JP3541222B2

JP3541222B2 - Communication method, communication system, transmission method, transmission device, reception method, and reception device

Info

Publication number: JP3541222B2
Application number: JP2001057174A
Authority: JP
Inventors: 博司原田; 誠沖田; 雅行藤瀬
Original assignee: National Institute of Information and Communications Technology
Current assignee: National Institute of Information and Communications Technology
Priority date: 2001-03-01
Filing date: 2001-03-01
Publication date: 2004-07-07
Anticipated expiration: 2021-03-01
Also published as: JP2002261823A

Description

【０００１】
【発明の属する技術分野】
この発明は、例えばマルチメディアデータを車両に対して伝送する路車間通信システムに対して適用可能な通信方法、通信システム、送信方法、送信装置、受信方法および受信装置に関する。
【０００２】
【従来の技術】
路車間通信システムに対する要求としてマルチメディア通信の実現がある。マルチメディア通信では、端末から情報の要求を行い、画像や音楽データ等のマルチメディアデータをダウンロードする場合が多く、端末からの送信（上り）データ量に比して受信（下り）データ量が多いという特徴がある。したがって、路車間通信システムによってマルチメディア通信を実現するためには、バースト的に発生する大量のデータを効率良く端末に伝送するアクセス方式が必要である。
【０００３】
従来から無線ＬＡＮ(Local Area Network) 等で使用されるアクセス方式として、ＣＳＭＡ(Carrier Sense Multiple Access：搬送波検出多元接続) 方式が知られている。この方式は、ステーションがキャリアセンスによってチャンネルの使用状況を見てからフレームを送信するかどうかを決定する方式である。キャリア検出に加えて何らかの衝突回避機構を備えたＣＳＭＡ／ＣＡ(ＣＳＭＡ with Collision Avoidance)も知られている。
【０００４】
【発明が解決しようとする課題】
無線通信において、ステーション間の距離が長すぎたり、壁などの電波を通過させない障害物があるために、電波が到達しないことがある。互いの送信信号が到達しないステーションが隠れ端末と呼ばれる。隠れ端末に対しては、キャリアセンスが有効に機能しないために、ＣＳＭＡ方式においてフレームの衝突の頻度が増え、特性が劣化する。路車間通信では、車載アンテナが比較的指向性が高く、隠れ端末問題が生じ易い。そのため、ＣＳＭＡを路車間通信に適用するのが困難であった。
【０００５】
さらに、従来の無線通信方式として、プリアサイン方式やポーリング方式が知られている。プリアサイン方式は、周波数や時間によって分割された各帯域を一対のステーション間の通信に専用に固定的に割り当てる方式である。ポーリング方式は、中央のステーションが他のステーションに対して送信フレームの有無を順次問い合わせるポーリングを繰り返す方式である。路車間通信では、高速で車がセル内を移動し、端末数が不定であるので、プリアサイン方式やポーリング方式の適用が難しい。
【０００６】
したがって、この発明の目的は、例えば路車間のマルチメディア通信を円滑に行うことを可能とする通信方法、通信システム、送信方法、送信装置、受信方法および受信装置を提供することにある。
【０００７】
【課題を解決するための手段】
上述した課題を解決するために、請求項１の発明は、同時に通信可能な下り回線および上り回線からなり、且つスロット化された通信路によって送信装置と１以上の受信装置が接続され、データパケットが下り回線を介して送信装置から受信装置に伝送され、要求パケットが上り回線を介して受信装置から送信装置に伝送される通信システムにおける通信方法において、
１フレームが少なくとも一つの通知スロットと複数のデータスロットとで構成され、
送信装置が同一フレーム内および次のフレームの下り回線のデータスロットの使用状況を表す通知パケットを生成し、生成した通知パケットを通知スロットを使用して受信装置に送信するステップと、
受信装置から要求パケットを受信した場合に、要求パケットを受信したフレームの次のフレーム以降のフレームに含まれ、且つ空きの１以上のデータスロットを受信装置に対して割り当て、要求パケットに対応するデータパケットを１以上の割り当てられたデータスロットを使用して伝送するステップと、
受信装置に対する送信が終了した場合に、受信装置に割り当てていたデータスロットを解放するステップとからなり、
次のフレームに空きのデータスロットがある、という通知パケットを受け取った受信装置であって、要求パケットを持っている受信装置が次の通知パケットを受け取るまでの間の上り回線の任意の空きスロットを使用して要求パケットが伝送されることを特徴とする通信方法である。請求項１２の発明は、請求項１の通信方法による通信システムである。
【０００８】
請求項２３の発明は、同時に通信可能な下り回線および上り回線からなり、且つスロット化された通信路によって送信装置と１以上の受信装置が接続され、データパケットが下り回線を介して送信装置から受信装置に伝送され、要求パケットが上り回線を介して受信装置から送信装置に伝送される通信システムにおける送信方法において、
１フレームが少なくとも一つの通知スロットと複数のデータスロットとで構成され、
同一フレーム内および次のフレームの下り回線のデータスロットの使用状況を表す通知パケットを生成し、生成した通知パケットを通知スロットを使用して受信装置に送信するステップと、
受信装置から要求パケットを受信した場合に、要求パケットを受信したフレームの次のフレーム以降のフレームに含まれ、且つ空きの１以上のデータスロットを規則にしたがって受信装置に対して割り当て、要求パケットに対応するデータパケットを１以上の割り当てられたデータスロットを使用して伝送するステップと、
受信装置に対する送信が終了した場合に、受信装置に割り当てていたデータスロットを解放するステップとからなり、
規則は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信しない場合には、空きのデータスロットの全てを受信装置に割り当てる第１の規則と、
受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのデータスロットを割り当て、送信すべきデータパケットの残り数が最も少ない受信装置に対して、各フレーム中の残りの空きデータスロットを割り当て、さらに、各フレーム内にまだ空きデータスロットがあれば、送信すべきデータパケットの残り数が少ない受信装置の順に残りの空きデータスロットを割り当てる第２の規則とからなり、
第２の規則に基づく処理が空きのデータスロットが無くなるか、または割り当てる受信装置が無くなるまで行なわれることを特徴とする送信方法である。
請求項２７の発明は、請求項２３の送信方法による送信装置である。
【０００９】
請求項２４の発明は、同時に通信可能な下り回線および上り回線からなり、且つスロット化された通信路によって送信装置と１以上の受信装置が接続され、データパケットが下り回線を介して送信装置から受信装置に伝送され、要求パケットが上り回線を介して受信装置から送信装置に伝送される通信システムにおける送信方法において、
１フレームが少なくとも一つの通知スロットと複数のデータスロットとで構成され、
同一フレーム内および次のフレームの下り回線のデータスロットの使用状況を表す通知パケットを生成し、生成した通知パケットを通知スロットを使用して受信装置に送信するステップと、
受信装置から要求パケットを受信した場合に、要求パケットを受信したフレームの次のフレーム以降のフレームに含まれ、且つ空きの１以上のデータスロットを規則にしたがって受信装置に対して割り当て、要求パケットに対応するデータパケットを１以上の割り当てられたデータスロットを使用して伝送するステップと、
受信装置に対する送信が終了した場合に、受信装置に割り当てていたデータスロットを解放するステップとからなり、
規則は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信しない場合には、空きのデータスロットの全てを受信装置に割り当てる第１の規則と、
受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのデータスロットを割り当て、要求パケットの到着の最も早い受信装置に対して、各フレーム中の残りの空きデータスロットを割り当て、さらに、各フレーム内にまだ空きデータスロットがあれば、要求パケットの到着が早い受信装置の順に残りの空きデータスロットを割り当てる第２の規則とからなり、
第２の規則に基づく処理が空きのデータスロットが無くなるか、または割り当てる受信装置が無くなるまで行なわれることを特徴とする送信方法である。
請求項２８の発明は、請求項２４の送信方法による送信装置である。
【００１０】
請求項２５の発明は、同時に通信可能な下り回線および上り回線からなり、且つスロット化された通信路によって送信装置と１以上の受信装置が接続され、データパケットが下り回線を介して送信装置から受信装置に伝送され、要求パケットが上り回線を介して受信装置から送信装置に伝送される通信システムにおける送信方法において、
１フレームが少なくとも一つの通知スロットと複数のデータスロットとで構成され、
同一フレーム内および次のフレームの下り回線のデータスロットの使用状況を表す通知パケットを生成し、生成した通知パケットを通知スロットを使用して受信装置に送信するステップと、
受信装置から要求パケットを受信した場合に、要求パケットを受信したフレームの次のフレーム以降のフレームに含まれ、且つ空きの１以上のデータスロットを規則にしたがって受信装置に対して割り当て、要求パケットに対応するデータパケットを１以上の割り当てられたデータスロットを使用して伝送するステップと、
受信装置に対する送信が終了した場合に、受信装置に割り当てていたデータスロットを解放するステップとからなり、
規則は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信しない場合には、空きのデータスロットの全てを受信装置に割り当てる第１の規則と、
受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのフレーム内のデータスロットを等分に割り当てる第２の規則とからなり、
第２の規則に基づく処理が空きのデータスロットが無くなるか、または割り当てる受信装置が無くなるまで行なわれることを特徴とする送信方法である。請求項２９の発明は、請求項２５の送信方法による送信装置である。
【００１１】
請求項２６の発明は、同時に通信可能な下り回線および上り回線からなり、且つスロット化された通信路によって送信装置と１以上の受信装置が接続され、データパケットが下り回線を介して送信装置から受信装置に伝送され、要求パケットが上り回線を介して受信装置から送信装置に伝送される通信システムにおける送信方法において、
１フレームが少なくとも一つの通知スロットと複数のデータスロットとで構成され、
同一フレーム内および次のフレームの下り回線のデータスロットの使用状況を表す通知パケットを生成し、生成した通知パケットを通知スロットを使用して受信装置に送信するステップと、
受信装置から要求パケットを受信した場合に、要求パケットを受信したフレームの次のフレーム以降のフレームに含まれ、且つ空きの１以上のデータスロットを規則にしたがって受信装置に対して割り当て、要求パケットに対応するデータパケットを１以上の割り当てられたデータスロットを使用して伝送するステップと、
受信装置に対する送信が終了した場合に、受信装置に割り当てていたデータスロットを解放するステップとからなり、
受信装置に対するデータスロットが規則にしたがって割り当てられ、
規則は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信しない場合には、空きのデータスロットの全てを受信装置に割り当てる第１の規則と、
受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのデータスロットを割り当て、さらに、各フレーム内にまだ空きのデータスロットがあれば、送信すべきデータパケットの優先順位が最も高い受信装置に対して残りの空きのデータスロットを割り当てる第２の規則とからなり、
第２の規則に基づく処理が空きのデータスロットが無くなるか、または割り当てる受信装置が無くなるまで行なわれることを特徴とする送信方法である。請求項３０の発明は、請求項２６の送信方法による送信装置である。
【００１２】
請求項３１の発明は、同時に通信可能な下り回線および上り回線からなり、且つスロット化された通信路によって送信装置と１以上の受信装置が接続され、データパケットが下り回線を介して送信装置から受信装置に伝送され、要求パケットが上り回線を介して受信装置から送信装置に伝送される通信システムにおける受信方法において、
１フレームが少なくとも一つの通知スロットと複数のデータスロットとで構成され、通知スロットに配置された通知パケットが同一フレーム内および次のフレームの下り回線のデータスロットの使用状況を表し、
要求パケットを生成するステップと、
次のフレームに空きのデータスロットがある、という通知パケットを受け取った場合に、次の通知パケットを受け取るまでの間の上り回線の任意の空きスロットを使用して要求パケットを送信するステップと、
要求パケットの送信が成功した後に、割り当てられたデータスロットを介して要求パケットに対応するデータパケットを受信するステップとからなる受信方法である。請求項３２の発明は、請求項３１の受信方法による受信装置である。
【００１３】
請求項３３の発明は、送信装置が統合基地局と統合基地局と光通信路で接続され、それぞれアンテナを備える複数の局地基地局とからなり、
下り回線においては、統合基地局によって、無線変調方式で変調されたデータパケット、通知パケットが生成され、生成されたデータパケット、通知パケットが光信号へ変換され、光信号が光通信路を介して局地基地局に伝送され、局地基地局によって光無線変換され、局地基地局のアンテナから受信装置に対して放射され、
要求パケットが受信装置から局地基地局のアンテナによって受信され、受信信号が局地基地局によって無線光変換され、光信号が局地基地局から光通信路を介して統合基地局に伝送され、統合基地局において光無線変換される。
【００１４】
この発明によれば、１フレーム内の複数のデータスロットをある受信装置に対して割り当てることができるので、１フレーム内で、一つのデータスロットを一つの受信装置に対して割り当てる方法と比較して、スループットを高くすることができる。
【００１５】
【発明の実施の形態】
以下、この発明の一実施形態について図面を参照して説明する。図１において、参照符号１は、基地局を示す。基地局１は、ネットワークと接続されたネットワーク制御部２と、データパケット生成部３と、通知パケット生成部４と、データパケットおよび通知パケットを選択的に出力するセレクタ５と、セレクタ５の出力が供給され、無線装置６に含まれる送信部７と、送信部７からの無線信号を放射するアンテナ８と、アンテナ８の受信信号が供給される受信部９と、受信パケット判定部１０とから構成されている。
【００１６】
ネットワーク制御部２を介してマルチメディアデータがネットワークからデータパケット生成部３に供給され、データパケット生成部３によって、データパケットが生成される。通知パケット生成部４によって、通知パケットが生成される。受信パケット判定部１０によって判定された受信パケットがネットワーク制御部２を介してネットワークに送信される。ネットワークとしては、携帯電話ネットワーク、放送ネットワーク、インターネット等が可能である。
【００１７】
基地局１は、各フレームの先頭の通知スロットに配置される通知パケットによって、今から送信しようとしているフレーム内の各データスロットの使用状況と次のフレーム内の各データスロットの使用状況を端末に通知する。すなわち、通知パケットは、それぞれのフレーム内の各データスロットがどの端末に割り当てられているかの情報（または確保されているかの情報）を有する。各端末は、通知パケットの内容から自分がどのデータスロットのデータを受信すべきかを判断できる。今から送信しようとしているフレームで、データパケットの送信が終了しない場合には、次のフレームでも続けてデータパケットの残りを送信する必要がある。そのために、次のフレームのデータスロットに関してもどの端末に割り当てられているかの情報を通知パケットが有する。
【００１８】
通知パケットを受信した端末は、通知パケットの情報からそのフレームのどのデータスロットのデータを自分が受信すべきかを判断できる。さらに、データパケットを受信している端末は、次のフレームに関する情報から次のフレームでも受信すべきデータパケットがあるか否かを判断することができる。この場合、要求が発生している端末は、次のフレームに関する情報から要求パケットを送信しても良いかどうかを判断することができる。例えば、このフレームでデータパケットの送信が終了し、次のフレームで続けて送信するデータパケットが無い場合には、このフレーム内で使用しなかったデータスロットと、次のフレームの全データスロットが空きとなる。
【００１９】
なお、通知パケットが上述した下り回線の使用状況以外の情報を持つことも可能である。例えば要求パケットの受信状況、上り回線の使用状況等の情報を持つようにしても良い。
【００２０】
図２において、参照符号２１が端末を示す。参照符号２２がネットワーク制御部を示し、ネットワーク制御部２２に対して受信データを利用するデータ機器が接続される。データ機器としては、携帯電話端末、ディジタル放送受信機等である。他のデータ機器として、カーナビゲーション装置、ＧＰＳ(Global Positioning System) 、ディスプレイ、オーディオシステム等が可能である。
【００２１】
参照符号２３が要求パケット生成部を示す。要求パケット生成部２３によって生成された要求パケットが無線装置２４に含まれる送信装置２５に供給される。送信装置２５からの無線信号がアンテナ２６から放射される。アンテナ２６によって受信された受信信号が無線装置２４の受信部２７に供給される。受信部２７からの受信信号が受信パケット判定部２８に供給される。受信パケット判定部２８からの受信パケットがネットワーク制御部２２を介してデータ機器に供給される。
【００２２】
上述した基地局１（図１）および端末２１（図２）は、路車間通信システムにおける基地局および車両に搭載されている端末に相当するものである。より具体的には、図３に示すような路車間通信システムに対してこの発明を適用することができる。図３のシステムは、参照符号３１で示す統合基地局と、参照符号３２₁，３２₂，・・・で示す光ファイバと、参照符号３３₁，３３₂，・・・で示され、統合基地局３１と光ファイバ３２₁，３２₂，・・・で接続された複数の局地基地局とによって構成される。局地基地局３３₁，３３₂，・・・が例えば道路に沿って所定の間隔で設置され、車両３４に搭載されている端末との路車間通信が可能とされている。送信装置の内のアンテナ以外の部分は、統合基地局３１に設置され、アンテナが局地基地局３３₁，３３₂，・・・にそれぞれ設置される。
【００２３】
