JP3989857B2

JP3989857B2 - Communication terminal, communication system, communication method, and communication program

Info

Publication number: JP3989857B2
Application number: JP2003051751A
Authority: JP
Inventors: 純生宮▲崎▼; 宏之中村; 清志上田
Original assignee: Nippon Telegraph and Telephone Corp
Current assignee: Nippon Telegraph and Telephone Corp
Priority date: 2003-02-27
Filing date: 2003-02-27
Publication date: 2007-10-10
Anticipated expiration: 2023-02-27
Also published as: JP2004260748A

Description

【０００１】
【発明の属する技術分野】
本発明は、主に通信端末間の通信のみで実現されるモバイルアドホックネットワークに適用される通信端末、通信システム及び通信方法並びに通信プログラムに関する。
【０００２】
【従来の技術】
モバイル端末の普及および高機能化に伴い、モバイル端末を利用したサービスが注目を集めている。特に、端末間の通信のみで実現されるモバイルアドホックネットワークでは、利用エリアに縛られない、端末以外に設備がいらないといった特徴をもち、移動体の特性を生かせることができる。端末間の通信でネットワークの実現に、Ｐ２Ｐ技術を適用することで、集中的に振舞う端末が不要となり、参加者端末の役割が平等となることや、ネットワーク全体を把握する必要がないことから、参加離脱が多く、接続状態が変化し続けるネットワークにおいても比較的大規模な参加者へ提供するネットワークサービスを可能とする。
【０００３】
従来、集中管理的な端末の存在が必要とされるものがほとんどであり、大規模のサービスに適用できない。また、集中管理部がなく端末間をマルチホップで通信するプロトコルは考案されているが、実用化されているものはなく、確実にこの通信を利用できる状況はまだ実現されていない。また、このマルチホップ通信が実現されたとしても、一対一の通信については制御が行われるが、Ｐ２Ｐのようなバケツリレー通信においては、移動者の移動に伴い非常に入り組んだネットワーク構成となることが想定される。
【０００４】
【非特許文献１】
ＭＡＮＥＴインターネット＜ URL：http://www.ietf.org/html.charters/manet-charter.html＞
【０００５】
【発明が解決しようとする課題】
ＭＡＮＥＴでは、モバイルアドホックネットワークプロトコルの標準化が検討されている（非特許文献１を参照）。これはIPレベルでのアドホック通信を実現するが、スケラビリティの問題や、Hop数が増加することによる通信能力低下等の問題が指摘されている。また、Ｐ２Ｐ通信を行う場合、Ｐ２Ｐ通信のそれぞれの通信はＭＡＮＥＴで効率化が行えるが、Ｐ２Ｐ通信でバケツリレーの部分はそれぞれが通信を終端するため、効率化を行うことは出来ない。
【０００６】
本発明は、このような事情を考慮してなされたものであり、その目的は、通信端末が任意の方向に移動することによって発生する、無用なアドホック通信を削減し、アドホックネットワーク全体としての効率を向上させることができる通信端末、通信システム及び通信方法並びに通信プログラムを提供することにある。
【０００７】
【課題を解決するための手段】
この発明は上記の課題を解決すべくなされたもので、請求項１に記載の発明は、接続先の通信端末の情報を記憶する接続先データベースと、通信圏内に存在する不特定多数の通信端末に対して、該通信圏内に存在する通信端末の近隣検索要求と、該通信端末が接続している端末の情報を含む接続情報の要求とを送信し、該近隣検索要求に対して、通信圏内に存在することを示す近隣フラグと、該接続情報とを受信する近隣情報取得手段と、前記通信圏内に存在する不特定多数の通信端末から前記接続情報の要求、又は前記近隣検索要求を受信すると、前記接続先データベースより、接続先の通信端末の情報を読み出して、該接続情報と、前記近隣フラグとを前記通信端末に対して送信する近隣情報応答手段と、前記他の通信端末へ転送する転送データの入力を受けて、該転送データをＰ２Ｐ転送手段に出力するとともに、該Ｐ２Ｐ転送手段を介して他の通信端末から転送データを受信する情報送受信手段と、他の情報端末との通信インターフェイスであって、上位レイヤからの通信要求に基づいて、他の情報端末との通信処理を行うアドホック通信手段と、前記接続先データベースから前記接続情報を読み出して、該読み出した前記接続情報に従って、前記情報送受信手段が出力する転送データを、前記アドホック通信手段を介して他の情報通信端末に転送するとともに、該アドホック通信手段を介して、他の情報端末から受信した転送データを前記情報送受信手段に出力するＰ２Ｐ転送手段と、前記接続先データベースが記憶する接続先の通信端末の情報、前記受信した近隣検索要求結果及び接続情報に基づいて、一端仮接続を行い任意のＴＴＬ（ＴｉｍｅｔｏＬｉｖｅ）で接続情報を取得する評価イベント方式により、Ｐ２Ｐトポロジの接続情報を管理し、Ｐ２Ｐトポロジの変更判断及び変更制御を行うトポロジ制御手段とを具備し、前記上位レイヤが前記Ｐ２Ｐ転送手段、トポロジ制御手段、近隣情報取得手段、近隣情報応答手段であることを特徴とする。
【０００８】
また、請求項２に記載の発明は、請求項１に記載の発明において、前記トポロジ制御手段は、前記近隣情報取得手段受信した接続情報が、前記接続先データベースに書き込まれていない通信端末に関する接続情報である場合、前記接続先データベースに書き込むことを特徴とする。
【０００９】
また、請求項３に記載の発明は、請求項１に記載の発明において、前記トポロジ制御手段は、前記近隣情報取得手段受信した接続情報が、前記接続先データベースに書き込まれていない通信端末に関する接続情報である場合、前記接続先データベースに書き込まれていない通信端末数を、前記受信した複数の接続情報間で比較し、該通信端末数が多い接続情報を前記接続先データベースに書き込むことを特徴とする。
【００１０】
また、請求項４に記載の発明は、請求項１に記載の発明において、前記トポロジ制御手段は、前記近隣情報取得手段受信した接続情報が、前記接続先データベースに書き込まれていない通信端末に関する接続情報である場合、前記接続先データベースに書き込まれていない通信端末数を、前記受信した複数の接続情報間で比較し、該通信端末数が多い接続情報を予め設定された転送数まで前記接続先データベースに書き込み、トポロジの構築を行うことを特徴とする。
【００１１】
また、請求項５に記載の発明は、請求項１に記載の発明において、前記トポロジ制御手段は、さらに、前記近隣情報取得手段が前記近隣フラグを受信すると、前記近隣フラグの送信元の通信端末に対して仮接続要求を前記Ｐ２Ｐ転送手段に出力し、前記Ｐ２Ｐ転送手段は、該仮接続要求の入力を受けて、前記アドホック通信手段を介して、前記接続情報要求を任意のＴＴＬ数で他の情報通信端末に転送し、該アドホック通信手段を介して、他の情報端末から受信した接続情報を前記トポロジ制御手段に出力し、前記トポロジ制御手段は、さらに、前記Ｐ２Ｐ制御手段受信した接続情報が、前記接続先データベースに書き込まれていない通信端末に関する接続情報である場合、前記接続先データベースに書き込まれていない通信端末数を、前記受信した複数の接続情報間で比較し、該通信端末数が多い接続情報を前記接続先データベースに書き込むことを特徴とする。
【００１２】
また、請求項６に記載の発明は、第１から第ｎ（ｎは自然数）の通信端末から構成される通信制御システムであって、該第１から第ｎの通信端末が、前記第１から第ｎの通信端末のうち、接続先の通信端末の情報を記憶する接続先データベースと、前記第１から第ｎの通信端末のうち、通信圏内に存在する不特定多数の通信端末に対して、該通信圏内に存在する通信端末の近隣検索要求と、該通信端末が接続している端末の情報を含む接続情報の要求とを送信し、該近隣検索要求に対して、通信圏内に存在することを示す近隣フラグと、該接続情報とを受信する近隣情報取得手段と、前記通信圏内に存在する不特定多数の通信端末から前記接続情報の要求、又は前記近隣検索要求を受信すると、前記接続先データベースより、接続先の通信端末の情報を読み出して、該接続情報と、前記近隣フラグとを前記通信端末に対して送信する近隣情報応答手段と、前記接続先の通信端末へ転送する転送データの入力を受けて、該転送データをＰ２Ｐ転送手段に出力するとともに、該Ｐ２Ｐ転送手段を介して他の通信端末から転送データを受信する情報送受信手段と、前記接続先データベースから前記接続情報を読み出して、該読み出した前記接続情報に従って、前記情報送受信手段が出力する転送データを、アドホック通信手段を介して他の情報通信端末に転送するとともに、該アドホック通信手段を介して、他の情報端末から受信した転送データを前記情報送受信手段に出力するＰ２Ｐ転送手段と、前記接続先データベースが記憶する接続先の通信端末の情報、前記受信した近隣検索要求結果及び接続情報に基づいて、所定の方式により、Ｐ２Ｐトポロジの接続情報を管理し、Ｐ２Ｐトポロジの変更判断及び変更制御を行うトポロジ制御手段とを具備することを特徴とする。
