JP3766346B2 - Data link transmission control method, mobile communication system, and data link transmission control device - Google Patents

Description

【０１３８】
ここで、Ｐmed(i)は、第ｉ番目の基地局が送信する報知信号若しくは共通パイロット信号などに関する時間平均的な受信電力値（例えば、短区間受信電力中央値など）、又は当該時間平均的な受信電力と干渉電力との比（以下「時間平均的な受信電力対干渉電力比」という。）を表す。Ｐmed_maxは、第１番目から第Ｎ番目までの基地局についての時間平均的な受信電力値の最大値または時間平均的な受信電力対干渉電力比の最大値を表す。Ψ_i は、Ｐmed_maxとＰmed(i)との差を所定の閾値Ｔｈに対して比較判定した結果の二値（１または０）を表す。また、本実施形態では、Ｎ＝３の場合について説明し、図７の基地局２０２、基地局２１２、基地局２２２をそれぞれ、第１番目の基地局、第２番目の基地局、第３番目の基地局として説明する。
【０１３９】
上記式（１）が成立している場合とは、図９の地点Ａに移動局２３１が位置する場合のように、移動局２３１において測定される、複数基地局（本実施形態では、基地局２０２〜基地局２２２）が送信する報知信号、または、共通パイロット信号などの時間平均的な受信電力値または受信電力対干渉電力比などが１つだけ大きい場合である。これは、例えば、Ψ₁ =１、 Ψ₂ =０、 Ψ₃ =０となっている場合であり、基地局２０２が該移動局２３１に対してパケット送信可能状態となり、基地局２１２および基地局２２２がアイドル状態となっている。
【０１４０】
パケットが該パケット送信可能状態の基地局に到着した場合の処理について図１０を用いて説明する。基地局２０２は、ネットワーク１から到着した該パケットに対してデータリンク伝送制御部２０３にて一意の番号を付与し、移動局での受信パケットの誤り検出のためにＣＲＣなどを付加した後に蓄積する（図１０のＳ３０１およびＳ３０２）。そして、データリンク伝送制御部２０３は、パケット複製部２０６に対してそのまま送受信機２０７に出力するように制御することにより、移動局２３１に対して該パケットを送信する（Ｓ３０３）。移動局２３１は、受信したパケットについて誤り検出処理（Ｓ３０４） を行い、誤りが検出されない場合、パケットの到達確認を該基地局２０２に対して通知する（Ｓ３０５およびＳ３０６）。また、誤りが検出された場合、移動局２３１はパケットの再送要求を該基地局２０２に対して通知する（Ｓ３０５およびＳ３０７）。基地局２０２は、移動局２３１からの通知が到達確認の場合、一意の番号に対応する蓄積しているパケットを削除する（Ｓ３０８よびＳ３１０）。また、移動局２３１からの通知が再送要求の場合、基地局２０２は、一意の番号に対応するパケットを再送する（Ｓ３０８よびＳ３０９）。
【０１４１】
（２）アイドル状態における基地局および移動局の動作
前述のように、Ψ_j =０である第ｊ番目の基地局は、移動局に対してアイドル状態となる。
【０１４２】
パケットが該アイドル状態の基地局に到着した場合の処理について図１１を用いて説明する。ここでは、基地局２１２および基地局２２２がアイドル状態とする。アイドル状態にある基地局２１２は、移動局２３１宛てのパケットをそのまま他の基地局又はパケット送信可能状態の基地局２０２に直接転送するように、データリンク伝送制御部２１３が配布部２１５を制御する。このため、パケットが基地局２１２に到着した場合、基地局２１２は、転送先である他の基地局又は基地局２０２にパケットを転送する（図１１のＳ３１１およびＳ３１２） 。
【０１４３】
なお、基地局２１２、２２２は同様の構成をしているため、パケットが基地局２２２に到着した場合も、上記同様の動作が行われる。
【０１４４】
（３）パケット複製および送信可能状態、複製パケット送信可能状態における基地局および移動局の動作
以下の式（２）が成立している場合には、Ψ_i =１となる複数基地局のいずれか１つの基地局が、移動局２３１に対してパケット複製および送信可能状態となり、Ψ_i =１であり且つ該パケット複製および送信可能状態でない基地局は、複製パケット送信可能状態となる。
【０１４５】
【数２】

用いられる記号は、式（１）と同様である。
【０１４６】
式（２）が成立している場合は、図９の地点Ｂに移動局２３１が位置する場合のように、移動局２３１において測定される時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が複数大きい場合、例えば、本実施形態のようにΨ₁ =１、 Ψ₂ =１、 Ψ₃ =０となっている場合であり、基地局２０２または基地局２１２のいずれか１つの基地局が、パケット複製および送信可能状態となる。このいずれか１つの基地局は、遷移前においてパケット送信可能状態であった基地局、または、時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が大きい基地局とすることが可能である。本実施形態では、基地局２０２をパケット複製および送信可能状態とし、基地局２１２を複製パケット送信可能状態として説明を続ける。
【０１４７】
パケットがパケット複製および送信可能状態である基地局２０２に到着した場合の処理について図１２を用いて説明する。基地局２０２は、ネットワーク１から到着した該パケットに対して一意の番号を付加し、移動局での受信パケットの誤り検出のためにＣＲＣなどを付加した後に、該パケットを蓄積すると共に、該番号を含めて該パケットの複製を行う（図１２のＳ３２１およびＳ３２２）。そして、基地局２０２は複製パケットを複製パケット送信可能状態である基地局２１２に配布し（Ｓ３２３）、基地局２１２は配布されたパケットを蓄積する（Ｓ３２４）。さらに、基地局２０２は、該移動局２３１宛てパケットを蓄積していることを移動局２３１に通知する（Ｓ３２５ｂ）。
【０１４８】
また、移動局２３１は、前述のように、時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が最大となる基地局が、パケット複製および送信可能状態となるように、状態遷移を要求する。これにより、移動局２３１への新たなパケットの通知を行う基地局を１つにすることができる。これは、時間平均的な受信品質が最高となる基地局から通知させるため、実現可能となる。この場合、該通知のための余分な電力を削減することができ干渉を抑制することが可能となる。
【０１４９】
但し、該干渉の影響がさほど問題とならない場合は、図１２のＳ３２５ｂおよびＳ３２５ａに示すように、パケットを受信した基地局（パケット複製および送信可能状態の基地局、または複製パケット送信可能状態の基地局）がそれぞれ移動局２３１に通知する方法も可能である。
【０１５０】
該通知を受信した移動局２３１は、その時点において複数基地局（本実施形態では、基地局２０２および基地局２１２の２局）から送信されている報知信号、共通パイロット信号などの信号の瞬時の受信電力または瞬時の受信電力対干渉電力比が最大となる基地局を選択し（Ｓ３２６）、移動局２３１にパケットを送信するよう該選択した基地局に対し要求する（Ｓ３２７）。この要求の具体的な方法は、該基地局を特定できる基地局の番号と通知されたパケットの番号を基地局に要求することで可能となる。
【０１５１】
また、該要求の方法については、選択した基地局に直接上り回線で要求する方法、または、選択されなかった基地局で受信された該要求を選択した基地局に基地局間ネットワークを介して通知する方法を採用可能である。これは、移動局と各基地局間の瞬時の受信品質は、上り回線と下り回線では異なり、下り回線の受信品質では選択した基地局と移動局間が最高であっても、上り回線の受信品質では、他の基地局と移動局間が最高となり得るためである。
【０１５２】
そして、該要求を受けた基地局（本実施形態では基地局２０２）は、移動局２３１に対して該パケットを送信する（Ｓ３２８）。このとき、基地局２０２は、移動局２３１宛のパケットを複数蓄積している旨を移動局２３１に通知してもよい。これにより蓄積されている以降のパケットについては、基地局は改めて通知を行う必要がなくなるためである。
【０１５３】
移動局２３１は、受信したパケットについて誤り検出処理（Ｓ３２９）を行い、誤りが検出されない場合、パケットの到達確認をパケット複製および送信可能状態の基地局２０２に通知する（Ｓ３３０およびＳ３３１）。この通知は、基地局２０２に直接、または、基地局２１２を介して行ってもよい。また、誤りが検出された場合、移動局２３１は、その時点において瞬時の又は時間平均的な受信品質が最高となる基地局を選択し（Ｓ３３２）、該基地局に対してパケットの再送要求を通知する（Ｓ３３３）。
【０１５４】
到達確認を受け取った基地局２０２は、一意の番号に対応する蓄積しているパケットを削除する（Ｓ３３４よびＳ３３７）。また、基地局２０２は該パケットの番号を複製パケット送信可能状態の基地局２１２に通知する（Ｓ３３６）。通知を受けた基地局２１２は、該通知により蓄積している複製パケットを削除する（Ｓ３３８）。
【０１５５】
一方、基地局２０２は、再送要求を受信した場合、一意の番号に対応するパケットを再送する（Ｓ３３３、Ｓ３３４、Ｓ３３５）。
【０１５６】
以上のようにして、パケットの配布を行う回線制御局を基地局とは別に設けずに、各基地局においてパケットを蓄積して、１つ又は複数の基地局がパケットを移動局へ送信するため、ネットワーク内のトラヒックを低減することができ、パケットの伝送遅延時間を短縮することでスループットを増大しシステム全体の性能を向上することができる。
【０１５７】
なお、図１２において基地局２０２から基地局２１２へのＳ３３６の複製パケット削除通知については、図１４に示す３つの方法を採用することができる。
【０１５８】
即ち、第１の方法では図１４（ａ）のように、基地局２０２は、Ｓ３３１の移動局からの到達確認を受信する度に、基地局２１２へ削除すべきパケットの一意のパケット番号を通知する（Ａ１）。このとき通知と同時に、基地局２０２内に蓄積された該当パケットを削除してもよい。
【０１５９】
また、第２の方法では、基地局２０２が所定時間内における最新パケット番号の通知を行う。即ち、基地局２０２は、Ｓ３３１の移動局からの到達確認の受信により、図１４（ｂ）の処理を開始し、所定の削除間隔の時間が設定された削除タイマーを起動し（Ｂ１）、上記の到達確認に対応するパケット番号を記憶する（Ｂ２）。なお、このとき、同時に、基地局２０２内に蓄積された該当パケットを削除してもよい。その後、新たな到達確認を受信すると（Ｂ３で肯定判定）、該到達確認に対応するパケット番号を記憶していく（Ｂ２）。そして、削除タイマーがタイムアウトするに至ると（Ｂ４で肯定判定）、その時点で記憶しているパケット番号のうち最新のパケット番号、即ち、タイマーで計時された所定時間内に受信された到達確認に対応するパケットのうち最新パケットの番号を通知する（Ｂ５）。
【０１６０】
さらに、第３の方法では、基地局２０２が特定パケットの削除により（例えば削除された１０パケットごとに）通知を行う。即ち、基地局２０２は、Ｓ３３１の移動局からの到達確認の受信により、図１４（ｃ）の処理を開始し、カウンタｎ＝１にリセットした後（Ｃ１）、上記の到達確認に対応するパケット番号を記憶する（Ｃ２）。なお、この記憶と同時に、基地局２０２内に蓄積された該当パケットを削除してもよい（Ｃ５でも同様）。その後、新たな到達確認を受信すると（Ｃ３で肯定判定）、カウンタｎを１つカウントアップして（Ｃ４）、該到達確認に対応するパケット番号を記憶していく（Ｃ５）。そして、カウンタｎが１０になった時点、即ち、到達確認を１０パケット分受信した時点でＣ６にて肯定判定され、その時点で記憶しているパケット番号のうち最新のパケット番号を通知する（Ｃ７）。
【０１６１】
上記のうち第１の方法では、通知の頻度が高いため通知によるトラヒック量が多いもののバッファ管理が容易になるという利点がある。第２の方法では、一般的に、通知の頻度が低いためバッファ管理が煩雑になるものの通知によるトラヒック量が少なくなるという利点がある。第３の方法は、一般的に、トラヒック量とバッファ管理の両面につき第１、第２の方法の中間的な位置にある。
【０１６２】
本実施形態では、上記３つの方法を適宜採用することで、トラヒック量とバッファ管理の両面をバランス良く制御することが可能となる。
【０１６３】
ところで、図１２において基地局２０２、２１２にて蓄積されたパケットを削除するトリガーとしてタイマーを採用してもよい。この例を図１３に基づき説明する。
【０１６４】
即ち、図１３に示すように、基地局２０２は、ネットワーク１から到着した該パケットに対して一意の番号を付与し、移動局での受信パケットの誤り検出のためにＣＲＣなどを付加した後に、該パケットを蓄積すると共に、該番号を含めて該パケットの複製を行う（図１３のＳ３２１およびＳ３２２Ｘ）。また、このとき基地局２０２にパケットが入力されたことをトリガーとして、蓄積したパケットに関する削除タイミングを計時するための削除タイマーを基地局２０２が起動する。なお、基地局２０２は、対象のパケットを初めて送信する時点で削除タイマーを起動してもよい。
【０１６５】
そして、基地局２０２は、複製パケットを複製パケット送信可能状態である基地局２１２に対して配布する（Ｓ３２３）。基地局２１２は、配布されたパケットを蓄積すると共に、基地局２１２にパケットが入力されたことをトリガーとして、蓄積したパケットに関する削除タイミングを計時する削除タイマーを起動する（Ｓ３２４Ｘ）。さらに、基地局２０２は、該移動局２３１宛てパケットを蓄積していることを移動局２３１に通知する（Ｓ３２５ｂ）。
【０１６６】
また、移動局２３１は、前述のように、時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が最大となる基地局がパケット複製および送信可能状態となるように、状態遷移を要求することで、移動局への新たなパケットの通知を行う基地局を１つにすることができる。これは、時間平均的な受信品質が最高の基地局から通知させるため、実現可能となる。この場合、該通知のための余分な電力を削減することができ干渉を抑制することが可能となる。
【０１６７】
但し、該干渉の影響がさほど問題とならない場合は、図１２のＳ３２５ｂおよびＳ３２５ａに示すように、パケットを受取った基地局（パケット複製および送信可能状態の基地局、または複製パケット送信可能状態の基地局）がそれぞれ移動局２３１に通知する方法も可能である。
【０１６８】
該通知を受信した移動局２３１は、その時点において複数基地局（ここでは基地局２０２および基地局２１２の２局）から送信されている報知信号、共通パイロット信号などの信号の瞬時の受信電力または瞬時の受信電力対干渉電力比が最大となる基地局を選択し（Ｓ３２６）、該基地局に対して該パケットを送信することを要求する（Ｓ３２７）。この要求の具体的な方法は、該基地局を特定できる基地局の番号と通知されたパケットの番号を基地局に要求することで可能となる。
【０１６９】
また、該要求の方法は、選択した基地局に直接上り回線で要求する方法、または、選択されなかった基地局で受信された該要求を選択した基地局に基地局間ネットワークを介して通知する方法を採用可能である。これは、移動局と各基地局間の瞬時の受信品質は、上り回線と下り回線では異なり、下り回線の受信品質では選択した基地局と移動局間が最高であっても、上り回線の受信品質では、他の基地局と移動局間が最高となり得るためである。
【０１７０】
そして、該要求を受けた基地局（ここでは基地局２０２）は、移動局２３１に対して該パケットを送信する（Ｓ３２８）。このとき、基地局２０２は、移動局２３１宛のパケットを複数蓄積している旨を移動局２３１に通知してもよい。
【０１７１】
移動局２３１は、受信したパケットについて誤り検出処理（Ｓ３２９）を行い、誤りが検出されない場合、パケットの到達確認をパケット複製および送信可能状態の基地局２０２に通知する（Ｓ３３０およびＳ３３１）。この通知は、基地局２０２に直接、または、基地局２１２を介して行ってもよい。また、誤りが検出された場合、移動局２３１は、その時点において瞬時の又は時間平均的な受信品質が最高となる基地局を選択し（Ｓ３３２）、該基地局に対してパケットの再送要求を通知する（Ｓ３３３）。
【０１７２】
その後、基地局２０２は、移動局２３１から再送要求を受信した場合には、一意の番号に対応するパケットを再送する（Ｓ３３３、Ｓ３３４、Ｓ３３５）。
【０１７３】
図１３の例では、基地局２０２において、Ｓ３２２Ｘで開始した削除タイマーがタイムアウトになった時点で、該タイマーに対応する蓄積パケットを削除する（Ｓ３３６ＸおよびＳ３３７）。また、基地局２１２でも、Ｓ３２４Ｘで開始した削除タイマーがタイムアウトになった時点で、該タイマーに対応する蓄積パケットを削除する（Ｓ３３６ＹおよびＳ３３８）。
【０１７４】
このような図１３の処理によれば、削除通知（図１２のＳ３３６）を行う必要がなくなるので、これらの制御パケットによる基地局間ネットワークのトラヒック増加を抑制することができる。また、移動局からのパケットの到達確認（図１３のＳ３３１）も必ずしも必要ではないので、さらなるトラヒック削減も図ることができる。なお、図１３での削除タイマーのタイムアウト値は、該パケットに対する再送要求が到着しないと考えられる時間に設定するものとする。
【０１７５】
ところで、本実施形態では、パケットを送信する基地局が１つの場合（図１２、図１３）について説明したが、干渉などがさほど問題にならない場合、または複数基地局から送信される同一パケットを移動局においてダイバーシチ受信により受信品質を向上できる場合などでは、基地局２０２および基地局２１２が、同一のパケットをそれぞれ送信することも可能である。つぎに、この例について、図１５を用いて具体的に説明する。
【０１７６】
基地局２０２は、ネットワーク１から到着した該パケットに対して一意の番号を付加し、移動局での受信パケットの誤り検出のためにＣＲＣなどを付加した後に、該パケットを蓄積すると共に、該番号を含めて該パケットの複製を行う（図１５のＳ３４１およびＳ３４２）。そして、基地局２０２は、複製パケットを複製パケット送信可能状態である基地局２１２に配布し（Ｓ３４３）、基地局２１２は配布されたパケットを蓄積する（Ｓ３４４）。
【０１７７】
つぎに、基地局２０２および基地局２１２は、それぞれ蓄積パケットがあることを移動局に通知する（Ｓ３４５）。なお、移動局が、パケットを受信可能な状態である場合には、該Ｓ３４５の通知は省略可能である。そして、基地局２０２および基地局２１２は、それぞれ蓄積パケットを移動局に対して送信する（Ｓ３４６）。
【０１７８】
移動局２３１は、受信したパケットについて誤り検出処理（Ｓ３４７）を行う。この時に、複数基地局から送信された同一のパケットに対して、ダイバーシチを行うことも可能である。また、該ダイバーシチの方法としては、受信された同一パケットの同一ビットについて、ビット毎にそのまま合成する第１の方法、または受信電力または受信電力対干渉電力比で重み付けした後にビット毎に合成する第２の方法、誤り検出後のパケットの中から誤りが検出されないパケットを選択する第３の方法などを採用可能である。そして、誤りが検出されない場合、移動局２３１は、パケットの到達確認をパケット複製および送信可能状態の基地局２０２に通知する（Ｓ３４８およびＳ３４９）。
【０１７９】
到達確認を受け取った基地局２０２は、一意の番号に対応する蓄積しているパケットを削除する（Ｓ３５１およびＳ３５５）。また、基地局２０２は、該パケットの番号を複製パケット送信可能状態である基地局２１２に通知する（Ｓ３５４）。通知を受けた基地局２１２は、該通知により、蓄積している複製パケットを削除する（Ｓ３５６）。前述した図１３のようなタイマーを使用する方法により、Ｓ３５４の該通知を省略することは可能である。
【０１８０】
一方、Ｓ３４８で誤りが検出された場合、移動局は、基地局２０２または基地局２１２の一方に対してパケットの再送要求を通知する（Ｓ３５０）。基地局２０２は、再送要求を受取った場合、基地局２１２に該再送パケットを再配布するか、または該再送パケットの番号を通知する（Ｓ３５２）。そして、基地局２０２および基地局２１２は、それぞれ要求されたパケットを再送する（Ｓ３５３）。
【０１８１】
さらに、図９において移動局２３１が移動して地点Ｃ付近に到着し、大きな時間平均的な受信電力値または時間平均的な受信電力対干渉電力比がさらに得られるような状態になった場合、例えば、Ψ₁ =１、 Ψ₂ =１、 Ψ₃ =１となった場合も同様に、基地局２０２は、基地局２０２に到着するパケットの複製を基地局２１２および基地局２２２に配布する。
【０１８２】
つぎに、図８（ｂ）に示したある状態から別の状態に遷移する各種のイベントにおける基地局および移動局の動作について説明する。
【０１８３】
（４）イベントＡの説明
移動局において、上記の式（１）が成立している状態から式（２）が成立する状態に遷移することにより、移動局２３１が、パケット送信可能状態の基地局（Ψ_i =１であった第ｉ番目の基地局）に対しパケット複製および送信可能状態に遷移するよう要求し、新たにΨ_i =１となったアイドル状態の基地局に対し複製パケット送信可能状態に遷移するよう要求することが、イベントＡである（図８（ａ）、（ｂ）参照）。
【０１８４】
パケット送信可能状態からパケット複製および送信可能状態に遷移する基地局を基地局２０２とし、アイドル状態から複製パケット送信状態に遷移する基地局を基地局２１２として図１６を用いて具体的に説明する。
【０１８５】
移動局２３１は、式（１）から式（２）が成立する状態になったら、基地局２０２に対してパケット複製および送信可能状態に遷移することと、新たにΨ_i =１となった基地局２１２を特定する基地局の番号とを基地局２０２に通知する（図１６のＳ３６１およびＳ３６２）。
【０１８６】
該通知を受けた基地局２０２は、基地局２１２に対して複製パケット送信可能状態に遷移することを要求する（Ｓ３６３）と共に、 その時点において蓄積している該移動局２３１宛てのパケットを複製して（Ｓ３６４）、複製パケットを基地局２１２に配布（Ｓ３６６）する。そして、基地局２０２は、パケット複製および送信可能状態に遷移する（Ｓ３６７）。
【０１８７】
基地局２１２は、基地局２０２からの遷移要求により、複製パケット送信可能状態に遷移する（Ｓ３６５）。また、基地局２１２は、配布された複製パケットを蓄積する（Ｓ３６８）。これにより、基地局２１２に対して再送が要求されても、即座に再送を行うことが可能となる。
【０１８８】
そして、以降において基地局２０２に到着するパケットは、前述したように基地局２０２により複製されて基地局２１２に配布される。
【０１８９】
（５）イベントＢの説明
移動局において、式（２）が成立している状態から式（１）が成立する状態に遷移することにより、複製パケット送信可能状態の基地局がΨ_i =０になり、パケット複製および送信可能状態の基地局のみがΨ_i =１（他の基地局は、Ψ_i =０）となった場合、移動局２３１が、パケット複製および送信可能状態の基地局に対してパケット送信可能状態に遷移するよう要求し、複製パケット送信可能状態の基地局に対してアイドル状態に遷移するよう要求することが、イベントＢである（図８（ａ）、（ｂ）参照）。
【０１９０】
パケット複製および送信可能状態からパケット送信可能状態に遷移する基地局を基地局２０２とし、複製パケット送信可能状態からアイドル状態に遷移する基地局を基地局２１２として図１７を用いて具体的に説明する。
【０１９１】
移動局２３１は、式（２）から式（１）が成立する状態になったら、基地局２０２に対してパケット送信可能状態に遷移することと、Ψ_i =０ つまりアイドル状態となる基地局２１２を特定する基地局の番号とを基地局２０２に通知する（図１７のＳ３７１およびＳ３７２）。２つの基地局は、該移動局宛てのパケットを扱っているので、基地局２１２に対して要求する方法でも可能である。この場合は、基地局２１２に対して、アイドル状態に遷移することを要求し、パケット送信可能状態に遷移する基地局の番号（基地局２０２）を通知することで可能である。本実施形態では、前者の方法として説明を続ける。
【０１９２】
該通知を受けた基地局２０２は、基地局２１２に対してアイドル状態に遷移するよう要求し（Ｓ３７３）、パケット送信可能状態に遷移する（Ｓ３７４）。
【０１９３】
基地局２１２は、アイドル状態に遷移すると共に、蓄積している該パケットを削除する（Ｓ３７５）。基地局２０２は、以降において到着するパケットは、複製を行わず、また他の基地局に配布も行わない。
【０１９４】
（６）イベントＣの説明
移動局において、式（２）が成立している状態から式（１）が成立する状態に遷移することにより、パケット複製および送信可能状態の基地局がΨ_i =０になり、複製パケット送信可能状態の基地局がΨ_i =１となった場合、移動局２３１が、パケット複製および送信可能状態の基地局に対してアイドル状態に遷移するよう要求し、複製パケット送信可能状態の基地局に対してパケット送信可能状態に遷移するようが要求することが、イベントＣである。
【０１９５】
パケット複製および送信可能状態からアイドル状態に遷移する基地局を基地局２０２とし、複製パケット送信可能状態からパケット送信可能状態に遷移する基地局を基地局２１２として図１８を用いて具体的に説明する。
【０１９６】
移動局２３１は、式（２）から式（１）が成立する状態になったら、基地局２０２に対してアイドル状態に遷移することと、パケット送信可能状態に遷移する基地局２１２を特定する基地局の番号とを基地局２０２に通知する（図１８のＳ３８１およびＳ３８２）。
【０１９７】
該通知を受けた基地局２０２は、基地局２１２に対して、パケット送信可能状態に遷移するよう要求する。そして、一意の番号を付与する基地局が変更になるので、基地局２０２は、さらに、第１実施形態にて明記したように、現在蓄積しているパケット（到達確認が得られていないパケット）の番号とパケットに付与する一意の番号の最新値とを通知する（Ｓ３８３ａ）。本イベント発生時では、基地局２１２もパケットを蓄積しているので、基地局２１２に問合せをすることにより両基地局にて蓄積されている異なるパケットのみを送信する方法でも可能である（Ｓ３８３ｂ）。よって、Ｓ３８３ａまたはＳ３８３ｂの何れかの方法が行われる。
【０１９８】
そして、基地局２０２は、アイドル状態に遷移し、蓄積しているパケットを削除する（Ｓ３８４）。また、基地局２０２は、アイドル状態において該移動局２３１宛てのパケットを受信した場合は、前述の「（２）アイドル状態における基地局および移動局の動作」で説明したように、基地局２１２にそのまま転送するように制御する。
【０１９９】
一方、基地局２１２は、基地局２０２からの遷移要求により、パケット送信可能状態に遷移する（Ｓ３８５）。
【０２００】
（７）イベントＤの説明
移動局において、式（１）が成立している状態から式（２）が成立する状態に遷移すると共に、新たにΨ_i =１となった基地局からの時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が最大となること等により、移動局２３１が、パケット送信可能状態の基地局（Ψ_i =１であった第ｉ番目の基地局）に対して複製パケット送信可能状態に遷移するよう要求し、新たにΨ_i =１となったアイドル状態の基地局に対してパケット複製および送信可能状態に遷移するよう要求することが、イベントＤである。
【０２０１】
パケット送信可能状態から複製パケット送信可能状態に遷移する基地局を基地局２０２とし、アイドル状態からパケット複製および送信可能状態に遷移する基地局を基地局２１２として図１９を用いて具体的に説明する。
【０２０２】
移動局２３１は、式（１）から式（２）が成立する状態になったら、基地局２０２に対して複製パケット送信可能状態に遷移することと、新たにパケット複製および送信可能状態に遷移する基地局を特定する基地局の番号とを基地局２０２に通知する（図１９のＳ３９１およびＳ３９２）。
【０２０３】
該通知を受けた基地局２０２は、基地局２１２に対して、パケット複製および送信可能状態に遷移するよう要求する。そして、一意の番号を付与する基地局が変更になるので、基地局２０２は、さらに、第１実施形態にて明記したように、現在基地局２０２が蓄積しているパケット（到達確認が得られていないパケット）の番号とパケットに付与する一意の番号の最新値とを通知する（Ｓ３９３）。これは、基地局２１２は、移動局宛てのパケットを蓄積していないアイドル状態から遷移するためである。そして、基地局２０２は、複製パケット送信可能状態に遷移する（Ｓ３９４）。
【０２０４】
基地局２１２は、これらの通知に基づいて、パケット複製および送信可能状態に遷移し、基地局２０２から送出された該パケットを蓄積する（Ｓ３９５）。そして、基地局２１２は、新たに基地局２１２に到達するパケットを複製し、該複製パケットを基地局２０２に配布するように制御する。
【０２０５】
（８）イベントＥの説明
移動局において、式（２）が成立しており、時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が最大となる基地局に変更が生じたことなどにより、移動局２３１が、パケット複製および送信可能状態の基地局に対して複製パケット送信可能状態に遷移するよう要求し、複製パケット送信可能状態の基地局に対してパケット複製および送信可能状態に遷移するよう要求することが、イベントＥである。
【０２０６】
パケット複製および送信可能状態から複製パケット送信可能状態に遷移する基地局を基地局２０２とし、複製パケット送信可能状態からパケット複製および送信可能状態に遷移する基地局を基地局２１２として図２０を用いて具体的に説明する。
【０２０７】
時間平均的な受信電力値または時間平均的な受信電力対干渉電力比が最大となる基地局が基地局２０２から基地局２１２になったら、 移動局２３１は、 基地局２０２に対して複製パケット送信可能状態に遷移するよう要求するとともに、基地局２１２に対してパケット複製および送信可能状態に遷移するよう要求する（図２０のＳ４０１およびＳ４０２）。
【０２０８】
該通知を受けた基地局２０２は、複製パケット送信可能状態に遷移する（Ｓ４０４）。そして、一意の番号を付与する基地局が変更になるので、基地局２０２は、第１実施形態にて明記したように、現在蓄積しているパケット（到達確認が得られていないパケット）の番号とパケットに付与する一意の番号の最新値とを通知する。また、基地局２１２もパケットを蓄積しているので、基地局２０２は、基地局２１２に問合せをすることで両基地局にて蓄積されている異なるパケットのみを送信する方法でも可能である（Ｓ４０３）。基地局２０２にて蓄積しているパケットは、そのまま蓄積されるが、タイムアウトにより削除する方法の場合は、蓄積している全てのパケットに対して、この時点で削除タイマーが起動される。
【０２０９】
基地局２１２は、これらの通知に基づいて、パケット複製および送信可能状態に遷移する（Ｓ４０５）。そして、基地局２１２は、新たに基地局２１２に到達するパケットを複製し、該複製パケットを基地局２０２に配布するように制御する。
【０２１０】
以上の第３実施形態によれば、パケットの配布を行う回線制御局を基地局とは別に設けずに、各基地局においてパケットを蓄積して、１つ又は複数の基地局がパケットを移動局へ送信するため、ネットワーク内のトラヒックを低減することができ、パケットの伝送遅延時間を短縮することでスループットを増大しシステム全体の性能を向上することができる。
【０２１１】
［第４実施形態］
次に、図２１を用いて、ハンドオーバ送信制御に関する動作を説明する。移動通信システムの構成は、第３実施形態と同様の図７の構成とする。
【０２１２】
移動局は、複数基地局から送信される報知信号、共通パイロット信号などを受信することにより、移動局と複数基地局間の時間平均的な受信品質（ここでは例えば、伝搬損失）を求める。そして、移動局は、求めた時間平均的な受信品質を、一意の番号を付加するパケット複製および送信可能状態の基地局に通知する。該パケット複製および送信可能状態の基地局は、通知された複数の時間平均的な受信品質に基づいて、複製パケット送信可能状態の基地局のそれぞれに対してパケット単位での送信を指示する。各基地局は、該指示に従って新規のパケットを送信する。また、再送時は、移動局が再送要求した基地局のみが、パケットを再送する。
【０２１３】
一意の番号を付加する基地局によるパケット単位での送信指示は、具体的には次のように実行される。一意の番号を付加する基地局は、複数の時間平均的な伝搬損失を用いて以下の式（３）に基づいてＳ_i（ｊ）を求め、自局に入力されるパケットに対して該Ｓ_i（ｊ）が小さい基地局順に「送信を指示する識別子」を付加する。また、該Ｓ_i（ｊ）が同じ場合、一意の番号を付加する基地局は、時間平均的な伝搬損失がより小さい基地局に「送信を指示する識別子」を付加する。なお、以下の式（３）の伝播損失については、更に受信品質を示す指標である、希望波信号対干渉電力比（ＣＩＲ）、受信信号対干渉電力比（ＳＩＲ）、希望波信号対雑音電力比（ＣＮＲ）、受信信号対雑音電力比（ＳＮＲ）の何れであっても良い。
【０２１４】
【数３】