かかる路車間通信システムにおいて、統合基地局３１は、所定の無線変調方式によって変調された、データパケット、通知パケットを生成し、その無線信号を無線光変換装置によって光信号に変換する。無線光変換装置は、例えばレーザダイオードからの光信号を直接若しくは光変調器によって光信号に変換する構成とされている。この光信号が光ファイバ３２₁，３２₂，・・・を介して１以上の局地基地局３３₁，３３₂，・・・に送信される。局地基地局３３₁，３３₂，・・・においては、ホトダイオードに代表される光無線変換装置によって光信号を無線周波数帯の信号へ変換し、無線信号を路側アンテナから受信装置にデータパケットおよび通知パケットを伝送する。
【００２４】
車両３４に搭載された受信装置（端末）は、路側アンテナから放射された無線信号を受信するアンテナと、アンテナにて受信された無線信号をそれぞれ対応する携帯電話機や放送受信機に送る接続部とを備えている。上り回線においては、受信装置からの所定の無線変調方式によって変調された要求パケットを局地基地局３３₁，３３₂，・・・で受信し、上述した無線光変換装置と同様の原理を持つ、無線光変換装置によって光信号へ変換し、光ファイバ３２₁，３２₂，・・・を介して統合基地局３１へ伝送する。統合基地局３１においては、上述した光無線変換装置と同様の原理を持つ光無線変換装置によって無線周波数帯の信号に変換し、送信された要求パケットを受信する。
【００２５】
なお、統合基地局３１に設けた、周波数変換統合分配装置によって携帯電話や放送等の変調された個別の無線周波数または中間周波数を、ある特定の周波数帯例えばミリ波帯に含まれるように、統合変換し共用周波数帯の無線信号を路側アンテナから放射しても良い。この場合には、車両３４に搭載された端末は、共用周波数帯に感度を有するアンテナと、アンテナにて受信された無線信号を個別の無線周波数や中間周波数の無線信号に変換し、分配する周波数変換分配装置と、周波数変換分配装置からの個別の無線周波数や中間周波数の無線信号をそれぞれ対応する携帯電話機や放送受信機に送る接続部とを備えている。
【００２６】
図１に示される基地局１は、図３のシステムにおける統合基地局３１および局地基地局３３₁，３３₂，・・・の全体に対応したものである。図２に示される端末２１は、車両３４に搭載されている端末に対応するものである。一実施形態では、基地局１から端末２１に対する下り回線と、その逆の端末２１から基地局１に対する上り回線とが同時に通信可能なように構成されている。例えば両回線の間で、キャリア周波数が異なる変調方式が使用されている。
【００２７】
この発明の一実施形態では、下り回線を通じて伝送される１フレームが少なくとも一つの通知スロットと複数例えば５個のデータスロットとから構成される。連続した時間を一定の間隔に区切ることがスロット化と呼ばれ、区切りの一つ一つがスロットと称される。なお、通知スロットとデータスロットとは、等しい長さに限らず、異なる長さでも良い。基地局１は、このフレームの先頭の通知スロットに配置される通知パケットによって、このフレーム内の各データスロットの使用状況と次のフレーム内の各データスロットの使用状況を端末２１に通知する。上述したように、通知パケットには、送信しようとしているフレーム内および次のフレーム内のデータスロットのそれぞれがどの端末に割り当てられているかが記述されている。
【００２８】
なお、１スロットには、１個のパケットが配置されるものとするが、２個以上のパケットが１スロットに配置されても良い。一例として、各データスロットには、イーサネットで用いられる一つのパケットが伝送される。この場合、各データスロットにおいて、イーサネットで用いられる一つのパケットがセグメント化されたものが伝送されるようにしても良い。さらに、各通知スロットにおいては、イーサネットで用いられるブロードキャストパケットが伝送される。イーサネットは、IEEE(Institute of Electrical and Electronics Engineers)802.3規格を意味する。この規格が使用する伝送媒体、伝送速度などによって、10BASE-T,100BASE-T, ギガビットイーサなどの規格がある。
【００２９】
端末２１に要求が発生した場合、端末２１は、基地局１から通知された内容にしたがって、次フレームの任意の空きスロットを使用して要求パケットを上り回線を介して基地局１に対して送信する。端末２１は、受信した通知パケットの内容に基づいて次のフレームに空きデータスロットがある場合に、要求パケットを送信する。また、同一データスロットにおいて複数の端末が要求パケットを送信することによって、送信装置において衝突が発生し、どの受信装置から要求パケットが送信されたのか識別できない場合には、衝突処理にしたがって要求パケットが再送される。なお、衝突が発生した場合に、送信装置と各端末との間に電力差が存在していると、最も高い受信電力を持つ受信装置からの要求パケットが届く可能性がある。
【００３０】
衝突処理の一例は、後述する例に示されるように、異なる時間間隔で要求パケットが再送されるものである。他の例は、ランダムに決められたスロット数に相当する時間待った後に要求パケットが再送されるものである。さらに他の例は、下り回線の通知スロットにより、データスロットの空きを検知するまで待った後、その次の通知パケットを受信する時間までの間の何れかのデータスロットをランダムに選択し、選択したデータスロットで要求パケットが再送されるものである。
【００３１】
図４は、基地局１が各フレームにおいて行う処理の流れをより詳細に示すフローチャートである。破線で囲んで示す処理部分Ｓ９が通知パケット生成処理を示す。図１における通知パケット生成部４がこの生成処理を行なう。通知パケットは、上述したように、送信しようとしているフレームと次のフレームの各データスロットがどの端末に割り当てられているかの情報（または確保されているかの情報）を有する。各端末は、通知パケットの内容から自分がどのデータスロットのデータを受信すべきかを判断できる。今から送信しようとしているフレームで、データパケットの送信が終了しない場合には、次のフレームでも続けてデータパケットの残りを送信する必要がある。そのために、次のフレームのデータスロットに関してもどの端末に割り当てられているかの情報を通知パケットが有する。
【００３２】
最初のステップＳ１において、このフレームで端末に送信するデータパケットの有無が決定される。若し、ステップＳ１において、送信するパケットが無いと決定されると、ステップＳ８の通知パケット生成処理に処理が移る。この場合では、このフレームおよび次のフレームのデータスロットが全て空きデータスロットであることを示す通知パケットが生成される。
【００３３】
ステップＳ１において、端末に送信するデータパケットがあると決定されると、ステップＳ２において、各端末用にデータスロットを一つ割り当てる。そして、ステップＳ３において、端末に送信すべきデータが残っているか否がが決定される。若し、ステップＳ３において、送信するデータが残っていないと決定されると、ステップＳ８の通知パケット生成処理に処理が移る。ステップＳ３において、送信するデータが残っていると決定されると、ステップＳ４において、データスロットに空きがあるか否かが決定される。
【００３４】
ステップＳ４において、データスロットに空きがあると決定されると、ステップＳ５において、データパケットに残がある端末に空きデータスロットを割り当てる。ステップＳ４において、空きのデータスロットが無いと決定されるときには、ステップＳ５がスキップされる。
【００３５】
次のステップＳ６では、続けて次のフレームでもデータパケットを送信する端末の有るか否かが決定される。若し、ステップＳ６において、送信する端末が無いと決定されると、ステップＳ８の通知パケット生成処理に処理が移る。この場合では、次のフレームのデータスロットが全て空きとなる。ステップＳ６において、送信する端末があると決定されると、ステップＳ７では、次フレーム内のデータスロットを必要数確保する。そして、ステップＳ８において、このフレームおよび次フレームのデータスロットの使用状況を表す通知パケットが生成される。
【００３６】
通知パケット生成処理Ｓ９に続いて、ステップＳ１０では、通知パケットの送信がなされる。ステップＳ１１では、下り回線を介して各データスロットでデータパケットが送信される。同時に、上り回線を介してステップＳ１２では、各スロットで要求パケットが受信される。そして、処理が最初のステップＳ１に戻る。
【００３７】
一実施形態では、端末２１が基地局１から次のフレームに空きがある、という通知を受け取った場合、要求パケットを持っている端末２１は、次の通知パケットを受け取るまでの任意の空きスロットを使用して要求パケットを送信する。図５は、端末２１の処理の流れをより詳細に示すフローチャートである。破線で囲んで示す処理部分Ｓ３０が要求パケット送信処理を示す。図２における要求パケット生成部２３がこの生成処理を行なう。
【００３８】
最初のステップＳ２１は、待機状態を示す。次のステップＳ２２において、要求が発生したか否かが決定される。要求が発生しないと決定されると、待機状態（ステップＳ２１）に戻る。ステップＳ２２で、要求が発生したと決定されると、ステップＳ２３において、要求パケットが生成される。
【００３９】
ステップＳ２４は、待機状態を示し、ステップＳ２５において、基地局１から通知パケットを受信したか否かが決定される。通知パケットを受信するまで、端末２１が待機する。ステップＳ２５において、通知パケットを受信したと決定されると、ステップＳ２６において、次フレームに空きデータスロットがあるか否かが通知パケットの内容に基づいて決定される。空きデータスロットが無いと決定されると、データパケットを次のフレームで受信することができないので、ステップＳ２４に処理が戻り、要求パケットを送信せずに、待機する。
【００４０】
空きデータスロットが無い場合についてより具体的に説明する。例えば５個のデータスロットによって１フレームが構成されている場合、今から送信しようとしているフレーム内の５個のデータスロットのそれぞれが５個の端末に割り当てられていると想定する。そして、５個の端末に送信するデータパケットが複数あり、このフレームでは全てのデータパケットが送信できないと想定する。この場合には、続けて次のフレームでもデータパケットを５個の端末に送信することになるので、次のフレーム内の各データスロットを５個の端末にそれぞれ割り当てる。その結果、次のフレーム内に空いているデータスロットが無い。このように、データスロットと端末とが１対１に割り当てられ、各端末に大量のデータを送信する場合には、このフレームと次のフレームに空きのデータスロットが無い状況が生じる。
【００４１】
ステップＳ２６において、受信した通知パケットの内容に基づいて次フレームに空きデータスロットがあるか否かが決定される。空きデータスロットがあると決定されると、ステップＳ２７において、要求パケットを送信するデータスロットを任意に決定する。そして、ステップＳ２８において、そのデータスロットを使用して要求パケットを送信する。ステップＳ２９において、送信した要求パケットが基地局１に受信されたか否かが決定される。複数の端末が同一のデータスロットを使用して要求パケットを送信すると、衝突が生じ、基地局１が要求パケットを受信することができない。この場合には、ステップＳ２４に処理が戻り、予め定められた時間待機する。
【００４２】
以上のステップＳ２１からＳ２９までの処理が要求パケット送信処理Ｓ３０である。ステップＳ２９において、要求パケットが基地局１によって受信されたと決定されると、ステップＳ３１の待機状態となる。そして、ステップＳ３２において、データパケットが受信され、ステップＳ３３において、データパケットの受信が終了したか否かが決定される。データパケットが受信が終了しないと決定されると、処理がステップＳ３１の待機に戻る。そして、データパケットの受信が終了したと決定されると、最初のステップＳ２１に処理が戻る。なお、ある端末へのデータの送信が全て終了した場合には、その端末に割り当てていたデータスロットが解放される。
【００４３】
一実施形態において、基地局１がある端末にデータパケットを送信している間に、他の端末から要求パケットを受信した場合では、要求パケットを受信したフレームの次のフレーム以降のフレームに含まれ、且つ空きの１以上のデータスロットを規則にしたがって端末に対して割り当て、要求パケットに対応するデータパケットを１以上の割り当てられたデータスロットを使用して伝送する。空きデータスロットの割り当ての規則のいくつかの例を以下に説明する。
【００４４】
この規則は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信しない場合には、空きのデータスロットの全てを受信装置に割り当てる第１の規則と、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのデータスロットを割り当て、送信すべきデータパケットの残り数が最も少ない受信装置に対して、各フレーム中の残りの空きデータスロットを割り当て、さらに、各フレーム内にまだ空きデータスロットがあれば、送信すべきデータパケットの残り数が少ない受信装置の順に残りの空きデータスロットを割り当てる第２の規則とからなり、第２の規則に基づく処理が空きのデータスロットが無くなるか、または割り当てる受信装置が無くなるまで行なわれるものである。
【００４５】
第２の規則については、いくつかの変形が可能である。第２の規則に関する第１の変形例は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのデータスロットを割り当て、要求パケットの到着の最も早い受信装置に対して、各フレーム中の残りの空きデータスロットを割り当て、さらに、各フレーム内にまだ空きデータスロットがあれば、要求パケットの到着が早い受信装置の順に残りの空きデータスロットを割り当てるものである。
【００４６】
第２の規則に関する第２の変形例は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのフレーム内のデータスロットを等分に割り当てるものである。
【００４７】
第２の規則に関する第３の変形例は、受信装置に対してデータパケットを送信中に、他の１以上の受信装置から要求パケットを受信する場合には、要求パケットを受信したフレームの次のフレーム以降の各フレームにおいて、要求パケットを送信した各受信装置に対して、１つのデータスロットを割り当て、さらに、各フレーム内にまだ空きのデータスロットがあれば、送信すべきデータパケットの優先順位が最も高い受信装置に対して残りの空きのデータスロットを割り当てるものである。
【００４８】
上述したこの発明の一実施形態の通信動作の一例を図６のタイミングチャートを参照して概念的に説明する。図６Ａは、基地局１から端末２１への下り回線を使用したパケット伝送動作を示す。図６Ｂは、端末２１から基地局１への上り回線を使用したパケット伝送動作を示す。端末２１として、ｎ個の端末（端末Ｔ１，端末Ｔ２，・・・，端末Ｔｎと表記する）が存在している。
【００４９】
フレームＦ０，Ｆ１，Ｆ２，・・・の先頭に通知スロットが配置され、通知スロットを使用して通知パケットが伝送される。通知パケットは、基地局１から端末Ｔ１〜Ｔｎに対して一斉に送信される。通知スロットの後に所定数例えば５個のデータスロットが配置され、データスロットを使用してデータパケットが伝送される。一例として、各端末に対して送信されるデータ量は、１０個のデータスロットを使用して伝送される量と仮定している。
【００５０】
図６Ｂに示すように、端末Ｔ１に要求が発生し、全データスロットが空きである次のフレームＦ０において、要求パケットが基地局１に送信される。この要求パケットが基地局１で受信される。すなわち、端末Ｔ１の要求が成功する。基地局１は、要求パケットを受信すると、フレームＦ１で送信するデータパケットの有無が調べられる。図６Ａに示す例では、端末Ｔ１に送信するデータパケットのみがあるので、フレームＦ１の全てのデータスロットを使用して基地局１から端末Ｔ１にデータパケットが送信される。
【００５１】
また、図６Ｂに示すように、端末Ｔ２およびＴｎが同じフレームＦ０の同じデータスロットを使用して要求パケットを送信すると、衝突が発生する。要求が発生したフレームの次のフレームの任意のデータスロットを使用して要求パケットを送信するので、衝突が生じうる。この場合，次のフレームＦ１の通知パケットを基地局１から端末Ｔ２およびＴｎが受信し、衝突を生じた二つの要求パケットが異なる再送間隔でもって再送される。
【００５２】
図６Ｂに示すように、端末Ｔ２の要求パケットが次のフレームＦ１で再送され、端末Ｔｎの要求パケットがさらに後のフレームＦ２で再送される。再送間隔は、予め定められている。例えば、ｎ個の端末間で優先順位が付けられ、優先順位の高い端末ほど、再生間隔が短く設定される。フレームＦ１の上り回線のデータスロットを使用して基地局１へ再送された要求パケットが基地局１で受信され、端末Ｔ２の要求が成功する。
【００５３】
基地局１では、フレームＦ１において、端末Ｔ１に対してデータパケットを送信している間に端末Ｔ２からの要求パケットを受信するので、次のフレームＦ２では、上述した規則にしたがって空きデータスロットを端末Ｔ１およびＴ２に対して割り当てる。先ず、各端末にデータスロットを一つずつ割り当てる。残りの３個の空きデータスロットは、送信するデータパケットの残り数が最も少ない端末に全ての空きデータスロットを割り当てる。
【００５４】
図６Ａの例では、フレームＦ２の直前では、端末Ｔ１に送信するデータパケットの残り数が５データスロット分で、端末Ｔ２に送信するデータパケットの残り数が１０データスロット分である。各端末にデータスロットを一つずつ割り当てた後でも、残りのデータパケット数が最も少ない端末がＴ１である。したがって、フレームＦ２の残りの三つのデータスロットが端末Ｔ１に割り当てられる。その結果、端末Ｔ１に送信するデータパケットの残り数が１データスロット分となる。
【００５５】
フレームＦ０における衝突によって基地局１で受信されなかった端末Ｔｎの要求パケットがフレームＦ２の上り回線のデータスロットを使用して基地局１へ再送される。この要求パケットが基地局１で受信され、端末Ｔｎの要求が成功する。基地局１では、フレームＦ２において、端末Ｔ１およびＴ２に対してデータパケットを送信している間に端末Ｔｎからの要求パケットを受信するので、次のフレームＦ３では、上述した規則にしたがって空きデータスロットを端末Ｔ１，Ｔ２およびＴｎに対して割り当てる。先ず、各端末にデータスロットを一つずつ割り当てる。残りの２個の空きデータスロットは、送信するデータパケットの残り数が最も少ない端末に全ての空きデータスロットを割り当てる。
【００５６】
図６Ａの例では、フレームＦ３の直前では、端末Ｔ１に送信するデータパケットの残り数が１データスロット分で、端末Ｔ２に送信するデータパケットの残り数が９データスロット分で、端末Ｔｎに送信するデータパケットの残り数が１０データスロット分である。各端末にデータスロットを一つずつ割り当てた後でも、残りのデータパケット数が最も少ない端末がＴ２である。したがって、フレームＦ３の残りの二つのデータスロットが端末Ｔ２に割り当てられる。
【００５７】
次のフレームＦ４では、端末Ｔ２およびＴｎに対してそれぞれ一つずつのデータスロットを割り当て、残りの３個のデータスロットを端末Ｔ２に割り当てる。さらに、次のフレームＦ５では、端末Ｔ２およびＴｎに対してそれぞれ一つずつのデータスロットを割り当て、残りの３個のデータスロットの中の１個のデータスロットを端末Ｔ２に割り当てる。端末Ｔ２に対してのデータパケットが１０データスロット分となり、残りの２個のデータスロットを端末Ｔｎに割り当てる。このフレームＦ５では、端末Ｔ１からの新たな要求パケットを基地局１が受信する。そして、次のフレームＦ６では、上述したのと同様に、各データスロットが端末Ｔ１およびＴｎに対して割り当てられる。
【００５８】
この発明は、上述したこの発明の一実施形態等に限定されるものでは無く、この発明の要旨を逸脱しない範囲内で様々な変形や応用が可能である。例えばこの発明は、路車間通信に限らず、無線ＬＡＮ等の他の無線データ通信に対しても適用することができる。また、通知パケット用の通知スロットを１フレームに２以上設けても良い。さらに、通知パケットがそのフレームと次のフレームに加えて、より後のフレームのデータスロットの使用状況の情報を含むようにしても良い。