【００１３】
また、請求項７に記載の発明は、通信圏内に存在する不特定多数の通信端末に対して、該通信圏内に存在する通信端末の近隣検索要求と、該通信端末が接続している端末の情報を含む接続情報の要求とを送信し、該近隣検索要求に対して、通信圏内に存在することを示す近隣フラグと、該接続情報とを受信するステップと、前記通信圏内に存在する不特定多数の通信端末から前記接続情報の要求、又は前記近隣検索要求を受信すると、接続先の通信端末の情報を記憶する接続先データベースより、接続先の通信端末の情報を読み出して、該接続情報と、前記近隣フラグとを前記通信端末に対して送信するステップと、前記他の通信端末へ転送する転送データの入力を受けて、該転送データを出力するとともに、他の通信端末から転送データを受信するステップと、前記接続先データベースから前記接続情報を読み出して、該読み出した前記接続情報に従って、前記転送データを他の情報通信端末に転送するとともに、他の情報端末から受信した転送データを出力するステップと、前記接続先データベースが記憶する接続先の通信端末の情報、前記受信した近隣検索要求結果及び接続情報に基づいて、所定の方式により、Ｐ２Ｐトポロジの接続情報を管理し、Ｐ２Ｐトポロジの変更判断及び変更制御を行うステップとを具備することを特徴とする。
【００１４】
また、請求項８に記載の発明は、通信圏内に存在する不特定多数の通信端末に対して、該通信圏内に存在する通信端末の近隣検索要求と、該通信端末が接続している端末の情報を含む接続情報の要求とを送信し、該近隣検索要求に対して、通信圏内に存在することを示す近隣フラグと、該接続情報とを受信する近隣情報取得処理と、前記通信圏内に存在する不特定多数の通信端末から前記接続情報の要求、又は前記近隣検索要求を受信すると、接続先の通信端末の情報を記憶する接続先データベースより、接続先の通信端末の情報を読み出して、該接続情報と、前記近隣フラグとを前記通信端末に対して送信する近隣情報応答処理と、前記他の通信端末へ転送する転送データの入力を受けて、該転送データをＰ２Ｐ転送手段に出力するとともに、該Ｐ２Ｐ転送手段を介して他の通信端末から転送データを受信する情報送受信処理と、前記接続先データベースから前記接続情報を読み出して、該読み出した前記接続情報に従って、前記情報送受信手段が出力する転送データを、アドホック通信手段を介して他の情報通信端末に転送するとともに、該アドホック通信手段を介して、他の情報端末から受信した転送データを前記情報送受信手段に出力するＰ２Ｐ転送処理と、前記接続先データベースが記憶する接続先の通信端末の情報、前記受信した近隣検索要求結果及び接続情報に基づいて、所定の方式により、Ｐ２Ｐトポロジの接続情報を管理し、Ｐ２Ｐトポロジの変更判断及び変更制御を行うトポロジ制御処理とをコンピュータに実行させるための通信プログラムである。
【００１５】
【発明の実施の形態】
以下、図面を参照して、本発明の通信端末の一実施形態について詳細に説明する。実施例１では本発明の基本動作について説明し、実施例２，３で、複数接続先が存在する場合の接続先選択（実施例２では接続情報方式、実施例３では評価イベント方式）について説明する。
図１は、本実施形態の３つの通信端末♯１〜♯３から構成されるモバイルアドホックＰ２Ｐトポロジ制御システムの構成を示す構成図である。本実施形態の通信端末♯１〜♯３は、情報送受信手段１１と、Ｐ２Ｐ転送手段１２と、アドホック通信手段１３と、トポロジ制御手段１４と、近隣情報取得手段１５と、近隣情報応答手段１６とから構成される。
【００１６】
情報送受信手段１１は、他の通信端末へ転送する転送データの入力を受けて、転送データをＰ２Ｐ転送手段１２に出力するとともに、Ｐ２Ｐ転送手段１２を介して他の通信端末（例えば、通信端末♯１から見た場合、通信端末♯２、♯３）から転送データを受信する。
Ｐ２Ｐ転送手段１２は、接続先データベース１４１から接続情報を読み出して、読み出した接続情報に従って、情報送受信手段１１が出力する転送データを、アドホック通信手段１３を介して他の情報通信端末に転送するとともに、同様に、アドホック通信手段１３を介して、他の情報端末から受信した転送データを情報送受信手段１１に出力する。
ここで、接続先データベース１４１は、接続先の通信端末の情報を記憶する記憶部であって、トポロジ制御手段１４内に構成される。
また、接続情報とは、自己が接続している端末の識別情報（＝通信識別情報）であって、図２に示すように、例えば、通信端末♯１が通信端末♯２、３と接続している場合、通信端末♯２、３の識別情報が接続情報として格納される。
アドホック通信手段１３は、外部端末との通信インターフェイスであって、上位レイヤ（アドホック通信手段１３から見た場合、Ｐ２Ｐ転送手段１２、トポロジ制御手段１４、近隣情報応答手段１６、近隣情報取得手段１５が該当する）からの通信要求に基づいて、他の通信端末との通信処理を実行する。
トポロジ制御手段１４は、接続先データベース１４１が記憶する接続先の通信端末の情報、近隣情報取得手段１５が受信した近隣検索要求結果及び接続情報に基づいて、所定の方式により、Ｐ２Ｐトポロジの接続情報を管理し、Ｐ２Ｐトポロジの変更判断及び変更制御を行う。
具体的には、トポロジ制御手段１４は、近隣情報取得手段が受信した接続情報が、接続先データベース１４１に書き込まれていない通信端末に関する接続情報である場合、接続先データベース１４１に書き込まれていない通信端末数（以下、接続数という）を、受信した複数の接続情報間で比較し、通信端末数が多い接続情報を予め設定された転送数まで接続先データベース１４１に書き込み、トポロジの構築を行う（後述する）。
また、上述したように、トポロジ制御手段１４は、内部に接続先データベース１４１を有する。
近隣情報取得手段１５は、通信圏内に存在する不特定多数の通信端末に対して、通信圏内に存在する通信端末の近隣検索要求と、通信端末が接続している端末の情報を含む接続情報の要求とを送信する。また、近隣情報取得手段１５は、近隣検索要求に対して、通信圏内に存在することを示す近隣フラグと、接続情報とを受信する。
近隣情報応答手段１６は、通信圏内に存在する不特定多数の通信端末から接続情報の要求、又は近隣検索要求を受信すると、接続先データベースより、接続先の通信端末の情報を読み出して、接続情報と、近隣フラグとを通信端末に対して送信する。
【００１７】
次に、図面を参照して、本実施形態のモバイルアドホックＰ２Ｐトポロジ制御システムの動作について説明する。図２〜図１２は、本実施形態のモバイルアドホックＰ２Ｐトポロジ制御システムによる通信制御処理の過程を示すフローチャートである。
まず、図２に本システムにおける情報交換の際に行われる転送データの伝播について示す。通信端末♯１において、情報送信手段１１は、転送データの入力を受けると、Ｐ２Ｐ転送手段１２に対して出力する。Ｐ２Ｐ転送手段１２は、トポロジ制御手段１４内に存在する接続先データベース１４１（以下、ＤＢとする）に格納される接続情報に基づいて、他の通信端末（本実施形態では、通信端末♯２と通信端末♯３）へアドホック通信手段１３を介して転送する。
【００１８】
今、図３に示すように端末の物理空間上で通信端末♯２が移動した場合、トポロジ制御手段１４内の接続先ＤＢ・１４１が格納する接続情報は、図２の場合と比べて変更されていないため、図３の矢印で示すように、アドホック通信手段１３は、
通信端末♯１→通信端末♯２
通信端末♯１→（通信端末♯２）→通信端末♯３
という経路で通信を行う。
この場合、通信端末♯１から通信端末♯２への通信は通信端末♯３を経由することから、下位のレイヤでは通信端末♯１と通信端末♯３の間で同じ情報が転送されるため、通信効率が低下するという不具合が生じる。
また、アドホック通信手段１３を備えない通信システムの場合、通信端末♯２への情報転送が行えなくなるという不具合が生じる。
【００１９】
したがって、上記不具合を解消するために、Ｐ２Ｐのトポロジを変更において、どの端末と接続すると効率良いのか判断する必要がある。
図４に、この判断の材料となる近隣の端末の情報を収集する手順を示す。
まず、通信端末♯１において、近隣情報取得手段１５が、近隣検索として、接続情報要求を送信し、近隣の端末から必要な情報、すなわち、近隣接続情報を取得する。なお、本明細書においては、近隣であることと、通信圏内に存在することとは同義である。
また、近隣接続情報とは、近隣フラグが立っている通信端末の接続情報（接続元端末、接続先配列）であって、具体的には、図４に示すように、接続元の通信端末の識別情報と、この接続元の通信端末から近隣検索に対する応答として返信された接続先配列（＝接続元の通信端末が接続情報として、自身の接続先ＤＢ・１４１に格納する接続先の通信端末の識別情報）である。
