JP3835175B2 - Narrow-range communication method for mobile communication device - Google Patents

Description

【００６５】
また、前左のアンテナが他車の信号を受信したとして、その受信信号を送信したアンテナの情報により、車両の位置が次のように推定できる。
【００６６】

【００６７】
なお、受信アンテナは位置を推定するだけであれば、方向性が無くても良い。一方、接触防止を目的とする場合には、各方向の車両までの距離を測定する必要があるため、方向性が必要になる。
【００６８】
他の車両との間で通信を行う場合に、自車が他車の強い電波すなわち設定値よりも電界強度が大きい電波を受信した場合には、他車が至近距離に存在する場合が想定されるので、運転手に対して表示装置４ａ〜４ｄなどを用いたり、あるいはブザーや音声出力により警告を発して他車との接触を防止するようになっている。
【００６９】
また、自己の通信エリア１８内に存在する車両が増えすぎるなどして、通信処理に負担がかかったり、至近距離の車両との迅速な通信が必要となるような場合には、ＤＳＲＣ通信機２ａ〜２ｆの受信感度や送信強度を調整して通信エリア１８の範囲を必要に応じて変動させることができる。また、通信が必要となる相手の車両までの距離を自車の走行速度などとも連動して通信エリア１８を変えることもできる。
【００７０】
上述のようにして通信エリア１８内に存在する他の車両の相対的な位置を判定すると、これを表示装置４ａ〜４ｄに表示させる。例えば、図４に示したような道路２０における車両の存在状態である場合には、図８に示すような上方から見た状態で示す表示画面Ｓとなる。ここでは、自車１の位置が分かりやすくなるように、他車とは色を変えたり、点滅表示させるなどしている。
【００７１】
なお、この表示画面Ｓは、画面下部に設けているスクロールバーＢを操作することにより自己の通信エリア１８よりも前方あるいは後方の車両の存在を表示させることができる。これは、渋滞などの発生で、通信エリアが互いにリンクすることで広い範囲の車両の位置上方が検出できることを利用したもので、渋滞が発生している先頭付近の位置を表示させたり、指定した速度（例えば、時速５０ｋｍ程度の速度で、渋滞を脱したと想定される速度）以下で走行する車両の先頭位置を表示させたりすることができる。また、他車との相対位置を詳細に見たり全体を俯瞰して見たりするのに都合が良くなるように、拡大表示ボタンＭや縮小表示ボタンＮなども表示されている。
【００７２】
このように、自車の通信エリア１８の範囲だけではなく、他の車両の通信エリアを中継して得られる広い範囲の車両の位置情報を得ることができ、これによって、上述したように渋滞情報などをリアルタイムで把握することができ、渋滞を回避するルート探索を迅速且つ的確に行えるようになると共に、渋滞を脱するまでの時間をある程度予測することができるので、渋滞による運転者のイライラなども緩和させることができるようになる。
【００７３】
また、他車の相対位置を表示する場合に、ＣＣＤカメラ７ａ〜７ｄなどの画像情報を利用して図９（ａ）に示すような画像を表示させることもできる。この場合、他の車両の車種等を通信処理のデータで受けることにより、その車両の三次元情報及び周囲の地図情報（地形情報）をデータベース１２から読出し、自車と他車との相対位置の検出結果に基づいて、車両と地形の三次元モデルをリアルタイムで測定結果に合わせて配置して描画させることで、人口現実的な仮想画像として表示装置４ａ〜４ｄに表示させることができる。
【００７４】
そして、このように生成した仮想画像の表示では、その視点を移動させて自由に移動させた視点からの状態を表示させることができる。例えば、表示画面Ｓの一部に操作レバーＬを表示し、その操作レバーＬを上下左右の好みの方向に操作させることで視点を移動させることができる。上方に視点を移動させると（同図（ｂ）参照）、高い位置から全体の状況を立体的に把握でき、直前の車両の陰になって見えなかった前方の車両の存在を三次元的に確認することができる。また、視点を道路の横方向から見るような位置に移動させると（同図（ｃ）参照）、自車やその前後に存在する他車の状態を側方から客観的に表示させることができるようになる。