【００５９】
【発明の効果】
この発明によれば、１フレーム内の複数のデータスロットをある受信装置に対して割り当てることができるので、１フレーム内の一つのデータスロットを一つの受信装置に対して割り当てる方法と比較して、スループットを高くすることができる。この発明は、マルチメディアデータのように、バースト的に発生するデータを送信するのに好適なものである。
【図面の簡単な説明】
【図１】この発明の一実施形態における基地局の構成例を示すブロック図である。
【図２】この発明の一実施形態における端末の構成例を示すブロック図である。
【図３】この発明を適用できる路車間通信システムの説明に用いる略線図である。
【図４】基地局の処理動作を説明するためのフローチャートである。
【図５】端末の処理動作を説明するためのフローチャートである。
【図６】この発明の一実施形態の通信動作を説明するためのタイミングチャートである。
【符号の説明】
１・・・基地局、３・・・データパケット生成部、４・・・通知パケット生成部、６・・・無線装置、１０・・・受信パケット判定部、２１・・・端末、２３・・・要求パケット生成部、２４・・・無線装置、２８・・・受信パケット判定部３１・・・統合基地局、３３₁，３３₂ ，３３₃ ・・・局地基地局、３４・・・車両[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication method, a communication system, a transmission method, a transmission device, a reception method, and a reception device applicable to, for example, a road-vehicle communication system that transmits multimedia data to a vehicle.
[0002]
[Prior art]
A demand for a road-vehicle communication system is the realization of multimedia communication. In multimedia communication, a terminal requests information and downloads multimedia data such as images and music data in many cases, and the amount of received (down) data is larger than the amount of transmitted (up) data from the terminal. There is a feature. Therefore, in order to realize multimedia communication by the road-vehicle communication system, an access method for efficiently transmitting a large amount of data generated in a burst manner to a terminal is required.
[0003]
2. Description of the Related Art As an access method used in a wireless LAN (Local Area Network) or the like, a CSMA (Carrier Sense Multiple Access) method has been known. This method is a method in which a station determines whether to transmit a frame after observing a channel use status by carrier sense. Also known is CSMA / CA (CSMA with Collision Avoidance) provided with some collision avoidance mechanism in addition to carrier detection.
[0004]
[Problems to be solved by the invention]
In wireless communication, radio waves may not reach because the distance between stations is too long or there is an obstacle such as a wall that does not allow radio waves to pass. Stations that do not reach each other's transmission signals are called hidden terminals. For hidden terminals, carrier sense does not function effectively, so the frequency of frame collisions increases in the CSMA scheme, and the characteristics deteriorate. In road-to-vehicle communication, the on-vehicle antenna has relatively high directivity, and the hidden terminal problem is likely to occur. Therefore, it has been difficult to apply CSMA to road-to-vehicle communication.
[0005]
Further, a pre-assignment method and a polling method are known as conventional wireless communication methods. The pre-assignment method is a method in which each band divided by frequency or time is fixedly allocated exclusively to communication between a pair of stations. The polling method is a method in which a central station repeats polling for sequentially inquiring other stations about the presence or absence of a transmission frame. In road-vehicle communication, a car moves in a cell at a high speed and the number of terminals is indefinite, so that it is difficult to apply a pre-assignment method or a polling method.
[0006]
Accordingly, an object of the present invention is to provide a communication method, a communication system, a transmission method, a transmission device, a reception method, and a reception device that enable smooth multimedia communication between road and vehicle, for example.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, an invention according to claim 1 comprises a downlink and an uplink capable of simultaneously communicating, and a transmission apparatus and one or more reception apparatuses are connected by a slotted communication path, Is transmitted from the transmitting device to the receiving device via the downlink, and the request packet is transmitted from the receiving device to the transmitting device via the uplink, a communication method in a communication system,
One frame includes at least one notification slot and a plurality of data slots,
If the transmitting device is in the same frame and in the next frame Downlink Generating a notification packet indicating the usage status of the data slot, and transmitting the generated notification packet to the receiving device using the notification slot;
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame following the frame in which the request packet is received and assigned to the receiving device are assigned to the data corresponding to the request packet. Transmitting the packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
A receiving device that has received a notification packet indicating that there is an empty data slot in the next frame until the receiving device having the request packet receives the next notification packet. Uplink A communication method characterized in that a request packet is transmitted using an arbitrary empty slot. The invention of claim 12 is a communication system according to the communication method of claim 1.
[0008]
According to a twenty-third aspect of the present invention, a transmitting device and one or more receiving devices are connected by a slotted communication path, and the data packet is transmitted from the transmitting device via the downlink. A transmission method in a communication system in which a request packet is transmitted to a receiving device and a request packet is transmitted from the receiving device to the transmitting device via the uplink.
One frame includes at least one notification slot and a plurality of data slots,
In the same frame and the next frame Downlink Generating a notification packet indicating the usage status of the data slot, and transmitting the generated notification packet to the receiving device using the notification slot;
When a request packet is received from the receiving device, one or more data slots that are included in a frame subsequent to the frame after the request packet is received and are vacant are assigned to the receiving device in accordance with rules, and the request packet is assigned to the request packet. Transmitting a corresponding data packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
The rules are: a first rule for allocating all empty data slots to a receiving device while transmitting a data packet to the receiving device and not receiving a request packet from one or more other receiving devices;
When a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device having the smallest remaining number of data packets to be transmitted. If there is an empty data slot, the second rule is to allocate the remaining empty data slots in the order of the receiving device having the smaller remaining number of data packets to be transmitted,
A transmission method characterized in that processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.
The invention according to claim 27 is a transmission device according to the transmission method according to claim 23.
[0009]
According to a twenty-fourth aspect of the present invention, a transmitting apparatus and one or more receiving apparatuses are connected by a slotted communication path, and a data packet is transmitted from the transmitting apparatus via the downlink. A transmission method in a communication system in which a request packet is transmitted to a receiving device and a request packet is transmitted from the receiving device to the transmitting device via the uplink.
One frame includes at least one notification slot and a plurality of data slots,
In the same frame and the next frame Downlink Generating a notification packet indicating the usage status of the data slot, and transmitting the generated notification packet to the receiving device using the notification slot;
When a request packet is received from the receiving device, one or more data slots that are included in a frame subsequent to the frame after the request packet is received and are vacant are assigned to the receiving device in accordance with rules, and the request packet is assigned to the request packet. Transmitting a corresponding data packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
The rules are: a first rule for allocating all empty data slots to a receiving device while transmitting a data packet to the receiving device and not receiving a request packet from one or more other receiving devices;
When a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device that has the earliest arrival of the request packet. If so, the second rule of allocating the remaining free data slots in the order of the receiving device having the earliest arrival of the request packet,