この近隣接続情報に基づいて、トポロジ制御手段１４が、トポロジの接続先を選択する方式としては、接続情報方式と評価イベント方式があり、やり取りされる情報はそれぞれ異なる。詳細については後述する。
【００２０】
図５に示すように、トポロジ制御手段１４は、収集した近隣接続情報に基づいて、接続先を決定する。すなわち、トポロジ制御手段１４は、収集した近隣接続情報と、接続先情報ＤＢ・１４１に格納された接続情報とを比較し、これらが一致しない通信端末について、接続先変更があったと判定する。そして、接続先変更があった通信端末に対して、接続要求を行い、新たな接続を確立する。
また、トポロジ制御手段１４は、これまで接続されていた端末が近隣に居なくなった場合（近隣端末として接続情報を返信しない場合）、この接続情報をトポロジ制御手段１４内の接続先ＤＢ・１４１から削除する。ただし、近隣検索で発見された端末をＤＢに登録した場合において、規定の転送数に満たない場合、トポロジ制御手段１４は、近隣に居ない端末を接続先ＤＢ・１４１から削除しない。
【００２１】
以上説明したように、本実施形態のモバイルアドホックＰ２Ｐトポロジ制御システムによれば、通信端末においてトポロジを組みなおすので、図６に示すように、無用な中継トラフィックを減少させることができる効果が得られる。また、アドホック通信手段１６が、マルチホップ機能を備えなくとも全体に転送データを伝えることができる効果が得られる。
【００２２】
次に、上述したトポロジ制御手段１４が、トポロジの接続先を選択する方式について説明する。まず接続情報方式について説明すると、接続情報方式では、近隣の端末から該端末の接続情報を取得し、その情報をもとに接続先の選択を行う。
【００２３】
本方式では、図７に示すように近隣（＝１Ｈｏｐで通信可能な端末）に対して接続情報要求を送信する。また、全ての通信端末♯１〜♯７は、近隣情報応答手段１６において、接続情報を返答する機構を備えている。
すなわち、通信端末♯１において、近隣情報取得手段１５が、近隣検索として、接続情報要求を送信し、この近隣検索要求を受け取った通信端末は、近隣情報応答手段１６において、現在接続している通信端末に関する接続情報を返信する。そして、近隣検索要求送信元の通信端末♯１は、この接続情報を受信する。
したがって、接続情報要求の送信元である通信端末は、どの端末が近隣にあり、その端末は、他のどの端末と接続しているのか、について情報を得ることができる。
本実施形態においては、通信端末♯２，３，４が近隣にあり、それぞれの接続情報は図７の通信端末♯１にある近隣接続情報に示すとおり、
端末２端末３、５、６
端末３端末２、４、６
端末４端末３、７
となっている。
【００２４】
この場合、近隣の端末でない通信端末（通信端末♯２，３，４以外）との接続数は、
端末２端末５、６接続数：２
端末３端末６接続数：１
端末４端末７接続数：１
であるから、トポロジ制御手段１４は、近隣の端末でない通信端末との接続数がより多い通信端末♯２を接続先として決定する。
次に、端末３、４について比較すると、近隣の端末および通信端末♯２で接続される端末以外（通信端末♯２，３，４，５，６）との接続数は、
端末３接続数：０
端末４端末７接続数：１
であるから、トポロジ制御手段１４は、近隣の端末および通信端末♯２で接続される端末以外との接続数がより多い通信端末♯４を接続先として決定する。
そして、トポロジ制御手段１４は、取得された情報全てに伝播することを確認（今回、通信端末♯３の接続先は、通信端末♯２と通信端末♯４の接続先に含まれている）するとともに、最大接続数に達するか、近隣の端末全てに接続を行うかのいずれかになるまで繰り返し行う。
【００２５】
そして、トポロジ制御手段１４は、図８に示すように、上記判断された接続先について接続先変更があった端末に対して、接続要求を行い新たな接続を確立する。
また、これまで接続されていた端末が近隣に居なくなった場合（近隣端末として接続情報を返信しない場合）については、この接続情報をトポロジ制御手段１４内の接続先ＤＢ・１４１から削除する。
【００２６】
次に、上述したトポロジ制御手段１４が、トポロジの接続先を選択する方式として、評価イベント方式について説明する。評価イベント方式では、一旦仮接続を行い、任意のＴＴＬ（ＴｉｍｅＴｏＬｉｖｅ）で接続情報を取得する方式である。このため、評価イベント方式では、上記接続情報方式に比べ、よりきめの細かい判断が行える一方で、判断が完了するまでの手順が多くなる。
【００２７】
本方式では、図９に示すように、近隣情報取得手段１５が、近隣（１Ｈｏｐで通信可能な端末）に対して、近隣検索を送信する。全ての通信端末♯１〜♯７は、近隣情報応答手段１６において、近隣フラグを返答する機構を備えている。
すなわち、通信端末♯１において、近隣情報取得手段１５が、近隣検索として、接続情報要求を送信し、この近隣検索要求を受け取った通信端末は、近隣情報応答手段１６において、近隣フラグを返信する。そして、近隣検索要求の送信元である通信端末は、この接続情報を受信する。
したがって、近隣探索の送信元である通信端末は、どの端末が近隣にあるかを知ることができる。
【００２８】
次に、Ｐ２Ｐ転送手段１２は、図１０に示すように、近隣情報取得手段１５が取得した近隣の通信端末の接続情報に基づいて、これらの近隣の通信端末に対してそれぞれ仮接続を行う。すなわち、Ｐ２Ｐ転送手段１２は、任意のＴＴＬを接続情報要求パケットに設定し、この接続情報を要求する接続情報要求の転送を、これらの近隣の通信端末に対して行う。
【００２９】
接続情報要求を受け取った通信端末は、図１１に示すように、近隣情報応答手段１６において、トポロジ制御手段１４内の接続先ＤＢ・１４１情報を接続情報として返信する。接続情報要求の送信元である通信端末は、トポロジ制御手段１４において、返信された接続情報数、及びその接続情報を近隣の通信端末ごとに集計する。そして、トポロジ制御手段１４は、集計情報をもとに接続先を決定する。
ここで、返信された接続情報数が多いとは、任意のＴＴＬで送信できる端末が多いことを示す。
まず、トポロジ制御手段１４は、近隣の通信端末ごとの接続情報の集計結果を比較し、近隣の通信端末に対する複数の仮接続の中から、より多くの接続情報が戻ってきた接続を決定する。
ここで、もし２以上の通信端末から同じ数の接続情報が返信された場合、トポロジ制御手段１４は、近隣に存在しない通信端末に関する接続情報をより多く返した接続を有する通信端末を選択する。
【００３０】
図１１に示すように、本実施形態においては、近隣の通信端末ごとの接続情報の集計結果は、
端末２端末５、６、３接続数：３
端末３端末２、６、４接続数：３
端末４端末３、７接続数：２
となっており、通信端末♯２、通信端末♯３への仮接続の場合、より多くの接続情報が戻っている。また、通信端末♯２、通信端末♯３とを比較すると、近隣の端末ではない接続情報をより多く含む接続は、通信端末♯２への接続であり、これを選択する。
次に、近隣の端末および通信端末♯２で接続される端末以外（通信端末♯２，３，４、５，６）と、より多く接続する端末は通信端末♯４となる。
そして、トポロジ制御手段１４は、取得された情報全てに伝播することを確認（今回、通信端末♯３の接続先は、通信端末♯２と通信端末♯４の接続先に含まれている）するとともに、最大接続数に達するか、近隣の端末全てに接続を行うかのいずれかになるまで繰り返し行う。
【００３１】
そして、トポロジ制御手段１４は、図１２に示すように、上記判断された接続先について、接続先変更があった端末に対して、接続要求を行い新たな接続を確立する。
また、これまで接続されていた端末が近隣に居なくなった場合（近隣端末として接続情報を返信しない場合）については、この接続情報をトポロジ制御手段１４内の接続先ＤＢ・１４１から削除する。
【００３２】
以上説明したように、本実施形態のモバイルアドホックＰ２Ｐトポロジ制御システムによれば、情報や処理が集中するサーバを持たずに、モバイルアドホックネットワーク上で情報交換を実現することができる効果が得られる。
また、各通信端末で情報を転送することにより、一部の利用者に対して情報を転送することで全体の利用者に対する送信を行うことができる効果が得られる。
また、アドホック通信の機能を持たない端末間においても、接続可能な端末を検出、再接続を行うことによりネットワークとして整合性を保つことができる効果が得られる。
また、上記のアドホック通信機能を持たない場合においても、Ｐ２Ｐ通信としては特に意識することなく通信が行うことができる効果が得られる。
【００３３】
また、Ｐ２Ｐの通信システムを利用することから以下の作用が期待される。すなわち、
（１）集中管理部が存在しないことから、トラフィックおよび処理の集中が発生しない。
（２）ネットワーク全体を知ることなく、ネットワークに参加している任意の利用者と接続することで、サービスが享受できる。
（３）個々の端末間の接続を、個々の端末で最適となるように制御することで、ＮＷ全体としてのトラフィックを削減することができる。
