communication devices A to D and used as the transmission wavelength of the user side communication devices A to D. However, in this embodiment, only one specific wavelength is received from the center side communication device 10 by the user side communication devices A to D, and the transmission wavelength from the user side communication devices A to D is a diffraction grating. Are provided between the user side communication devices A to D and the wavelength selection mechanism 40, and a specific wavelength is transmitted by the diffraction grating.
[0033]
In the communication system of the present embodiment, each wavelength signal from the center side communication device 10 is transmitted through a single wavelength optical fiber through the optical wavelength multiplexing / demultiplexing filter in the center side communication device 10, and in the vicinity of the user on the transmission line. The wavelength selection mechanism unit 40 to the user side communication devices A to D provided in the network are configured by a two-core optical fiber, and the wavelength selection mechanism unit 40 sends a specific one wavelength signal to each of the user side communication devices A to D. To do.
Each of the user side communication devices A to D uses a Bragg reflection type semiconductor laser in which a wavelength to be emitted is determined by Bragg reflection using a diffraction grating as a light emitting element, and the semiconductor element and the diffraction grating are installed separately.
[0034]
That is, a semiconductor element (SOA: Semiconductor Optical Amplifier) is installed in the user side communication devices A to D, and a diffraction grating constituted by the fiber grating mechanism 60 or the like is provided between the user side communication devices A to D and the wavelength selection mechanism unit 40. Is provided. Therefore, in the diffraction grating part, a specific wavelength is reflected to the SOA in the user side communication devices A to D to be transmitted from the user side communication devices A to D and transmitted from each user side communication device A to D. Each wavelength signal reaches the center-side communication device 10 via the single-core optical fiber transmission line via the wavelength selection mechanism 40 near the user on the transmission line.
[0035]
On the center side, the arrived signal is again distributed to the corresponding user for each signal via the wavelength selection mechanism 40.
As shown in FIG. 7, the wavelength selection mechanism unit 40 may be mounted inside the optical terminal box 50 for connecting the outdoor optical cable and the indoor optical cable, and as shown in FIG. And may be mounted on an optical connector that connects the optical fiber.
[0036]
In the present embodiment, there is no need to mount a transmission laser for returning light in the user's home in the center side communication device 10 as described in the above-described embodiment.
In the present embodiment, the wavelength selection mechanism unit 40 is disposed in the vicinity of a user that can be easily replaced, and the user-side device has wavelength dependency in the user-side communication devices A to D as compared with the conventional communication method. In addition to being unnecessary, since the wavelength selection mechanism 40 is provided for each user, it is possible to eliminate the replacement work on the utility pole, and it is possible to reduce the cost.
For example, even if the wavelength assigned to the user is changed, such as when a user moves or another wavelength is required for each user, the service provider replaces the wavelength selection mechanism unit 40 corresponding to the wavelength. By doing so, the user can use the communication device used so far as it is.
[0037]
Example 4
A fourth embodiment of the present invention is shown in FIGS.
In the first to third embodiments, the case where each user-side communication device A to D individually communicates with the center-side communication device 10 has been described. However, in this embodiment, the center-side communication device 10 further transmits a broadcast format. It is related with the communication system which transmits this signal and receives with all the user side communication apparatuses AD.
[0038]
Moreover, it is possible to use any of the methods in the first to third embodiments for individual communication between the user side communication devices A to D and the center side communication device 10.
Here, the center side communication device 10 uses the wavelength λ9 different from the wavelengths λ1 to λ8 that each of the user side communication devices A to D individually uses for communication with the center side communication device 10 in the downstream direction. A broadcast format communication signal is transmitted.
The wavelength selection mechanism unit 40 connected to each of the user side communication devices A to D broadcasts the wavelengths λ1 and λ2 that the user side communication devices A to D individually communicate with the center side communication device 10 and the downlink. Transmits the wavelength λ9 used in the format communication signal.
[0039]
As a result, the user side communication devices A to D can also receive broadcast format communication signals.
As shown in FIG. 9, both individual communication and broadcast format communication can be performed by one user side communication apparatus A. As shown in FIG. 10, individual communication and broadcast format communication are performed by different users. It is also possible to use the side communication devices A and A ′.
In the present embodiment, the wavelength selection mechanism unit 40 is disposed in the vicinity of a user that can be easily replaced, and the user-side device has wavelength dependency in the user-side communication devices A to D as compared with the conventional communication method. In addition to being unnecessary, since the wavelength selection mechanism 40 is provided for each user, it is possible to eliminate the replacement work on the utility pole, and it is possible to reduce the cost.
[0040]
For example, even if the wavelength assigned to the user is changed, such as when a user moves or another wavelength is required for each user, the service provider replaces the wavelength selection mechanism unit 40 corresponding to the wavelength. By doing so, the user can use the communication device used so far as it is.
In the conventional WDM system, broadcast-type communication cannot be multiplexed into individual communication. However, in this embodiment, by using the optical splitter 30 having no wavelength dependency as an optical branching element, broadcasting is possible. Type communication is also possible.
[0041]
Example 5
A fifth embodiment of the present invention is shown in FIGS.
In the communication system of the present embodiment, each wavelength signal from the center side device is transmitted through a single wavelength optical fiber through the optical wavelength multiplexing / demultiplexing filter in the center side device, and is transmitted from the optical splitter 30 on the transmission line to the user side. The communication devices A to D are configured by a two-core optical fiber, a wavelength selection mechanism unit 40 is provided for each of the two cores, and two specific wavelengths are transmitted to each of the user side communication devices A to D.