【０２１５】
なお、ｉは基地局の番号、ｊはＬ_iの更新後に入力されたパケット数を表す。
【０２１６】
一例として、移動局に対してパケットを送信することが可能な３つの基地局（ｉ＝１〜３）が存在する状態で時間平均的な伝搬損失が更新されたとき以降の動作を説明する。また、ｉ＝１をパケット複製および送信可能状態の基地局とし、ｉ＝２および３を複製パケット送信可能状態の基地局とし、それぞれの時間平均的な伝搬損失が以下の場合とする。
【０２１７】
第１番目基地局（ｉ＝１）と移動局間の伝搬損失：Ｌ₁＝１
第２番目基地局（ｉ＝２）と移動局間の伝搬損失：Ｌ₂＝２
第３番目基地局（ｉ＝３）と移動局間の伝搬損失：Ｌ₃＝３
【０２１８】
時間平均的な伝搬損失の更新後における第１番目のパケットを第Ｋ番目パケットとする。この時点において各Ｓ_i（ｊ）は全てゼロであるので、一意の番号を付加する基地局は、最小の伝搬損失である第１番目の基地局から送信するよう識別子を付加する。
【０２１９】
この識別子は、１ビット長で可能である。即ち、識別子が“１”とされたパケットは送信するよう動作させ、識別子が“０”とされたパケットは送信せずそのまま蓄積するよう動作させることで、１ビットの識別子による指示が可能となる。該識別子の付加後における各Ｓ_i（ｊ）値は、以下の通りとなる。
【０２２０】
【数４】

【０２２１】
次に、第（Ｋ＋１）番目のパケットが入力される。この時点においてＳ₂（０）およびＳ₃（０）がゼロであるので、一意の番号を付加する基地局は、より小さい伝搬損失である第２番目の基地局から送信するよう識別子を付加する。そして、この時点における各Ｓ_i（ｊ）値は、以下の通りとなる。
【０２２２】
【数５】

【０２２３】
第（Ｋ＋２）番目のパケットが入力された時点において、Ｓ₃（０）のみがゼロで最小値であるので、一意の番号を付加する基地局は、第３番目の基地局から送信するよう識別子を付加する。そして、この時点における各Ｓ_i（ｊ）値は、以下の通りとなる。
【０２２４】
【数６】