（４）アドホックネットワークでは、各端末を経由して通信が行われるため、上記によりＮＷ全体のトラフィック削減はすなわち個々の端末の中継トラフィックの削減になる。
【００３４】
また、上記中継トラフィックの削減により以下の作用が期待される。
(ア) 通信帯域の節約
(イ) 端末CPUリソースの節約
(ウ) 消費電力の削減
【００３５】
以上、詳細に説明した如く、モバイル端末の普及および高機能化に伴い、モバイル端末を利用したサービスが注目を集めており、特に、端末間の通信のみで実現されるモバイルアドホックネットワークでは、利用エリアに縛られない、端末以外に設備がいらないといった特微をもち、移動体の特性を生かせることができる効果が得られる。
また、端末間の通信でネットワークの実現に、Ｐ２Ｐ技術を適用することで、集中的に振舞う端末が不要となり、参加者端末の役割が平等となることや、ネットワーク全体を把握する必要がないことから、参加離説が多く、接続状態が変化し続けるネットワークにおいても比較的大規摸な参加者へ提供するネットワークサービスを可能とすることができる効果が得られる。
【００３６】
上述の通信端末は、内部に、コンピュータシステムを有している。
そして、上述した通信処理に関する一連の処理の過程は、プログラムの形式でコンピュータ読み取り可能な記録媒体に記憶されており、このプログラムをコンピュータが読み出して実行することによって、上記処理が行われる。
すなわち、通信端末における、各処理手段、処理部は、ＣＰＵ等の中央演算処理装置がＲＯＭやＲＡＭ等の主記憶装置に上記プログラムを読み出して、情報の加工・演算処理を実行することにより、実現されるものである。
ここでコンピュータ読み取り可能な記録媒体とは、磁気ディスク、光磁気ディスク、ＣＤ−ＲＯＭ、ＤＶＤ−ＲＯＭ、半導体メモリ等をいう。また、このコンピュータプログラムを通信回線によってコンピュータに配信し、この配信を受けたコンピュータが当該プログラムを実行するようにしても良い。
【００３７】
【発明の効果】
以上説明したように、本発明は、接続先の通信端末の情報を記憶する接続先データベースと、通信圏内に存在する不特定多数の通信端末に対して、通信圏内に存在する通信端末の近隣検索要求と、通信端末が接続している端末の情報を含む接続情報の要求とを送信し、近隣検索要求に対して、通信圏内に存在することを示す近隣フラグと、接続情報とを受信する近隣情報取得手段と、通信圏内に存在する不特定多数の通信端末から接続情報の要求、又は近隣検索要求を受信すると、接続先データベースより、接続先の通信端末の情報を読み出して、接続情報と、近隣フラグとを通信端末に対して送信する近隣情報応答手段と、他の通信端末へ転送する転送データの入力を受けて、転送データをＰ２Ｐ転送手段に出力するとともに、Ｐ２Ｐ転送手段を介して他の通信端末から転送データを受信する情報送受信手段と、接続先データベースから接続情報を読み出して、読み出した接続情報に従って、情報送受信手段が出力する転送データを、アドホック通信手段を介して他の情報通信端末に転送するとともに、アドホック通信手段を介して、他の情報端末から受信した転送データを情報送受信手段に出力するＰ２Ｐ転送手段と、接続先データベースが記憶する接続先の通信端末の情報、受信した近隣検索要求結果及び接続情報に基づいて、所定の方式により、Ｐ２Ｐトポロジの接続情報を管理し、Ｐ２Ｐトポロジの変更判断及び変更制御を行うトポロジ制御手段とを具備するので、通信端末が任意の方向に移動することによって発生する、無用なアドホック通信を削減し、アドホックネットワーク全体としての効率を向上させることができる効果を得ることができる。
【図面の簡単な説明】
【図１】モバイルアドホックＰ２Ｐトポロジ制御システム構成図である。
【図２】転送データの伝播の流れを示す図である。
【図３】端末が移動し、通信状態が変化した場合の転送データの伝播の流れを示す図である。
【図４】端末の移動等により通信状態が変化した際に適切な接続先を判断するために情報収集を行う流れを示す図である。
【図５】収集結果によるＰ２Ｐトポロジの変更の流れを示す図である。
【図６】トポロジの効率化を実施した後の転送データの伝播の流れを示す図である。
【図７】接続先の判断として接続情報方式を利用した場合の近隣の接続情報の収集の流れを示す図である。
【図８】接続先の判断として接続情報方式を利用した場合のトポロジの変更の流れを示す図である。
【図９】接続先の判断として評価イベント方式を利用した場合の近隣検索の流れを示す図である。
【図１０】接続先の判断として評価イベント方式を利用した場合の接続情報の検索の流れを示す図である。
【図１１】接続先の判断として評価イベント方式を利用した場合の接続情報の収集の流れを示す図である。
【図１２】接続先の判断として評価イベント方式を利用した場合のトポロジの変更の流れを示す図である。
【符号の説明】
１〜３…通信端末
１１…情報送受信手段
１２…Ｐ２Ｐ転送手段
１３…アドホック通信手段
１４…トポロジ制御手段
１５…近隣情報取得手段
１６…近隣情報応答手段
１４１…接続先データベース[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication terminal, a communication system, a communication method, and a communication program applied to a mobile ad hoc network that is mainly realized only by communication between communication terminals.
[0002]
[Prior art]
With the spread of mobile terminals and higher functionality, services using mobile terminals are attracting attention. In particular, a mobile ad hoc network that is realized only by communication between terminals has features that it is not restricted to a use area and that there is no need for equipment other than terminals, and can make use of the characteristics of a mobile object. By applying P2P technology to the realization of network by communication between terminals, terminals that behave intensively become unnecessary, the roles of participant terminals become equal, and it is not necessary to grasp the entire network. Even in a network where there are many participations and withdrawals and the connection state keeps changing, it is possible to provide a network service provided to relatively large-scale participants.
[0003]
Conventionally, most devices that require centrally managed terminals are not applicable to large-scale services. In addition, although a protocol for communicating between terminals in a multi-hop manner without a centralized management unit has been devised, none has been put into practical use, and a situation in which this communication can be used reliably has not yet been realized. Even if this multi-hop communication is realized, one-to-one communication is controlled, but in bucket relay communication such as P2P, the network configuration must be very complicated as the mover moves. Is assumed.