A transmission method characterized in that processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.
The invention according to claim 28 is a transmission device according to the transmission method according to claim 24.
[0010]
According to a twenty-fifth aspect of the present invention, a transmitting apparatus and one or more receiving apparatuses are connected by a slotted communication path, and a data packet is transmitted from the transmitting apparatus via the downlink. A transmission method in a communication system in which a request packet is transmitted to a receiving device and a request packet is transmitted from the receiving device to the transmitting device via the uplink.
One frame includes at least one notification slot and a plurality of data slots,
In the same frame and the next frame Downlink Generating a notification packet indicating the usage status of the data slot, and transmitting the generated notification packet to the receiving device using the notification slot;
When a request packet is received from the receiving device, one or more data slots that are included in a frame subsequent to the frame after the request packet is received and are vacant are assigned to the receiving device in accordance with rules, and the request packet is assigned to the request packet. Transmitting a corresponding data packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
The rules are: a first rule for allocating all empty data slots to a receiving device while transmitting a data packet to the receiving device and not receiving a request packet from one or more other receiving devices;
When a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. A second rule for equally allocating data slots in one frame to each receiving device,
A transmission method characterized in that processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned. The invention according to claim 29 is a transmission device according to the transmission method according to claim 25.
[0011]
According to a twenty-sixth aspect of the present invention, a transmitting device and one or more receiving devices are connected by a slotted communication path, comprising a downlink and an uplink that can communicate simultaneously, and a data packet is transmitted from the transmitting device via the downlink. A transmission method in a communication system in which a request packet is transmitted to a receiving device and a request packet is transmitted from the receiving device to the transmitting device via the uplink.
One frame includes at least one notification slot and a plurality of data slots,
In the same frame and the next frame Downlink Generating a notification packet indicating the usage status of the data slot, and transmitting the generated notification packet to the receiving device using the notification slot;
When a request packet is received from the receiving device, one or more data slots that are included in a frame subsequent to the frame after the request packet is received and are vacant are assigned to the receiving device in accordance with rules, and the request packet is assigned to the request packet. Transmitting a corresponding data packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
Data slots for receiving devices are allocated according to rules,
The rules are: a first rule for allocating all empty data slots to a receiving device while transmitting a data packet to the receiving device and not receiving a request packet from one or more other receiving devices;
When a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and if there are still empty data slots in each frame, the remaining empty data is sent to the receiving device with the highest priority of the data packet to be transmitted. The second rule of allocating slots,
A transmission method characterized in that processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned. The invention according to claim 30 is a transmission device according to the transmission method according to claim 26.
[0012]
According to a thirty-first aspect of the present invention, a transmitting apparatus and one or more receiving apparatuses are connected by a slotted communication path, and a data packet is transmitted from the transmitting apparatus via the downlink. A receiving method in a communication system in which a request packet is transmitted to a receiving device and the request packet is transmitted from the receiving device to the transmitting device via an uplink,
One frame is composed of at least one notification slot and a plurality of data slots, and the notification packet arranged in the notification slot indicates the use status of the downlink data slot in the same frame and in the next frame,
Generating a request packet;
Transmitting a request packet using any empty slot in the uplink until receiving the next notification packet, when receiving a notification packet indicating that there is an empty data slot in the next frame;
After the successful transmission of the request packet, via the allocated data slot Corresponding to the request packet Receiving a data packet. The invention according to claim 32 is a receiving device according to the receiving method according to claim 31.
[0013]
The invention according to claim 33, wherein the transmitting device is connected to the integrated base station and the integrated base station by an optical communication path, and includes a plurality of local base stations each having an antenna,
In the downlink, the integrated base station generates a data packet and a notification packet modulated by the wireless modulation method, converts the generated data packet and the notification packet into an optical signal, and converts the optical signal through an optical communication path. Transmitted to the local base station, optical-to-wireless conversion by the local base station, radiated from the antenna of the local base station to the receiving device,
The request packet is received from the receiving device by the antenna of the local base station, the received signal is wirelessly converted by the local base station, and the optical signal is transmitted from the local base station to the integrated base station via the optical communication path, Optical-to-wireless conversion is performed in the integrated base station.
[0014]
According to the present invention, a plurality of data slots in one frame can be allocated to a certain receiving apparatus, so that one data slot can be allocated to one receiving apparatus in one frame. Thus, the throughput can be increased.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 indicates a base station. The base station 1 includes a network control unit 2 connected to a network, a data packet generation unit 3, a notification packet generation unit 4, a selector 5 for selectively outputting a data packet and a notification packet, and an output of the selector 5. A transmitting unit 7 that is supplied and included in the wireless device 6, an antenna 8 that emits a radio signal from the transmitting unit 7, a receiving unit 9 to which a received signal of the antenna 8 is supplied, and a received packet determining unit 10 Have been.
[0016]
The multimedia data is supplied from the network to the data packet generation unit 3 via the network control unit 2, and the data packet generation unit 3 generates a data packet. The notification packet generator 4 generates a notification packet. The received packet determined by the received packet determination unit 10 is transmitted to the network via the network control unit 2. As the network, a mobile phone network, a broadcast network, the Internet, and the like are possible.
[0017]
The base station 1 informs the terminal of the usage status of each data slot in the frame to be transmitted and the usage status of each data slot in the next frame by using a notification packet arranged in the first notification slot of each frame. Notice. That is, the notification packet has information indicating to which terminal each data slot in each frame is assigned (or information indicating whether each data slot is reserved). Each terminal can determine which data slot the terminal should receive from the content of the notification packet. If the transmission of the data packet is not completed in the frame to be transmitted from now on, it is necessary to continue transmitting the rest of the data packet in the next frame. For this purpose, the notification packet has information indicating to which terminal the data slot of the next frame is allocated.
[0018]