【００７５】
［狭域通信方法の説明］
次に、通信エリア１８内でのＤＳＲＣ通信機２ａ〜２ｆによる狭域通信方法について詳述する。この実施形態において達成している通信方法は、車車間通信を路側などに中継器を設けることなく車両同士で直接通信を制御できるようにすることが特徴となっている。各車両１に搭載される移動体用通信装置は、自己の通信エリア１８内に存在する他の車両１の移動体用通信装置との間で、干渉を起こすことなく互いに信号データの授受が行えるように構成されている。
【００７６】
周知のように、電磁波信号は、さまざまな用途に用いられており、広い周波数帯を車車間通信用に占有することはできない。そこで、周波数帯域が狭く、且つノイズや電波干渉に強い通信方式が必要となる。また、車両の周辺には、複数の車両が存在するため、それらとも干渉や通信衝突が生じないようにして通信を制御する必要がある。この実施形態においては、これらの課題を解決すべく、例えばスペクトラム拡散通信方式を採用すると共に、以下に説明するような通信方法を採用して車車間通信において通信衝突を回避して行えるようにしている。
【００７７】
通信方法を説明するにあたり、前提となる条件について説明する。各車両が通信するタイミングは、車両あるいは通信用ＩＤコードの値を元にして決定する。ここで、各車両に設定される通信用ＩＤコードは複数桁の数字を用いている。この実施形態においては、簡単のために４桁の数字を通信用ＩＤコードとして設定している場合を例にとって説明する。
【００７８】
４桁の数字で示される通信用ＩＤコードのうち、上位の第１の桁の数が「０」となっている車両１を同期ベースＩＤ車両として設定する。この理由は、通信シークエンスを第１の桁の数字が「０」の車両から開始しているためである。また、第１の桁の数字が「０」でない車両のグループは、通信用ＩＤコードが最小の車両を同期ベース車両として設定している。
【００７９】
通信に使用する通信フレームの構成は、図１０に示すとおりである。すなわち、後述する基準時刻を開始時刻とした通信フレームは、先頭に位置するパイロットウインドウＷＰと是に続く１０個の通信ウインドウＷＣとから構成され、各ウインドウＷＰ，ＷＣは１ｍｓｅｃ単位の時間に設定されている。パイロットウインドウＷＰは、「０」から「９」までの１０個のパイロットスロットＳＰから構成されている。各パイロットスロットＳＰは、さらにイニシャルスロットとこれに続く１０個のリカバリスロットＳＲとから構成されている。
【００８０】
通信用ＩＤコードの第１の桁の値が「０」の車両は、パイロットウインドウの番号「０」のスロットに自車の通信用ＩＤコードと同期ベースＩＤコードを送信する。また、通信用ＩＤコードの第１の桁の値が「０」である車両は、通信データを０番目の通信スロットに送信する。
【００８１】
なお、スロット数を可変とする場合には、使用通信スロット数も含めて送信する。たとえば、通信スロットを１０個から１６個に増加する場合、下二桁を１６で割ったあまりの数が通信を行うスロット番号になる。
【００８２】
上述の場合、同期ベースＩＤコードとは、複数の車両が集団で走行する場合に、同期時刻の基準時刻を決定する車両のＩＤコードを示している。同期ベース車両は、前述のように、通常は通信用ＩＤコードの第１の桁の値が「０」の車両に設定している。もし通信を行うべき集団の車両の中に、同期時刻の基準時刻を設定するものつまり第１の桁の値が「０」となる車両が存在しない場合には、第１の桁の値が「０」に近い方の車両が同期ベースＩＤ車両として機能させることになる。そして、通信用ＩＤコードの第１の桁の値によって、パイロットウインドウ内のスロット番号と通信スロット番号が各車両毎に独立に選択設定される。
【００８３】