[0004]
[Non-Patent Document 1]
MANET Internet <URL: http://www.ietf.org/html.charters/manet-charter.html>
[0005]
[Problems to be solved by the invention]
In MANET, standardization of a mobile ad hoc network protocol is being studied (see Non-Patent Document 1). This realizes ad-hoc communication at the IP level, but problems such as scalability and reduced communication capacity due to an increase in the number of Hops have been pointed out. In addition, when performing P2P communication, efficiency of each communication of P2P communication can be improved by MANET. However, efficiency of the bucket relay portion cannot be improved because each of the bucket relay parts terminates communication in P2P communication.
[0006]
The present invention has been made in view of such circumstances, and its purpose is to reduce unnecessary ad hoc communication that occurs when a communication terminal moves in an arbitrary direction, and to improve the efficiency of the entire ad hoc network. A communication terminal, a communication system, a communication method, and a communication program.
[0007]
[Means for Solving the Problems]
The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is directed to a connection destination database for storing information of communication terminals of connection destinations, and an unspecified number of communication terminals existing in a communication area. In response to the neighbor search request, a neighbor search request for a communication terminal existing in the communication area and a connection information request including information on a terminal to which the communication terminal is connected are transmitted. When receiving the connection information request or the neighbor search request from an unspecified number of communication terminals existing in the communication area, the neighbor information acquisition means for receiving the neighbor flag indicating that the connection information is present, and the connection information The information of the communication terminal of the connection destination is read from the connection destination database, and the connection information and the proximity flag are transmitted to the communication terminal and transferred to the other communication terminal. Roll Receiving input data, and outputs the transfer data to the P2P transfer means, information transmitting and receiving means for receiving transferred data from another communication terminal through the P2P transfer means, An ad hoc communication means that is a communication interface with another information terminal and performs communication processing with another information terminal based on a communication request from an upper layer; Read the connection information from the connection destination database, and according to the read connection information, transfer data output by the information transmitting and receiving means, Said P2P transfer means for transferring to the other information communication terminal via the ad hoc communication means, and outputting the transfer data received from the other information terminal to the information transmission / reception means via the ad hoc communication means, and the connection destination database On the basis of the information of the communication terminal of the connection destination stored in the memory, the received neighbor search request result and the connection information, An evaluation event in which temporary connection is made and connection information is acquired using an arbitrary TTL (Time to Live) And topology control means for managing connection information of the P2P topology according to the system, and performing change judgment and change control of the P2P topology. The upper layer is the P2P transfer means, topology control means, neighborhood information acquisition means, neighborhood information response means It is characterized by that.
[0008]
The invention according to claim 2 is the connection according to the invention according to claim 1, wherein the topology control unit is connected to a communication terminal in which the connection information received by the neighbor information acquisition unit is not written in the connection destination database. If it is information, it is written in the connection destination database.
[0009]
The invention according to claim 3 is the connection according to the invention according to claim 1, wherein the topology control unit is connected to a communication terminal in which the connection information received by the neighbor information acquisition unit is not written in the connection destination database. If it is information, the number of communication terminals not written in the connection destination database is compared among the plurality of received connection information, and the connection information having a large number of communication terminals is written in the connection destination database. To do.
[0010]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the topology control unit is configured to connect the communication terminal related to the communication terminal in which the connection information received by the neighbor information acquisition unit is not written in the connection destination database. If it is information, the number of communication terminals not written in the connection destination database is compared among the plurality of received connection information, and the connection destination with a large number of communication terminals is connected up to a preset transfer number. It is characterized by writing to a database and building a topology.
[0011]
The invention according to claim 5 is the communication terminal according to claim 1, wherein the topology control means further receives the neighbor flag when the neighbor information acquisition means receives the neighbor flag. The temporary connection request is output to the P2P transfer means, and the P2P transfer means receives the input of the temporary connection request and sends the connection information request with an arbitrary TTL number via the ad hoc communication means. The connection information received from the other information terminal is output to the topology control means via the ad hoc communication means, and the topology control means further receives the connection information received from the P2P control means. Is connection information related to communication terminals that are not written in the connection destination database, the number of communication terminals that are not written in the connection destination database, Compared among a plurality of connection information signal, and writes the connection information number the communication terminal is larger in the destination database.
[0012]
The invention according to claim 6 is a communication control system including first to nth (n is a natural number) communication terminals, wherein the first to nth communication terminals are the first to nth communication terminals. Among the n-th communication terminals, a connection-destination database that stores information of a connection-destination communication terminal, and among the first to n-th communication terminals, an unspecified number of communication terminals that exist within a communication area, A proximity search request for a communication terminal existing in the communication area and a connection information request including information on a terminal to which the communication terminal is connected are transmitted, and the communication terminal exists in the communication area for the proximity search request. When receiving the connection information request or the neighborhood search request from an unspecified number of communication terminals existing in the communication area, the connection destination is received. Communication destination of the connection destination from the database And receiving the input of transfer data to be transferred to the communication terminal of the connection destination, the neighbor information response means for transmitting the connection information and the neighbor flag to the communication terminal, and the transfer data Is output to the P2P transfer means, and information transmission / reception means for receiving transfer data from another communication terminal via the P2P transfer means, and the connection information is read from the connection destination database, and the connection information is read out according to the read connection information. The transfer data output from the information transmission / reception means is transferred to another information communication terminal via the ad hoc communication means, and the transfer data received from the other information terminal via the ad hoc communication means is transmitted to the information transmission / reception means. P2P transfer means to output to the terminal, information of the communication terminal of the connection destination stored in the connection destination database, the received neighbor search request Based on the result and the connection information, by a predetermined method, and manages connection information of P2P topology, characterized by comprising a topology control means for changing judgment and change control of the P2P topology.
[0013]
Further, the invention according to claim 7 is directed to an unspecified number of communication terminals existing in a communication area and a proximity search request for the communication terminal existing in the communication area and a terminal connected to the communication terminal. A request for connection information including information, and a step of receiving a proximity flag indicating the presence in the communication range and the connection information in response to the neighborhood search request; and unspecified existing in the communication range Upon receiving the connection information request or the neighbor search request from a number of communication terminals, the connection destination communication terminal information is read from the connection destination database storing the connection destination communication terminal information, and the connection information and , Transmitting the neighbor flag to the communication terminal, receiving transfer data to be transferred to the other communication terminal, outputting the transfer data, and transferring transfer data from the other communication terminal. And reading the connection information from the connection destination database, transferring the transfer data to another information communication terminal according to the read connection information, and outputting the transfer data received from the other information terminal Managing the connection information of the P2P topology by a predetermined method based on the information of the communication terminal of the connection destination stored in the connection destination database, the received neighbor search request result and the connection information, And a step of performing change judgment and change control.
[0014]
Further, the invention according to claim 8 is directed to an unspecified number of communication terminals existing in a communication area, and a neighbor search request for a communication terminal existing in the communication area and a terminal connected to the communication terminal. A connection information request including information, and in response to the proximity search request, a proximity flag indicating that the mobile terminal is within the communication range and the connection information are received, and a proximity information acquisition process for receiving the connection information; When receiving the connection information request or the neighbor search request from an unspecified number of communication terminals, the information of the connection destination communication terminal is read from the connection destination database storing the information of the connection destination communication terminal, In response to a proximity information response process for transmitting connection information and the proximity flag to the communication terminal, and input of transfer data to be transferred to the other communication terminal, the transfer data is output to the P2P transfer means. , Information transmission / reception processing for receiving transfer data from another communication terminal via the P2P transfer means, reading the connection information from the connection destination database, and outputting the information transmission / reception means in accordance with the read connection information P2P transfer processing for transferring transfer data to another information communication terminal via ad hoc communication means, and outputting transfer data received from another information terminal to the information transmission / reception means via the ad hoc communication means; Based on the information of the communication terminal of the connection destination stored in the connection destination database, the received neighbor search request result and the connection information, the connection information of the P2P topology is managed by a predetermined method, and the change judgment and change of the P2P topology are performed. A communication program for causing a computer to execute topology control processing for performing control.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a communication terminal of the present invention will be described in detail with reference to the drawings. In the first embodiment, the basic operation of the present invention will be described, and in the second and third embodiments, connection destination selection (a connection information method in the second embodiment and an evaluation event method in the third embodiment) when there are multiple connection destinations will be described. To do.