The terminal that has received the notification packet can determine which data slot data of the frame should be received from the information of the notification packet. Further, the terminal receiving the data packet can determine whether there is a data packet to be received also in the next frame from information on the next frame. In this case, the terminal that has generated the request can determine whether the request packet can be transmitted based on the information on the next frame. For example, if transmission of a data packet ends in this frame and there is no data packet to be transmitted continuously in the next frame, unused data slots in this frame and all data slots in the next frame are free. It becomes.
[0019]
It should be noted that the notification packet can also have information other than the above-mentioned downlink usage status. For example, information such as the reception status of the request packet and the usage status of the uplink may be stored.
[0020]
In FIG. 2, reference numeral 21 indicates a terminal. Reference numeral 22 indicates a network control unit, and a data device using received data is connected to the network control unit 22. Examples of the data device include a mobile phone terminal and a digital broadcast receiver. Other data devices include a car navigation device, a GPS (Global Positioning System), a display, an audio system, and the like.
[0021]
Reference numeral 23 indicates a request packet generator. The request packet generated by the request packet generator 23 is supplied to the transmitting device 25 included in the wireless device 24. A radio signal from the transmitting device 25 is radiated from the antenna 26. The received signal received by the antenna 26 is supplied to the receiving unit 27 of the wireless device 24. The reception signal from the reception unit 27 is supplied to the reception packet determination unit 28. The received packet from the received packet determination unit 28 is supplied to the data device via the network control unit 22.
[0022]
The above-described base station 1 (FIG. 1) and terminal 21 (FIG. 2) correspond to the base station and the terminal mounted on the vehicle in the road-vehicle communication system. More specifically, the present invention can be applied to a road-to-vehicle communication system as shown in FIG. The system of FIG. 3 comprises an integrated base station indicated by reference numeral 31 and a reference ₁ , 32 _Two ,... And 33 ₁ , 33 _Two ,..., The integrated base station 31 and the optical fiber 32 ₁ , 32 _Two , Are connected with a plurality of local base stations. Local base station 33 ₁ , 33 _Two Are installed at predetermined intervals along a road, for example, to enable road-vehicle communication with a terminal mounted on the vehicle 34. The portion of the transmitting device other than the antenna is installed in the integrated base station 31, and the antenna is connected to the local base station 33. ₁ , 33 _Two ,... Respectively.
[0023]
In such a road-vehicle communication system, the integrated base station 31 generates a data packet and a notification packet modulated by a predetermined wireless modulation method, and converts the wireless signal into an optical signal by a wireless optical conversion device. The wireless optical converter is configured to convert, for example, an optical signal from a laser diode into an optical signal directly or by an optical modulator. This optical signal is transmitted to the optical fiber 32 ₁ , 32 _Two ,..., One or more local base stations 33 ₁ , 33 _Two ,... Local base station 33 ₁ , 33 _Two , ..., the optical signal is converted into a signal in a radio frequency band by an optical wireless conversion device represented by a photodiode, and the wireless signal is transmitted from the roadside antenna to the receiving device with a data packet and a notification packet.
[0024]
The receiving device (terminal) mounted on the vehicle 34 includes an antenna for receiving a radio signal radiated from the roadside antenna, and a connection unit for transmitting the radio signal received by the antenna to a corresponding mobile phone or broadcast receiver. It has. In the uplink, the request packet modulated by the predetermined radio modulation scheme from the receiving apparatus is transmitted to the local base station 33. ₁ , 33 _Two ,... And converted into an optical signal by a wireless optical converter having the same principle as that of the above-described wireless optical converter. ₁ , 32 _Two ,... To the integrated base station 31. In the integrated base station 31, the signal is converted into a signal in a radio frequency band by an optical wireless converter having the same principle as that of the optical wireless converter described above, and the transmitted request packet is received.
[0025]
It should be noted that individual radio frequencies or intermediate frequencies modulated by a frequency conversion integrated distribution device provided in the integrated base station 31 such as mobile phones and broadcasts are integrated so as to be included in a specific frequency band, for example, a millimeter wave band. The converted radio signal in the shared frequency band may be radiated from the roadside antenna. In this case, the terminal mounted on the vehicle 34 includes an antenna having sensitivity in the shared frequency band, and a radio frequency signal for converting the radio signal received by the antenna into an individual radio frequency or an intermediate frequency radio signal and distributing the radio signal. It includes a conversion and distribution device, and a connection unit that transmits individual radio frequency and intermediate frequency radio signals from the frequency conversion and distribution device to corresponding mobile phones and broadcast receivers.
[0026]
The base station 1 shown in FIG. 1 is an integrated base station 31 and a local base station 33 in the system of FIG. ₁ , 33 _Two ,... Correspond to the whole. The terminal 21 shown in FIG. 2 corresponds to a terminal mounted on the vehicle 34. In one embodiment, the downlink from the base station 1 to the terminal 21 and the reverse uplink from the terminal 21 to the base station 1 can be simultaneously communicated. For example, a modulation scheme with a different carrier frequency is used between the two lines.
[0027]
In one embodiment of the present invention, one frame transmitted through the downlink includes at least one notification slot and a plurality of, for example, five data slots. Dividing continuous time into fixed intervals is called slotting, and each partition is called a slot. Note that the notification slot and the data slot are not limited to the same length, but may be different lengths. The base station 1 notifies the terminal 21 of the usage status of each data slot in this frame and the usage status of each data slot in the next frame by using a notification packet arranged in the first notification slot of this frame. As described above, the notification packet describes to which terminal each of the data slots in the frame to be transmitted and in the next frame is allocated.
[0028]
Note that one packet is arranged in one slot, but two or more packets may be arranged in one slot. As an example, one packet used in Ethernet is transmitted in each data slot. In this case, a segmented packet of one packet used in Ethernet may be transmitted in each data slot. Further, in each notification slot, a broadcast packet used in Ethernet is transmitted. Ethernet means the IEEE (Institute of Electrical and Electronics Engineers) 802.3 standard. There are standards such as 10BASE-T, 100BASE-T, and Gigabit Ethernet depending on the transmission medium and transmission speed used by this standard.
[0029]
When a request is issued to the terminal 21, the terminal 21 transmits a request packet to the base station 1 via an uplink using an arbitrary empty slot of the next frame according to the content notified from the base station 1. I do. The terminal 21 transmits a request packet when there is an empty data slot in the next frame based on the content of the received notification packet. Also, when a plurality of terminals transmit request packets in the same data slot, a collision occurs in the transmitting device, and when it is not possible to identify from which receiving device the request packet was transmitted, the request packet is transmitted according to the collision processing. Resent. When a collision occurs, if there is a power difference between the transmitting device and each terminal, a request packet from a receiving device having the highest received power may arrive.
[0030]
In an example of the collision processing, request packets are retransmitted at different time intervals as shown in an example described later. In another example, the request packet is retransmitted after waiting for a time corresponding to the number of slots determined at random. Still another example is that, by a downlink notification slot, after waiting until the detection of a data slot vacancy, any data slot is randomly selected until the time when the next notification packet is received and selected. The request packet is retransmitted in the data slot.