通信を行うためには、通信データの先頭の位置つまりタイミングをとるための基準時刻を知る必要がある。ここで、データの復調処理には遅延線整合フィルタＦを用いている。図１１は信号の構成を示しており、同期信号に続けてデータ部が送られるようになっている。なお、整合する可能性を高めるために、同期信号が複数個設定されている。
【００８４】
同図中、遅延整合フィルタＦは、指定された信号が来た時だけデータが出力される構成となっており、整合できたタイミングから基準時刻（０時刻）が計算できるようになっている。また、他車との同期補正（これを同期捕捉と呼ぶ）は、この基準時刻に合うように位相（時間）が制御される（時間を合わせる）。また、同期が確定すると、その条件からずれないように位相ロックループ（ＰＬＬ）と呼ばれる同期追跡を行い、通信タイミングのずれが起こらないように制御している。
【００８５】
次に、通信の基本的な流れについて図１２を参照して説明する。通信処理を開始すると（ステップＳ１）、まず、バッファの初期化及び制御パラメータのセット、カウンタの安定度チェックなどを実行する。続いて、自車のＩＤデータとして、通信用ＩＤコードを送信する（ステップＳ２）。ここでは、通信用ＩＤコードを定期的に送信する場合を例にとって示している。なお、この方式では、送信間隔が長くなると通信エリア１８内に他の車両が進入してから通信を開始するまでの時間に遅れを生じるので、悪影響が出ないように適切な時間間隔を設定して通信用ＩＤコードの送信を行うことが好ましい。
【００８６】
また、上記の場合に代えて、通信用ＩＤコードの送信を、ＣＣＤカメラ７ａ〜７ｄのいずれかにより通信エリア１８内に通信対象となる車両が存在することが検出したことを以て送信するようにしても良い。この場合には、他車が通信不能でない限りデータを受信することができるので、ステップＳ３は不要となるが、この通信処理のフローを開始する時点で他車の存在を検知するステップが付加されることになる。
【００８７】
次に、他車データを受信したかをチェックする（ステップＳ３）。これは、他の車両から通信用ＩＤコードを受信したか否かを判断するもので、受信データが無ければ、ステップＳ２に戻り、定期的に通信用ＩＤコードを送信する処理を繰り返すことになる。また、受信データがある場合には、続いて調時処理（同期捕捉）を実行するようになる（ステップＳ４）。同期捕捉が終了すると、同期追跡とユーザ通信処理を並行して実施するようになる（ステップＳ５、６）。これにより、通信エリア１８内に存在する他の車両との間で行う通信処理が終了する。
【００８８】
次に、上記の通信処理の基本的な流れにおいて、車両１のＤＳＲＣ通信機２ａ〜２ｆは、全二重通信すなわち送信と受信とを同時に行うように構成されている。この場合、受信においては、データをいつ受信してもそのデータ処理を実行できるように構成している。受信データは、前述したように変調がかけられているので、復調用フィルタを通して復号化する。復調用フィルタからの出力があったときを受信ありと判断する。一方、出力がない場合は、ノイズ受信として処理される。
【００８９】
受信データには、データ送信した他の車両の通信用ＩＤコードと、送信した他の車両が同期をとるため使用している同期タイミングのベースになる車両（同期ベースＩＤコード）のデータが含まれている。なお、オプションとして、通信スロット数が可変の場合には、スロット数もデータに含まれている。そして、これらのデータが受信データから読めない場合には、受信エラーとして受信処理を継続するようになる。
【００９０】
続いて、調時処理（同期捕捉）の処理について説明する。この調時処理は、車両が動作を開始した時点からの説明を行うことにする。車両の通信は、グループ走行すれば、グループで同期をとって通信しながら走行し、単独走行なら、他車と通信するために同期を取る必要がある。通信パターンとしては、次のようなものがある。
【００９１】
単独←→単独
単独←→集団 単独車両が集団に含まれる場合
集団←→集団 集団対集団の場合
集団←→単独 集団から離脱する場合
【００９２】