FIG. 1 is a configuration diagram illustrating a configuration of a mobile ad hoc P2P topology control system including three communication terminals # 1 to # 3 according to the present embodiment. The communication terminals # 1 to # 3 of the present embodiment include information transmission / reception means 11, P2P transfer means 12, ad hoc communication means 13, topology control means 14, neighborhood information acquisition means 15, and neighborhood information response means 16. Consists of
[0016]
The information transmitting / receiving unit 11 receives input of transfer data to be transferred to another communication terminal, outputs the transfer data to the P2P transfer unit 12, and also transmits another transfer terminal (for example, communication terminal #) via the P2P transfer unit 12. When viewed from 1, the transfer data is received from the communication terminals # 2, # 3).
The P2P transfer unit 12 reads connection information from the connection destination database 141, and transfers transfer data output from the information transmission / reception unit 11 to another information communication terminal via the ad hoc communication unit 13 according to the read connection information. Similarly, the transfer data received from other information terminals is output to the information transmitting / receiving unit 11 via the ad hoc communication unit 13.
Here, the connection destination database 141 is a storage unit that stores information on the communication terminal of the connection destination, and is configured in the topology control unit 14.
The connection information is identification information (= communication identification information) of a terminal to which the terminal itself is connected. As shown in FIG. 2, for example, the communication terminal # 1 is connected to the communication terminals # 2 and # 3. The identification information of the communication terminals # 2, 3 is stored as connection information.
The ad hoc communication means 13 is a communication interface with an external terminal. The upper layer (when viewed from the ad hoc communication means 13, the P2P transfer means 12, the topology control means 14, the neighborhood information response means 16, and the neighborhood information acquisition means 15 Communication processing with other communication terminals is executed based on the communication request from the corresponding).
The topology control unit 14 uses a predetermined method based on the connection destination communication terminal information stored in the connection destination database 141, the neighbor search request result received by the neighbor information acquisition unit 15, and the connection information to connect the P2P topology. Are managed, and P2P topology change determination and change control are performed.
Specifically, when the connection information received by the neighborhood information acquisition unit is connection information regarding a communication terminal that is not written in the connection destination database 141, the topology control unit 14 does not write communication in the connection destination database 141. The number of terminals (hereinafter referred to as the number of connections) is compared between the received plurality of connection information, and the connection information with a large number of communication terminals is written in the connection destination database 141 up to a preset transfer number to construct the topology ( Will be described later).
Further, as described above, the topology control unit 14 includes the connection destination database 141 inside.
The neighborhood information acquisition means 15 is configured to obtain, for an unspecified number of communication terminals existing in the communication area, connection search information including a neighbor search request for the communication terminal existing in the communication area and information on the terminal to which the communication terminal is connected. Send a request. Further, the neighborhood information acquisition unit 15 receives a neighborhood flag indicating that the mobile phone is within the communication range and connection information in response to the neighborhood search request.
When the neighborhood information response means 16 receives a connection information request or a neighborhood search request from an unspecified number of communication terminals existing in the communication area, the neighborhood information response means 16 reads information on the connection destination communication terminal from the connection destination database. And the neighbor flag are transmitted to the communication terminal.
[0017]
Next, the operation of the mobile ad hoc P2P topology control system of this embodiment will be described with reference to the drawings. 2 to 12 are flowcharts showing a process of communication control processing by the mobile ad hoc P2P topology control system of this embodiment.
First, FIG. 2 shows propagation of transfer data performed at the time of information exchange in this system. In communication terminal # 1, information transmission means 11 outputs to P2P transfer means 12 upon receipt of transfer data. Based on connection information stored in a connection destination database 141 (hereinafter referred to as DB) existing in the topology control means 14, the P2P transfer means 12 is connected to another communication terminal (in this embodiment, communication terminal # 2 and Ad hoc communication means 1 to communication terminal # 3) 3 Forward through.
[0018]
When the communication terminal # 2 moves on the physical space of the terminal as shown in FIG. 3, the connection information stored in the connection destination DB 141 in the topology control means 14 is changed compared to the case of FIG. As shown by the arrow in FIG. Communication means 13 Is
Communication terminal # 1 → Communication terminal # 2
Communication terminal # 1 → (Communication terminal # 2) → Communication terminal # 3
It communicates with the path.
In this case, since communication from the communication terminal # 1 to the communication terminal # 2 passes through the communication terminal # 3, the same information is transferred between the communication terminal # 1 and the communication terminal # 3 in the lower layer. There arises a problem that communication efficiency is lowered.
Ad hoc communication means 1 3 In the case of a communication system that does not include, there is a problem that information cannot be transferred to the communication terminal # 2.
[0019]
Therefore, in order to eliminate the above-mentioned problem, it is necessary to determine which terminal is connected efficiently in changing the P2P topology.
FIG. 4 shows a procedure for collecting information on neighboring terminals that are the basis for this determination.
First, in the communication terminal # 1, the neighborhood information acquisition means 15 transmits a connection information request as a neighborhood search, and acquires necessary information, ie, neighborhood connection information, from the neighborhood terminal. In the present specification, being in the vicinity is synonymous with being in the communication area.
Also, the neighbor connection information is connection information (connection source terminal, connection destination array) of the communication terminal in which the neighbor flag is set. Specifically, as shown in FIG. The identification information and the connection destination array returned as a response to the neighborhood search from the connection source communication terminal (= the connection destination communication terminal stored in its connection destination DB 141 as connection information by the connection source communication terminal) Identification information).
There are a connection information method and an evaluation event method as a method by which the topology control unit 14 selects a connection destination of the topology based on this neighboring connection information, and information exchanged is different. Details will be described later.
[0020]
As shown in FIG. 5, the topology control unit 14 determines a connection destination based on the collected neighboring connection information. That is, the topology control unit 14 compares the collected neighboring connection information with the connection information stored in the connection destination information DB 141, and determines that the connection destination has changed for the communication terminals that do not match. Then, a connection request is made to the communication terminal whose connection destination has been changed, and a new connection is established.
In addition, when the terminal connected so far no longer exists in the vicinity (when connection information is not returned as a neighboring terminal), the topology control unit 14 sends the connection information from the connection destination DB 141 in the topology control unit 14. delete. However, when the terminal discovered by the proximity search is registered in the DB and the prescribed transfer number is not reached, the topology control unit 14 does not delete the terminal that is not in the vicinity from the connection destination DB 141.
[0021]
As described above, according to the mobile ad hoc P2P topology control system of the present embodiment, the topology is reconfigured in the communication terminal, so that an effect of reducing unnecessary relay traffic can be obtained as shown in FIG. . Further, the ad hoc communication unit 16 can transmit the transfer data to the whole without providing the multi-hop function.
[0022]
Next, a method in which the topology control unit 14 described above selects a topology connection destination will be described. First, the connection information method will be described. In the connection information method, connection information of a terminal is acquired from a neighboring terminal, and a connection destination is selected based on the information.
[0023]
In this system, as shown in FIG. 7, a connection information request is transmitted to a neighbor (a terminal that can communicate at 1 Hop). Further, all the communication terminals # 1 to # 7 are provided with a mechanism for returning connection information in the neighborhood information response means 16.
That is, in communication terminal # 1, neighborhood information acquisition means 15 transmits a connection information request as a neighborhood search, and the communication terminal that has received this neighborhood search request uses communication information currently connected in neighborhood information response means 16. Returns connection information about the device. Then, the communication terminal # 1 that is the transmission source of the neighborhood search request receives this connection information.
Therefore, the communication terminal that is the transmission source of the connection information request can obtain information about which terminal is in the vicinity and to which other terminal the terminal is connected.
In the present embodiment, communication terminals # 2, 3, and 4 are in the vicinity, and each connection information is as shown in the vicinity connection information in communication terminal # 1 in FIG.
Terminal 2 Terminal 3, 5, 6
Terminal 3 Terminal 2, 4, 6
Terminal 4 Terminal 3, 7
It has become.
[0024]
In this case, the number of connections with non-neighboring communication terminals (other than communication terminals # 2, 3, 4) is
Terminal 2 Terminal 5, 6 Number of connections: 2
Terminal 3 Terminal 6 Number of connections: 1
Terminal 4 Terminal 7 Number of connections: 1
Therefore, the topology control means 14 determines the communication terminal # 2 having a larger number of connections with communication terminals that are not neighboring terminals as the connection destination.