[0031]
FIG. 4 is a flowchart showing in more detail the flow of processing performed by the base station 1 in each frame. A processing portion S9 enclosed by a broken line indicates a notification packet generation process. The notification packet generator 4 in FIG. 1 performs this generation processing. As described above, the notification packet includes information indicating to which terminal each data slot of the frame to be transmitted and the next frame is allocated (or information of whether each data slot is reserved). Each terminal can determine which data slot the terminal should receive from the content of the notification packet. If the transmission of the data packet is not completed in the frame to be transmitted from now on, it is necessary to continue transmitting the rest of the data packet in the next frame. For this purpose, the notification packet has information indicating to which terminal the data slot of the next frame is allocated.
[0032]
In the first step S1, the presence or absence of a data packet to be transmitted to the terminal in this frame is determined. If it is determined in step S1 that there is no packet to be transmitted, the process proceeds to a notification packet generation process in step S8. In this case, a notification packet indicating that all data slots of this frame and the next frame are empty data slots is generated.
[0033]
If it is determined in step S1 that there is a data packet to be transmitted to the terminal, in step S2, one data slot is allocated to each terminal. Then, in step S3, it is determined whether data to be transmitted to the terminal remains. If it is determined in step S3 that there is no data to be transmitted, the process proceeds to a notification packet generation process in step S8. If it is determined in step S3 that there is data to be transmitted, it is determined in step S4 whether or not there is an empty data slot.
[0034]
If it is determined in step S4 that there is a vacancy in the data slot, in step S5 a vacant data slot is assigned to a terminal having a remaining data packet. When it is determined in step S4 that there is no empty data slot, step S5 is skipped.
[0035]
In the next step S6, it is determined whether or not there is a terminal that transmits a data packet also in the next frame. If it is determined in step S6 that there is no terminal to transmit, the process proceeds to a notification packet generation process in step S8. In this case, the data slots of the next frame are all empty. If it is determined in step S6 that there is a terminal to transmit, in step S7, the required number of data slots in the next frame is secured. Then, in step S8, a notification packet indicating the use status of the data slot of this frame and the next frame is generated.
[0036]
Subsequent to the notification packet generation processing S9, in step S10, a notification packet is transmitted. In step S11, a data packet is transmitted in each data slot via the downlink. At the same time, in step S12, a request packet is received in each slot via the uplink. Then, the process returns to the first step S1.
[0037]
In one embodiment, when the terminal 21 receives a notification from the base station 1 that there is a free space in the next frame, the terminal 21 having the request packet allocates any free slot until the next notification packet is received. Use to send request packets. FIG. 5 is a flowchart showing the processing flow of the terminal 21 in more detail. The processing part S30 enclosed by a broken line indicates the request packet transmission processing. The request packet generator 23 in FIG. 2 performs this generation processing.
[0038]
The first step S21 shows a standby state. In the next step S22, it is determined whether or not a request has occurred. When it is determined that the request does not occur, the process returns to the standby state (Step S21). If it is determined in step S22 that a request has occurred, a request packet is generated in step S23.
[0039]
Step S24 indicates a standby state. In step S25, it is determined whether a notification packet has been received from the base station 1. The terminal 21 waits until receiving the notification packet. If it is determined in step S25 that the notification packet has been received, it is determined in step S26 whether or not there is an empty data slot in the next frame based on the content of the notification packet. If it is determined that there is no empty data slot, the data packet cannot be received in the next frame, so the process returns to step S24 and waits without transmitting a request packet.
[0040]
A case where there is no empty data slot will be described more specifically. For example, when one frame is constituted by five data slots, it is assumed that each of the five data slots in the frame to be transmitted from now is assigned to five terminals. It is assumed that there are a plurality of data packets to be transmitted to five terminals, and that all the data packets cannot be transmitted in this frame. In this case, the data packet is continuously transmitted to the five terminals in the next frame. Therefore, each data slot in the next frame is allocated to each of the five terminals. As a result, there is no empty data slot in the next frame. As described above, when a data slot and a terminal are assigned one-to-one and a large amount of data is transmitted to each terminal, a situation occurs in which there is no empty data slot between this frame and the next frame.
[0041]
In step S26, whether or not there is an empty data slot in the next frame is determined based on the contents of the received notification packet. If it is determined that there is a free data slot, in step S27, the data slot for transmitting the request packet is arbitrarily determined. Then, in step S28, a request packet is transmitted using the data slot. In step S29, it is determined whether the transmitted request packet has been received by the base station 1. When a plurality of terminals transmit a request packet using the same data slot, a collision occurs, and the base station 1 cannot receive the request packet. In this case, the process returns to step S24, and waits for a predetermined time.
[0042]
The processing from steps S21 to S29 is request packet transmission processing S30. If it is determined in step S29 that the request packet has been received by the base station 1, the process enters the standby state of step S31. Then, in step S32, the data packet is received, and in step S33, it is determined whether the data packet has been received. If it is determined that the reception of the data packet has not been completed, the process returns to the standby of step S31. Then, when it is determined that the reception of the data packet has been completed, the process returns to the first step S21. When all data transmission to a certain terminal is completed, the data slot allocated to that terminal is released.
[0043]
In one embodiment, when the base station 1 receives a request packet from another terminal while transmitting a data packet to one terminal, the base station 1 includes the request packet in a frame subsequent to the frame in which the request packet was received. In addition, one or more free data slots are allocated to the terminal according to the rules, and the data packet corresponding to the request packet is transmitted using the one or more allocated data slots. Some examples of rules for allocating free data slots are described below.
[0044]
This rule includes: a first rule for allocating all empty data slots to a receiving device while transmitting a data packet to the receiving device and not receiving a request packet from one or more other receiving devices; When a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device having the smallest remaining number of data packets to be transmitted. If there are empty data slots, the remaining empty data slots are allocated in the order of the receiving device with the least number of remaining data packets to be transmitted. Consists of a Teru second rule, in which processing based on the second rule is made up or empty data slot is eliminated, or assigned receiving device is eliminated.
[0045]