【０２２５】
このようにして、一意の番号を付加する基地局は、入力されたパケットを複製すると共に、複製パケットを配布する際に、上記の式（３）に基づいて、ある基地局に対するパケットの送信可の識別子を有効にする。その後の第（Ｋ＋３）番目から第（Ｋ＋１０）番目のパケットに対する式（３）の計算結果と識別子の状態が図２１に示されている。
【０２２６】
図２１に示すように、その後、第（Ｋ＋３）番目のパケットが入力されると、上記のようにＳ₁（１）が最小値であるので、一意の番号を付加する基地局は、第１番目の基地局から送信するよう識別子を付加する。
【０２２７】
第（Ｋ＋４）番目のパケットが入力された時点では、Ｓ₁（２）およびＳ₂（１）が“２／６”で等しいので、一意の番号を付加する基地局は、より小さい伝搬損失である第１番目の基地局から送信するよう識別子を付加する。
【０２２８】
第（Ｋ＋５）番目のパケットが入力された時点では、Ｓ₂（１）が最小値であるので、一意の番号を付加する基地局は、第２番目の基地局から送信するよう識別子を付加する。
【０２２９】
第（Ｋ＋６）番目のパケットが入力された時点では、Ｓ₁（３）およびＳ₃（１）が“３／６”で等しいので、一意の番号を付加する基地局は、より小さい伝搬損失である第１番目の基地局から送信するよう識別子を付加する。
【０２３０】
第（Ｋ＋７）番目のパケットが入力された時点では、Ｓ₃（１）が最小値であるので、一意の番号を付加する基地局は、第３番目の基地局から送信するよう識別子を付加する。
【０２３１】
第（Ｋ＋８）番目のパケットが入力された時点では、Ｓ₁（４）およびＳ₂（２）が“４／６”で等しいので、一意の番号を付加する基地局は、より小さい伝搬損失である第１番目の基地局から送信するよう識別子を付加する。
【０２３２】
第（Ｋ＋９）番目のパケットが入力された時点では、Ｓ₂（２）が最小値であるので、一意の番号を付加する基地局は、第２番目の基地局から送信するよう識別子を付加する。
【０２３３】
第（Ｋ＋１０）番目のパケットが入力された時点では、Ｓ₁（５）が最小値であるので、一意の番号を付加する基地局は、第１番目の基地局から送信するよう識別子を付加する。
【０２３４】
そして、各基地局は、識別子が１となっているパケットのみを移動局に送信する。
【０２３５】
なお、時間平均的な伝搬損失が更新された場合、一意の番号を付加する基地局は、ｊ＝０とリセットすることによりＳ_i（ｊ）をクリアした後に、上記処理の実行を継続する。
【０２３６】
また、移動局が再送を要求する時は、移動局はその時点において最小の伝搬損失となる基地局を選択し、選択された基地局からパケットを再送するよう要求する。このように移動局により選択された任意の基地局からパケットの再送が実行できるのは、各基地局が、配布された複製パケットを蓄積しているからである。
【０２３７】
以上説明した構成および動作とすることにより、移動局からパケット到着を報知する手順を行うことなく、各基地局は、時間平均的な伝搬損失に基づいて適切なパケット送信を行うことができると共に、再送パケットはその時点における最小伝搬損失となる基地局から即座に送信することが可能となるので、他セルまたは他移動局に対する干渉を低減しながら迅速な再送を行うことが可能となる。
【０２３８】
［第５実施形態］
次に、本発明の第５実施形態について図２８〜図３１を用いて説明する。図２８に示すように第５実施形態における移動通信システムは、前述した第１実施形態の移動通信システム（図１）と同様に、移動局１１３１と、複数の基地局１１０２、１１１２とを含んで構成されており、各基地局はネットワーク１を介して相互に通信可能とされている。
【０２３９】
このうち移動局１１３１の構成は、第１実施形態の移動局１３１と同様である。基地局１１０２の構成については、第１実施形態の基地局１０２に対し、パケットを複製するパケット複製部１１０７が追加され、図１の転送部１０５に代わり、他の基地局への複製パケットの配布及び他のデータリンク伝送制御を行う基地局へのパケットの転送を行う転送／配布部１１０５が設けられている。また、データリンク伝送制御部１１０３は、移動局との間でパケットの送受信を行うための自動再送要求制御を含むデータリンク伝送制御を行うとともに、データリンク伝送制御情報に代わり、データリンク伝送制御を行う基地局を識別するための制御基地局識別情報を移動局に送信する点で、第１実施形態と異なる。また、基地局１１１２は、基地局１１０２と同様の構成とされている。
【０２４０】
次に、本第５実施形態での動作を説明する。ここでは、当初、移動局１１３１と基地局１１０２の間の無線通信品質は良好であるが、移動局１１３１と基地局１１１２の間の無線通信品質は良好でないため、移動局１１３１は基地局１１０２とのみ通信可能な初期状態であるとする。この初期状態での動作を図２９に沿って説明する。
【０２４１】
基地局１１０２では、図２９のＳ４１でネットワーク１から入力されたパケットがデータリンク伝送制御部１１０３に入力され、データリンク伝送制御部１１０３は、自動再送要求制御を含むデータリンク伝送制御を行う。ここでデータリンク伝送制御部１１０３は、各パケットに対して識別情報を付与する（Ｓ４２）。本実施形態で用いる識別情報は、データリンク伝送制御部１１０３に入力されたパケットの識別を可能とするためのパケット識別情報と、該データリンク伝送制御を行っている制御基地局（即ち、識別情報の付与を行う基地局）の識別を可能とするための制御基地局識別情報とで構成される。また、データリンク伝送制御部１１０３は、受信したパケットの誤り検出のためにＣＲＣなどをパケットに付加して該付加後のパケット（即ち、識別情報が付与されたパケット）を蓄積部１０４に記憶する（Ｓ４２）と共に送受信機５に出力する。送受信機５は、該パケットを送信信号に変調した後に、基地局アンテナ６を介して移動局１１３１に送信信号を送信する（Ｓ４３）。
【０２４２】
一方、移動局１１３１は、移動局アンテナ３２からの信号を送受信機３３により受信・復調した後に、該復調で得られたパケットをデータリンク伝送制御部１０３４に入力する。データリンク伝送制御部１０３４は、自動再送要求制御を含むデータリンク伝送制御を行うとともに、入力されたパケットに対し、付加されているＣＲＣを用いて誤り検出を行う（Ｓ４４）。その検出の結果、パケットに誤りがある場合、データリンク伝送制御部１０３４は、付与されている識別情報に基づいて、再送を要求するパケットの番号と、制御基地局である基地局１１０２とを認識し、該認識結果に基づいてＮＡＣＫ信号を基地局１１０２に対して送信する（Ｓ４５）。これにより、該パケットの再送要求がデータリンク伝送制御部１１０３に通知される。なお、この通知方法としては、基地局１１０２に直接通知する方法や、他の基地局を介して通知する方法等を採用することができる。そして、データリンク伝送制御部１１０３は、ＡＣＫ信号が入力されたものでないと判断し（Ｓ４７）、記憶してある該パケットを再送する（Ｓ４３）。
【０２４３】
一方、誤り検出にてパケットに誤りがない場合、デ一タリンク伝送制御部１０３４は、付与されている識別情報に基づいて、制御基地局である基地局１１０２を認識し、該認識結果に基づいてＡＣＫ信号を基地局１１０２に対して送信する（Ｓ４６）。これにより、該パケットの到達確認がデータリンク伝送制御部１１０３に通知される。そして、データリンク伝送制御部１１０３は、ＡＣＫ信号が入力されたと判断し（Ｓ４７）、再送のために記憶してあるパケットを削除する（Ｓ４８）。
【０２４４】
次に、移動局１１３１が移動することにより、移動局１１３１と今まで通信していた基地局１１０２との通信品質が劣化してきて、隣接の基地局１１０２との通信品質と同等程度になってきた場合、前述した実施形態で説明したように、移動局１１３１は基地局１１０２と基地局１１１２から同一のパケットを送信するよう、基地局１１０２に要求する（Ｓ４９）。該要求により、基地局１１０２のデータリンク伝送制御部１１０３は、その時以降において基地局１１０２にパケットが入力されると（Ｓ５０）、該パケットに対し上記Ｓ４２と同様の処理を行って（Ｓ５１）送受信機５により移動局１１３１へ送信する（Ｓ５２）と共に、パケット複製部１１０７により該パケットを複製し（Ｓ５３）、複製したパケットを転送／配布部１１０５により基地局１１１２のデータリンク伝送制御部１１１３へ配布する（Ｓ５４）。
【０２４５】
データリンク伝送制御部１１１３は、データリンク伝送制御部１１０３によって、そのまま送受信機１５に配布パケットを出力するよう制御されるので、基地局１１０２と基地局１１１２から同一のパケットが送信される（Ｓ５２）。
【０２４６】
ここでデータリンク伝送制御部１１１３が、到着したパケットをそのまま出力するか、前述のような自動再送要求制御を含むデータリンク伝送制御を行うか、の判断は、到着したパケットに識別情報が付与されているか否かを検出することで可能となる。つまり、データリンク伝送制御部１１１３は、入力されたパケットに識別情報が付与されていることを検出した場合、到着したパケットをそのまま送受信機１５に出力する。一方、データリンク伝送制御部１１１３は、入力されたパケットに識別情報が付与されていないと検出した場合、自動再送要求制御を含むデータリンク伝送制御を行う。
【０２４７】
移動局１１３１は、前述と同様に受信パケットについて誤り検出を行い（Ｓ５５）、ＮＡＣＫまたはＡＣＫを基地局１１０２に出力する（Ｓ５６およびＳ５７）。基地局１１０２では、上記と同様に、ＡＣＫが入力されたか否かが判断され（Ｓ５８）、ＮＡＣＫであればパケットが再送され（Ｓ５２）、ＡＣＫであれば、記憶しているパケットが削除される（Ｓ５９）。
【０２４８】
次に、移動局１１３１と基地局１１０２との通信品質が劣化してきて、基地局１１１２との通信品質が良好になってきたとする。この遷移状態で複数の基地局から移動局へパケットを送信する場合の動作を図３０に沿って説明する。
【０２４９】
移動局１１３１は、基地局１１０２のデータリンク伝送制御部１１０３に対して、データリンク伝送制御を実行する基地局変更の要求を通知する（図３０のＳ６１）。該通知も、前述と同様に、基地局１１０２に直接通知する方法や、他の基地局を介して通知する方法等を採用することが可能である。
【０２５０】
該基地局変更の要求を受けたデータリンク伝送制御部１１０３は、転送／配布部１１０５を介し、変更先である基地局１１１２に移動局１１３１に対するデータリンク伝送制御の開始を要求する（Ｓ６２）。さらに、この時以降において、データリンク伝送制御部１１０３に入力されるパケットは、そのまま転送／配布部１１０５により基地局１１１２に転送させる設定とする。このため、データリンク伝送制御１１０３にパケットが入力されると（Ｓ６３）、該パケットは、そのまま転送／配布部１１０５により基地局１１１２に転送される（Ｓ６４）。
【０２５１】
変更元のデータリンク伝送制御部１１０３は、再送のために記憶しているパケットに対してのみデータリンク伝送制御を、図２９のＳ５２からＳ５９までの動作と同様に、そのまま引き続き行う。つまり、これらパケットについては到達確認が終了するまで、変更元のデータリンク伝送制御部１１０３が、そのまま再送制御を行う。この時も、前述と同様に、基地局１１０２と基地局１１１２から同一のパケットが移動局１１３１へ送信されている。
【０２５２】
一方、変更先である基地局１１１２のデータリンク伝送制御部１１１３は、到着した識別情報が付加されていないパケット（Ｓ６４又はＳ６５により到達したパケット）に対して、自動再送要求制御を含むデータリンク伝送制御を行う。ここでデータリンク伝送制御部１１１３は、各パケットに対して識別情報を付与するとともに、受信したパケットの誤り検出のためにＣＲＣなどをパケットに付加して該付加後のパケット（即ち、識別情報が付与されたパケット）を蓄積部１１４に記憶する（Ｓ６６）と共に送受信機１５に出力する。送受信機１５は、該パケットを送信信号に変調した後に、基地局アンテナ１６を介して移動局１１３１に送信信号を送信する（Ｓ６７）。
【０２５３】
上記識別情報が付与されたパケットは複製部１１１７により複製され（Ｓ６８）、該複製パケットは転送／配布部１１１５を介して基地局１１０２のデータリンク伝送制御部１１０３に配布される（Ｓ６９）。該データリンク伝送制御部１１０３では、パケットに識別情報が付与されているので、該パケットはそのまま送受信機５に出力するように制御されるので、基地局１１０２と基地局１１１２から同一のパケットが送信される（Ｓ６７）。
【０２５４】
移動局１１３１は、前述と同様に受信パケットについて誤り検出を行い（Ｓ７０）、基地局１１１２を認識し、ＮＡＣＫまたはＡＣＫを基地局１１１２に出力する（Ｓ７１およびＳ７２）。基地局１１１２では、ＡＣＫが入力されたか否かが判断され（Ｓ７３）、ＮＡＣＫであればパケットが再送され（Ｓ６７）、ＡＣＫであれば、記憶しているパケットが削除される（Ｓ７４）。
【０２５５】
次に、上記同様に、移動局１１３１と基地局１１０２との通信品質が劣化し基地局１１１２との通信品質が良好になってきた遷移状態において、単一の基地局から移動局へパケットを送信する場合の動作を図３１に沿って説明する。
【０２５６】
前述した実施形態で説明したように、基地局１１１２のデータリンク伝送制御部１１１３は、基地局１１１２のみからパケット送信を受ける旨の要求を移動局１１３１から受信したことにより（図３１のＳ８１）、パケットの複製を行わないように制御する。このため、その時以降において基地局１１０２にパケットが入力された場合（Ｓ８２）、該パケットは基地局１１１２に転送され（Ｓ８３）、基地局１１１２でのみ前述の処理が実行される（Ｓ８４〜Ｓ９０）。
【０２５７】
即ち、基地局１１１２のデータリンク伝送制御部１１１３は、各パケットに対して識別情報を付与するとともに、受信したパケットの誤り検出のためにＣＲＣなどをパケットに付加して該付加後のパケット（即ち、識別情報が付与されたパケット）を蓄積部１１４に記憶する（Ｓ８４）と共に送受信機１５に出力する。送受信機１５は、該パケットを送信信号に変調した後に、基地局アンテナ１６を介して移動局１１３１に送信信号を送信する（Ｓ８５）。
【０２５８】
移動局１１３１は、前述と同様に受信パケットについて誤り検出を行い（Ｓ８６）、基地局１１１２を認識し、ＮＡＣＫまたはＡＣＫを基地局１１１２に出力する（Ｓ８７およびＳ８８）。基地局１１１２では、ＡＣＫが入力されたか否かが判断され（Ｓ８９）、ＮＡＣＫであればパケットが再送され（Ｓ８５）、ＡＣＫであれば、記憶しているパケットが削除される（Ｓ９０）。
【０２５９】
以上説明したように、データリンク伝送制御を行う制御基地局が、データリンク伝送制御情報に代わり、該制御基地局を識別するための制御基地局識別情報を移動局に送信することで、移動局は、制御基地局識別情報に基づいて該制御基地局を認識することができ、移動局は制御基地局との間で、自動再送要求制御を含むデータリンク伝送制御（例えば、新たな基地局との接続要求等）を行うことができる。このように、移動局と基地局が、データリンク伝送制御情報に代わり、制御基地局識別情報を用いてデータリンク伝送制御を行うことにより、送受信される制御情報のデータ量を削減することができ、ネットワークトラヒック量を軽減することができる。
【０２６０】
また、本実施形態では、識別情報は、常に、基地局を識別する情報とパケットを識別する情報とから構成されるものとして説明したが、１つの基地局のデータリンク伝送制御部のみが自動再送要求制御を含むデータリンク伝送制御を実行している状態では、パケットを識別する情報のみで識別情報を構成し、２つ以上の基地局のデータリンク伝送制御部が自動再送要求制御を含むデータリンク伝送制御を実行している状態では、パケットを識別する情報と基地局を識別する情報とで識別情報を構成することで、識別情報のビット数をさほど増加させないで本発明が可能となる。
【０２６１】
［第６実施形態］
次に、本発明の第６実施形態について説明する。この第６実施形態では、一の基地局から他の基地局にデータリンク伝送制御情報のみを転送する第１の方法と、データリンク伝送制御情報とパケットを同時に転送するか又は識別情報が付加されたパケットを転送する第２の方法について順に説明する。なお、本実施形態ではＩＰ（Internet Protocol）パケットを用いた場合について説明するが、該ＩＰパケットと同様なパケット構成であるパケットであれば、本実施形態は適用可能である。
【０２６２】
まず、第１の方法を説明する。図３２には、この第１の方法を実行するための装置構成例を示す。図３２に示す移動通信システムでは、複数の基地局２１０２、２１１２がネットワーク１を介して相互に通信可能とされている。
【０２６３】
基地局２１０２は、基地局アンテナ６を介して、無線ネットワークからのデータの受信及び無線ネットワークへのデータの送信を行う送受信機５と、第１実施形態で述べた自動再送要求制御を含むデータリンク伝送制御を行うとともに基地局２１０２内の各構成部を制御するデータリンク伝送制御部２１０３と、基地局変更の要求を受けた場合等に変更先の基地局へデータリンク伝送制御情報を送信するとともに後述のカプセル化を行うカプセル化および転送部２１０５と、データリンク伝送制御部２１０３によるパケットデータ等の一時記憶域として機能する蓄積部２１０４と、受信されたカプセル化パケットのデカプセル化を行う（カプセルを解く）デカプセル部２１０６とを含んで構成されている。
【０２６４】
このうちカプセル化および転送部２１０５は、機能的には図３３（ａ）に示す機能ブロックより構成される。即ち、カプセル化および転送部２１０５は、データリンク伝送制御情報と転送するパケットとをカプセル化するカプセル化部２１０５Ａと、カプセル化により得られたカプセル化パケットの長さを表す、データリンク伝送制御情報の長さと転送するパケットの長さの合計値を、該カプセル化パケットのヘッダに記録して該カプセル化パケットを転送するカプセル化パケット転送部２１０５Ｂと、転送されてきたカプセル化パケットのヘッダに記録された該カプセル化パケットの長さから該カプセル化パケットのヘッダの長さを引いた長さと、転送するパケットのヘッダに記録された該転送するパケットの長さとが等しくない場合、該カプセル化パケットがデータリンク伝送制御情報を含んで構成されていると判断する構成判断部２１０５Ｃとを含んで構成されている。
【０２６５】
なお、他の基地局２１１２も、上記のような基地局２１０２と同様に構成されている。
【０２６６】
次に、第１の方法に係る動作を説明する。基地局２１０２のデータリンク伝送制御部２１０３は、データリンク伝送制御情報をカプセル化及び転送部２１０５に出力する。該カプセル化及び転送部２１０５は、図３４に示したように、ＩＰヘッダ部の発信元ＩＰアドレスには基地局２１０２のＩＰアドレスを、宛先ＩＰアドレスには基地局２１１２のＩＰアドレスをそれぞれ設定する。さらに、データリンク伝送制御情報をＵＤＰ又はＴＣＰのデータとして基地局に転送するために、プロトコル番号にはＵＤＰ又はＴＣＰを表す番号を設定し、パケット長にはＩＰヘッダ部とＩＰデータ部（ＵＤＰ又はＴＣＰヘッダ部とＵＤＰ又はＴＣＰのデータ部）のそれぞれの長さの合計値を設定する。そして、ＵＤＰ又はＴＣＰのデータ部には、転送するデータリンク伝送制御情報を入力し、基地局に転送するＩＰパケットを構成する。構成した該ＩＰパケットは、ネットワーク１に送出される。送出された該ＩＰパケットは、設定した宛先ＩＰアドレスにより基地局２１１２に到達する。
【０２６７】
基地局２１１２では、到達した該ＩＰパケットはデカプセル部２１１６に入力される。該デカプセル部２１１６は、図３５に示した流れ図に沿って処理を行う。なお、図３５は後述の第２の方法に係る処理手順も記述している。
【０２６８】
まず始めに、入力したパケットの最も外側にあるＩＰヘッダ部のプロトコル番号を識別する（図３５のＳ５０１）。この例の場合、識別したプロトコル番号はＩＰのカプセル化を表さない（Ｓ５０２で否定判断される）ので、ＩＰデータ部の中にあるＵＤＰ又はＴＣＰのデータ部を抽出してデータリンク伝送制御情報とする（Ｓ５０７）。抽出した該データリンク伝送制御情報は、データリンク伝送制御部２１１３に入力される。該データリンク伝送制御部２１１３では、入力されたデータリンク伝送制御情報により、前述した実施形態で説明してきたデータリンク伝送制御が実行される。
【０２６９】
例えば、データリンク伝送制御情報に移動局のＩＰアドレス又は機体番号などのように移動局を特定する情報と、最新パケットのパケットを一意に識別する番号とが含まれている場合、該移動局宛てパケットの自動再送制御には、該番号の次の番号が用いられる。また、データリンク伝送制御情報に、移動局を特定する情報と、移動局からのＡＣＫの情報又は蓄積パケットの削除の情報とが含まれている場合、蓄積部２１１４に蓄積されている該移動局宛てのＡＣＫに対応するパケット又は削除情報に対応するパケットを削除する。
【０２７０】
次に、第２の方法（データリンク伝送制御情報とパケットを同時に転送するか又は識別情報が付加されたパケットを転送する方法）について説明する。第２の方法は、パケット伝送中のハンドオーバ又はサイトダイバーシチなどにより、ＡＣＫ待ちとして蓄積しているパケットと該パケットを一意に識別する情報とをハンドオーバ先基地局に転送する場合、送信待ちとして保持しているパケットと該パケットを一意に識別する情報とをハンドオーバ先基地局に転送する場合、ハンドオーバ先基地局から送信するために、パケットと、該パケットを一意に識別する情報と制御基地局識別情報の両方又は一方とを転送する場合、該パケットを一意に識別する情報、制御基地局識別情報、パケットを送信するか否かを示す情報又はこれらの組合せと複製したパケットとを複製パケット送信可能状態の基地局に配布する場合などに用いられる。
【０２７１】
図３６には、第２の方法を実行するための装置構成例を示す。図３６に示す基地局２２０２は、図３２の基地局２１０２の構成に加えて、パケットを複製するパケット複製部２２０６をさらに備え、カプセル化および転送部２１０５に代わって、複製したパケットを他の基地局に配布するとともに後述のカプセル化を行うカプセル化および配布部２２０５を備えている。
【０２７２】
このうちカプセル化および配布部２２０５は、機能的には図３３（ｂ）に示す機能ブロックより構成される。即ち、カプセル化および配布部２２０５は、データリンク伝送制御情報と配布するパケットとをカプセル化するカプセル化部２２０５Ａと、カプセル化により得られたカプセル化パケットの長さを表す、データリンク伝送制御情報の長さと配布するパケットの長さの合計値を、該カプセル化パケットのヘッダに記録して該カプセル化パケットを配布するカプセル化パケット配布部２２０５Ｂと、配布されてきたカプセル化パケットのヘッダに記録された該カプセル化パケットの長さから該カプセル化パケットのヘッダの長さを引いた長さと、配布するパケットのヘッダに記録された該配布するパケットの長さとが等しくない場合、該カプセル化パケットがデータリンク伝送制御情報を含んで構成されていると判断する構成判断部２２０５Ｃとを含んで構成されている。
【０２７３】
なお、他の基地局２２１２も、上記のような基地局２２０２と同様に構成されている。
【０２７４】
次に、第２の方法に係る動作を説明する。ここでは、基地局２２０２から基地局２２１２に、複製した識別情報が付加されたパケットを配布する場合について説明する。
【０２７５】
基地局２２０２のデータリンク伝送制御部２１０３は、識別情報を付加したパケットをパケット複製部２２０６に入力する。該パケット複製部２２０６は、入力した該識別情報を付加したパケットを送受信送受信機５に出力すると共に、該パケットを複製した後にカプセル化及び配布部２２０５に出力する。該カプセル化及び配布部２２０５は、図３７に示したように、ＩＰヘッダ部（ａ）の発信元ＩＰアドレスには基地局２２０２のＩＰアドレス、 宛先ＩＰアドレスには基地局２２１２のＩＰアドレスをそれぞれ設定する。さらに、目的の移動局に転送するＩＰ パケットを他の基地局に転送するために、プロトコル番号にはＩＰのカプセル化を表す番号を設定し、パケット長にはＩＰヘッダ部（ａ）と目的の基地局に転送するＩＰパケットと識別情報のそれぞれの長さの合計値を設定する。
【０２７６】
そして、ＩＰヘッダ部（ａ）のＩＰデータ部には、目的の移動局に転送するＩＰパケットと識別情報を入力して基地局に転送するＩＰパケットを構成する。構成した該ＩＰパケットは、ネットワーク１に送出される。 送出された該ＩＰパケットは、設定した宛先ＩＰアドレスにより基地局２２１２に到達する。
【０２７７】
基地局２１１２では、到達した該ＩＰパケットはデカプセル部２１１６に入力される。該デカプセル部２１１６は、前述と同様に、図３５に示した流れ図に沿って処理を行う。まず始めに、入力されたパケットの最も外側にあるＩＰヘッダ部のプロトコル番号を識別する（図３５のＳ５０１）。この例の場合、識別したプロトコル番号はＩＰのカプセル化を表す（Ｓ５０２で肯定判断される）ので、最も外側にあるＩＰヘッダ部（図３７のＩＰヘッダ部（ａ））のパケット長を解析することにより、基地局へ転送するパケットのパケット長Ｘ１を取得する（Ｓ５０３）。次に、外側から２番目のＩＰヘッダ部（図３７のＩＰヘッダ部（ｂ））のパケット長を解析することにより、目的の移動局に転送するパケットのパケット長Ｘ２を取得する（Ｓ５０４）。そして、得られたパケット長Ｘ１とＸ２と最も外側にあるＩＰヘッダ部の長さを用いた次の式（４）が成立する場合（Ｓ５０５で肯定判断される場合）、識別情報がない、つまりＩＰヘッダ部（ａ）のＩＰデータ部には目的の基地局に転送するＩＰパケットのみがあると判断される。
【０２７８】
（Ｘ１）−（最も外側にあるＩＰヘッダの長さ）＝（Ｘ２） ・・・（４）
【０２７９】
この場合は、ＩＰヘッダ部（ａ）のＩＰデータ部を抽出して目的の移動局に転送するＩＰパケットとして以下の処理を行う（Ｓ５０８）。即ち、抽出された目的の移動局に転送するＩＰパケットは、データリンク伝送制御部２１１３に入力され、該データリンク伝送制御部２１１３では、入力された該ＩＰパケットに対して、前述した実施形態で説明してきたデータリンク伝送制御が実行される。
【０２８０】
一方、式（４）が成立しない場合（Ｓ５０５で否定判断される場合）、識別情報があると判断して以下の処理を行う（Ｓ５０６）。この場合は、ＩＰヘッダ部（ａ）のＩＰデータ部の先頭から長さＸ２だけの情報が、目的の移動局に転送するＩＰパケットとして分離して抽出され、ＩＰヘッダ部（ａ）のＩＰデータ部の残りが識別情報として分離して抽出される。抽出された目的の移動局に転送するＩＰパケットと識別情報とは、データリンク伝送制御部２１１３に入力され、該データリンク伝送制御部２１１３では、入力された該ＩＰパケットと該識別情報を用いて、前述した実施形態で説明してきたデータリンク伝送制御が実行される。
【０２８１】
ここでは、基地局に転送又は配布するパケットとして、図３４、図３７に示した２つの異なる構成のＩＰパケットの場合についてそれぞれ説明したが、以上説明した方法を用いることにより、ある基地局から他の基地局に転送又は配布するパケットが、データリンク伝送制御情報のみを含む場合、データリンク伝送制御情報と目的の移動局に転送するＩＰパケットとを含む場合又は識別情報が付加されたＩＰパケットである場合、及び、目的の移動局に転送するＩＰパケットのみを含む場合を、それぞれ識別することが可能となり、データリンク伝送制御情報や識別情報に基づく制御を円滑に実行することが可能となる。
【０２８２】
【発明の効果】
以上説明したように、本発明によれば、移動局の移動に応じて、自動再送要求制御を含むデータリンク伝送制御を実行する基地局を変更することにより、伝送遅延時間の増大を抑制して従来よりもスループットを増大することが可能となる。また、自動再送要求制御を含むデータリンク伝送制御を行う基地局が変更しても一連のデータリンク伝送制御情報を転送することにより新たな基地局が引継いで未到達確認のパケットまたはブロックのみの再送を行うので、スループットの低下を回避できる。
【０２８３】
また、本発明によれば、各基地局がパケットを蓄積することにより、再送の遅延時間および基地局間ネットワーク内のトラヒックの増加を低減することが可能となる。また、ハンドオーバ時でもスムーズなパケット伝送が可能となる。
【０２８４】
また、本発明によれば、ハンドオーバすべき所定の受信レベルの範囲に移動局が存在する場合には、複数の基地局から同じパケットを送信し、移動局が前記範囲外に移動した段階で基地局を切り替えることで、最も移動局に近い基地局でハンドオーバ制御を行うことを実現しながらハンドオーバ制御にかかる時間をなくし、再送までの遅延を短縮化することで、より効率的なデータリンク伝送を実現することができる。
【図面の簡単な説明】
【図１】第１、第２実施形態に係る移動通信システムのシステム構成図である。
【図２】第１実施形態の動作を説明するためのタイムチャートである。
【図３】第１実施形態での動作を具体的に説明するための動作相関図である。
【図４】（ａ）は第１実施形態のデータリンク伝送制御部でのパケット構成を示す図であり、（ｂ）は第２実施形態のデータリンク伝送制御部でのパケットおよびブロック構成を示す図である。
【図５】従来の移動通信システムのシステム構成図である。
【図６】従来の移動通信システムにおけるデータリンク伝送制御方法の動作を説明するためのタイムチャートである。
【図７】第３実施形態に係る移動通信システムのシステム構成図である。
【図８】（ａ）は第３実施形態に係る送信制御の方法を説明するための状態遷移図であり、（ｂ）は各イベント毎の状態遷移を示す表である。
【図９】第３実施形態における移動局の位置を説明するための図である。
【図１０】パケットがパケット送信可能状態の基地局に到着した場合の処理を説明するための図である。
【図１１】パケットがアイドル状態の基地局に到着した場合の処理を説明するための図である。
【図１２】パケットがパケット複製および送信可能状態の基地局に到着した場合の処理を説明するための図である。
【図１３】図１２の処理で各基地局にて蓄積されたパケットを削除するトリガーとしてタイマーを採用した例を説明するための図である。
【図１４】図１２において基地局２０２から基地局２１２へのパケット削除通知に関する各種方法を説明するための図であり、（ａ）は基地局２０２がパケットを削除する度に削除対象のパケット番号を通知する第１の方法、（ｂ）は所定時間内において最後に削除されたパケットの番号を通知する第２の方法、（ｃ）は１０個のパケットが削除される度に最後に削除されたパケットの番号を通知する第３の方法をそれぞれ示す。
【図１５】図１２において基地局２０２、２１２が同一のパケットをそれぞれ移動局に送信する例を説明するための図である。
【図１６】イベントＡにおける対象基地局及び移動局の動作を説明するための図である。
【図１７】イベントＢにおける対象基地局及び移動局の動作を説明するための図である。
【図１８】イベントＣにおける対象基地局及び移動局の動作を説明するための図である。
【図１９】イベントＤにおける対象基地局及び移動局の動作を説明するための図である。
【図２０】イベントＥにおける対象基地局及び移動局の動作を説明するための図である。
【図２１】第４実施形態におけるパケット伝送ハンドオーバ送信制御の動作を説明するための表である。
【図２２】第３実施形態の基地局内のデータリンク伝送制御部を構成する機能ブロックを示す図である。
【図２３】第３実施形態の移動局内のデータリンク伝送制御部を構成する機能ブロックを示す図である。
【図２４】本発明に係る移動局制御プログラムの第１の態様を示す流れ図である。
【図２５】本発明に係る移動局制御プログラムの第２の態様を示す流れ図である。
【図２６】本発明に係る移動局制御プログラムの第３の態様を示す流れ図である。
【図２７】移動局制御プログラムが記録された記録媒体及びその周辺機器の構成図である。
【図２８】第５実施形態に係る移動通信システムのシステム構成図である。
【図２９】第５実施形態における初期状態での動作を説明するための図である。
【図３０】第５実施形態の遷移状態で複数の基地局から移動局へパケットを送信する場合の動作を説明するための図である。
【図３１】第５実施形態の遷移状態で単一の基地局から移動局へパケットを送信する場合の動作を説明するための図である。
【図３２】第６実施形態に係る第１の方法を実行する移動通信システムのシステム構成図である。
【図３３】（ａ）はカプセル化および転送部の機能ブロック図であり、（ｂ）はカプセル化および配布部の機能ブロック図である。
【図３４】第６実施形態の第１の方法に係るＩＰパケットの構成を示す図である。
【図３５】第６実施形態の第１、第２の方法に係る処理手順を示す流れ図である。
【図３６】第６実施形態に係る第２の方法を実行する移動通信システムのシステム構成図である。
【図３７】第６実施形態の第２の方法に係るＩＰパケットの構成を示す図である。
【符号の説明】
１…ネットワーク、２、１２、２２、１０２、１１２、１２２、１１０２、１１１２…基地局、３、１３、２３、３４、１０３、１１３、１２３、１０３４、１１０３、１１１３…データリンク伝送制御部、１１０５、１１１５…転送／配布部、１１０７、１１１７…パケット複製部、４、１４、２４…切替器、１０４、１１４、１２４…蓄積部、１０５、１１５、１２５…転送部、５、１５、２５、３３…送受信機、６、１６、２６…基地局アンテナ、３１、１３１、１１３１…移動局、３２…移動局アンテナ、３４Ａ、１０３４Ａ…移動局伝送制御部、３４Ｂ、１０３４Ｂ…接続要求部、３５…データ入出力端、２０２、２１２、２２２…基地局、２０３…データリンク伝送制御部、２０３Ａ…識別情報付加部、２０３Ｂ…削除部、２０３Ｃ…削除部、２０３Ｄ…削除部、２０３Ｅ…削除パケット通知部、２０３Ｆ…配布制御部、２０３Ｇ…パケット再送部、２０３Ｈ…蓄積通知部、２０３Ｉ…通知制御部、２０３Ｊ…判断部、２０３Ｋ…指示部、２０４…蓄積部、２０５…配布部、２０６…パケット複製部、２０７…送受信機、２０８…基地局アンテナ、２３１…移動局、２３２…移動局アンテナ、２３３…送受信機、２３３Ａ…ダイバーシチ受信部、２３４…データリンク伝送制御部、２３４Ａ…選択部、２３４Ｂ…送信要求部、２３４Ｃ…変更時通知部、２３４Ｄ…測定部、２３４Ｅ…受信品質通知部、２３４Ｆ…判定部、２３４Ｇ…状態遷移要求部、２３５…データ入出力端、２１０２、２１１２、２２０２、２２１２…基地局、２１０３、２１１３…データリンク伝送制御部、２１０４、２１１４…蓄積部、２１０５、２１１５…カプセル化および転送部、２１０５Ａ…カプセル化部、２１０５Ｂ…カプセル化パケット転送部、２１０５Ｃ…構成判断部、２１０６、２１１６…デカプセル部、２２０５、２２１５…カプセル化および配布部、２２０５Ａ…カプセル化部、２２０５Ｂ…カプセル化パケット配布部、２２０５Ｃ…構成判断部、２２０６、２２１６…パケット複製部。[0001]
BACKGROUND OF THE INVENTION
The present invention Data link transmission control method, mobile communication system, and data link transmission control device More specifically, a data link transmission control method for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets between a mobile station and a plurality of base stations, a mobile station and a plurality of base stations A mobile communication system configured to transmit and receive information using packets, And Data link transmission control device mounted on a base station that transmits / receives information to / from a mobile station by packet Concerning .
[0002]
[Prior art]
FIGS. 5 and 6 are configuration diagrams and flowcharts for explaining a data link transmission control method including automatic retransmission request control in a conventional mobile communication system.
[0003]
In the base station 2, a packet input from the network 1 at the arrow T1 in FIG. 6 is first input to the data link transmission control unit 3, and data link transmission control is executed while performing automatic retransmission request control. The data link transmission control unit 3 assigns a packet number to enable identification of the inputted packet, and a CRC (cyclic redundancy check) so that an error occurring during transmission can be detected for the packet. ) Etc. are added, and then the packet is stored and output to the transceiver 5 via the switch 4. The transceiver 5 then modulates the transmission signal and transmits it to the mobile station 31 via the base station antenna 6 (arrow T2 in FIG. 6).
[0004]
On the other hand, in the mobile station 31, after the signal from the mobile station antenna 32 is received by the transceiver 33, the received packet is output to the data link transmission control unit 34, and data link transmission control including automatic retransmission request control is performed. Execute. The data link transmission control unit 34 performs error detection using the parity added to the input packet. If there is an error in the packet as a result of the detection, the data link transmission control unit 34 transmits a NACK (Negative Acknowledgment) signal to the base station 2, thereby transmitting a retransmission request for the packet to the data link transmission of the base station 2. The control unit 3 is notified (arrow T3 in FIG. 6). The data link transmission control unit 3 retransmits the packet requested for retransmission (arrow T4 in FIG. 6).
[0005]
When there is no error in the packet, the data link transmission control unit 34 outputs the packet from the data input / output terminal 35 and transmits an ACK (Acknowledgment) signal to the base station 2 to reach the packet. The confirmation is notified to the data link transmission control unit 3 of the base station 2 (arrow T5 in FIG. 6). Then, the data link transmission control unit 3 deletes the packet having the packet number stored for retransmission.
[0006]
By the way, when the mobile station 31 moves and the communication quality between the mobile station 31 and the base station 2 that has been communicating so far deteriorates and the communication quality with other base stations 12 becomes good, The mobile station 31 requests the base station 2 to communicate with the base station 2 via the base station 12 (arrows T6 and T7 in FIG. 6). In response to the request, the data link transmission control unit 3 of the base station 2 transfers the packet subjected to the automatic retransmission request control to the changed base station 12 by changing the connection destination of the switch 4 from the transceiver 5 to the network 1. This is made possible (arrows T8 and T9 in FIG. 6). Then, control is performed so that the data link transmission control unit 13 of the base station 12 outputs the data to the transceiver 15 via the switch 14 as it is without executing automatic retransmission request control (arrow T10 in FIG. 6).
[0007]
With this method, the automatic retransmission request control is performed as it is by one data link transmission control unit 3 as it is regardless of the change of the communication partner base station (arrows T8 to T16 in FIG. 6). Packet transmission is possible without resetting the packet number.
[0008]
Even when the base station 22 is further away from the base station 2, packet transmission can be performed while performing automatic retransmission request control using the above method.
[0009]
As for handover of the conventional mobile communication system, as described in Japanese Patent Laid-Open No. 10-136426, the base station switching performed at the time of handover is performed by the virtual zone control device, thereby reducing the radio zone. The amount of handover control at the time was reduced, and the instantaneous interruption time of the communication line was shortened.
[0010]
[Problems to be solved by the invention]
However, in the data link transmission control method in the conventional mobile communication system as described above, the data link of the base station 2 in which a series of packet transmissions is started for data link transmission including automatic retransmission request control regardless of movement of the mobile station. Since the transmission control unit 3 performs the batch processing, the packet transmission delay time increases because the transfer between the base stations after the data link transmission control increases as the mobile station moves. Further, there is a problem that the throughput is lowered due to the increase in the transmission delay time.
[0011]
As described above, in the data link transmission control method in the conventional mobile communication system, one base station performs data link transmission control including automatic retransmission request control even when the mobile station moves into a cell of another base station. Thus, the mobility of the mobile station can be accommodated, but there is a problem that the throughput is lowered due to an increase in the transmission delay time.
[0012]
In addition, in a mobile communication system, a technique for providing a line control station for performing retransmission control separately from a base station in order to reduce the load on an exchange in the network (for example, also described in the above-mentioned JP-A-10-136426) Is also known.
[0013]
However, in this technique, a packet that arrives from the network first arrives at the line control station, is duplicated by the line control station, and is distributed to the distribution destination base station. The distribution-destination base station receives a signal designating the base station to which the packet is to be transmitted from the mobile station. The distribution-destination base station determines whether or not the local station should transmit based on the signal, and when determining that the local station should transmit, transmits the packet to the mobile station. At this time, if an error occurs in the packet received by the mobile station, the mobile station requests the line control station to retransmit the packet via the base station. As described above, since the line control station, not the base station, retransmits the packet, there is a problem in that the delay time until the retransmission increases, and the amount of traffic between the line control station and the base station increases.
[0014]
On the other hand, in the system described in Japanese Patent Laid-Open No. 10-136426, although the amount of handover control is reduced, the time required for one handover and retransmission is still the same as before or requires extra time. There was a problem that was interrupted.
[0015]
The present invention has been made in order to solve the above-described problems, and can improve throughput and overall system performance by reducing packet transmission delay time while accommodating movement of a mobile station. it can Data link transmission control method, mobile communication system, and data link transmission control device The purpose is to provide.
[0016]
[Means for Solving the Problems]
In order to solve the above problems, a data link transmission control method according to the present invention is a data link transmission control including automatic retransmission request control for transmitting and receiving packets between a mobile station and a plurality of base stations. In the link transmission control method, when the mobile station requests one base station to connect to another base station during connection with one base station, the one base station transmits data link transmission control information. Is transferred to the other base station.
[0017]
The mobile communication system according to the present invention is a mobile communication system that includes a mobile station and a plurality of base stations, and transmits and receives information using packets. The mobile station transmits and receives packets to and from the base station. Mobile station transmission control means for performing data link transmission control including automatic retransmission request control for performing transmission and reception, and connection request means for requesting connection with a base station as a communication partner, the base station, Base station transmission control means for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets to and from a mobile station; and transfer means for transferring data link transmission control information to other base stations; And the base station transmission control means causes the transfer means to transfer the data link transmission control information to the other base station when there is a connection request with the other base station from the mobile station. It is characterized in.
[0018]
A data link transmission control apparatus according to the present invention is a data link transmission control apparatus mounted on a base station that transmits and receives information to and from a mobile station by using a packet, and performs automatic retransmission for transmitting and receiving packets. When there is a connection request between the mobile station and the transfer means for transferring the data link transmission control information related to the data link transmission control including the request control to the other base station, the other base station Base station transmission control means for causing the base station to transfer the data link transmission control information by the transfer means.
[0019]
Since the invention related to the data link transmission control method, the invention related to the mobile communication system, and the invention related to the data link transmission control device are the same in terms of technical idea, the following will be described.・ Explain the effect.
[0020]
The data link transmission control method according to the present invention is a method for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets between a mobile station and a plurality of base stations. When a connection with another base station is requested during connection with another base station, one base station transmits data link transmission control information related to data link transmission control including automatic retransmission request control for performing packet transmission / reception. Transfer to another base station. As a result, a series of data link transmission control information is transferred between the base stations executing the data link transmission control according to the movement of the mobile station, and the new base station takes over the data link transmission control and the unreachable confirmation is performed. Resend only packets.
[0021]
Therefore, compared to the case where one base station continuously performs data link transmission control as in the prior art, an increase in packet transmission delay time due to an increase in packet transfer between base stations can be avoided. By reducing the packet transmission delay time, the throughput can be increased and the performance of the entire system can be improved.
[0022]
In such a data link transmission control method according to the present invention, one base station transmits data link transmission control information to another base station simultaneously with the transfer timing of the packet addressed to the mobile station to the other base station. It may be transferred, or may be transferred to another base station at a timing different from the transfer timing of the packet addressed to the mobile station.
[0023]
That is, in the mobile communication system according to the present invention, transfer means provided in a base station also transfers packets addressed to the mobile station to other base stations, and the base station transmission control means includes the data link transmission control The information can be configured to be transferred to the other base station by the transfer means at the same time as the transfer timing of the packet addressed to the mobile station to the other base station or at a different timing. Further, in the data link transmission control device according to the present invention, the transfer means also transfers a packet addressed to the mobile station to another base station, and the base station transmission control means transmits the data link transmission control information, It can be configured such that the transfer unit transfers the packet addressed to the mobile station to the other base station simultaneously with the transfer timing or at a different timing.
[0024]
Further, in the data link transmission control method according to the present invention, one base station serving as a transfer source, based on a connection request from a mobile station to another base station, data link transmission control information related to the mobile station, or When the packet addressed to the mobile station is received after the packet addressed to the mobile station and the data link transmission control information are transferred to another base station, it is desirable to transfer the received packet to the other base station. Further, in the mobile communication system according to the present invention, the base station transmission control means provided in the base station, based on a connection request from the mobile station to another base station, data link transmission control information related to the mobile station, or When the packet addressed to the mobile station is received after the packet addressed to the mobile station and the data link transmission control information are transferred to another base station, the received packet is transferred to the other base station by the transfer means. It is desirable to configure. Further, in the data link transmission control device according to the present invention, the base station transmission control means, based on a connection request from the mobile station to another base station, data link transmission control information related to the mobile station, or the mobile station When the packet addressed to the mobile station is received after the addressed packet and the data link transmission control information are transferred to another base station, the received packet is transferred to the other base station by the transfer means. It is desirable.
[0025]
In this case, since the packet addressed to the mobile station received by one base station (transfer base station) after being transferred to another base station is transferred to the other base station without exception, The data link transmission control can be taken over more reliably, and the reliability of the data link transmission control can be improved.
[0026]
Further, in the data link transmission control method according to the present invention, the other base station serving as the transfer destination receives the movement from the one base station immediately after the mobile station requests connection with the other base station. If the data link transmission control information related to the station, or the packet addressed to the mobile station and the data link transmission control information are received before receiving the packet addressed to the mobile station, the received packet is stored in the memory. Is desirable. Further, in the mobile communication system according to the present invention, the base station transmission control means provided in the base station is immediately after the connection request with the base station from the mobile station, from the base station that was connected before, When receiving the data link transmission control information related to the mobile station, or the packet addressed to the mobile station and the data link transmission control information before receiving the packet addressed to the mobile station, the received packet is stored in the memory. It is desirable to configure as follows. Further, in the data link transmission control device according to the present invention, the base station transmission control means connects to the base station on which the data link transmission control device is mounted immediately before the connection request from the mobile station. If a packet addressed to the mobile station is received before receiving the data link transmission control information related to the mobile station or the packet addressed to the mobile station and the data link transmission control information from the base station It is desirable that the packet is stored in the memory.
[0027]
In this case, in the other base station that is the transfer destination, immediately after the connection request from the mobile station to the other base station, the data link transmission control information related to the mobile station from the one base station, or Since the received packet addressed to the mobile station is stored in the memory without being discarded until the packet addressed to the mobile station and the data link transmission control information are received, the data link transmission between the base stations is performed. Control takeover can be executed more reliably and the reliability of data link transmission control can be improved.
[0028]
In the data link transmission control method according to the present invention, the other base station as the transfer destination receives a packet retransmission request from the mobile station and receives a packet addressed to the mobile station from one base station. If not, it is desirable to transmit a packet transfer request addressed to the mobile station to the one base station. Further, in the mobile communication system according to the present invention, the base station transmission control means provided in the base station receives a packet retransmission request from the mobile station, and the packet addressed to the mobile station from the previously connected base station In the case where the mobile station is not received, it is desirable to transmit a packet transfer request addressed to the mobile station to the previously connected base station. In the data link transmission control device according to the present invention, the base station transmission control means receives a packet retransmission request from the mobile station and receives a packet addressed to the mobile station from a previously connected base station. If not, it is desirable to transmit a packet transfer request addressed to the mobile station to the previously connected base station.
[0029]
In this case, if another base station as a transfer destination receives a packet retransmission request from the mobile station, but does not receive a packet addressed to the mobile station from one base station of the transfer source, Since the transfer request for the packet addressed to the mobile station is transmitted to the base station, the packet addressed to the mobile station can be transferred earlier, and the throughput can be increased by speeding up the processing relating to the takeover.
[0030]
By the way, the present invention is not limited to a mode in which a packet addressed to a mobile station and data link transmission control information are simultaneously transferred in taking over data link transmission control from one base station to another base station. It may be transferred step by step. That is, in the data link transmission control method according to the present invention, when there is a connection request from the mobile station to another base station, only one data link transmission control information for the mobile station is transferred. When a transfer request for the packet addressed to the mobile station is received from another base station, the packet addressed to the mobile station may be transferred to the other base station. Also, in the mobile communication system according to the present invention, when the base station transmission control means provided in the base station has a connection request with another base station from the mobile station, only the data link transmission control information for the mobile station When the transfer request for the packet addressed to the mobile station is received from the other base station, the packet addressed to the mobile station may be transferred to the other base station. In the data link transmission control apparatus according to the present invention, the base station transmission control means transfers only the data link transmission control information for the mobile station when there is a connection request from the mobile station to another base station. When receiving a transfer request for the packet addressed to the mobile station from the other base station, the other base station may be configured to transfer the packet addressed to the mobile station.
[0031]
In this way, when one base station communicates with another base station and receives a transfer request for the packet addressed to the mobile station from the other base station to which the transfer is made, By transferring the packet addressed to the mobile station to the station, the data link transmission control can be taken over more reliably.
[0032]
Note that it is desirable to transfer packets not only in units of packets but also in units of blocks obtained by dividing one packet. By enabling transfer in units of blocks, it is possible to retransmit only unreachable blocks between base stations, and there is an advantage that the amount of packet transfer can be reduced.
[0033]
By the way, in the data link transmission control method according to the present invention, one base station encapsulates the data link transmission control information and the packet to be transferred, and represents the length of the encapsulated packet obtained by the encapsulation. The total value of the length of the transmission control information and the length of the packet to be transferred is recorded in the header of the encapsulated packet, the encapsulated packet is transferred, and the capsule recorded in the header of the transferred encapsulated packet If the length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred, the encapsulated packet is transmitted through the data link. It is desirable to determine that it is configured to include control information.
[0034]
Further, in the mobile communication system according to the present invention, the transfer means represents an encapsulating means for encapsulating the data link transmission control information and the packet to be transferred, and the length of the encapsulated packet obtained by the encapsulation, The encapsulated packet transfer means for transferring the encapsulated packet by recording the total value of the length of the data link transmission control information and the length of the packet to be transferred in the header of the encapsulated packet, and the encapsulated packet transferred When the length of the encapsulated packet recorded in the header of the packet minus the length of the encapsulated packet header is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred, Configuration determining means for determining that the encapsulated packet includes data link transmission control information. Configuration and it is desirable to.
[0035]
In the data link transmission control apparatus according to the present invention, the transfer means represents an encapsulation means for encapsulating the data link transmission control information and the packet to be transferred, and the length of the encapsulated packet obtained by the encapsulation. An encapsulated packet transfer means for recording the total value of the length of the data link transmission control information and the length of the packet to be transferred in the header of the encapsulated packet and transferring the encapsulated packet; and the transferred capsule The length of the encapsulated packet recorded in the header of the encapsulated packet minus the length of the encapsulated packet header is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred A configuration determining means for determining that the encapsulated packet includes data link transmission control information; It is desirable to comprise configure.
[0036]
In these inventions, in one base station, it can be reliably determined whether or not the encapsulated packet transferred includes data link transmission control information, and control based on the data link transmission control information is smoothly executed. It becomes possible to do.
[0037]
By the way, in this invention, the base station which performs data link transmission control transmits the control base station identification information for identifying the base station which performs this data link transmission control to a mobile station instead of data link transmission control information. Can also be adopted.
[0038]
That is, the data link transmission control method according to the present invention is a data link transmission control method for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets between a mobile station and a plurality of base stations. The base station that performs data link transmission control transmits control base station identification information for identifying the base station that performs data link transmission control to the mobile station, instead of the data link transmission control information. Recognizes the base station that performs the data link transmission control based on the control base station identification information.
[0039]
A mobile communication system according to the present invention is a mobile communication system that includes a mobile station and a plurality of base stations, and transmits and receives information using packets. The base station transmits and receives packets to and from the mobile station. Base station transmission control means for performing data link transmission control including automatic retransmission request control for performing transmission and reception, and control base station identification information for identifying a base station performing data link transmission control instead of data link transmission control information Transmitting means to the mobile station, the mobile station recognizes a base station that performs the data link transmission control based on the control base station identification information, and communicates with the base station. Mobile station transmission control means for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets, and connection request means for requesting connection with a base station as a communication partner. Characterized in that it.
[0040]
The data link transmission control device according to the present invention is a data link transmission control device mounted on a base station that transmits and receives information to and from a mobile station by using a packet, and transmits a packet to and from the mobile station. Base station transmission control means for performing data link transmission control including automatic retransmission request control for performing transmission and reception, and control base station identification information for identifying a base station performing data link transmission control instead of data link transmission control information Transmitting means for transmitting to the mobile station.
[0041]
In this case, the base station that performs data link transmission control transmits, to the mobile station, control base station identification information for identifying the base station that performs data link transmission control instead of the data link transmission control information. The station can recognize the base station that performs the data link transmission control based on the control base station identification information. As a result, the mobile station performs data link transmission control including automatic retransmission request control for transmitting and receiving packets to and from the base station that performs the data link transmission control (for example, a connection request with a new base station). It can be performed. In this way, the mobile station and the base station can reduce the amount of control information transmitted and received by performing data link transmission control using the control base station identification information instead of the data link transmission control information. The amount of network traffic can be reduced.
[0042]
By the way, in the data link transmission control method according to the present invention, the base station encapsulates the control base station identification information and the packet to be transferred, and represents the length of the encapsulated packet obtained by the encapsulation. The total value of the length of the information and the length of the packet to be transferred is recorded in the header of the encapsulated packet, the encapsulated packet is transferred, and the encapsulated packet recorded in the header of the transferred encapsulated packet If the length obtained by subtracting the length of the header of the encapsulated packet from the length of the packet is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred, the encapsulated packet is identified as control base station identification information. It is desirable to judge that it is configured to include.
[0043]
Further, in the mobile communication system according to the present invention, the transmission means includes a control means for encapsulating the control base station identification information and the packet to be transferred, and a control indicating the length of the encapsulated packet obtained by the encapsulation. The total value of the length of the base station identification information and the length of the packet to be transferred is recorded in the header of the encapsulated packet, and the encapsulated packet transfer means for transferring the encapsulated packet; When the length of the encapsulated packet recorded in the header minus the length of the encapsulated packet header is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred, And a configuration determination unit that determines that the encapsulated packet includes the control base station identification information. There.
[0044]
In the data link transmission control device according to the present invention, the transmission means represents the encapsulation means for encapsulating the control base station identification information and the packet to be transferred, and the length of the encapsulated packet obtained by the encapsulation. Encapsulating packet transfer means for transferring the encapsulated packet by recording the total value of the length of the control base station identification information and the length of the packet to be transferred in the header of the encapsulated packet; When the length of the encapsulated packet recorded in the packet header minus the length of the encapsulated packet header is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred Configuration determining means for determining that the encapsulated packet includes control base station identification information. It is desirable
[0045]
In these inventions, the base station can reliably determine whether or not the transferred encapsulated packet includes control base station identification information, and smoothly executes control based on the control base station identification information. Is possible.
[0046]
In order to achieve the above object, a data link transmission control method according to the present invention performs data link transmission control including automatic retransmission request control for transmitting and receiving packets between a mobile station and a plurality of base stations. A link transmission control method, wherein one base station stores and duplicates a packet to which identification information for identifying the packet is added to a packet addressed to the mobile station, and the one base station The duplicated packet is distributed to other base stations, the other base station accumulates the distributed packets, and one or more base stations including the one base station are added with the identification information. The transmitted packet or the distributed packet is transmitted to the mobile station.
[0047]
That is, in this method, one base station out of a plurality of base stations has identification information (for example, a unique number, a character, a symbol, or a combination thereof) for identifying the packet addressed to the mobile station. Is added to the base station, and the duplicated packet is distributed to other base stations. As for the packet with the identification information added, one base station may add the identification information to the packet at its own station, or it may receive a packet with the identification information added in advance from another base station. Also good.
[0048]
Then, another base station accumulates the distributed packet. Thereafter, one or a plurality of base stations including one base station transmits the packet to which the identification information is added or the distributed packet to the mobile station. In this way, since a line control station for distributing packets is not provided separately from the base station, packets are accumulated in each base station, and one or a plurality of base stations transmit packets to the mobile station. Traffic can be reduced, and by reducing the packet transmission delay time, the throughput can be increased and the performance of the entire system can be improved.
[0049]
In the data link transmission control method according to the present invention, a base station (including one base station and another base station) deletes the packet due to a timer timeout for the packet, or the same packet as the packet. It is desirable to delete the packet by notifying that the mobile station has reached the mobile station, or to delete the packet corresponding to the identification information based on the notification of the identification information for specifying the packet to be deleted . As a result, it is possible to facilitate the process of deleting packets being accumulated in the base station.
[0050]
At this time, when one base station notifies the other base station of the identification information for specifying the packet to be deleted, the identification information is stored each time the one base station deletes the packet. The first method for notifying, the second method for notifying the identification information of the packet last deleted within a predetermined time, or the identification information of the packet when a specific packet determined based on a predetermined rule is deleted It is desirable to use one method or a combination of a plurality of methods among the third methods of notifying the user.
[0051]
In the data link transmission control method according to the present invention, when one base station receives a request from the mobile station to designate a new base station as a packet distribution destination base station, the one base station It is desirable to duplicate the packet with the identification information added at the station and distribute the duplicated packet to the new base station. As a result, the new base station can obtain a packet to which the identification information stored in one base station is added, and can operate as a packet distribution destination base station in accordance with a request from the mobile station. It becomes possible.
[0052]
In the data link transmission control method according to the present invention, when another base station receives a request from the mobile station to exclude the other base station from the base station to which the packet is distributed, It is desirable to delete the packet addressed to the mobile station stored in the base station. Thereby, in the base station excluded from the base station to which the packet is distributed, the packet addressed to the mobile station being stored is deleted, and the unnecessary packets can be quickly arranged. The other base station may receive a request from the mobile station to be excluded directly from the mobile station, or may receive it via one base station.
[0053]
In the data link transmission control method according to the present invention, when one base station, another base station, or both receive and accumulate packets addressed to a mobile station, the packets are accumulated. To the mobile station, and after receiving the notification, the mobile station selects one base station from the notified base stations, requests the base station to transmit a packet, It is desirable for the station to transmit the packet. That is, not only one base station but also other base stations store packets addressed to the mobile station, so that the mobile station selects the packet by notifying the mobile station that the packet is stored. Transmission of the packet from one base station that requested transmission to the mobile station is realized.
[0054]
At this time, if one base station, another base station, or both receive a transmission request from the mobile station while accumulating a plurality of packets addressed to the mobile station, the packet is sent to the mobile station. It is desirable to notify the mobile station that a plurality of packets addressed to the mobile station are accumulated. As a result, it is possible to collectively notify the mobile station that packets are being accumulated, and the load of the notification process can be reduced. For example, a mode in which a packet transmitted from the base station is notified by piggybacking that there is a subsequent packet can be considered.
[0055]
Further, in the data link transmission control method according to the present invention, when a mobile station changes a base station that transmits a packet addressed to the mobile station, the mobile station notifies the change source base station to stop transmission thereafter, and changes It is desirable to notify the destination base station that it requests transmission of a packet addressed to itself and the identification information of the first packet to be transmitted. As a result, communication with the base station of the change source is stopped, and packet transmission from the base station of the change destination to the mobile station resumes from the packet corresponding to the identification information of the first packet to be transmitted according to the request of the mobile station. Thus, the base station that transmits the packet addressed to the mobile station can be changed smoothly.
[0056]