Next, when comparing the terminals 3 and 4, the number of connections to the terminals other than the terminal connected by the nearby terminal and the communication terminal # 2 (communication terminals # 2, 3, 4, 5, 6) is
Number of terminals 3 connected: 0
Terminal 4 Terminal 7 Number of connections: 1
Therefore, topology control means 14 determines communication terminal # 4 having a larger number of connections with terminals other than those connected by neighboring terminals and communication terminal # 2, as the connection destination.
Then, the topology control means 14 confirms that it propagates to all the acquired information (this time, the connection destination of the communication terminal # 3 is included in the connection destinations of the communication terminal # 2 and the communication terminal # 4). At the same time, the process is repeated until either the maximum number of connections is reached or connection is made to all neighboring terminals.
[0025]
Then, as shown in FIG. 8, the topology control unit 14 makes a connection request to the terminal whose connection destination has been changed with respect to the determined connection destination and establishes a new connection.
Further, when the terminal connected so far no longer exists in the vicinity (when the connection information is not returned as a neighboring terminal), this connection information is deleted from the connection destination DB 141 in the topology control means 14.
[0026]
Next, an evaluation event method will be described as a method by which the topology control unit 14 described above selects a topology connection destination. The evaluation event method is a method in which temporary connection is once performed and connection information is acquired with an arbitrary TTL (Time To Live). For this reason, in the evaluation event method, more detailed determination can be performed as compared with the connection information method, but more procedures are required until the determination is completed.
[0027]
In this method, as shown in FIG. 9, the neighborhood information acquisition unit 15 transmits a neighborhood search to the neighborhood (terminal that can communicate with 1 Hop). All the communication terminals # 1 to # 7 are provided with a mechanism for returning a neighborhood flag in the neighborhood information response means 16.
That is, in the communication terminal # 1, the neighborhood information acquisition unit 15 transmits a connection information request as a neighborhood search, and the communication terminal that has received the neighborhood search request returns a neighborhood flag in the neighborhood information response unit 16. Then, the communication terminal that is the transmission source of the neighborhood search request receives this connection information.
Therefore, the communication terminal that is the transmission source of the neighbor search can know which terminal is in the vicinity.
[0028]
Next, as shown in FIG. 10, the P2P transfer unit 12 makes temporary connections to these neighboring communication terminals based on the neighboring communication terminal connection information obtained by the neighboring information obtaining unit 15. That is, the P2P transfer means 12 sets an arbitrary TTL in the connection information request packet, and transfers the connection information request for requesting the connection information to these neighboring communication terminals.
[0029]
As shown in FIG. 11, the communication terminal that has received the connection information request returns the connection destination DB • 141 information in the topology control unit 14 as connection information in the neighborhood information response unit 16. The communication terminal that is the transmission source of the connection information request aggregates the number of returned connection information and the connection information for each neighboring communication terminal in the topology control means 14. Then, the topology control unit 14 determines a connection destination based on the total information.
Here, a large number of returned connection information indicates that there are many terminals that can be transmitted with an arbitrary TTL.
First, the topology control unit 14 compares the summation results of connection information for each neighboring communication terminal, and determines a connection to which more connection information has returned from a plurality of temporary connections to the neighboring communication terminal.
Here, if the same number of connection information is returned from two or more communication terminals, the topology control means 14 selects a communication terminal having a connection that has returned more connection information regarding communication terminals that do not exist in the vicinity.
[0030]
As shown in FIG. 11, in the present embodiment, the aggregation result of the connection information for each neighboring communication terminal is
Terminal 2 Terminals 5, 6, 3 Number of connections: 3
Terminal 3 Terminals 2, 6, 4 Number of connections: 3
Terminal 4 Terminal 3, 7 Number of connections: 2
In the case of temporary connection to communication terminal # 2 and communication terminal # 3, more connection information is returned. Further, when communication terminal # 2 and communication terminal # 3 are compared, a connection including more connection information that is not a neighboring terminal is a connection to communication terminal # 2, and is selected.
Next, a terminal connected more than the terminals connected by the nearby terminal and communication terminal # 2 (communication terminals # 2, 3, 4, 5, 6) is communication terminal # 4.
Then, the topology control means 14 confirms that it propagates to all the acquired information (this time, the connection destination of the communication terminal # 3 is included in the connection destinations of the communication terminal # 2 and the communication terminal # 4). At the same time, the process is repeated until either the maximum number of connections is reached or connection is made to all neighboring terminals.
[0031]
Then, as shown in FIG. 12, the topology control means 14 establishes a new connection by making a connection request to the terminal whose connection destination has been changed with respect to the determined connection destination.
Further, when the terminal connected so far no longer exists in the vicinity (when the connection information is not returned as a neighboring terminal), this connection information is deleted from the connection destination DB 141 in the topology control means 14.
[0032]
As described above, according to the mobile ad hoc P2P topology control system of this embodiment, there is an effect that information exchange can be realized on a mobile ad hoc network without having a server on which information and processing are concentrated.
Further, by transferring information at each communication terminal, it is possible to perform transmission to all users by transferring information to some users.
Further, even between terminals that do not have the ad hoc communication function, it is possible to maintain the consistency as a network by detecting connectable terminals and performing reconnection.
In addition, even when the above-described ad hoc communication function is not provided, an effect that communication can be performed without particular awareness as P2P communication is obtained.
[0033]
Further, since the P2P communication system is used, the following effects are expected. That is,
(1) Since there is no centralized management unit, traffic and processing are not concentrated.
(2) The service can be enjoyed by connecting to any user participating in the network without knowing the entire network.
(3) By controlling the connection between individual terminals so that the individual terminals are optimized, it is possible to reduce the traffic of the entire NW.
(4) In an ad hoc network, communication is performed via each terminal. Therefore, the traffic reduction of the entire NW is reduced as described above, that is, the relay traffic of individual terminals is reduced.
[0034]
In addition, the following effects are expected by reducing the relay traffic.
(A) Saving communication bandwidth
(B) Saving of terminal CPU resources
(C) Reduction of power consumption
[0035]
As described above in detail, with the widespread use and high functionality of mobile terminals, services using mobile terminals are attracting attention. Especially in mobile ad hoc networks realized only by communication between terminals, the usage area It has the characteristics that no equipment other than the terminal is required, and the effect that the characteristics of the moving body can be utilized is obtained.
In addition, by applying P2P technology to the realization of network by communication between terminals, terminals that behave intensively are not required, the roles of participant terminals are equal, and it is not necessary to grasp the entire network Therefore, there is an effect that it is possible to provide a network service provided to a relatively large number of participants even in a network where there are many paradoxes and the connection state keeps changing.
[0036]
The communication terminal described above has a computer system inside.
A series of processes related to the communication process described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing the program.
That is, each processing means and processing unit in the communication terminal is realized by a central processing unit such as a CPU reading the above program into a main storage device such as a ROM or RAM, and executing information processing / arithmetic processing. It is what is done.
Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.
[0037]
【The invention's effect】
As described above, the present invention provides a connection destination database that stores information of communication terminals that are connection destinations, and a proximity search of communication terminals that exist within the communication area with respect to an unspecified number of communication terminals that exist within the communication area. Neighbors that transmit a request and a request for connection information including information on a terminal to which the communication terminal is connected, and receive a neighbor flag indicating that the communication terminal is within the communication range and connection information in response to a neighbor search request When receiving a connection information request or a neighbor search request from an unspecified number of communication terminals existing in the communication area with the information acquisition means, the information of the connection destination communication terminal is read from the connection destination database, and the connection information, In response to the input of the neighbor information response means for transmitting the neighbor flag to the communication terminal and the transfer data to be transferred to another communication terminal, the transfer data is output to the P2P transfer means and the P2P transfer Information transmission / reception means for receiving transfer data from other communication terminals via the stage, and reading connection information from the connection destination database, and transferring data output by the information transmission / reception means according to the read connection information via the ad hoc communication means A P2P transfer means for transferring the transfer data received from the other information terminal to the information transmitting / receiving means via the ad hoc communication means, and a connection destination communication terminal stored in the connection destination database. And topology control means for managing the connection information of the P2P topology by a predetermined method based on the received neighbor search request result and the connection information, and performing the change judgment and the change control of the P2P topology. Reduce unnecessary ad hoc communication that occurs when a terminal moves in any direction, It is possible to obtain an effect capable of improving the efficiency of the entire network.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a mobile ad hoc P2P topology control system.
FIG. 2 is a diagram illustrating a flow of transmission of transfer data.
FIG. 3 is a diagram showing a flow of transfer of transfer data when a terminal moves and a communication state changes.