Several variations on the second rule are possible. A first modified example of the second rule is that when a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the next packet following the frame in which the request packet was received is received. In each frame after the frame, one data slot is allocated to each receiving device that has transmitted the request packet, and the remaining empty data slots in each frame are allocated to the receiving device that has received the request packet earliest. Further, if there is still a free data slot in each frame, the remaining free data slots are allocated in the order of the receiving device having the earliest arrival of the request packet.
[0046]
A second modification of the second rule is that, when a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the next packet following the frame in which the request packet was received is received. In each frame after the frame, a data slot in one frame is equally allocated to each receiving device that has transmitted the request packet.
[0047]
A third modification of the second rule is that, when a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the next packet following the frame in which the request packet was received is received. In each frame after the frame, one data slot is allocated to each receiving device that has transmitted the request packet, and if there are still empty data slots in each frame, the priority of the data packet to be transmitted is determined. The remaining empty data slots are allocated to the highest receiving device.
[0048]
An example of the communication operation of the embodiment of the present invention described above will be conceptually described with reference to the timing chart of FIG. FIG. 6A shows a packet transmission operation using a downlink from base station 1 to terminal 21. FIG. 6B shows a packet transmission operation from the terminal 21 to the base station 1 using the uplink. As the terminal 21, there are n terminals (referred to as terminals T1, T2,..., Terminal Tn).
[0049]
A notification slot is arranged at the head of each of the frames F0, F1, F2,..., And a notification packet is transmitted using the notification slot. The notification packet is transmitted from the base station 1 to the terminals T1 to Tn all at once. After the notification slot, a predetermined number, for example, five data slots are arranged, and data packets are transmitted using the data slots. As an example, it is assumed that the amount of data transmitted to each terminal is the amount transmitted using ten data slots.
[0050]
As shown in FIG. 6B, a request is issued to terminal T1, and a request packet is transmitted to base station 1 in the next frame F0 in which all data slots are empty. This request packet is received by the base station 1. That is, the request from the terminal T1 is successful. Upon receiving the request packet, the base station 1 checks whether there is a data packet to be transmitted in the frame F1. In the example shown in FIG. 6A, since there is only a data packet to be transmitted to the terminal T1, the data packet is transmitted from the base station 1 to the terminal T1 using all the data slots of the frame F1.
[0051]
Also, as shown in FIG. 6B, when the terminals T2 and Tn transmit request packets using the same data slot of the same frame F0, a collision occurs. Because the request packet is transmitted using any data slot of the frame following the frame in which the request occurred, collisions may occur. In this case, the terminals T2 and Tn receive the notification packet of the next frame F1 from the base station 1, and the two request packets having a collision are retransmitted at different retransmission intervals.
[0052]
As shown in FIG. 6B, the request packet of terminal T2 is retransmitted in the next frame F1, and the request packet of terminal Tn is retransmitted in a further later frame F2. The retransmission interval is predetermined. For example, priorities are assigned among n terminals, and the higher the priority, the shorter the playback interval is set. The request packet retransmitted to the base station 1 using the uplink data slot of the frame F1 is received by the base station 1, and the request from the terminal T2 succeeds.
[0053]
The base station 1 receives the request packet from the terminal T2 while transmitting the data packet to the terminal T1 in the frame F1, so that in the next frame F2, the free data slot is allocated to the terminal T1 according to the above-described rule. Assign to T1 and T2. First, one data slot is allocated to each terminal. As for the remaining three free data slots, all free data slots are allocated to the terminal having the smallest remaining number of data packets to be transmitted.
[0054]
In the example of FIG. 6A, immediately before the frame F2, the remaining number of data packets to be transmitted to the terminal T1 is 5 data slots, and the remaining number of data packets to be transmitted to the terminal T2 is 10 data slots. Even after one data slot is allocated to each terminal, the terminal with the least number of remaining data packets is T1. Therefore, the remaining three data slots of frame F2 are allocated to terminal T1. As a result, the remaining number of data packets to be transmitted to the terminal T1 becomes one data slot.
[0055]
The request packet of the terminal Tn that has not been received by the base station 1 due to the collision in the frame F0 is retransmitted to the base station 1 using the uplink data slot of the frame F2. This request packet is received by the base station 1, and the request from the terminal Tn succeeds. The base station 1 receives the request packet from the terminal Tn while transmitting the data packet to the terminals T1 and T2 in the frame F2. Are assigned to the terminals T1, T2 and Tn. First, one data slot is allocated to each terminal. The remaining two free data slots allocate all free data slots to the terminal having the smallest remaining number of data packets to be transmitted.
[0056]
In the example of FIG. 6A, immediately before the frame F3, the remaining number of data packets to be transmitted to the terminal T1 is one data slot, the remaining number of data packets to be transmitted to the terminal T2 is nine data slots, and the transmission to the terminal Tn is performed. The remaining number of data packets to be transmitted corresponds to 10 data slots. Even after one data slot is assigned to each terminal, the terminal with the least number of remaining data packets is T2. Therefore, the remaining two data slots of frame F3 are allocated to terminal T2.
[0057]
In the next frame F4, one data slot is allocated to each of the terminals T2 and Tn, and the remaining three data slots are allocated to the terminal T2. Further, in the next frame F5, one data slot is allocated to each of the terminals T2 and Tn, and one data slot among the remaining three data slots is allocated to the terminal T2. The data packet for the terminal T2 corresponds to 10 data slots, and the remaining two data slots are allocated to the terminal Tn. In this frame F5, the base station 1 receives a new request packet from the terminal T1. Then, in the next frame F6, as described above, each data slot is allocated to the terminals T1 and Tn.
[0058]
The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the gist of the present invention. For example, the present invention can be applied not only to road-to-vehicle communication but also to other wireless data communication such as a wireless LAN. Further, two or more notification slots for notification packets may be provided in one frame. Further, the notification packet may include, in addition to the frame and the next frame, information on the use status of the data slot of a later frame.
[0059]
【The invention's effect】
According to the present invention, since a plurality of data slots in one frame can be allocated to a certain receiving device, compared with a method of allocating one data slot in one frame to one receiving device, Throughput can be increased. The present invention is suitable for transmitting data that occurs in a burst, such as multimedia data.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a base station according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a terminal according to an embodiment of the present invention.
FIG. 3 is a schematic diagram used for describing a road-vehicle communication system to which the present invention can be applied;
FIG. 4 is a flowchart illustrating a processing operation of a base station.
FIG. 5 is a flowchart illustrating a processing operation of the terminal.
FIG. 6 is a timing chart for explaining a communication operation according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base station, 3 ... Data packet generation part, 4 ... Notification packet generation part, 6 ... Wireless apparatus, 10 ... Reception packet judgment part, 21 ... Terminal, 23 ... Request packet generator 24, wireless device 28, received packet determiner 31, integrated base station 33 ₁ , 33 _Two , 33 _Three ... Local base station, 34 ... Vehicle