In the data link transmission control method according to the present invention, the mobile station measures the reception quality of signals transmitted from a plurality of base stations, and the mobile station determines its own station based on the reception quality for each base station. It is preferable that one base station that transmits a packet addressed to the mobile station is selected, and the mobile station requests the selected one base station to transmit a packet addressed to itself. Thereby, for example, a base station having the highest reception quality can be selected as one base station, and packet transmission from the selected base station to the mobile station can be realized in a good state.
[0057]
In the data link transmission control method according to the present invention, the mobile station measures the reception quality of signals transmitted from a plurality of base stations, and the mobile station determines its own station based on the reception quality for each base station. The mobile station selects one base station that transmits the addressed packet, the mobile station notifies the selected one base station of the reception quality for each base station, and the one base station receives the reception quality for each base station. Based on the base station, each of the other base stations determines whether or not to transmit the packet to be distributed from the one base station to the mobile station, and the one base station performs a transmission operation based on the determination result. It is desirable to instruct other base stations. Thereby, according to the operation instruction to each of the other base stations according to the above determination result based on the reception quality for each base station, it is possible for other base stations to appropriately perform the transmission operation or the transmission avoidance operation. Become.
[0058]
Also, in the data link transmission control method according to the present invention, when the mobile station receives the same packet from each of the plurality of base stations, it is desirable to perform diversity reception on the packet, thereby improving reception quality. it can.
[0059]
In the data link transmission control method according to the present invention, the mobile station measures the reception quality of signals transmitted from a plurality of base stations, and the mobile station or each base station determines the reception quality for each base station. Based on this, it is desirable to request the base station to change the communication state to change the communication state. As a result, an appropriate communication state transition request corresponding to the time-average reception quality is issued from the mobile station, and the base station can transition to an appropriate communication state.
[0060]
The communication state includes a first state in which no packet is transmitted to and received from the mobile station, and identification information for identifying the packet is added to the packet addressed to the mobile station, and the added packet is transmitted to the mobile station. To the second state that can be transmitted to the mobile station, identification information for identifying the packet is added to the packet addressed to the mobile station, the packet after the addition is duplicated, and the duplicated packet is distributed, A third state in which the packet after the addition can be transmitted, and a fourth state in which the duplicate packet is received from the base station in the third state and the duplicate packet can be transmitted to the mobile station It is desirable to have a configuration including
[0061]
Also, in the data link transmission control method according to the present invention, one base station encapsulates the identification information and the packet to be distributed, and represents the length of the identification information representing the length of the encapsulated packet obtained by the encapsulation. And the total length of the packet to be distributed is recorded in the header of the encapsulated packet to distribute the encapsulated packet, and the length of the encapsulated packet recorded in the header of the encapsulated packet that has been distributed If the length obtained by subtracting the length of the header of the encapsulated packet from the length of the packet to be distributed recorded in the header of the packet to be distributed is not equal, the encapsulated packet is configured to include identification information. It is desirable to judge that In this case, the base station can reliably determine whether or not the distributed encapsulated packet includes identification information, and can smoothly execute control based on the identification information.
[0062]
By the way, the invention relating to the data link transmission control can also be understood as the invention of the following mobile communication system. Since these inventions are the same in terms of technical idea, they exhibit the same actions and effects.
[0063]
That is, the mobile communication system according to the present invention is a mobile communication system that includes a mobile station and a plurality of base stations, and performs data link transmission control including automatic retransmission request control while performing transmission / reception of information by packets. A base station that replicates a packet in which identification information for identifying the packet is added to the packet addressed to the mobile station; a distribution unit that distributes the copied packet to other base stations; Storing means for storing the packet to which the identification information is added or a packet distributed from another base station, and transmission means for transmitting the packet to which the identification information is added or the distributed packet to the mobile station; , Provided.
[0064]
At this time, in the mobile communication system according to the present invention, it is desirable that the base station further includes a deletion unit that deletes the packet stored by the storage unit.
[0065]
Here, the first method of notifying the identification information of the deleted packet every time the base station deletes the packet, the first notification of the identification information of the packet deleted last within a predetermined time. The method should be deleted by one method or a combination of a plurality of methods in the second method, or when a specific packet defined based on a predetermined rule is deleted and the identification information of the packet is notified. It is desirable to further include a deletion packet notification means for notifying other base stations of packet identification information.
[0066]
In addition, the mobile communication system according to the present invention is configured to further include packet retransmission means for retransmitting a packet in response to the retransmission request when the base station receives the packet retransmission request from the mobile station. Is desirable.
[0067]
Further, in the mobile communication system according to the present invention, when the base station receives and stores packets addressed to the mobile station, the mobile communication system further includes an accumulation notification means for notifying the mobile station that the packets are being accumulated. And the transmission means transmits a packet to the mobile station in response to a request from the mobile station, and when the mobile station receives the notification, 1 It is desirable to further include a selection unit that selects one base station, and a transmission request unit that requests the selected base station to transmit a packet.
[0068]
Here, when the base station receives a transmission request from the mobile station while accumulating a plurality of packets addressed to the mobile station, the base station transmits the packet to the mobile station by the transmission means, and It is desirable to further comprise notification control means for controlling the mobile station to notify the mobile station that a plurality of packets are being stored.
[0069]
Further, in the mobile communication system according to the present invention, when a mobile station changes a base station that transmits a packet addressed to the mobile station, the mobile station notifies the change source base station to stop transmission thereafter, and It is desirable that the base station further includes a change notification means for requesting transmission of a packet addressed to the base station and identification information of the first packet to be transmitted.
[0070]
In the mobile communication system according to the present invention, the mobile station measures the reception quality of signals transmitted from a plurality of base stations, and the packet addressed to the mobile station based on the reception quality of each base station. It is desirable to further include a selection unit that selects one base station that transmits the packet, and a transmission request unit that requests the selected one base station to transmit a packet addressed to itself.
[0071]
In the mobile communication system according to the present invention, the mobile station measures the reception quality of signals transmitted from a plurality of base stations, and the packet addressed to the mobile station based on the reception quality of each base station. Selecting means for selecting one base station that transmits the received signal, and reception quality notifying means for notifying the selected one base station of the reception quality for each base station, wherein the base station serves as one base station. Judgment means for judging whether to transmit a packet to be distributed from the own station to the mobile station based on the reception quality for each base station when the own station is selected. And an instruction means for instructing another base station to perform a transmission operation based on the determination result.
[0072]
In the mobile communication system according to the present invention, it is preferable that the mobile station further includes diversity receiving means for performing diversity reception on the packet when receiving the same packet from a plurality of base stations. .
[0073]
Further, in the mobile communication system according to the present invention, the mobile station is configured to measure each reception quality of signals transmitted from a plurality of base stations and each base station based on the reception quality for each base station. Determining means for determining which communication state among the plurality of communication states, and a state transition requesting means for requesting the base station to change the communication state based on the determination result, It is desirable to have a configuration further comprising
[0074]
Here, a plurality of predetermined communication states are added to the first state in which packets are not transmitted / received to / from the mobile station, and identification information for identifying the packet is added to the packet addressed to the mobile station. A second state in which a later packet can be transmitted to the mobile station, and identification information for identifying the packet is added to the packet addressed to the mobile station, the packet after the addition is duplicated, A third state in which the packet is distributed and the packet after the addition can be transmitted, and the duplicate packet is received from the base station in the third state, and the duplicate packet is transmitted to the mobile station. It is desirable to have a configuration including a fourth state that can be used.
[0075]
Further, in the mobile communication system according to the present invention, the distribution unit includes an encapsulation unit that encapsulates the identification information and the packet to be distributed, and a length of the identification information that represents a length of the encapsulated packet obtained by the encapsulation. And the total length of the packet to be distributed is recorded in the header of the encapsulated packet and the encapsulated packet distributing means for distributing the encapsulated packet, and the recorded in the header of the encapsulated packet distributed When the length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet is not equal to the length of the packet to be distributed recorded in the header of the packet to be distributed, the encapsulated packet is identified by the identification information. It is desirable that the configuration includes a configuration determination unit that determines that the configuration is included.
[0076]
By the way, the main part of the invention related to the data link transmission control and the invention related to the mobile communication system can be understood as the invention of the base station and the invention of the mobile station described below. Since these inventions are the same in terms of technical idea, they exhibit the same actions and effects.
[0077]
That is, the base station according to the present invention is a base station that, together with a mobile station, constitutes a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information using packets, A plurality of units, a duplicating unit for duplicating a packet to which identification information for identifying the packet is added to a packet addressed to the mobile station, and a distributing unit for distributing the duplicated packet to other base stations; A storage means for storing the packet to which the identification information is added and a packet distributed from another base station, and a transmission means for transmitting the stored packet to the mobile station. Features.
[0078]
Here, one base station that transmits a packet addressed to the mobile station is selected based on the reception quality of signals transmitted from a plurality of base stations, and the reception quality of each base station is notified to the one base station Whether or not to transmit a packet to be distributed from the mobile station to the mobile station based on the reception quality of each base station when the mobile station selects the base station as the one base station. It is desirable to further comprise a determination means for determining each of the other base stations, and an instruction means for instructing the other base station to perform a transmission operation based on the determination result.
[0079]
In the base station according to the present invention, the distribution means includes an encapsulation means for encapsulating the identification information and the packet to be distributed, and the length of the identification information indicating the length of the encapsulated packet obtained by the encapsulation. An encapsulated packet distribution means for distributing the encapsulated packet by recording the total value of the length of the packet to be distributed in the header of the encapsulated packet, and the capsule recorded in the header of the encapsulated packet that has been distributed If the length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet is not equal to the length of the packet to be distributed recorded in the header of the packet to be distributed, the encapsulated packet receives identification information. It is desirable to include a configuration determination unit that determines that the configuration is included.
[0080]
A mobile station according to the present invention is a mobile station that configures a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information by a packet, Measuring means for measuring the reception quality of the signal transmitted from the base station, selection means for selecting one base station for transmitting a packet addressed to the own station based on the reception quality for each base station, and the selected One base station comprises transmission request means for requesting transmission of a packet addressed to the own station.
[0081]
The mobile station according to the present invention is a mobile station that configures a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information using packets, Based on the reception quality of the station, it is determined for each of the other base stations whether or not to transmit the packet scheduled to be distributed from the own station to each of the other base stations, and the transmission operation based on the determination result is determined for the other base station. Selects a measurement unit that measures the reception quality of signals transmitted from multiple base stations that have the function of instructing and one base station that transmits packets addressed to itself based on the reception quality of each base station And a reception quality notifying unit for notifying the selected one base station of the reception quality of each base station.
[0082]
A mobile station according to the present invention is a mobile station that configures a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information by a packet, Based on the measurement means for measuring the reception quality of the signal transmitted from the base station and the reception quality for each base station, it is determined which of the predetermined communication states each base station is in. And a state transition requesting unit for requesting the base station to change the communication state based on the determination result.
[0083]
Here, a plurality of predetermined communication states are added to the first state in which packets are not transmitted / received to / from the mobile station, and identification information for identifying the packet is added to the packet addressed to the mobile station. A second state in which a later packet can be transmitted to the mobile station, and identification information for identifying the packet is added to the packet addressed to the mobile station, the packet after the addition is duplicated, A third state in which the packet is distributed and the packet after the addition can be transmitted, and the duplicate packet is received from the base station in the third state, and the duplicate packet is transmitted to the mobile station. It is desirable to comprise including the 4th state which can be performed.
[0084]
In addition, it is desirable to further include diversity receiving means for performing diversity reception for the same packet when receiving the same packet from a plurality of base stations.
[0085]
By the way, the invention according to the above mobile station can be described as follows as a mobile station control program to be executed by a computer mounted on the mobile station.
[0086]
That is, the mobile station control program according to the present invention is mounted on a mobile station that configures a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information by packets. 24. A mobile station control program to be executed by a computer, as shown in FIG. 24, based on measurement step S441 for measuring reception quality of signals transmitted from a plurality of base stations, and reception quality for each base station The computer includes a selection step S442 for selecting one base station for transmitting a packet addressed to the own station, and a transmission request step S443 for requesting the selected one base station to transmit a packet addressed to the own station. It is made to perform.
[0087]
The mobile station control program according to the present invention is installed in a mobile station that configures a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information using packets. A mobile station control program to be executed by a computer, as shown in FIG. 25, based on the reception quality of each base station, whether or not to send a packet to be distributed from the own station to the mobile station. Measuring each of the other base stations and measuring reception quality of signals transmitted from a plurality of base stations having a function of instructing another base station to perform a transmission operation based on the determination result, Based on the reception quality of the base station, a selection step S452 for selecting one base station for transmitting a packet addressed to the own station, and one selected base And a reception quality notification step S453 to notify the reception quality for each base station to the station, and characterized by causing the computer to perform.
[0088]
The mobile station control program according to the present invention is installed in a mobile station that configures a mobile communication system that performs data link transmission control including automatic retransmission request control while performing transmission and reception of information using packets. 26. A mobile station control program to be executed by a computer, as shown in FIG. 26, based on measurement step S461 for measuring reception quality of signals transmitted from a plurality of base stations, and reception quality for each base station Then, a determination step S462 for determining which of the predetermined communication states each base station is in, and a transition of the communication state to the base station to which the communication state should be changed based on the determination result The computer is caused to execute a transition request step S463 for requesting the above.
[0089]
A computer-readable recording medium according to the present invention stores any one of the above-described mobile station control programs. As shown in FIG. 27, the mobile station control program recorded on the recording medium 62 can be read by the reading unit 61 </ b> A of the computer 61 mounted on the mobile station 60.
[0090]
DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of a data link transmission control method and a mobile communication system according to the present invention will be described.
[0091]
[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIG. 1 and FIG. First, the configuration of the mobile communication system in the first embodiment will be described with reference to FIG. The mobile communication system according to the first embodiment includes a mobile station 131 and a plurality of base stations 102, 112, and 122. The base stations can communicate with each other via the network 1. Yes.
[0092]
The mobile station 131 receives data from the wireless network via the mobile station antenna 32 and transmits / receives data to / from the wireless network, and data for performing data link transmission control including automatic retransmission request control described later. The link transmission control unit 34 includes a data input / output terminal 35 as an input / output terminal for packet data. Among these, the data link transmission control unit 34 includes a mobile station transmission control unit 34A that performs data link transmission control including automatic retransmission request control for transmitting and receiving packets to and from the base station, and a base station that is a communication partner. And a connection request unit 34B for requesting connection.
[0093]
The base station 102 performs transmission and reception of data from the wireless network and transmission of data to the wireless network via the base station antenna 6 and data link transmission control including automatic retransmission request control described later. A data link transmission control unit 103 that controls each component in the base station 102, a transfer unit 105 that transmits data link transmission control information to the base station to be changed when receiving a request to change the base station, and data The storage unit 104 functions as a temporary storage area for packet data and the like by the link transmission control unit 103. The other base stations 112 and 122 are configured similarly to the base station 102.
[0094]
Next, the operation in the first embodiment will be described. Here, when the mobile station monitors the communication quality with the nearest one or more base stations and determines that another base station can perform communication with better communication quality than the currently communicating base station, The mobile station shall request a base station change. Initially, it is assumed that the mobile station 131 has good communication quality with the base station 102 and can communicate only with the base station 102.
[0095]
In the base station 102, a packet input from the network 1 by the arrow S1 in FIG. 2 is input to the data link transmission control unit 103, and data link transmission control including automatic retransmission request control is performed. The data link transmission control unit 103 first assigns a packet number to enable packet identification, and then stores the packet and outputs it to the transceiver 5.
[0096]
If the packet number described in the header of the packet input to the data link transmission control unit 103 can be identified, the packet is stored as it is without adding a new packet number as described above. Output to the transceiver 5. The transceiver 5 modulates the input packet into a transmission signal and then transmits the packet to the mobile station 131 via the base station antenna 6 (arrow S2 in FIG. 2).
[0097]
On the other hand, in the mobile station 131, after the signal from the mobile station antenna 32 is received by the transceiver 33, the received packet is input to the data link transmission control unit 34, and data link transmission control including automatic retransmission request control is performed. . The data link transmission control unit 34 performs error detection using the parity added to the input packet. If there is an error in the packet as a result of detection, the data link transmission control unit 34 transmits a NACK (Negative Acknowledgment) signal to the base station 102, thereby requesting the retransmission of the packet to the data link transmission control unit 103. (Arrow S3 in FIG. 2). Then, the data link transmission control unit 103 retransmits the packet with the stored packet number (arrow S4 in FIG. 2).
[0098]
If there is no error in the packet, the data link transmission control unit 34 outputs the packet from the data input / output terminal 35 and transmits an ACK (Acknowledgment) signal to the base station 102 to reach the packet. The confirmation is notified to the data link transmission control unit 103 of the base station 102 (arrow S5 in FIG. 2). Then, the data link transmission control unit 103 deletes the packet with the packet number stored for retransmission.
[0099]
Next, when the mobile station 131 moves, the communication quality between the mobile station 131 and the base station 102 that has been communicating so far deteriorates and the communication with the adjacent base station 112 becomes good. 131 first transmits a base station change request to the data link transmission control unit 103 of the base station 102 via the base station 112 (arrows S6 and S7 in FIG. 2). In the present embodiment, a method of notifying a change destination base station number together with a request for changing a base station is adopted.
[0100]
The data link transmission control unit 103 of the base station 102 that has received the request to change the base station transmits data link transmission control information to the base station 112 that is the change destination via the transfer unit 105 (arrow in FIG. 2). S8). This embodiment will be described as a method using a packet number that has not been confirmed for arrival as data link transmission control information and the latest packet number. Then, the data link transmission control unit 103 deletes all the stored packets for the mobile station 131 and stops packet transmission. Further, the packet addressed to the mobile station 131 arriving at the data link transmission control unit 103 as indicated by arrow S9 in FIG. 2 is set to be transferred to the base station 112 as it is by the transfer unit 105 as indicated by arrow S10. .
[0101]
In the data link transmission control unit 113 of the base station 112 that is the change destination, if the packet addressed to the mobile station 131 is input before the data link transmission control information from the base station 102 is input, the data link transmission control information is The packet is temporarily stored in the storage unit 114 until it is input. Then, after inputting the data link transmission control information, the packet stored in the storage unit 114 is given the number next to the latest packet number, which is the data link transmission control information, and so on. The process (arrows S11, S12, S13, S14) is performed and transmitted.
[0102]
Further, even if the mobile station moves into a cell of another base station, the above-described operation enables the data link transmission control method of the present invention.
[0103]
In this way, it is not necessary to execute the procedure for resetting the packet number, and the data link transmission control unit of the base station directly communicating with the mobile station can be used. Data link transfer control along the route can be performed, and the packet transfer delay time can be shortened compared to the conventional case.
[0104]
Next, the above operation will be described more specifically with reference to FIG.
[0105]
First, the mobile station 131 is in a state where the communication quality with the base station 102 of the change source is good. When the change-destination base station 112 is a base station adjacent to the base station 102 that is performing data link transmission control, there is not much influence of an increase in traffic due to retransmission and an increase in delay time. When the station 102 performs data link transmission control including automatic retransmission request control and the change-destination base station becomes a base station 122 remote from the base station 102 performing the data link transmission control, the mobile station An embodiment will be described in which a packet and data link transmission control information are transferred to the change destination base station 122, and data link transmission control including automatic retransmission request control is performed in the change destination base station 122.
[0106]
At the point (1) in FIG. 3, a packet addressed to the mobile station is input from the network to the base station 102. The base station 102 assigns packet number 1 to the input packet, adds a CRC, stores the packet, and transmits the packet to the mobile station 131. The mobile station 131 transmits an arrival confirmation to the base station 102 because no error is detected in the received packet. Then, the base station 102 deletes the stored packet of the packet number 1 by confirming the arrival of the packet number 1.
[0107]
Next, at the point (2) in FIG. 3, a packet addressed to the mobile station is input to the base station 102. The base station 102 assigns a packet number 2 and adds a CRC, stores the packet, and transmits the packet to the mobile station 131. Since an error is detected in the packet received by the mobile station 131 this time, a NACK (Negative Acknowledgment) signal is transmitted to the base station 102 to request the base station 102 to retransmit the packet with the packet number 2. The base station 102 retransmits the packet with the packet number 2 in response to the retransmission request. However, since an error is detected in the packet received again, the mobile station 131 requests the base station 102 to retransmit the packet number 2 again. At this time, since the communication quality with the base station 112 is better than that with the base station 102, the base station 102 is requested to change the base station via the base station 112. Since the base station 112 is an adjacent base station of the base station 102, the base station 102 performs data link transmission control including automatic retransmission request control as it is, and therefore controls the base station 112 to transmit as it is. Then, the packet with the packet number 2 as the retransmission packet is transmitted to the mobile station 131 via the base station 112. Since the mobile station 131 has not detected an error in the received packet, the mobile station 131 transmits an ACK (Acknowledgment) signal to the base station 102 via the base station 112, thereby transmitting an arrival confirmation to the base station 102. Since the base station 102 confirms the arrival of the packet with the packet number 2, the stored packet with the packet number 2 is deleted.
[0108]
The next packet is input to the base station 102 at the point (3) in FIG. The base station 102 assigns the packet number 3 and adds the CRC, stores the packet, and transmits the packet to the mobile station 131 via the base station 112. Since the mobile station 131 has not detected an error in the received packet, the mobile station 131 transmits an arrival confirmation to the base station 102 via the base station 112. The base station 102 deletes the stored packet of the packet number 3 by confirming the arrival of the packet number 3.
[0109]
The next packet is input to the base station 102 at time (4) in FIG. In the same manner as described above, packet number 4 is added and CRC is added and the packet is stored, and then transmitted to mobile station 131 via base station 112. Here, since an error is detected in the packet received by the mobile station 131, the base station 102 is requested to retransmit the packet number 4 through the base station 112. At this time, since the communication quality with the base station 122 is better than that with the base station 112, the mobile station 131 requests the base station 102 to change the base station via the base station 122. Since the base station 102 is not the adjacent base station, the base station 102 notifies the base station 122 of a change in data link transmission control including automatic retransmission request control.
[0110]
Here, by notifying the mobile station 131 of the base station number that is currently performing data link transmission control, the base station 122 can recognize that it is necessary to perform data link transmission control for the mobile station 131 thereafter. Therefore, in this case, the base station 102 does not need to make the notification. Then, it requests a device that changes the packet transmission destination in the network to input the subsequent packet addressed to the mobile station to the base station 122. This apparatus has a function capable of changing a packet transmission destination using location registration information of the mobile station 131 or the like. In addition, since the base station 102 receives the base station change request immediately after transmitting the retransmission packet with the packet number 4, the mobile station 131 has not notified the arrival confirmation or the retransmission request for the packet. Therefore, the base station 102 does not output the data link transmission control information to the base station 122 until the arrival confirmation of the retransmission packet or a retransmission request is notified. Therefore, the base station 122 at this time is in a state that only keeps accumulating the packets addressed to the mobile station inputted at the time (5) in FIG.
[0111]
Then, it is assumed that the mobile station 131 has not detected an error in the retransmission packet. Therefore, the mobile station 131 transmits an arrival confirmation of the packet number 4 to the base station 102 via the base station 122. Since the arrival of the retransmission packet number 4 has been confirmed in the base station 102, only the fact that the latest packet number is 4 is notified as the data link transmission control information to the base station 122 which is the change destination base station. If there is a packet whose arrival has not been confirmed, the packet number whose arrival has not been confirmed and the latest packet number are notified. Further, since there is no packet addressed to the mobile station that is transmitted and received using the base station 112, the base station 102 notifies the base station 112 of this fact. Thereby, the base station 112 can release the resources of the base station 112 allocated to the mobile station 131.
[0112]
In addition, the base station 122 determines that the packet input from the time point (5) in FIG. 3 and accumulated is the packet number 4 because the latest packet number as the data link transmission control information from the base station 102 is 4. The number 5 is assigned to the packet, and after the CRC is added, the packet is stored and transmitted to the mobile station 131. The mobile station 131 transmits an arrival confirmation to the base station 122 because no error is detected in the received packet. The base station 122 deletes the stored packet of the packet number 5 by confirming the arrival of the packet number 5.
[0113]
As described above, the data link transmission control method of the present invention can be performed regardless of the movement of the mobile station 131 by repeating the above operation.
[0114]
According to the first embodiment, it is not necessary to execute a procedure for resetting the packet number, and the data link transmission control unit of the base station that is directly communicating with the mobile station 131 can be used. Regardless of the movement of the station 131, the data link transfer control can always be performed on the shortest path, the packet transfer delay time can be shortened compared to the conventional case, and the system throughput can be increased.
[0115]
[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. First, it is assumed that the communication quality between the mobile station 131 and the base station 102 is good. That is, the mobile station 131 can communicate only with the base station 102.
[0116]
The base station 102 inputs a packet input from the network 1 to the data link transmission control unit 103 and performs data link transmission control including automatic retransmission request control. In the present embodiment, a case will be described in which one packet is divided into a plurality of blocks so as to be adapted to a radio frame. As specified in FIG. 4B, the data link transmission control unit 103 divides the input packet into a plurality of blocks, and in order to maintain the order of the divided blocks, After assigning a packet number so that the packet before division can be identified, an error detectable parity such as CRC is added and output to the transceiver 5 so that an error occurring during transmission can be detected. The transceiver 5 modulates the input block into a transmission signal, and then transmits the block to the mobile station 131 via the base station antenna 6. FIG. 4A shows a packet configuration in the data link transmission control unit of the first embodiment.
[0117]
On the other hand, in the mobile station 131, after the signal from the mobile station antenna 32 is received by the transceiver 33, the received block is output to the data link transmission control unit 34. The data link transmission control unit 34 performs error detection using the parity added to the input block. If there is no error in the block as a result of detection, the data link transmission control unit 34 notifies the data link transmission control unit 103 of the base station 102 of the arrival confirmation of the block. If there is an error in the block, the data link transmission control unit 34 notifies the data link transmission control unit 103 of the base station 102 of a retransmission request for the block. Then, the data link transmission control unit 103 retransmits the stored block. In this way, when all blocks for one packet are received without error, the data link transmission control unit 34 synthesizes the blocks by performing the reverse operation of dividing the data link transmission control unit 103 into the respective blocks. After forming one packet, the data input terminal 35 outputs the packet.
[0118]
Next, a case where the base station is changed due to movement of the mobile station 131 will be described. In this embodiment, the mobile station can receive packets from a plurality of base stations at the same time without limiting the number of base stations that communicate simultaneously with the mobile station. Further, as described in the first embodiment, it is naturally possible even when the number of simultaneously communicating partner base stations with the mobile station is one.
[0119]
Communication quality between the mobile station 131 and the base station 102 that has been communicating until now is slightly deteriorated, and the communication with the adjacent base station 112 is improved, and communication with the two base stations of the base station 102 and the base station 112 is possible. Suppose that In this case, the mobile station 131 requests the data link transmission control unit 103 of the base station 102 to connect to the base station. Since the communication quality is only slightly deteriorated, the mobile station 131 is in communication with the two stations of the base station 102 and the base station 112, unlike the first embodiment. The data link transmission control unit 103 of the base station 102 that has received the connection request notifies the base station 112 that the mobile station 131 is requesting connection. Then, the data link transmission control unit 103 associates some of the packets addressed to the mobile station 131 that are input thereafter with the packet number, and transmits the packet to the base station 112 via the transfer unit 105. The data link transmission control unit 113 performs automatic retransmission request control for each block, but the data link transmission control unit in either base station associates packet numbers to maintain the order of packets received by the mobile station. Done in In the present embodiment, the data link transmission control unit 103 of the base station 102 associates the packet number. The data link transmission control unit 113 of the base station 112 divides the packet input from the base station 102 into blocks, and then determines the block number and the packet number before division associated with the data link transmission control unit 103. Then, after further adding parity, the data is transmitted to the mobile station 131.
[0120]
Next, it is assumed that the communication quality between the mobile station 131 and the base station 102 is further deteriorated and only communication with the base station 112 is possible. In this case, the mobile station 131 requests the data link transmission control unit 103 of the base station 102 to stop packet transmission from the base station 102 via the base station 112 with good communication quality. Upon receiving the request, the data link transmission control unit 103 of the base station 102 transfers the packet including the block whose arrival has not been confirmed, the packet number of the packet, the block number whose arrival has not been confirmed, and the latest packet number. The data link transmission control information is transmitted to the data link transmission control unit 113 of the base station 112 via the unit 105. The block or packet addressed to the mobile station 131 is stored as it is until a transfer request for the block or packet addressed to the mobile station 131 is received from the base station 112. Further, the packet addressed to the mobile station input from the network 1 is stored as it is until the transfer request is made.
[0121]
At a certain timing, the base station 112 requests the base station 102 that transmitted the data link transmission control information to transfer the packet or block addressed to the mobile station. This certain timing may be a point in time when a signal for promoting data transmission transmitted from the mobile station is received. Upon receiving the transfer request, the data link transmission control unit 103 of the base station 102 deletes all the stored blocks or packets addressed to the mobile station 131 after transferring them to the base station 112, and thereafter the base station 102 The packet addressed to the mobile station 131 arriving at is set to be transferred to the base station 112 as it is. The data link transmission control unit 113 of the base station 112 divides the packet including the block whose arrival has not been confirmed transferred from the base station 102 into each block, and then sends only the block for which retransmission is requested to the mobile station 131. resend. Since the block has a fixed length, only the necessary block can be retransmitted if the input packet and its packet number and block number are known. Further, a new packet addressed to the mobile station 131 input to the base station 112 is given a packet number based on the latest notified packet number. Note that the data link transmission control unit 103 can also transfer only necessary blocks.
[0122]
With the above operation, the data link transmission control method of the present invention can be realized.
[0123]
As described above, since the data link transmission control unit of the base station communicating with the mobile station can be used without resetting the packet number, the data link transfer control is always performed on the shortest path regardless of the movement of the mobile station. Thus, the packet transfer delay time can be shortened compared to the conventional case, and the system throughput can be increased.
[0124]
The data link transmission control information includes the following items, and any of them can be adopted. (1) Packet number for which arrival confirmation has not been performed, (2) Packet number for which arrival confirmation has been performed, (3) Packet number for which retransmission has been requested, (4) Latest packet number, (5) Block number for which arrival confirmation has not been performed, (6) Block number for which arrival confirmation has been performed, (7) Block number for which retransmission has been requested, (8) Latest block number, (9) Above (1) to Items such as the combination of (8) can be adopted.
[0125]
[Third Embodiment]
Next, a third embodiment of the present invention will be described. Initially, the structure of the mobile communication system in 3rd Embodiment is demonstrated based on FIG.7, FIG.22, FIG.23. As shown in FIG. 7, the mobile communication system according to the third embodiment includes a mobile station 231 and a plurality of base stations 202, 212, and 222, and each base station is connected via the network 1. It is possible to communicate with each other.
[0126]
The mobile station 231 includes a transceiver 233 that receives data from the wireless network and transmits data to the wireless network via the mobile station antenna 232, and a data link that performs data link transmission control including automatic retransmission request control described later. The transmission control unit 234 includes a data input / output terminal 235 as an input / output terminal for packet data.
[0127]
Among these, the data link transmission control unit 234 is functionally composed of functional blocks shown in FIG. That is, the data link transmission control unit 234 selects one base station from the base stations upon reception of the packet accumulation notification from the base station, and sends a packet addressed to itself based on the reception quality of each base station. When changing the selection unit 234A that selects one base station to transmit, the transmission request unit 234B that requests the selected base station to transmit a packet, and the base station that transmits a packet addressed to itself, In addition to notifying the base station of the transmission suspension, the change time notification unit 234C for notifying the base station of the change destination of the transmission request and the target first packet number, and measuring the reception quality of signals transmitted from the plurality of base stations Measurement unit 234D, reception quality notification unit 234E for notifying the base station at the position selected based on the reception quality of the reception quality for each base station, and the reception quality for each base station Based on the determination unit 234F that determines which communication state each of the base stations is in a predetermined plurality of communication states, and based on the determination result, the communication state transitions to the base station that should change the communication state And a state transition request unit 234G for requesting. The transceiver 233 includes a diversity receiving unit 233A that performs diversity reception on the packets when receiving the same packets from a plurality of base stations.
[0128]
On the other hand, as shown in FIG. 7, the base station 202 receives a data from a wireless network via a base station antenna 208 and transmits / receives data to / from the wireless network, and an automatic retransmission control described later. A data link transmission control unit 203 that performs data link transmission control including automatic retransmission request control such as assigning a unique number as identification information to each packet for execution, and controls each component in the base station 202; A packet duplication unit 206 that duplicates the packet, a distribution unit 205 that distributes the duplicated packet to other base stations, and a storage unit 204 that functions as a temporary storage area for packet data and the like by the data link transmission control unit 203. It consists of
[0129]
Among these, the data link transmission control unit 203 is functionally composed of functional blocks shown in FIG. That is, the data link transmission control unit 203 includes a packet addressed to the mobile station based on an identification information adding unit 203A for adding identification information for identifying the packet, a timer timeout, or a packet arrival notification from the mobile station. A first deletion unit 203B that deletes the packet, a second deletion unit 203C that deletes the packet based on a timer timeout or notification of the number of the deleted packet from another base station, and the base station as a packet distribution destination base 3rd deletion part 203D which deletes the packet addressed to the mobile station stored in its own station based on a request from the mobile station to be excluded from the station, and notifies the other base station of the number of the packet to be deleted A deletion packet notification unit 203E to be transmitted, a distribution control unit 203F that distributes a packet to a base station that is a new packet distribution destination, and a retransmission request from the mobile station A packet retransmission unit 203G that retransmits the packet in response to the packet, a storage notification unit 203H that notifies the mobile station that the packet is stored when a packet addressed to the mobile station is received and stored, A notification for controlling to transmit a packet to the mobile station and to notify the mobile station that a plurality of packets are accumulated when a transmission request is received from the mobile station while a plurality of packets are accumulated. Control unit 203I, determination unit 203J for determining whether to transmit a packet to be distributed from the own station to the mobile station based on reception quality for each base station, and the determination result And an instruction unit 203K for instructing another base station to perform the transmission operation based on the above. The other base stations 212 and 222 are configured in the same manner as the base station 202.
[0130]
By the way, each of the base stations enters one of the four states shown in FIG. 8A with respect to the mobile station 231 and transitions to each state in response to a request from the mobile station 231. Here, these four states will be described.
[0131]
The first is an idle state. This state is a state in which the base station is not transmitting or receiving packets to the mobile station 231.
[0132]
The second is a packet transmittable state. In this state, when the base station receives a packet from the network 1, it can transmit the packet to the mobile station after adding a unique number to the packet. In addition, this state is a state in which only one base station can be present at a point in time (a plurality of base stations cannot be in the same state at the same time), and the other base stations are in an idle state.
[0133]
The third is a packet duplication and transmission enabled state. This state is a state in which the base station performs the following series of operations. That is, when the base station receives a packet from the network 1, it assigns a unique number to the packet, and then duplicates the packet including the number, and copies the packet (hereinafter referred to as “replicated packet”). Is distributed to other base stations requested by the mobile station 231. When the base station receives a packet transmission request from the mobile station 231, the base station transmits the packet to the mobile station 231. This is a state in which such an operation is performed. In addition, this state is also a state in which only one base station can be present at a point in time (a plurality of base stations cannot be in the state at the same time), and the other base stations are in a duplicate packet transmission state described later, Or it is idle.
[0134]
The fourth is a state where a duplicate packet can be transmitted. In this state, when the base station receives a duplicate packet from a base station in a state where packet duplication and transmission is possible, and the base station receives a request for packet transmission from the mobile station 231, the duplicate packet can be transmitted to the mobile station. State. This state is a state that occurs in another base station when a certain base station transitions to a packet duplication and transmittable state.
[0135]
Next, the operation of the third embodiment will be described. First, operations of the base station and the mobile station 231 in each of the above states will be described.
[0136]
(1) Operation of base station and mobile station in packet transmission enabled state
If the following equation (1) holds, Ψ _i The i-th base station with = 1 becomes ready for packet transmission to the mobile station 231 and Ψ _j Other (i ≠ j) base stations in which = 0 are in an idle state.
[0137]
[Expression 1]