[0042]
From each of the user side communication devices A to D, one of the two wavelengths is received by the user side device, and the remaining one wavelength is returned within the user side communication devices A to D and sent to the center side communication device 10.
Similar to the case of the first embodiment, the light having the wavelength to be turned back is modulated by performing amplification using a semiconductor optical amplifier or the like in the user side device, and the upstream signal is transmitted on the light having the corresponding wavelength. .
[0043]
Each wavelength signal transmitted from each user side device is transmitted through each optical fiber to the optical splitter 30 installed on the pillar on the transmission path via the wavelength selection mechanism 40 near the user on the transmission path. And reach the center side device via a single-core optical fiber transmission line.
On the center side, the arrived signal is again distributed to the corresponding user for each signal through the optical wavelength multiplexing / demultiplexing filter.
As shown in FIG. 11, the wavelength selection mechanism unit 40 may be mounted inside the optical terminal box 50 for connecting the outdoor optical cable and the indoor optical cable. As shown in FIG. And may be mounted on an optical connector that connects the optical fiber.
[0044]
In the present embodiment, compared with the first embodiment, by transmitting from the optical splitter 30 to the user-side communication devices A to D using a two-core optical fiber, the wavelength multiplexing / demultiplexing mechanism of the wavelength selection mechanism section 40 can be reduced. Figured.
That is, the wavelength selection mechanism unit 40 and the user side communication devices A to D receive the reception signal on physically different fibers and transmit the transmission signal. A mechanism for separating them becomes unnecessary.
[0045]
Further, the wavelength selection mechanism unit 40 is provided in the vicinity of a user that can be easily exchanged. As a user side device, the wavelength dependency in the user side device is not required as compared with the conventional communication method, and each user has Since the wavelength selection mechanism unit 40 is provided in the power source, it is possible to eliminate the replacement work with the utility pole, and it is possible to reduce the cost.
For example, even if the wavelength assigned to the user is changed, such as when a user moves or another wavelength is required for each user, the service provider sets the wavelength selection mechanism unit 40 corresponding to the wavelength. By exchanging, the user can use the communication device that has been used until now.
[0046]
As described above, according to the present invention, in the wavelength division multiplexing optical communication network in which the communication center and the user communicate with each other at different wavelengths, the optical splitter 30 for branching and coupling light and the wavelength selection mechanism for selecting the individual wavelength of the user. A wavelength division multiplexing communication system characterized by having a unit 40.
Therefore, according to the present invention, the user can use his / her own device even at the new location without being aware of the types of the user side communication devices A to D, and the service provider does not need to manage the user terminal type. The cost of service can be reduced.
Furthermore, equipment replacement costs and network reliability are also improved.
[0047]
【The invention's effect】
As described above, according to the present invention, the following four effects can be obtained.
(1) It is not necessary for the terminal user to be aware of the type of the user side communication device, and even when the user moves, device replacement is not necessary, and management of the user terminal type is not necessary on the service providing side. For this reason, the cost of the service can be reduced.
(2) By providing the wavelength selection mechanism in the vicinity of the user instead of the utility pole, when changing the wavelength used for each user or when using a completely different wavelength, the wavelength selection mechanism for each user is replaced. Therefore, the replacement cost can be reduced and the cost can be reduced.
(3) Unlike a system in the form of a passive optical network, the communication of other users sharing the same single optical fiber on the transmission line due to a failure of a specific user side communication device or the like, Therefore, it is possible to improve the reliability of the user and the network.
(4) When wavelength allocation is performed for many services in the future, it is possible to cope with the replacement of the wavelength selection mechanism unit on the user side without exchanging the equipment on the transmission path, thereby reducing the replacement cost.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a wavelength division multiplexing communication system according to an embodiment of the present invention.
FIG. 2 is a conceptual diagram of a wavelength division multiplexing communication system according to an embodiment of the present invention.
FIG. 3 is a conceptual diagram of a wavelength division multiplexing communication system according to a first embodiment of the present invention.
FIG. 4 is a conceptual diagram of a wavelength division multiplexing communication system according to a first embodiment of the present invention.
FIG. 5 is a conceptual diagram of a wavelength division multiplexing communication system according to a second embodiment of the present invention.
FIG. 6 is a conceptual diagram of a wavelength division multiplexing communication system according to a second embodiment of the present invention.
FIG. 7 is a conceptual diagram of a wavelength division multiplexing communication system according to a third embodiment of the present invention.
FIG. 8 is a conceptual diagram of a wavelength division multiplexing communication system according to a third embodiment of the present invention.
FIG. 9 is a conceptual diagram of a wavelength division multiplexing communication system according to a fourth embodiment of the present invention.
FIG. 10 is a conceptual diagram of a wavelength division multiplexing communication system according to a fourth embodiment of the present invention.
FIG. 11 is a conceptual diagram of a wavelength division multiplexing communication system according to a fifth embodiment of the present invention.
FIG. 12 is a conceptual diagram of a wavelength division multiplexing communication system according to a fifth embodiment of the present invention.
FIG. 13 is a conceptual diagram of a wavelength division multiplexing communication system using a conventional technique.
[Explanation of symbols]
10 Center side communication device
20 WDM filter
30 Optical splitter
40 Wavelength selection mechanism
50 Optical termination box
60 Fiber grating mechanism
A, A ', B, C, D User side communication device