Claims

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a communication method in a communication system in which a packet is transmitted from a receiving device to a transmitting device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
A transmitting device generates a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, and transmitting the generated notification packet to the receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame in which the request packet is received and allocated are allocated to the receiving device, and Transmitting a corresponding data packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
A receiving apparatus that has received the notification packet indicating that there is an empty data slot in the next frame, and that the receiving apparatus having the request packet has received an arbitrary empty line until the receiving apparatus receives the next notification packet. A communication method, wherein the request packet is transmitted using a slot.

In claim 1,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device having the smallest remaining number of data packets to be transmitted. If there are still empty data slots, the second rule is to allocate remaining empty data slots in the order of the receiving device with the smaller number of remaining data packets to be transmitted,
A communication method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 1,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device that has the earliest arrival of the request packet. , The second rule of allocating the remaining free data slots in the order of the receiving device having the earliest arrival of the request packet,
A communication method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 1,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. A second rule for equally assigning data slots in one frame to each receiving device
A communication method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 1,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and if there are still empty data slots in each frame, the remaining empty devices are assigned to the receiving device with the highest priority of the data packet to be transmitted. A second rule for allocating data slots,
A communication method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 1,
When a plurality of receiving devices transmit request packets in the same data slot, a collision occurs in the transmitting device, and when it is not possible to identify from which receiving device the request packet was transmitted, the request packet is retransmitted at different time intervals. Communication method used.

In claim 1,
When a plurality of receiving devices transmit request packets in the same data slot, a collision occurs in the transmitting device, and when it is not possible to identify from which receiving device the request packet was transmitted, the number of slots is determined to be randomly determined. A communication method in which a request packet is retransmitted after waiting a corresponding time.

In claim 1,
If a collision occurs in the transmitting device due to a plurality of receiving devices transmitting request packets in the same data slot, and it is not possible to identify from which receiving device the request packet was transmitted, the downlink notification slot uses A communication method in which after waiting until a slot is detected, any data slot is randomly selected until a time for receiving the next notification packet, and a request packet is retransmitted in the selected data slot.

In claim 1,
A communication method, wherein one packet used in Ethernet is transmitted in each data slot time.

In claim 1,
A communication method characterized in that a segmented packet of one used in Ethernet is transmitted in each data slot time.

In claim 1,
A communication method, wherein a broadcast packet used in Ethernet is transmitted in each notification slot time.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a communication system in which a packet is transmitted from a receiving device to a transmitting device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
The transmitting device generates a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, and transmits the generated notification packet to the receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame in which the request packet is received and allocated are allocated to the receiving device, and Transmitting corresponding data packets using one or more assigned data slots;
When the transmission to the receiving device is completed, the data slot allocated to the receiving device is released,
A receiving apparatus that has received the notification packet indicating that there is an empty data slot in the next frame, and that the receiving apparatus having the request packet has received an arbitrary empty line until the receiving apparatus receives the next notification packet. A communication system, wherein the request packet is transmitted using a slot.

In claim 12,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device having the smallest remaining number of data packets to be transmitted. If there are still empty data slots, the second rule is to allocate remaining empty data slots in the order of the receiving device with the smaller number of remaining data packets to be transmitted,
A communication system wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 12,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device that has the earliest arrival of the request packet. , The second rule of allocating the remaining free data slots in the order of the receiving device having the earliest arrival of the request packet,
A communication system wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 12,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. A second rule for equally assigning data slots in one frame to each receiving device
A communication system wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 12,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and if there are still empty data slots in each frame, the remaining empty devices are assigned to the receiving device with the highest priority of the data packet to be transmitted. A second rule for allocating data slots,
A communication method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

In claim 12,
When a plurality of receiving devices transmit request packets in the same data slot, a collision occurs in the transmitting device, and when it is not possible to identify from which receiving device the request packet was transmitted, the request packet is retransmitted at different time intervals. Communication system.

In claim 12,
When a plurality of receiving devices transmit request packets in the same data slot, a collision occurs in the transmitting device, and when it is not possible to identify from which receiving device the request packet was transmitted, the number of slots is determined to be randomly determined. A communication system in which a request packet is retransmitted after waiting a corresponding time.

In claim 12,
If a collision occurs in the transmitting device due to a plurality of receiving devices transmitting request packets in the same data slot, and it is not possible to identify from which receiving device the request packet was transmitted, the downlink notification slot uses A communication system in which, after waiting until a slot is detected, any data slot is randomly selected until a next notification packet is received, and a request packet is retransmitted in the selected data slot.

In claim 12,
A communication system wherein one packet used in Ethernet is transmitted in each data slot time.

In claim 12,
In each data slot time, a segmented packet of one packet used in the Ethernet is transmitted.

In claim 12,
A communication system wherein a broadcast packet used in Ethernet is transmitted in each notification slot time.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission method in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generating a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmitting the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device having the smallest remaining number of data packets to be transmitted. If there are still empty data slots, the second rule is to allocate remaining empty data slots in the order of the receiving device with the smaller number of remaining data packets to be transmitted,
A transmission method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission method in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generating a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmitting the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device that has the earliest arrival of the request packet. , The second rule of allocating the remaining free data slots in the order of the receiving device having the earliest arrival of the request packet,
A transmission method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission method in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generating a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmitting the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. A second rule for equally assigning data slots in one frame to each receiving device
A transmission method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission method in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generating a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmitting the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
Releasing the data slot allocated to the receiving device when transmission to the receiving device is completed,
Data slots for the receiving device are allocated according to rules,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and if there are still empty data slots in each frame, the remaining empty devices are assigned to the receiving device with the highest priority of the data packet to be transmitted. A second rule for allocating data slots,
A transmission method, wherein the processing based on the second rule is performed until there are no more empty data slots or there are no more receiving devices to be assigned.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission device in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generate a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmit the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
When the transmission to the receiving device is completed, the data slot allocated to the receiving device is released,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device having the smallest remaining number of data packets to be transmitted. If there are still empty data slots, the second rule is to allocate remaining empty data slots in the order of the receiving device with the smaller number of remaining data packets to be transmitted,
A transmitting apparatus, wherein the processing based on the second rule is performed until there is no empty data slot or there is no receiving apparatus to be allocated.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission device in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generate a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmit the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
When the transmission to the receiving device is completed, the data slot allocated to the receiving device is released,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and the remaining empty data slots in each frame are allocated to the receiving device that has the earliest arrival of the request packet. , The second rule of allocating the remaining free data slots in the order of the receiving device having the earliest arrival of the request packet,
A transmitting apparatus, wherein the processing based on the second rule is performed until there is no empty data slot or there is no receiving apparatus to be allocated.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission device in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generate a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmit the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
When the transmission to the receiving device is completed, the data slot allocated to the receiving device is released,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. A second rule for equally assigning data slots in one frame to each receiving device
A transmitting apparatus, wherein the processing based on the second rule is performed until there is no empty data slot or there is no receiving apparatus to be allocated.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a transmission device in a communication system in which a packet is transmitted from a reception device to a transmission device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
Generate a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, transmit the generated notification packet to a receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame after receiving the request packet and assigned to the receiving device according to rules are assigned to the receiving device. Transmitting a data packet corresponding to the request packet using one or more assigned data slots;
When the transmission to the receiving device is completed, the data slot allocated to the receiving device is released,
The rule is that, when a request packet is not received from one or more other receiving devices while a data packet is being transmitted to the receiving device, all of the empty data slots are allocated to the receiving device. Rules and
If a request packet is received from one or more other receiving devices while a data packet is being transmitted to the receiving device, the request packet is transmitted in each frame subsequent to the frame in which the request packet was received. One data slot is allocated to each receiving device, and if there are still empty data slots in each frame, the remaining empty devices are assigned to the receiving device with the highest priority of the data packet to be transmitted. A second rule for allocating data slots,
A transmitting apparatus, wherein the processing based on the second rule is performed until there is no empty data slot or there is no receiving apparatus to be allocated.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a receiving method in a communication system in which a packet is transmitted from a receiving device to a transmitting device via an uplink,
One frame is composed of at least one notification slot and a plurality of data slots, and a notification packet arranged in the notification slot indicates the use status of the data slot in the downlink in the same frame and in the next frame,
Generating a request packet;
Transmitting the request packet by using any available slot in the uplink until receiving the next notification packet, when receiving the notification packet indicating that there is an empty data slot in the next frame. When,
Receiving the data packet corresponding to the request packet via the allocated data slot after successful transmission of the request packet.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a receiving apparatus in a communication system in which a packet is transmitted from a receiving apparatus to a transmitting apparatus via an uplink,
One frame is composed of at least one notification slot and a plurality of data slots, and a notification packet arranged in the notification slot indicates the use status of the data slot in the downlink in the same frame and in the next frame,
When a request packet is generated and the above-mentioned notification packet indicating that there is an empty data slot in the next frame is received, the above-mentioned packet is used by using any empty slot in the uplink until the next notification packet is received. Transmitting a request packet and, after successful transmission of the request packet, receiving a data packet corresponding to the request packet via the allocated data slot.

A transmitting device and one or more receiving devices are connected by a slotted communication path, which comprises a downlink line and an uplink line that can communicate at the same time, and a data packet is transmitted from the transmitting device to the receiving device via the downlink and transmitted to the receiving device. In a communication system in which a packet is transmitted from a receiving device to a transmitting device via an uplink,
One frame includes at least one notification slot and a plurality of data slots,
The transmitting device generates a notification packet indicating the use status of the data slot of the downlink in the same frame and the next frame, and transmits the generated notification packet to the receiving device using the notification slot,
When a request packet is received from a receiving device, one or more empty data slots included in a frame subsequent to the frame in which the request packet is received and allocated are allocated to the receiving device, and Transmitting corresponding data packets using one or more assigned data slots;
When the transmission to the receiving device is completed, the data slot allocated to the receiving device is released,
A receiving apparatus that has received the notification packet indicating that there is an empty data slot in the next frame, and that the receiving apparatus having the request packet has received an arbitrary empty line until the receiving apparatus receives the next notification packet. A communication system in which the request packet is transmitted using a slot,
The transmitting device is connected to the integrated base station and the integrated base station by an optical communication path, and includes a plurality of local base stations each including an antenna,
In the downlink, the integrated base station generates the data packet and the notification packet modulated by the wireless modulation method, converts the generated data packet and the notification packet into an optical signal, and converts the optical signal into an optical signal. Transmitted to the local base station via the optical communication path, optical-to-wireless conversion by the local base station, radiated from the antenna of the local base station to a receiving device,
The request packet transmitted from the receiving device is received by the antenna of the local base station, a received signal is wirelessly converted by the local base station, and an optical signal is transmitted from the local base station to the optical communication path. A communication system, wherein the signal is transmitted to the integrated base station via the integrated base station, and optical-to-wireless conversion is performed in the integrated base station.