[0138]
Here, Pmed (i) is a time-average received power value (for example, a median short-term received power) related to a broadcast signal or a common pilot signal transmitted by the i-th base station, or the time-average The ratio between the received power and the interference power (hereinafter referred to as “time-average received power to interference power ratio”). Pmed_max represents the maximum value of the time-average received power value or the maximum value of the time-average received power to interference power ratio for the first to Nth base stations. Ψ _i Represents a binary value (1 or 0) as a result of comparing and determining the difference between Pmed_max and Pmed (i) with respect to a predetermined threshold Th. Further, in the present embodiment, a case where N = 3 will be described, and the base station 202, the base station 212, and the base station 222 in FIG. 7 are respectively set as the first base station, the second base station, and the third base station. As a base station.
[0139]
The case where the above formula (1) is established means that a plurality of base stations (in this embodiment, base stations are measured) at the mobile station 231 as in the case where the mobile station 231 is located at the point A in FIG. 202 to base station 222) is a case where a time-average received power value such as a broadcast signal or a common pilot signal or a received power-to-interference power ratio is increased by one. This is, for example, Ψ ₁ = 1, Ψ ₂ = 0, Ψ _Three In this case, the base station 202 is ready to transmit a packet to the mobile station 231 and the base station 212 and the base station 222 are in an idle state.
[0140]
Processing when a packet arrives at the base station in the packet transmission enabled state will be described with reference to FIG. The base station 202 assigns a unique number to the packet arriving from the network 1 by the data link transmission control unit 203, and stores it after adding CRC or the like for error detection of the received packet at the mobile station. (S301 and S302 in FIG. 10). Then, the data link transmission control unit 203 transmits the packet to the mobile station 231 by controlling the packet duplication unit 206 to output the packet duplication unit 206 as it is to the transceiver 207 (S303). The mobile station 231 performs error detection processing (S304) on the received packet, and if no error is detected, notifies the base station 202 of packet arrival confirmation (S305 and S306). If an error is detected, the mobile station 231 notifies the base station 202 of a packet retransmission request (S305 and S307). When the notification from the mobile station 231 is the arrival confirmation, the base station 202 deletes the accumulated packet corresponding to the unique number (S308 and S310). When the notification from the mobile station 231 is a retransmission request, the base station 202 retransmits the packet corresponding to the unique number (S308 and S309).
[0141]
(2) Operation of base station and mobile station in idle state
As mentioned above, Ψ _j The j-th base station with = 0 is in an idle state with respect to the mobile station.
[0142]
Processing when a packet arrives at the idle base station will be described with reference to FIG. Here, base station 212 and base station 222 are in an idle state. In the base station 212 in the idle state, the data link transmission control unit 213 controls the distribution unit 215 so that the packet addressed to the mobile station 231 is directly transferred to another base station or the base station 202 in a packet transmission enabled state. . Therefore, when the packet arrives at the base station 212, the base station 212 transfers the packet to another base station or the base station 202 that is a transfer destination (S311 and S312 in FIG. 11).
[0143]
Since the base stations 212 and 222 have the same configuration, even when a packet arrives at the base station 222, the same operation as described above is performed.
[0144]
(3) Operation of base station and mobile station in packet duplication and transmission enabled state, and duplicate packet transmission enabled state
If the following equation (2) holds, Ψ _i Any one of the plurality of base stations with = 1 becomes a packet duplicating and transmitting state to the mobile station 231, and Ψ _i = 1 and the base station that is not in the packet duplication / transmission enabled state enters the duplicate packet transmission enabled state.
[0145]
[Expression 2]