どのような場合でも、自車の通信用ＩＤコードと同期ベースＩＤコードとを設定し、同期ベース車両のタイミングを同期時刻設定に利用する。同期タイミングは、個々の車両が他車の同期ベース車両データを見て、それが自車の同期ベースＩＤコードと比較することで、同期時間の調節で行う。この場合、同期の基本は、個対個としている。これにより、同期ベース車両と直接通信できなくとも集団との同期がとれるようになる。同期ベース車両の設定には、例えば、集団の中で通信用ＩＤコードの第１の桁の値が一番小さい車両を選ぶようにする。このように同期ベース車両を選定することで、集団対集団の同期も円滑に行うことができるようになる。
【００９３】
また、一般車両と特殊車両（例えば、救急車、消防車、パトカー、特殊作業車、危険物車両等）を登録時に小さい番号あるいは「０」の付いた番号として設定することで分けておくこともできる。一般車両は、特殊車両にタイミングを合わせるようにして同期を取るようにすることができる。
【００９４】
以下においては、受信信号の例を具体的に示して説明する。図１６（ａ）には、同期捕捉前つまり基準時刻が定まらない状態で受信したデータの時間的推移を示している。矩形で示す部分は信号がある部分を示している。この図において、パイロットスロットには、車両の通信用ＩＤコードと同期ベースＩＤコードとが含まれた小さいサイズの信号があるはずである。
【００９５】
一方、車両の通信用ＩＤコードに応じて決定される通信ウインドウには、別の形の信号（通信データ）が受信されるようになっている。この通信データには、少なくとも、車両の通信用ＩＤコードと通信スロット番号とを含んでいる。個々のデータはそれぞれ独立に変調されているため、それぞれが個々に復号化されるようになっている。
【００９６】
さて、上記した受信データの時間的推移から、同期捕捉の処理を行った結果を同図（ｂ）に示す。図中、上段は全体の信号データの流れを示し、下段は各車両の個別の信号データの流れを示している。同期捕捉後は、信号データの受信タイミングから決定された時刻が求められ、それぞれのスロットのタイミングが割り出されている。ここで、下段に示した個別の信号データの流れにおいて、数字はそれぞれの車両の通信用ＩＤコード（４桁の数字）を示し、括弧内には同期ベース車両の通信用ＩＤコードを示している。
【００９７】
ここでは、個々の信号を読出すために、前出のフィルタＦが用いられる。信号の有無、信号データの内容が検出されたデータ毎に読み出される。データがパイロットスロット用か通信スロット用かは、データの内容（データヘッダ）をチェックして判定することができる。これにより、概略の通信フレームのウインドウを設定する。この後、パイロットフレームに出される他の車両からの通信用ＩＤコードの受信タイミングから、詳細な同期捕捉を行う。
【００９８】
詳細な同期捕捉については、次のようにして行われる。図１３はそのフローを示しており、車載機は、車両の周囲から送信されてくる信号の読取り処理を行う（ステップＰ１）。スペクトラム拡散信号はノイズと区別し難いため、車両が走行している状態では、常時受信電波をモニタする。受信電波信号のデータ読取り処理は、前記同期用フィルタを用いて行う。
【００９９】
次に、受信電波信号の復号化が実行できた場合には、フィルタ出力がデータ有り信号を出力するから、出力有りと判定する（ステップＰ２）。そのデータが読み出された時刻を時間計測の原点として記録し、データの読出しを行う。この場合、時間計測と、データ処理とは独立で行えるように構成しておく。また、ここではタイマーも暫定時間処理用と確定時間処理用とを設定して暫定時間処理は１つの命令で変更できるようにする。
【０１００】
次に、受信したデータが、パイロットスロット用かどうかがチェックされる（ステップＰ３）。パイロットスロット用のデータには、車両の通信用ＩＤコード及び同期ベースＩＤコードが含まれている。一方、通信データは、通信スロット番号、車両の通信用ＩＤコード、データ（データタグ＋データ）で構成されており、パイロットスロット用のデータとは構成が異なるので区別できる。あるいは、データに認識用のタグデータを付加して区別するようにしても良い。