Claims

In a communication system for performing communication between a plurality of user side communication devices and one center side communication device,
The communication from each user side communication device to the center side communication device and the communication from the center side communication device to each user side communication device use different wavelengths, respectively.
The user side communication device and the center side communication device are connected by an optical fiber via an optical splitter for branching and coupling optical fibers in a many-to-one manner,
The transmission path between the optical splitter and each of said user communication device, have a wavelength selection mechanism for selectively transmitting the wavelength for communication that are assigned to the corresponding user-side communication device,
In each of the user side communication devices, a wavelength division multiplexing communication system that folds back an uplink signal wavelength assigned to the user side communication device among the communication wavelengths.

The transmission path between the optical splitter and each wavelength selection mechanism is a single-core optical fiber, and the transmission path between the wavelength selection mechanism and the user-side communication device is a 2-core. The optical fiber is an optical fiber, and the wavelength selection mechanism unit is configured to transmit only light having a predetermined wavelength from the optical signal in the direction from the optical splitter to the user-side communication device. An optical signal that has passed through an optical fiber and is input to the wavelength selection mechanism unit from an optical fiber that is different from the optical fiber that is connected to the wavelength selection mechanism unit and the user-side communication device is different from the wavelength. A wavelength division multiplexing communication system, wherein only light having a different wavelength is transmitted through an optical fiber connected to the optical splitter.

2. The wavelength selection unit according to claim 1, wherein a transmission path between the optical splitter and each of the user side communication devices is a two-core optical fiber, and the wavelength selection is performed on each optical fiber between the optical splitter and the user side communication device. A wavelength division multiplexing communication system, wherein a mechanism unit is connected, and the wavelength selection mechanism unit is a wavelength filter that transmits only light of a specific wavelength determined so as not to overlap within the communication system.

In a communication system that performs communication between a plurality of user-side communication devices and one center-side communication device, communication from each user-side communication device to the center-side communication device, and from the center-side communication device to each user-side The communication to the communication device uses different wavelengths, and the user-side communication device and the center-side communication device are connected by an optical fiber via an optical splitter that branches and couples optical fibers in a many-to-one relationship, Having a wavelength selection mechanism for selectively transmitting a wavelength for communication assigned to the user side communication device in a transmission path between each of the user side communication devices;
The transmission path between the optical splitter and each wavelength selection mechanism is a one-core optical fiber, and the transmission path between the wavelength selection mechanism and the user side communication device is a two-core optical fiber, The light emitting element of the user side communication device is a Bragg reflection type semiconductor laser in which the wavelength to be emitted is determined by Bragg reflection using a diffraction grating, and the semiconductor element and the diffraction grating are separately installed, and the semiconductor element is It is installed in the user side communication device, the diffraction grating is installed in the wavelength selection mechanism unit, and the wavelength selection mechanism unit is predetermined among optical signals in a direction from the optical splitter to the user side communication device. A wavelength division multiplexing communication system, wherein only the light having a specified wavelength passes through an optical fiber on which the diffraction grating connected to the user side communication device is not installed.

In Claim 1, the transmission path between the optical splitter and each user-side communication device is a single-core optical fiber, the wavelength selection mechanism unit transmits only light in a predetermined wavelength range, Each user-side communication device does not transmit light of other wavelengths, and each user-side communication device communicates with the center-side communication device using light of two different wavelengths that can be transmitted by the connected wavelength selection mechanism unit. A wavelength division multiplexing communication system.

Claims 1, 3 or the center side communication device as claimed in any one of 5, each of said communication from the user communication device to the center side communication device and, each of said user-side from the center side communication device Using light of a wavelength different from the wavelength used for communication to the communication device, and transmitting a signal in a broadcast format to all the user-side communication devices, the wavelength selection mechanism unit, the corresponding user In addition to the two wavelengths used for the communication with the center-side communication device, the communication device on the side passes all the signals of the broadcast format by passing the wavelength of the signal transmitted in the broadcast format. A wavelength division multiplexing communication system, wherein the user side communication device receives the wavelength multiplexing communication system.

7. The wavelength division multiplexing communication system according to claim 1 , wherein the wavelength selection mechanism section is accommodated in an optical terminal box that connects optical fibers.

8. The wavelength division multiplexing communication system according to claim 7, wherein the optical termination box is an optical termination box for connecting an outdoor optical cable and a local optical cable.