The symbols used are the same as in equation (1).
[0146]
When Expression (2) holds, the time average received power value or the time average received power measured at the mobile station 231 as in the case where the mobile station 231 is located at the point B in FIG. When a plurality of interference power ratios are large, for example, as in this embodiment, Ψ ₁ = 1, Ψ ₂ = 1, Ψ _Three = 0, and one of the base station 202 and the base station 212 is in a packet duplication and transmission enabled state. Any one of these base stations may be a base station that is in a packet transmittable state before the transition, or a base station having a large time average received power value or a time average received power to interference power ratio. Is possible. In the present embodiment, the description will be continued assuming that the base station 202 is in a packet duplication and transmission enabled state and the base station 212 is in a replicated packet transmission enabled state.
[0147]
Processing when a packet arrives at the base station 202 in a packet duplication and transmission enabled state will be described with reference to FIG. The base station 202 adds a unique number to the packet arriving from the network 1, adds a CRC or the like for error detection of the received packet at the mobile station, stores the packet, and The packet is duplicated including S (S321 and S322 in FIG. 12). Then, the base station 202 distributes the duplicate packet to the base station 212 that is ready to transmit the duplicate packet (S323), and the base station 212 accumulates the distributed packet (S324). Further, the base station 202 notifies the mobile station 231 that the packets addressed to the mobile station 231 are accumulated (S325b).
[0148]
Further, as described above, the mobile station 231 is in a state in which the base station having the maximum time-average received power value or the time-average received power-to-interference power ratio is in a packet duplication and transmission enabled state. Request a transition. Thereby, the base station which notifies the mobile station 231 of a new packet can be made into one. This can be realized because the base station with the highest time-average reception quality is notified. In this case, extra power for the notification can be reduced and interference can be suppressed.
[0149]
However, if the influence of the interference does not matter so much, as shown in S325b and S325a of FIG. 12, the base station that received the packet (the base station in the packet duplication and transmission enabled state or the base station in the duplicate packet transmission enabled state) It is also possible to notify the mobile station 231 each of the stations).
[0150]
The mobile station 231 that has received the notification instantaneously transmits signals such as broadcast signals and common pilot signals transmitted from a plurality of base stations (two stations of the base station 202 and the base station 212 in this embodiment) at that time. A base station having the maximum received power or instantaneous received power to interference power ratio is selected (S326), and the selected base station is requested to transmit a packet to the mobile station 231 (S327). A specific method for this request is made possible by requesting the base station for the number of the base station that can identify the base station and the number of the notified packet.
[0151]
In addition, the request method is a method of directly requesting a selected base station via an uplink, or a request received by an unselected base station is notified to the selected base station via the inter-base station network. Can be adopted. This is because the instantaneous reception quality between the mobile station and each base station differs between the uplink and the downlink, and even if the downlink reception quality is the highest between the selected base station and the mobile station, the reception of the uplink This is because the quality can be the highest between other base stations and mobile stations.
[0152]
Then, the base station (base station 202 in this embodiment) that has received the request transmits the packet to the mobile station 231 (S328). At this time, the base station 202 may notify the mobile station 231 that a plurality of packets addressed to the mobile station 231 are accumulated. This is because the base station does not need to notify again about the subsequent packets accumulated by this.
[0153]
The mobile station 231 performs error detection processing (S329) on the received packet, and when no error is detected, notifies the base station 202 of packet duplication and transmission possible state when the error is not detected (S330 and S331). This notification may be made directly to the base station 202 or via the base station 212. If an error is detected, the mobile station 231 selects a base station that has the highest instantaneous or time-average reception quality at that time (S332), and requests the base station to retransmit the packet. Notification is made (S333).
[0154]
Receiving the arrival confirmation, the base station 202 deletes the accumulated packet corresponding to the unique number (S334 and S337). In addition, the base station 202 notifies the base station 212 of the packet transmission enabled state (S336). Receiving the notification, the base station 212 deletes the duplicate packet accumulated by the notification (S338).
[0155]
On the other hand, when receiving the retransmission request, the base station 202 retransmits the packet corresponding to the unique number (S333, S334, S335).
[0156]
As described above, without providing a line control station for distributing packets separately from the base station, packets are accumulated in each base station, and one or a plurality of base stations transmit packets to the mobile station. The traffic in the network can be reduced, and the throughput of the system can be improved by increasing the throughput by shortening the packet transmission delay time.
[0157]
In FIG. 12, the three methods shown in FIG. 14 can be adopted for the copy packet deletion notification in S336 from the base station 202 to the base station 212.
[0158]
That is, in the first method, as shown in FIG. 14A, the base station 202 notifies the base station 212 of the unique packet number of the packet to be deleted every time the arrival confirmation from the mobile station in S331 is received. (A1). At this time, the corresponding packet stored in the base station 202 may be deleted simultaneously with the notification.
[0159]
In the second method, the base station 202 notifies the latest packet number within a predetermined time. That is, the base station 202 starts the process of FIG. 14B upon receiving the arrival confirmation from the mobile station in S331, starts a deletion timer in which a predetermined deletion interval time is set (B1), and The packet number corresponding to the arrival confirmation is stored (B2). At this time, the corresponding packet stored in the base station 202 may be deleted at the same time. Thereafter, when a new arrival confirmation is received (positive determination at B3), the packet number corresponding to the arrival confirmation is stored (B2). When the deletion timer times out (positive determination at B4), the latest packet number among the packet numbers stored at that time, that is, the arrival confirmation received within the predetermined time counted by the timer is used. The number of the latest packet among the corresponding packets is notified (B5).
[0160]
Further, in the third method, the base station 202 performs notification by deleting a specific packet (for example, every 10 deleted packets). That is, the base station 202 starts the processing of FIG. 14C by receiving the arrival confirmation from the mobile station in S331, resets the counter n = 1 (C1), and then receives a packet corresponding to the above arrival confirmation. The number is stored (C2). At the same time as this storage, the corresponding packet stored in the base station 202 may be deleted (the same applies to C5). Thereafter, when a new arrival confirmation is received (positive determination at C3), the counter n is incremented by one (C4), and the packet number corresponding to the arrival confirmation is stored (C5). When the counter n reaches 10, that is, when arrival confirmation is received for 10 packets, an affirmative determination is made in C6, and the latest packet number among the packet numbers stored at that time is notified (C7). ).
[0161]
Among the above methods, the first method has an advantage in that buffer management becomes easy although the frequency of notification is high and the amount of traffic due to notification is large. In general, the second method has an advantage that the amount of traffic due to notification is reduced although the frequency of notification is low and buffer management becomes complicated. The third method is generally in an intermediate position between the first and second methods in terms of both traffic and buffer management.
[0162]
In the present embodiment, by appropriately adopting the above three methods, it is possible to control both the traffic amount and the buffer management with a good balance.
[0163]
By the way, a timer may be employed as a trigger for deleting packets accumulated in the base stations 202 and 212 in FIG. This example will be described with reference to FIG.
[0164]
That is, as shown in FIG. 13, the base station 202 assigns a unique number to the packet arriving from the network 1 and adds a CRC or the like for error detection of the received packet at the mobile station. The packet is accumulated and the packet is duplicated including the number (S321 and S322X in FIG. 13). At this time, the base station 202 starts a deletion timer for timing the deletion timing regarding the accumulated packets, triggered by the input of the packet to the base station 202 at this time. Note that the base station 202 may start a deletion timer when the target packet is transmitted for the first time.
[0165]
Then, the base station 202 distributes the duplicate packet to the base station 212 that is in a state where the duplicate packet can be transmitted (S323). The base station 212 accumulates the distributed packets, and starts a deletion timer that measures the deletion timing for the accumulated packets, triggered by the input of the packets to the base station 212 (S324X). Further, the base station 202 notifies the mobile station 231 that the packets addressed to the mobile station 231 are accumulated (S325b).
[0166]
Further, as described above, the mobile station 231 performs state transition so that the base station having the maximum time-average received power value or the time-average received power to interference power ratio is in a packet duplication and transmission enabled state. , It is possible to make one base station that notifies a mobile station of a new packet. This can be realized because the base station with the highest time average reception quality is notified. In this case, extra power for the notification can be reduced and interference can be suppressed.
[0167]
However, if the influence of the interference does not matter so much, as shown in S325b and S325a of FIG. 12, the base station that received the packet (the base station in the packet duplication and transmission enabled state or the base station in the duplicate packet transmission enabled state) It is also possible to notify the mobile station 231 each of the stations).
[0168]
The mobile station 231 that has received the notification receives instantaneous reception power of signals such as broadcast signals and common pilot signals transmitted from a plurality of base stations (two stations of the base station 202 and the base station 212 in this case) at that time, or A base station that maximizes the instantaneous received power to interference power ratio is selected (S326), and the base station is requested to transmit the packet (S327). A specific method for this request is made possible by requesting the base station for the number of the base station that can identify the base station and the number of the notified packet.
[0169]
The requesting method is a method of directly requesting the selected base station via an uplink, or notifying the selected base station of the request received by the unselected base station via the inter-base station network. The method can be adopted. This is because the instantaneous reception quality between the mobile station and each base station differs between the uplink and the downlink, and even if the downlink reception quality is the highest between the selected base station and the mobile station, the reception of the uplink This is because the quality can be the highest between other base stations and mobile stations.
[0170]
The base station (in this case, the base station 202) that has received the request transmits the packet to the mobile station 231 (S328). At this time, the base station 202 may notify the mobile station 231 that a plurality of packets addressed to the mobile station 231 are accumulated.
[0171]
The mobile station 231 performs error detection processing (S329) on the received packet, and when no error is detected, notifies the base station 202 of packet duplication and transmission possible state when the error is not detected (S330 and S331). This notification may be made directly to the base station 202 or via the base station 212. If an error is detected, the mobile station 231 selects a base station that has the highest instantaneous or time-average reception quality at that time (S332), and requests the base station to retransmit the packet. Notification is made (S333).
[0172]
Thereafter, when receiving a retransmission request from the mobile station 231, the base station 202 retransmits a packet corresponding to the unique number (S333, S334, S335).
[0173]
In the example of FIG. 13, in the base station 202, when the deletion timer started in S322X times out, the stored packet corresponding to the timer is deleted (S336X and S337). The base station 212 also deletes the stored packet corresponding to the timer when the deletion timer started in S324X times out (S336Y and S338).
[0174]
According to such processing in FIG. 13, it is not necessary to perform deletion notification (S336 in FIG. 12), so that an increase in traffic between base station networks due to these control packets can be suppressed. Further, since arrival confirmation of packets from the mobile station (S331 in FIG. 13) is not necessarily required, further traffic reduction can be achieved. Note that the timeout value of the deletion timer in FIG. 13 is set to a time when a retransmission request for the packet is considered not to arrive.
[0175]
By the way, although this embodiment demonstrated the case where there was one base station (FIG. 12, FIG. 13) which transmits a packet, when interference etc. do not become a problem so much, or the same packet transmitted from several base stations is moved. When the reception quality can be improved by diversity reception in the station, the base station 202 and the base station 212 can also transmit the same packet. Next, this example will be specifically described with reference to FIG.
[0176]
The base station 202 adds a unique number to the packet arriving from the network 1, adds a CRC or the like for error detection of the received packet at the mobile station, stores the packet, and The packet is duplicated including S (S341 and S342 in FIG. 15). Then, the base station 202 distributes the duplicate packet to the base station 212 that is ready to transmit the duplicate packet (S343), and the base station 212 accumulates the distributed packet (S344).
[0177]
Next, each of the base station 202 and the base station 212 notifies the mobile station that there is a stored packet (S345). When the mobile station is in a state where it can receive a packet, the notification in S345 can be omitted. Then, each of the base station 202 and the base station 212 transmits the accumulated packet to the mobile station (S346).
[0178]
The mobile station 231 performs error detection processing (S347) for the received packet. At this time, it is also possible to perform diversity on the same packet transmitted from a plurality of base stations. As the diversity method, the first method of combining the same bits of the same received packet for each bit as it is, or the first method of combining for each bit after weighting with the received power or the received power to interference power ratio. The second method, the third method for selecting a packet in which no error is detected from the packets after error detection, and the like can be employed. If no error is detected, the mobile station 231 notifies the packet arrival confirmation to the base station 202 in a packet duplicatable and transmittable state (S348 and S349).
[0179]
Receiving the arrival confirmation, the base station 202 deletes the accumulated packet corresponding to the unique number (S351 and S355). In addition, the base station 202 notifies the base station 212 that is in a state where the duplicate packet can be transmitted (S354). Receiving the notification, the base station 212 deletes the accumulated duplicate packet based on the notification (S356). The notification in S354 can be omitted by the method using the timer as shown in FIG.
[0180]
On the other hand, when an error is detected in S348, the mobile station notifies the base station 202 or the base station 212 of a packet retransmission request (S350). When the base station 202 receives the retransmission request, the base station 202 redistributes the retransmission packet to the base station 212 or notifies the retransmission packet number (S352). Then, each of the base station 202 and the base station 212 retransmits the requested packet (S353).
[0181]
Further, in FIG. 9, when the mobile station 231 moves and arrives near the point C, a large time-average received power value or a time-average received power to interference power ratio is further obtained. For example, Ψ ₁ = 1, Ψ ₂ = 1, Ψ _Three Similarly, when = 1, the base station 202 distributes a copy of the packet arriving at the base station 202 to the base station 212 and the base station 222.
[0182]
Next, operations of the base station and the mobile station in various events transitioning from one state to another state shown in FIG. 8B will be described.
[0183]
(4) Explanation of event A
In the mobile station, the mobile station 231 shifts from the state in which the above-described equation (1) is satisfied to the state in which the equation (2) is satisfied, so that the mobile station 231 can transmit the base station (Ψ _i Request to transition to a packet duplication and transmittable state, and a new Ψ _i It is event A to request the base station in the idle state that becomes = 1 to make a transition to the replica packet transmittable state (see FIGS. 8A and 8B).
[0184]
A base station that makes a transition from the packet transmittable state to the packet copy and transmittable state will be described as a base station 202, and a base station that makes a transition from the idle state to the replicated packet transmit state will be specifically described with reference to FIG.
[0185]
When the equation (1) is changed to the equation (2), the mobile station 231 shifts to the packet duplication and transmission enabled state for the base station 202, and newly _i The base station number that identifies the base station 212 that has become = 1 is notified to the base station 202 (S361 and S362 in FIG. 16).
[0186]
Receiving the notification, the base station 202 requests the base station 212 to transition to a copy packet transmittable state (S363) and copies the packet addressed to the mobile station 231 stored at that time. (S364) and distribute the duplicate packet to the base station 212 (S366). Then, the base station 202 transitions to a packet duplication and transmission enabled state (S367).
[0187]
In response to the transition request from the base station 202, the base station 212 transitions to a copy packet transmittable state (S365). Further, the base station 212 accumulates the distributed copy packet (S368). As a result, even if retransmission is requested to the base station 212, it is possible to perform retransmission immediately.
[0188]
Packets that arrive at the base station 202 thereafter are duplicated by the base station 202 and distributed to the base station 212 as described above.
[0189]
(5) Explanation of event B
In the mobile station, the transition from the state in which the equation (2) is established to the state in which the equation (1) is established makes it possible for the base station in a state where the duplicate packet can be transmitted to _i = 0, and only the base station in a state where packet duplication and transmission are possible is Ψ. _i = 1 (other base stations are Ψ _i = 0), the mobile station 231 requests the base station in the packet duplicatable and transmittable state to transition to the packet transmittable state, and sets the base station in the duplicate packet transmittable state to the idle state. Requesting a transition is event B (see FIGS. 8A and 8B).
[0190]
A base station that transitions from a packet duplication / transmission enabled state to a packet transmittable state is referred to as base station 202, and a base station that transitions from a duplicate packet transmittable state to an idle state is referred to as base station 212, which will be described in detail with reference to FIG. .
[0191]
The mobile station 231 transitions to a packet transmittable state with respect to the base station 202 when Formula (1) is satisfied from Formula (2), and Ψ _i = 0 That is, the base station number that identifies the base station 212 in the idle state is notified to the base station 202 (S371 and S372 in FIG. 17). Since the two base stations handle packets addressed to the mobile station, a method of requesting to the base station 212 is also possible. In this case, it is possible to request the base station 212 to transition to the idle state and to notify the base station number (base station 202) to transition to the packet transmittable state. In the present embodiment, the description will be continued as the former method.
[0192]
Receiving the notification, the base station 202 requests the base station 212 to transition to an idle state (S373), and transitions to a packet transmittable state (S374).
[0193]
The base station 212 shifts to the idle state and deletes the accumulated packet (S375). The base station 202 does not copy any packet that arrives thereafter, and does not distribute it to other base stations.
[0194]
(6) Explanation of event C
In the mobile station, the base station in the packet duplication and transmission enabled state is changed from the state in which Equation (2) is established to the state in which Equation (1) is established. _i = 0, and the base station that is ready to transmit duplicate packets is Ψ _i When = 1, the mobile station 231 requests the base station in the packet duplication and transmission enabled state to transition to the idle state, and transits to the packet transmission ready state in the base station in the duplicate packet transmission ready state. It is event C to request to do.
[0195]
A base station that transitions from a packet duplication / transmission enabled state to an idle state is referred to as a base station 202, and a base station that transitions from a duplicate packet transmittable state to a packet transmittable state is referred to as a base station 212, which will be specifically described with reference to FIG. .
[0196]
When the mobile station 231 enters a state in which the formula (1) is established from the formula (2), the mobile station 231 shifts to the idle state with respect to the base station 202 and specifies the base station 212 that transitions to the packet transmittable state. The base station 202 is notified of the station number (S381 and S382 in FIG. 18).
[0197]
Receiving the notification, the base station 202 requests the base station 212 to shift to a packet transmittable state. Since the base station to which the unique number is assigned is changed, the base station 202 further stores the packet currently accumulated (packet for which arrival confirmation has not been obtained) as specified in the first embodiment. And the latest value of the unique number assigned to the packet are notified (S383a). When this event occurs, the base station 212 also accumulates packets, so it is possible to send only different packets accumulated at both base stations by making an inquiry to the base station 212 (S383b). . Therefore, either method of S383a or S383b is performed.
[0198]
Then, the base station 202 transitions to the idle state and deletes the accumulated packets (S384). In addition, when the base station 202 receives a packet addressed to the mobile station 231 in the idle state, the base station 202 sends the packet to the base station 212 as described in “(2) Operation of the base station and mobile station in the idle state”. Control to transfer as it is.
[0199]
On the other hand, the base station 212 transitions to a packet transmittable state in response to a transition request from the base station 202 (S385).
[0200]
(7) Explanation of event D
In the mobile station, a transition is made from the state in which Equation (1) is established to the state in which Equation (2) is established, and a new Ψ _i When the time average received power value or the time average received power-to-interference power ratio from the base station that becomes = 1 is maximized, the mobile station 231 can transmit the base station (Ψ _i Request to transition to a replica packet transmittable state, and a new Ψ _i It is an event D to request the base station in the idle state where = 1 to make a transition to a packet duplication and transmittable state.
[0201]
A base station that transitions from a packet transmittable state to a replicated packet transmittable state is referred to as base station 202, and a base station that transitions from an idle state to a packet replicated and transmittable state is referred to as base station 212, which will be described in detail with reference to FIG. .
[0202]
When the formula (1) is changed to the formula (2), the mobile station 231 shifts to a copy packet transmittable state with respect to the base station 202 and newly shifts to a packet copy and transmittable state. The base station 202 is notified of the base station number that identifies the base station (S391 and S392 in FIG. 19).
[0203]
Receiving the notification, the base station 202 requests the base station 212 to transition to a packet duplication and transmission enabled state. Then, since the base station to which the unique number is assigned is changed, the base station 202 further transmits the packet (arrival confirmation can be obtained) currently stored in the base station 202, as specified in the first embodiment. The packet number) and the latest value of the unique number assigned to the packet (S393). This is because the base station 212 makes a transition from an idle state in which packets addressed to the mobile station are not accumulated. Then, the base station 202 transitions to a copy packet transmittable state (S394).
[0204]
Based on these notifications, the base station 212 transitions to a packet duplication and transmittable state and accumulates the packets sent from the base station 202 (S395). Then, the base station 212 controls to duplicate a packet that newly arrives at the base station 212 and distribute the duplicate packet to the base station 202.
[0205]
(8) Explanation of event E
In the mobile station, the equation (2) is established, and the mobile station 231 is changed due to a change in the base station that maximizes the time-average received power value or the time-average received power to interference power ratio. Requesting a base station in a packet duplication and transmission enabled state to make a transition to a duplicate packet transmission ready state and requesting a base station in a duplicate packet transmission ready state to make a transition to a packet replication and transmission ready state Is event E.
[0206]
The base station that transitions from the packet duplication and transmission enable state to the duplicate packet transmission ready state is the base station 202, and the base station that transits from the duplicate packet transmission possible state to the packet duplication and transmission possible state is the base station 212 with reference to FIG. This will be specifically described.
[0207]
When the base station having the maximum time-average received power value or time-average received power to interference power ratio changes from the base station 202 to the base station 212, the mobile station 231 transmits a duplicate packet to the base station 202. A request is made to make a transition to a possible state and a request is made to the base station 212 to make a transition to a packet duplication and transmission possible state (S401 and S402 in FIG. 20).
[0208]
Receiving the notification, the base station 202 shifts to a copy packet transmittable state (S404). Then, since the base station to which the unique number is assigned is changed, the base station 202 specifies the number of the packet (packet for which arrival confirmation has not been obtained) currently stored, as specified in the first embodiment. And the latest value of the unique number assigned to the packet. In addition, since the base station 212 also stores the packets, the base station 202 can transmit only different packets stored in both base stations by making an inquiry to the base station 212 (S403). ). The packets stored in the base station 202 are stored as they are. However, in the case of a method of deleting due to timeout, a deletion timer is started at this point for all the stored packets.
[0209]
Based on these notifications, the base station 212 transitions to a packet duplication and transmittable state (S405). Then, the base station 212 controls to duplicate a packet that newly arrives at the base station 212 and distribute the duplicate packet to the base station 202.
[0210]
According to the third embodiment described above, without providing a line control station for distributing packets separately from the base station, packets are accumulated in each base station, and one or a plurality of base stations transmit the packets to the mobile station. Therefore, the traffic in the network can be reduced, and the throughput of the system can be improved by increasing the throughput by reducing the packet transmission delay time.
[0211]
[Fourth Embodiment]
Next, operations related to handover transmission control will be described with reference to FIG. The configuration of the mobile communication system is the same as that of the third embodiment shown in FIG.
[0212]
The mobile station obtains time-average reception quality (eg, propagation loss here) between the mobile station and the plurality of base stations by receiving broadcast signals, common pilot signals, and the like transmitted from the plurality of base stations. Then, the mobile station notifies the obtained time-average reception quality to the base station in a packet duplicating and transmitting enabled state to which a unique number is added. The base station in the packet duplicatable and transmittable state instructs each base station in the replica packet transmittable state to transmit in units of packets based on the notified plurality of time average reception qualities. Each base station transmits a new packet according to the instruction. Also, at the time of retransmission, only the base station that has requested retransmission by the mobile station retransmits the packet.
[0213]
The transmission instruction in units of packets by the base station to which the unique number is added is specifically executed as follows. The base station to which the unique number is added uses the plurality of time-average propagation losses to calculate S based on the following equation (3). _i (J) is obtained and the S is determined for the packet input to the local station. _i “Identifiers that instruct transmission” are added in order of base stations having the smallest (j). The S _i When (j) is the same, the base station to which the unique number is added adds “an identifier for instructing transmission” to the base station having a smaller time-average propagation loss. For the propagation loss of the following equation (3), the desired signal / interference power ratio (CIR), the received signal / interference power ratio (SIR), and the desired signal / noise power, which are indicators of reception quality, are further shown. Any of the ratio (CNR) and the received signal-to-noise power ratio (SNR) may be used.
[0214]
[Equation 3]