FIG. 4 is a diagram illustrating a flow of collecting information in order to determine an appropriate connection destination when a communication state changes due to movement of a terminal or the like.
FIG. 5 is a diagram illustrating a flow of changing a P2P topology according to a collection result;
FIG. 6 is a diagram showing a flow of transfer of transfer data after the efficiency of the topology is implemented.
FIG. 7 is a diagram illustrating a flow of collecting neighboring connection information when a connection information method is used as a determination of a connection destination.
FIG. 8 is a diagram illustrating a flow of topology change when a connection information method is used as a connection destination determination.
FIG. 9 is a diagram illustrating a flow of neighborhood search when an evaluation event method is used as a determination of a connection destination.
FIG. 10 is a diagram illustrating a flow of searching connection information when an evaluation event method is used as a determination of a connection destination.
FIG. 11 is a diagram illustrating a flow of collecting connection information when an evaluation event method is used as a determination of a connection destination.
FIG. 12 is a diagram showing a flow of topology change when an evaluation event method is used as a connection destination determination.
[Explanation of symbols]
1-3 ... Communication terminal
11. Information transmitting / receiving means
12 ... P2P transfer means
13 ... Ad hoc communication means
14 ... Topology control means
15. Neighboring information acquisition means
16. Neighbor information response means
141 ... connection destination database

Claims

A connection destination database that stores information of communication terminals of connection destinations;
Sending an unspecified number of communication terminals in the communication area a neighbor search request for the communication terminal existing in the communication area and a request for connection information including information on the terminal to which the communication terminal is connected. A neighbor flag indicating that the mobile terminal is within a communication range in response to the neighbor search request, and neighbor information acquisition means for receiving the connection information;
Upon receiving the connection information request or the neighbor search request from an unspecified number of communication terminals existing in the communication area, the information of the connection destination communication terminal is read from the connection destination database, and the connection information, Neighborhood information response means for transmitting the neighborhood flag to the communication terminal;
An information transmission / reception means for receiving the transfer data to be transferred to the other communication terminal, outputting the transfer data to the P2P transfer means, and receiving the transfer data from the other communication terminal via the P2P transfer means;
An ad hoc communication means that is a communication interface with another information terminal and performs communication processing with another information terminal based on a communication request from an upper layer;
It reads the connection information from the connection destination database, in accordance with the said connection information read out, the transfer data by the information receiving means outputs, as well as transfer to another information communication terminal via the ad-hoc communication device, the ad-hoc P2P transfer means for outputting transfer data received from another information terminal to the information transmitting / receiving means via the communication means;
An evaluation event in which temporary connection is made and connection information is acquired with an arbitrary TTL (Time to Live) based on information of a communication terminal of a connection destination stored in the connection destination database, the received neighbor search request result, and connection information A topology control means for managing connection information of the P2P topology according to the system, and performing change judgment and change control of the P2P topology ;
Communication terminal the higher layers and the P2P transfer means, topology control unit, neighborhood information obtaining means, neighborhood information reply unit der wherein Rukoto.

The topology control means includes
2. The communication terminal according to claim 1, wherein, when the connection information received by the neighbor information acquisition unit is connection information related to a communication terminal that is not written in the connection destination database, the communication terminal writes the connection information in the connection destination database.

The topology control means includes
When the connection information received by the neighbor information acquisition means is connection information related to a communication terminal that is not written in the connection destination database, the number of communication terminals that are not written in the connection destination database is determined by the received plurality of connection information. The communication terminal according to claim 1, wherein connection information having a larger number of communication terminals is written in the connection destination database.

The topology control means includes
When the connection information received by the neighbor information acquisition means is connection information related to a communication terminal that is not written in the connection destination database, the number of communication terminals that are not written in the connection destination database is determined by the received plurality of connection information. 2. The communication terminal according to claim 1, wherein the connection information having a large number of communication terminals is written to the connection destination database up to a preset transfer number to construct a topology.

The topology control means further outputs a temporary connection request to the communication terminal that is the transmission source of the neighbor flag to the P2P transfer means when the neighbor information acquisition means receives the neighbor flag,
The P2P transfer means receives the input of the temporary connection request, transfers the connection information request to another information communication terminal with an arbitrary TTL number via the ad hoc communication means, and via the ad hoc communication means The connection information received from other information terminals is output to the topology control means,
The topology control means further includes the number of communication terminals not written in the connection destination database when the connection information received by the P2P control means is connection information related to communication terminals not written in the connection destination database. 2. The communication terminal according to claim 1, wherein the plurality of received connection information is compared, and connection information having a large number of communication terminals is written in the connection destination database.

A communication control system including first to n-th (n is a natural number) communication terminals,
The first to n-th communication terminals are
A connection destination database for storing information of a connection destination communication terminal among the first to nth communication terminals;
Among the first to n-th communication terminals, for an unspecified number of communication terminals existing in the communication area, a proximity search request for the communication terminal existing in the communication area and a terminal to which the communication terminal is connected A neighbor information acquisition means for receiving a neighbor flag indicating that the mobile terminal is within a communication range in response to the neighbor search request, and the connection information;
Upon receiving the connection information request or the neighbor search request from an unspecified number of communication terminals existing in the communication area, the information of the connection destination communication terminal is read from the connection destination database, and the connection information, Neighborhood information response means for transmitting the neighborhood flag to the communication terminal;
Information transmission / reception means for receiving transfer data to be transferred to the connection destination communication terminal, outputting the transfer data to a P2P transfer means, and receiving transfer data from another communication terminal via the P2P transfer means; ,
The connection information is read from the connection destination database, and transfer data output by the information transmitting / receiving means is transferred to another information communication terminal via the ad hoc communication means according to the read connection information, and the ad hoc communication P2P transfer means for outputting transfer data received from another information terminal to the information transmitting / receiving means via the means;
Based on the information of the communication terminal of the connection destination stored in the connection destination database, the received neighbor search request result and the connection information, the connection information of the P2P topology is managed by a predetermined method, and the change judgment and change of the P2P topology are performed. A communication control system comprising topology control means for performing control.

Sending an unspecified number of communication terminals in the communication area a neighbor search request for the communication terminal existing in the communication area and a request for connection information including information on the terminal to which the communication terminal is connected. Receiving, in response to the neighborhood search request, a neighborhood flag indicating the presence in the communication range and the connection information;
When the connection information request or the neighbor search request is received from an unspecified number of communication terminals existing in the communication area, information on the connection destination communication terminal is obtained from the connection destination database storing information on the connection destination communication terminal. And transmitting the connection information and the neighborhood flag to the communication terminal;
Receiving the transfer data to be transferred to the other communication terminal, outputting the transfer data, and receiving the transfer data from the other communication terminal;
Reading the connection information from the connection destination database, transferring the transfer data to another information communication terminal according to the read connection information, and outputting the transfer data received from another information terminal;
Based on the information of the communication terminal of the connection destination stored in the connection destination database, the received neighbor search request result and the connection information, the connection information of the P2P topology is managed by a predetermined method, and the change judgment and change of the P2P topology are performed. And a step of performing control.

Sending an unspecified number of communication terminals in the communication area a neighbor search request for the communication terminal existing in the communication area and a request for connection information including information on the terminal to which the communication terminal is connected. In response to the neighborhood search request, a neighborhood flag indicating that the mobile phone is within a communication range and the neighborhood information acquisition process for receiving the connection information;
When the connection information request or the neighbor search request is received from an unspecified number of communication terminals existing in the communication area, information on the connection destination communication terminal is obtained from the connection destination database storing information on the connection destination communication terminal. A proximity information response process for transmitting the connection information and the proximity flag to the communication terminal;
An information transmission / reception process for receiving transfer data to be transferred to the other communication terminal, outputting the transfer data to a P2P transfer means, and receiving transfer data from the other communication terminal via the P2P transfer means;
The connection information is read from the connection destination database, and transfer data output by the information transmitting / receiving means is transferred to another information communication terminal via the ad hoc communication means according to the read connection information, and the ad hoc communication P2P transfer processing for outputting transfer data received from another information terminal to the information transmitting / receiving means via the means;
Based on the information of the communication terminal of the connection destination stored in the connection destination database, the received neighbor search request result and the connection information, the connection information of the P2P topology is managed by a predetermined method, and the change judgment and change of the P2P topology are performed. A communication program for causing a computer to execute topology control processing for performing control.