[0215]
Where i is the base station number and j is L _i Represents the number of packets input after the update.
[0216]
As an example, an operation after the time average propagation loss is updated in a state where there are three base stations (i = 1 to 3) capable of transmitting packets to the mobile station will be described. Further, i = 1 is a base station in a packet duplication and transmission enabled state, i = 2 and 3 are base stations in a replicated packet transmission enabled state, and the respective time average propagation losses are as follows.
[0217]
Propagation loss between the first base station (i = 1) and the mobile station: L ₁ = 1
Propagation loss between the second base station (i = 2) and the mobile station: L ₂ = 2
Propagation loss between the third base station (i = 3) and the mobile station: L _Three = 3
[0218]
The first packet after the update of the time average propagation loss is defined as the Kth packet. Each S at this point _i Since (j) is all zero, the base station to which the unique number is added adds an identifier so as to transmit from the first base station having the smallest propagation loss.
[0219]
This identifier can be 1 bit long. That is, a packet with an identifier of “1” is operated to transmit, and a packet with an identifier of “0” is operated to accumulate without being transmitted, so that an instruction with a 1-bit identifier can be made. . Each S after the addition of the identifier _i (J) Values are as follows.
[0220]
[Expression 4]

[0221]
Next, the (K + 1) th packet is input. At this point S ₂ (0) and S _Three Since (0) is zero, the base station to which the unique number is added adds an identifier for transmission from the second base station having a smaller propagation loss. And each S at this point _i (J) Values are as follows.
[0222]
[Equation 5]

[0223]
When the (K + 2) th packet is input, S _Three Since only (0) is zero and the minimum value, the base station to which the unique number is added adds an identifier so as to transmit from the third base station. And each S at this point _i (J) Values are as follows.
[0224]
[Formula 6]

[0225]
In this way, the base station to which the unique number is added copies the input packet and, when distributing the duplicate packet, allows transmission of the packet to a certain base station based on the above equation (3). Enable the identifier for. FIG. 21 shows the calculation result of equation (3) and the state of the identifier for the subsequent (K + 3) to (K + 10) th packets.
[0226]
As shown in FIG. 21, when the (K + 3) -th packet is input thereafter, S as described above. ₁ Since (1) is the minimum value, the base station to which the unique number is added adds an identifier so as to transmit from the first base station.
[0227]
When the (K + 4) th packet is input, S ₁ (2) and S ₂ Since (1) is equal to “2/6”, the base station to which the unique number is added adds an identifier so as to be transmitted from the first base station having a smaller propagation loss.
[0228]
When the (K + 5) th packet is input, S ₂ Since (1) is the minimum value, the base station to which the unique number is added adds an identifier so as to be transmitted from the second base station.
[0229]
When the (K + 6) th packet is input, S ₁ (3) and S _Three Since (1) is equal to “3/6”, the base station to which the unique number is added adds an identifier so as to transmit from the first base station having a smaller propagation loss.
[0230]
When the (K + 7) th packet is input, S _Three Since (1) is the minimum value, the base station to which the unique number is added adds an identifier so as to transmit from the third base station.
[0231]
When the (K + 8) th packet is input, S ₁ (4) and S ₂ Since (2) is equal to “4/6”, the base station to which the unique number is added adds an identifier so as to transmit from the first base station having a smaller propagation loss.
[0232]
When the (K + 9) th packet is input, S ₂ Since (2) is the minimum value, the base station to which the unique number is added adds an identifier so as to transmit from the second base station.
[0233]
When the (K + 10) th packet is input, S ₁ Since (5) is the minimum value, the base station to which the unique number is added adds an identifier so as to transmit from the first base station.
[0234]
Each base station transmits only a packet having an identifier of 1 to the mobile station.
[0235]
When the time-average propagation loss is updated, the base station to which the unique number is added can reset S by resetting j = 0. _i After clearing (j), the above processing is continued.
[0236]
When the mobile station requests retransmission, the mobile station selects a base station that has the smallest propagation loss at that time, and requests the selected base station to retransmit the packet. The reason why packets can be retransmitted from an arbitrary base station selected by the mobile station in this way is that each base station accumulates distributed duplicate packets.
[0237]
With the configuration and operation described above, each base station can perform appropriate packet transmission based on a time-average propagation loss without performing a procedure for informing packet arrival from a mobile station, Since the retransmission packet can be immediately transmitted from the base station having the minimum propagation loss at that time, it is possible to perform a quick retransmission while reducing interference with other cells or other mobile stations.
[0238]
[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 28, the mobile communication system in the fifth embodiment includes a mobile station 1131 and a plurality of base stations 1102 and 1112 as in the mobile communication system (FIG. 1) of the first embodiment described above. Thus, the base stations can communicate with each other via the network 1.
[0239]
Among these, the configuration of the mobile station 1131 is the same as that of the mobile station 131 of the first embodiment. Regarding the configuration of the base station 1102, a packet duplicating unit 1107 for duplicating a packet is added to the base station 102 of the first embodiment, and the duplicating packet is distributed to other base stations instead of the transfer unit 105 in FIG. In addition, a transfer / distribution unit 1105 is provided that transfers packets to a base station that performs other data link transmission control. The data link transmission control unit 1103 performs data link transmission control including automatic retransmission request control for transmitting and receiving packets to and from the mobile station, and performs data link transmission control instead of data link transmission control information. This is different from the first embodiment in that control base station identification information for identifying a base station to be transmitted is transmitted to the mobile station. Further, the base station 1112 has the same configuration as the base station 1102.
[0240]
Next, the operation in the fifth embodiment will be described. Here, initially, the wireless communication quality between the mobile station 1131 and the base station 1102 is good, but the wireless communication quality between the mobile station 1131 and the base station 1112 is not good. It is assumed that this is an initial state in which only communication is possible. The operation in this initial state will be described with reference to FIG.
[0241]
In the base station 1102, the packet input from the network 1 in S41 of FIG. 29 is input to the data link transmission control unit 1103, and the data link transmission control unit 1103 performs data link transmission control including automatic retransmission request control. Here, the data link transmission control unit 1103 gives identification information to each packet (S42). The identification information used in this embodiment includes packet identification information for enabling identification of a packet input to the data link transmission control unit 1103, and a control base station that performs the data link transmission control (that is, identification information). And control base station identification information for enabling identification of the base station to which the information is assigned. Further, the data link transmission control unit 1103 adds a CRC or the like to the packet for error detection of the received packet, and stores the added packet (that is, a packet with identification information) in the storage unit 104. It outputs to the transmitter / receiver 5 with (S42). The transceiver 5 modulates the packet into a transmission signal, and then transmits the transmission signal to the mobile station 1131 via the base station antenna 6 (S43).
[0242]
On the other hand, the mobile station 1131 receives and demodulates the signal from the mobile station antenna 32 by the transceiver 33, and then inputs the packet obtained by the demodulation to the data link transmission control unit 1034. The data link transmission control unit 1034 performs data link transmission control including automatic retransmission request control, and performs error detection on the input packet using the added CRC (S44). If there is an error in the packet as a result of the detection, the data link transmission control unit 1034 recognizes the number of the packet requesting retransmission and the base station 1102, which is the control base station, based on the assigned identification information. Then, a NACK signal is transmitted to the base station 1102 based on the recognition result (S45). As a result, a retransmission request for the packet is notified to the data link transmission control unit 1103. As this notification method, a method of directly reporting to the base station 1102, a method of notifying through another base station, or the like can be employed. Then, the data link transmission control unit 1103 determines that the ACK signal has not been input (S47), and retransmits the stored packet (S43).
[0243]
On the other hand, if there is no error in the packet in error detection, the data link transmission control unit 1034 recognizes the base station 1102 that is the control base station based on the assigned identification information, and based on the recognition result. An ACK signal is transmitted to the base station 1102 (S46). As a result, the arrival confirmation of the packet is notified to the data link transmission control unit 1103. The data link transmission control unit 1103 determines that the ACK signal has been input (S47), and deletes the packet stored for retransmission (S48).
[0244]
Next, due to the movement of the mobile station 1131, the communication quality between the mobile station 1131 and the base station 1102 that has been communicating with the mobile station 1131 has deteriorated, and has become comparable to the communication quality with the adjacent base station 1102. In this case, as described in the above-described embodiment, the mobile station 1131 requests the base station 1102 to transmit the same packet from the base station 1102 and the base station 1112 (S49). In response to the request, when a packet is input to the base station 1102 after that time (S50), the data link transmission control unit 1103 of the base station 1102 performs the same processing as S42 on the packet (S51) Is transmitted to the mobile station 1131 by the machine 5 (S52), and the packet is duplicated by the packet duplicating unit 1107 (S53), and the duplicated packet is distributed to the data link transmission control unit 1113 of the base station 1112 by the transfer / distribution unit 1105. (S54).
[0245]
Since the data link transmission control unit 1113 is controlled by the data link transmission control unit 1103 to output the distribution packet to the transceiver 15 as it is, the same packet is transmitted from the base station 1102 and the base station 1112 (S52). .
[0246]
Here, whether the data link transmission control unit 1113 outputs the arrived packet as it is or performs data link transmission control including the automatic retransmission request control as described above is that identification information is given to the arrived packet. It becomes possible by detecting whether or not it is. That is, when the data link transmission control unit 1113 detects that identification information is added to the input packet, the data link transmission control unit 1113 outputs the arrived packet to the transceiver 15 as it is. On the other hand, when the data link transmission control unit 1113 detects that the identification information is not given to the input packet, the data link transmission control unit 1113 performs data link transmission control including automatic retransmission request control.
[0247]
The mobile station 1131 performs error detection on the received packet as described above (S55), and outputs NACK or ACK to the base station 1102 (S56 and S57). In the same way as described above, the base station 1102 determines whether or not ACK has been input (S58). If it is NACK, the packet is retransmitted (S52). If it is ACK, the stored packet is deleted. (S59).
[0248]
Next, it is assumed that the communication quality between the mobile station 1131 and the base station 1102 has deteriorated and the communication quality with the base station 1112 has improved. The operation when a packet is transmitted from a plurality of base stations to a mobile station in this transition state will be described with reference to FIG.
[0249]
The mobile station 1131 notifies the data link transmission control unit 1103 of the base station 1102 of a request for changing the base station that executes data link transmission control (S61 in FIG. 30). As for the notification, a method of notifying directly to the base station 1102, a method of notifying through another base station, and the like can be adopted as described above.
[0250]
Upon receiving the base station change request, the data link transmission control unit 1103 requests the base station 1112 that is the change destination to start data link transmission control for the mobile station 1131 via the transfer / distribution unit 1105 (S62). Further, after this time, the packet input to the data link transmission control unit 1103 is set to be transferred to the base station 1112 by the transfer / distribution unit 1105 as it is. Therefore, when a packet is input to the data link transmission control 1103 (S63), the packet is transferred as it is to the base station 1112 by the transfer / distribution unit 1105 (S64).
[0251]
The change source data link transmission control unit 1103 continues the data link transmission control only for the packets stored for retransmission, as is the case with the operations from S52 to S59 in FIG. That is, for these packets, the data link transmission control unit 1103 of the change source performs retransmission control as it is until the arrival confirmation is completed. Also at this time, the same packet is transmitted from the base station 1102 and the base station 1112 to the mobile station 1131 as described above.
[0252]
On the other hand, the data link transmission control unit 1113 of the base station 1112 that is the change destination performs data link transmission including automatic retransmission request control for packets that have arrived without identification information added (packets that have arrived in S64 or S65). Take control. Here, the data link transmission control unit 1113 gives identification information to each packet, adds CRC or the like to the packet for error detection of the received packet, and adds the packet (that is, the identification information is added). (Added packet) is stored in the storage unit 114 (S66) and output to the transceiver 15. The transceiver 15 modulates the packet into a transmission signal, and then transmits the transmission signal to the mobile station 1131 via the base station antenna 16 (S67).
[0253]
The packet provided with the identification information is duplicated by the duplicating unit 1117 (S68), and the duplicated packet is distributed to the data link transmission control unit 1103 of the base station 1102 via the transfer / distribution unit 1115 (S69). In the data link transmission control unit 1103, since identification information is added to the packet, the packet is controlled to be output to the transceiver 5 as it is, so that the same packet is transmitted from the base station 1102 and the base station 1112. (S67).
[0254]
The mobile station 1131 performs error detection on the received packet as described above (S70), recognizes the base station 1112, and outputs NACK or ACK to the base station 1112 (S71 and S72). The base station 1112 determines whether or not an ACK has been input (S73). If it is NACK, the packet is retransmitted (S67). If it is ACK, the stored packet is deleted (S74).
[0255]
Next, in the same manner as described above, packets are transmitted from a single base station to the mobile station in a transition state in which the communication quality between the mobile station 1131 and the base station 1102 deteriorates and the communication quality with the base station 1112 becomes better. The operation in this case will be described with reference to FIG.
[0256]
As described in the above-described embodiment, the data link transmission control unit 1113 of the base station 1112 receives a request for receiving packet transmission from only the base station 1112 from the mobile station 1131 (S81 in FIG. 31). Control not to duplicate the packet. Therefore, when a packet is input to the base station 1102 after that time (S82), the packet is transferred to the base station 1112 (S83), and the above-described processing is executed only by the base station 1112 (S84 to S90). .
[0257]
That is, the data link transmission control unit 1113 of the base station 1112 gives identification information to each packet, adds CRC or the like to the packet for error detection of the received packet, and adds the packet (that is, , The packet to which the identification information is attached) is stored in the storage unit 114 (S84) and output to the transceiver 15. The transceiver 15 modulates the packet into a transmission signal, and then transmits the transmission signal to the mobile station 1131 via the base station antenna 16 (S85).
[0258]
The mobile station 1131 performs error detection on the received packet as described above (S86), recognizes the base station 1112 and outputs NACK or ACK to the base station 1112 (S87 and S88). The base station 1112 determines whether or not an ACK has been input (S89). If it is NACK, the packet is retransmitted (S85). If it is ACK, the stored packet is deleted (S90).
[0259]
As described above, the control base station that performs data link transmission control transmits control base station identification information for identifying the control base station to the mobile station instead of the data link transmission control information. Can recognize the control base station based on the control base station identification information, and the mobile station can perform data link transmission control including automatic retransmission request control (for example, a new base station and Connection request, etc.). In this way, the mobile station and the base station can reduce the amount of control information transmitted and received by performing data link transmission control using the control base station identification information instead of the data link transmission control information. The amount of network traffic can be reduced.
[0260]
Further, in the present embodiment, the identification information has always been described as including information for identifying a base station and information for identifying a packet. However, only the data link transmission control unit of one base station performs automatic retransmission. In a state where data link transmission control including request control is being executed, the data link transmission control unit of two or more base stations includes identification information only with information for identifying a packet, and data link transmission control includes automatic retransmission request control. In a state in which transmission control is being executed, the present invention is possible without increasing the number of bits of identification information by configuring identification information with information identifying a packet and information identifying a base station.
[0261]
[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, the first method for transferring only the data link transmission control information from one base station to another base station, the data link transmission control information and the packet are simultaneously transferred, or identification information is added. A second method for transferring the received packets will be described in order. In this embodiment, a case where an IP (Internet Protocol) packet is used will be described. However, the present embodiment is applicable to any packet having a packet configuration similar to that of the IP packet.
[0262]
First, the first method will be described. FIG. 32 shows an example of a device configuration for executing the first method. In the mobile communication system shown in FIG. 32, a plurality of base stations 2102 and 2112 can communicate with each other via the network 1.
[0263]
The base station 2102 includes a transceiver 5 that receives data from the wireless network and transmits data to the wireless network via the base station antenna 6, and a data link that includes the automatic retransmission request control described in the first embodiment. A data link transmission control unit 2103 that performs transmission control and controls each component in the base station 2102, and transmits data link transmission control information to the base station to be changed when receiving a request to change the base station An encapsulation and transfer unit 2105 that performs encapsulation described later, a storage unit 2104 that functions as a temporary storage area for packet data and the like by the data link transmission control unit 2103, and decapsulates the received encapsulated packet (capsule And a decapsulation unit 2106.
[0264]
Of these, the encapsulation and transfer unit 2105 is functionally composed of functional blocks shown in FIG. That is, the encapsulation and transfer unit 2105 includes the encapsulation unit 2105A that encapsulates the data link transmission control information and the packet to be transferred, and the data link transmission control information that represents the length of the encapsulated packet obtained by the encapsulation. The total value of the length of the packet and the length of the packet to be transferred is recorded in the header of the encapsulated packet, and the encapsulated packet transfer unit 2105B that transfers the encapsulated packet is recorded in the header of the encapsulated packet that has been transferred When the length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet is not equal to the length of the packet to be transferred recorded in the header of the packet to be transferred, Is configured to include data link transmission control information, It is constituted comprise.
[0265]
The other base station 2112 is configured in the same manner as the base station 2102 as described above.
[0266]
Next, the operation according to the first method will be described. The data link transmission control unit 2103 of the base station 2102 outputs the data link transmission control information to the encapsulation and transfer unit 2105. As shown in FIG. 34, the encapsulation and transfer unit 2105 sets the IP address of the base station 2102 as the source IP address of the IP header and the IP address of the base station 2112 as the destination IP address. . Further, in order to transfer the data link transmission control information to the base station as UDP or TCP data, a number representing UDP or TCP is set in the protocol number, and an IP header part and an IP data part (UDP or TCP) are set in the packet length. A total value of the lengths of the TCP header part and the UDP or TCP data part) is set. Then, data link transmission control information to be transferred is input to the UDP or TCP data part, and an IP packet to be transferred to the base station is configured. The configured IP packet is sent to the network 1. The sent IP packet reaches the base station 2112 by the set destination IP address.
[0267]
In the base station 2112, the arrived IP packet is input to the decapsulation unit 2116. The decapsulation unit 2116 performs processing according to the flowchart shown in FIG. FIG. 35 also describes a processing procedure according to a second method described later.
[0268]
First, the protocol number of the outermost IP header part of the input packet is identified (S501 in FIG. 35). In this example, since the identified protocol number does not represent IP encapsulation (determination is negative in S502), the UDP or TCP data portion in the IP data portion is extracted to obtain data link transmission control information. (S507). The extracted data link transmission control information is input to the data link transmission control unit 2113. The data link transmission control unit 2113 executes the data link transmission control described in the above-described embodiment based on the input data link transmission control information.
[0269]
For example, when the data link transmission control information includes information for identifying a mobile station such as the IP address or machine number of the mobile station and a number that uniquely identifies the packet of the latest packet, The number next to the number is used for automatic packet retransmission control. Further, when the data link transmission control information includes information for identifying the mobile station and ACK information from the mobile station or deletion information of the stored packet, the mobile station stored in the storage unit 2114 The packet corresponding to the ACK addressed or the packet corresponding to the deletion information is deleted.
[0270]
Next, a second method (a method of transferring data link transmission control information and a packet at the same time or transferring a packet with identification information added) will be described. In the second method, when a packet accumulated as ACK waiting and information uniquely identifying the packet are transferred to the handover destination base station due to handover or site diversity during packet transmission, etc., it is held as waiting for transmission. A packet, information for uniquely identifying the packet, and control base station identification information for transmission from the handover destination base station when transferring the packet and information for uniquely identifying the packet to the handover destination base station When transferring both or one of the above, information for uniquely identifying the packet, control base station identification information, information indicating whether or not to transmit the packet, or a combination of these and a duplicate packet can be transmitted. This is used when distributing to other base stations.
[0271]
FIG. 36 shows an apparatus configuration example for executing the second method. The base station 2202 shown in FIG. 36 further includes a packet duplicating unit 2206 for duplicating the packet in addition to the configuration of the base station 2102 of FIG. 32, and the duplicated packet is transferred to another base station in place of the encapsulation and transfer unit 2105. An encapsulation and distribution unit 2205 that distributes to a station and performs encapsulation described later is provided.
[0272]
Of these, the encapsulation and distribution unit 2205 is functionally composed of functional blocks shown in FIG. That is, the encapsulation and distribution unit 2205 includes the encapsulation unit 2205A that encapsulates the data link transmission control information and the packet to be distributed, and the data link transmission control information that represents the length of the encapsulated packet obtained by the encapsulation. The total value of the length of the packet and the packet to be distributed is recorded in the header of the encapsulated packet, and the encapsulated packet distributing unit 2205B for distributing the encapsulated packet is recorded in the header of the encapsulated packet that has been distributed If the length obtained by subtracting the header length of the encapsulated packet from the length of the encapsulated packet and the length of the packet to be distributed recorded in the header of the packet to be distributed are not equal, Is configured to include data link transmission control information, It is constituted comprise.
[0273]
The other base station 2212 is configured in the same manner as the base station 2202 as described above.
[0274]
Next, the operation according to the second method will be described. Here, a case will be described in which a packet with duplicate identification information added is distributed from the base station 2202 to the base station 2212.
[0275]
The data link transmission control unit 2103 of the base station 2202 inputs the packet with the identification information added to the packet duplication unit 2206. The packet duplicating unit 2206 outputs the input packet to which the identification information is added to the transmission / reception transmitter / receiver 5, and after duplicating the packet, outputs the packet to the encapsulation and distribution unit 2205. As shown in FIG. 37, the encapsulation and distribution unit 2205 includes the IP address of the base station 2202 as the source IP address of the IP header (a) and the IP address of the base station 2212 as the destination IP address. Set. Further, in order to transfer an IP packet to be transferred to the target mobile station to another base station, a number indicating IP encapsulation is set in the protocol number, and the IP header (a) and the target number are set in the packet length. A total value of the lengths of the IP packet and identification information transferred to the base station is set.
[0276]
In the IP data part of the IP header part (a), an IP packet to be transferred to the target mobile station and identification information are input to constitute an IP packet to be transferred to the base station. The configured IP packet is sent to the network 1. The sent IP packet reaches the base station 2212 by the set destination IP address.
[0277]
In the base station 2112, the arrived IP packet is input to the decapsulation unit 2116. The decapsulation unit 2116 performs processing according to the flowchart shown in FIG. 35, as described above. First, the protocol number of the outermost IP header part of the input packet is identified (S501 in FIG. 35). In the case of this example, the identified protocol number represents IP encapsulation (Yes is determined in S502), so the packet length of the outermost IP header portion (IP header portion (a) in FIG. 37) is analyzed. Thus, the packet length X1 of the packet transferred to the base station is acquired (S503). Next, the packet length X2 of the packet transferred to the target mobile station is acquired by analyzing the packet length of the second IP header part (IP header part (b) in FIG. 37) from the outside (S504). When the following expression (4) using the obtained packet lengths X1 and X2 and the length of the outermost IP header portion is satisfied (when affirmative determination is made in S505), there is no identification information, that is, It is determined that there is only an IP packet to be transferred to the target base station in the IP data part of the IP header part (a).
[0278]
(X1)-(length of the outermost IP header) = (X2) (4)
[0279]
In this case, the following processing is performed as an IP packet extracted from the IP data portion of the IP header portion (a) and transferred to the target mobile station (S508). In other words, the extracted IP packet to be transferred to the target mobile station is input to the data link transmission control unit 2113, and the data link transmission control unit 2113 performs the same processing on the input IP packet in the above-described embodiment. The data link transmission control described above is executed.
[0280]
On the other hand, when Formula (4) is not materialized (when negative determination is made in S505), it is determined that there is identification information, and the following processing is performed (S506). In this case, information of length X2 from the beginning of the IP data part of the IP header part (a) is extracted as an IP packet to be transferred to the target mobile station, and the IP data of the IP header part (a) is extracted. The rest of the part is extracted separately as identification information. The extracted IP packet and identification information transferred to the target mobile station are input to the data link transmission control unit 2113. The data link transmission control unit 2113 uses the input IP packet and the identification information. The data link transmission control described in the above embodiment is executed.
[0281]
Here, the cases of the IP packets having two different configurations shown in FIGS. 34 and 37 have been described as the packets to be transferred or distributed to the base station. However, by using the method described above, it is possible to change from one base station to another. If the packet to be transferred or distributed to the base station includes only the data link transmission control information, includes the data link transmission control information and the IP packet to be transferred to the target mobile station, or is an IP packet to which identification information is added. In some cases, it is possible to identify cases where only IP packets to be transferred to a target mobile station are included, and it is possible to smoothly execute control based on data link transmission control information and identification information.
[0282]
【The invention's effect】
As described above, according to the present invention, an increase in transmission delay time can be suppressed by changing a base station that executes data link transmission control including automatic retransmission request control according to movement of a mobile station. Throughput can be increased as compared with the prior art. In addition, even if the base station that performs data link transmission control including automatic retransmission request control changes, a new base station takes over by transferring a series of data link transmission control information, so that only unreachable packets or blocks are retransmitted. Therefore, a decrease in throughput can be avoided.
[0283]
Also, according to the present invention, each base station accumulates packets, thereby reducing the retransmission delay time and the increase in traffic in the network between base stations. Also, smooth packet transmission is possible even during handover.
[0284]
In addition, according to the present invention, when a mobile station exists within a range of a predetermined reception level to be handed over, the same packet is transmitted from a plurality of base stations, and the base station is moved when the mobile station moves out of the range. By switching stations, it is possible to perform handover control at the base station closest to the mobile station while eliminating the time required for handover control and shortening the delay until retransmission, thereby enabling more efficient data link transmission. Can be realized.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a mobile communication system according to first and second embodiments.
FIG. 2 is a time chart for explaining the operation of the first embodiment.
FIG. 3 is an operation correlation diagram for specifically explaining the operation in the first embodiment.
4A is a diagram showing a packet configuration in the data link transmission control unit of the first embodiment, and FIG. 4B is a diagram showing a packet and block configuration in the data link transmission control unit of the second embodiment. FIG.
FIG. 5 is a system configuration diagram of a conventional mobile communication system.
FIG. 6 is a time chart for explaining the operation of a data link transmission control method in a conventional mobile communication system.
FIG. 7 is a system configuration diagram of a mobile communication system according to a third embodiment.
FIG. 8A is a state transition diagram for explaining a transmission control method according to the third embodiment, and FIG. 8B is a table showing a state transition for each event.
FIG. 9 is a diagram for explaining the position of a mobile station in the third embodiment.
FIG. 10 is a diagram for explaining processing when a packet arrives at a base station in a packet transmittable state.
FIG. 11 is a diagram for explaining processing when a packet arrives at an idle base station;
FIG. 12 is a diagram for explaining processing when a packet arrives at a base station in a state where packet duplication and transmission are possible.
13 is a diagram for explaining an example in which a timer is employed as a trigger for deleting packets accumulated in each base station in the process of FIG. 12;
14 is a diagram for explaining various methods related to packet deletion notification from the base station 202 to the base station 212 in FIG. 12, (a) is a packet number to be deleted every time the base station 202 deletes a packet; (B) is a second method of notifying the number of the last deleted packet within a predetermined time, and (c) is the last deleted every time 10 packets are deleted. Each of the third methods for notifying the number of the received packet is shown.
15 is a diagram for explaining an example in which the base stations 202 and 212 in FIG. 12 transmit the same packet to the mobile station, respectively.
FIG. 16 is a diagram for explaining operations of a target base station and a mobile station in an event A.
FIG. 17 is a diagram for explaining operations of a target base station and a mobile station in event B;
FIG. 18 is a diagram for explaining operations of a target base station and a mobile station in event C;
FIG. 19 is a diagram for explaining operations of a target base station and a mobile station in event D;
FIG. 20 is a diagram for explaining operations of a target base station and a mobile station in event E;
FIG. 21 is a table for explaining an operation of packet transmission handover transmission control in the fourth embodiment.
FIG. 22 is a diagram illustrating functional blocks constituting a data link transmission control unit in a base station according to the third embodiment.
FIG. 23 is a diagram illustrating functional blocks constituting a data link transmission control unit in a mobile station according to the third embodiment.
FIG. 24 is a flowchart showing a first mode of a mobile station control program according to the present invention.
FIG. 25 is a flowchart showing a second aspect of the mobile station control program according to the present invention.
FIG. 26 is a flowchart showing a third aspect of the mobile station control program according to the present invention.
FIG. 27 is a configuration diagram of a recording medium on which a mobile station control program is recorded and peripheral devices thereof.
FIG. 28 is a system configuration diagram of a mobile communication system according to a fifth embodiment.
FIG. 29 is a diagram for explaining an operation in an initial state according to the fifth embodiment.
FIG. 30 is a diagram for explaining an operation when a packet is transmitted from a plurality of base stations to a mobile station in the transition state of the fifth embodiment.
FIG. 31 is a diagram for explaining an operation when a packet is transmitted from a single base station to a mobile station in the transition state of the fifth embodiment.
FIG. 32 is a system configuration diagram of a mobile communication system that executes a first method according to a sixth embodiment.
33A is a functional block diagram of an encapsulation and transfer unit, and FIG. 33B is a functional block diagram of an encapsulation and distribution unit.
FIG. 34 is a diagram illustrating a configuration of an IP packet according to a first method of the sixth embodiment.
FIG. 35 is a flowchart showing a processing procedure according to the first and second methods of the sixth embodiment.
FIG. 36 is a system configuration diagram of a mobile communication system that executes a second method according to the sixth embodiment.
FIG. 37 is a diagram illustrating a configuration of an IP packet according to a second method of the sixth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Network 2, 12, 22, 102, 112, 122, 1102, 1112 ... Base station 3, 13, 23, 34, 103, 113, 123, 1034, 1103, 1113 ... Data link transmission control part, 1105 DESCRIPTION OF SYMBOLS 1115 ... Transfer / distribution part 1107, 1117 ... Packet duplication part 4, 14, 24 ... Switch, 104, 114, 124 ... Accumulation part, 105, 115, 125 ... Transfer part 5, 15, 25, 33 ... Transceiver, 6, 16, 26 ... Base station antenna, 31, 131, 1131 ... Mobile station, 32 ... Mobile station antenna, 34A, 1034A ... Mobile station transmission control unit, 34B, 1034B ... Connection request unit, 35 ... Data Input / output ends, 202, 212, 222 ... base station, 203 ... data link transmission control unit, 203A ... identification information addition unit, 203B ... deletion unit, 20 C ... Deletion unit, 203D ... Deletion unit, 203E ... Deletion packet notification unit, 203F ... Distribution control unit, 203G ... Packet retransmission unit, 203H ... Accumulation notification unit, 203I ... Notification control unit, 203J ... Judgment unit, 203K ... Instruction unit 204 ... Accumulation unit, 205 ... Distribution unit, 206 ... Packet replication unit, 207 ... Transceiver, 208 ... Base station antenna, 231 ... Mobile station, 232 ... Mobile station antenna, 233 ... Transceiver, 233A ... Diversity reception unit, 234 ... Data link transmission control unit, 234A ... Selection unit, 234B ... Transmission request unit, 234C ... Change time notification unit, 234D ... Measurement unit, 234E ... Reception quality notification unit, 234F ... Determination unit, 234G ... State transition request unit, 235 ... Data input / output terminal, 2102, 2112, 2202, 2212 ... Base station, 2103, 2113 ... Data link transmission Control unit, 2104, 2114 ... accumulation unit, 2105, 2115 ... encapsulation and transfer unit, 2105A ... encapsulation unit, 2105B ... encapsulated packet transfer unit, 2105C ... configuration judgment unit, 2106, 2116 ... decapsulation unit, 2205, 2215 ... encapsulation and distribution unit, 2205A ... encapsulation unit, 2205B ... encapsulated packet distribution unit, 2205C ... configuration determination unit, 2206, 2216 ... packet duplication unit.

Claims (3)

A data link transmission control method for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets between a mobile station and a plurality of base stations,
When the mobile station requests the one base station to connect to another base station while connecting to the one base station, and the one base station transfers data link transmission control information and a packet Are simultaneously transmitted, the one base station encapsulates the data link transmission control information and the packet, and transfers the encapsulated packet obtained by the encapsulation to the other base station ,
The one base station is
Encapsulating the data link transmission control information and the packet to be transferred;
The total value of the length of the data link transmission control information and the length of the packet to be transferred, which represents the length of the encapsulated packet obtained by the encapsulation, is recorded in the header of the encapsulated packet, and the encapsulated packet is recorded. Forward,
A length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet recorded in the header of the encapsulated packet that has been transferred, and the length of the packet to be transferred recorded in the header of the packet to be transferred If the lengths are not equal, it is determined that the encapsulated packet is configured to include data link transmission control information.
A data link transmission control method. A mobile communication system composed of a mobile station and a plurality of base stations, which transmits and receives information by packets
The mobile station
Mobile station transmission control means for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets with the base station;
Connection request means for requesting connection with a base station as a communication partner,
The base station
Base station transmission control means for performing data link transmission control including automatic retransmission request control for transmitting and receiving packets to and from the mobile station;
Transfer means for transferring data link transmission control information to another base station,
The base station transmission control means includes
When there is a connection request with another base station from the mobile station, and when the data link transmission control information and the packet to be transferred are transmitted simultaneously by the transfer means, the data link transmission control information and Encapsulating the packet, encapsulated packet obtained by the encapsulation is transferred to the other base station by the transfer means,
The transfer means includes
Encapsulation means for encapsulating the data link transmission control information and the packet to be transferred;
The total value of the length of the data link transmission control information and the length of the packet to be transferred, which represents the length of the encapsulated packet obtained by the encapsulation, is recorded in the header of the encapsulated packet, and the encapsulated packet is recorded. Encapsulated packet transfer means for transferring;
A length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet recorded in the header of the encapsulated packet that has been transferred, and the length of the packet to be transferred recorded in the header of the packet to be transferred Configuration determination means for determining that the encapsulated packet includes data link transmission control information when the lengths are not equal;
Mobile communication system, characterized in that configured to include a. A data link transmission control device mounted on a base station that transmits and receives information with a mobile station by a packet,
Transfer means for transferring data link transmission control information related to data link transmission control including automatic retransmission request control for transmitting and receiving packets to other base stations;
When there is a connection request with another base station from the mobile station, and when the data transfer transmission control information and the packet to be transferred are simultaneously transmitted by the transfer means, the data link transmission control information and the A base station transmission control unit that encapsulates the packet and causes the transfer unit to transfer the encapsulated packet obtained by the encapsulation to the other base station;
Have a,
The transfer means includes
Encapsulation means for encapsulating the data link transmission control information and the packet to be transferred;
The total value of the length of the data link transmission control information and the length of the packet to be transferred, which represents the length of the encapsulated packet obtained by the encapsulation, is recorded in the header of the encapsulated packet, and the encapsulated packet is recorded. Encapsulated packet transfer means for transferring;
A length obtained by subtracting the length of the header of the encapsulated packet from the length of the encapsulated packet recorded in the header of the encapsulated packet that has been transferred, and the length of the packet to be transferred recorded in the header of the packet to be transferred Configuration determination means for determining that the encapsulated packet includes data link transmission control information when the lengths are not equal;
A data link transmission control device comprising:

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