【０１０１】
続いて、他車から受信したデータがパイロットスロット用の場合は、他車の通信用ＩＤコードと他車が同期の基準時刻としてしている同期ベースＩＤコードを有する車両を読み取る（ステップＰ４）。次に、読み取りができた他車の受信データのうちで、他車両の通信用ＩＤコードの第１の桁の値を記憶する（ステップＰ５）。通信用ＩＤコードの第１の桁の値は、通常、他車が使用する通信スロットの番号を示すようになっている。したがって、通信用ＩＤコードの第１の桁の値は通信スロット番号と同じになる。ただし、通信用ＩＤコードの第１の桁の値が同じとなる車両が複数存在する場合には、通信用ＩＤコードの第１の桁の値と通信スロット番号とが一致しなくなることがある。この点については、後の説明で詳しく述べる。そして、その車両の通信用ＩＤコードの第１の桁の値で決定される通信スロットに、その通信用ＩＤコードに関する情報（位置情報、速度情報など）が送信される。
【０１０２】
次に、通信タイミング設定準備を行う（ステップＰ６）。ここで、通信基準時刻を暫定的に設定する。設定ルールに関する説明については後述する。時刻設定は、最初に設定した時刻を優先し、後から偶然に受け取ったパイロットウインドウへの信号による基準時刻の設定は行わないように制御している。ここで、同期していないと判断されたパイロットウインドウへの信号はその信号が読み取り可能ならば記憶しておく。
【０１０３】
次に、通信タイミング設定処理を行う（ステップＰ７）。ここでは、受信データの一つ一つに対し、タイミングを設定する方法を示したが、パイロットウインドウに、受信タイミング的に矛盾のない複数の信号が受信された場合は、それらの受信時間を統計的に処理して、スロットタイミングの時間精度を上げることも可能である。タイミングがずれ、スロット間にまたがったデータがあると、そのデータ判定処理に余分な時間が必要になる。パイロットスロットの受信データで通信タイミングが設定され、設定時間が経過すると、次に通信スロットが開始されるようになる。
【０１０４】
通信スロット時間に移行して、データ受信モード時にデータを受信したとき、その受信データが正しい通信スロットデータか否かがチェックされる（ステップＰ８）。通信スロット番号毎に通信の開始時刻が設定されているため、指定時刻に通信用ＩＤコードに応じたデータが受信されるようになる。次に、受信データが通信スロットデータの時には、そのデータが設定タイミングで開始されたか否かをチェックし（ステップＰ９）、「ＹＥＳ」の場合には通信スロットデータが設定されたタイミングで（予想時間内に）受信された場合は、そのデータを同期ベースＩＤコードのリストに記憶する（ステップＰ１０）。続いて、データが設定タイミングで受信できた場合には、同期捕捉完了として（ステップＰ１１）、０時刻すなわち基準時刻の設定を確定するようになる（ステップＰ１２）。
【０１０５】
一方、ステップＰ８において、「ＮＯ」と判断したときすなわちデータが設定された形ではないと判定されたときには、受信したデータがノイズであったとして処理されるようになる（ステップＰ１３）。この場合、別の方法として、読み取れたデータを元に、パイロットウインドウで受信されたデータなどを用いたり、あるいは通常の誤り訂正法を用いてデータを訂正することができるようにしても良い。
【０１０６】
また、ステップＰ９において「ＮＯ」と判断したときすなわち設定タイミングで通信が開始しない場合には、データに含まれる通信用ＩＤコードを読み、それが新規の通信用ＩＤコードであるか否かをチェックする（ステップＰ１４）。そして、それが新規車両の通信用ＩＤコードである場合には、非同期の通信用ＩＤコードとしてリストに記憶し（ステップＰ１５）、ステップＰ１４で「ＮＯ」と判断したときには、ノイズと判断してステップＰ１に戻るようになる（ステップＰ１６）。
【０１０７】
次に、上記したステップＰ６において行った通信タイミングの設定準備すなわち基準時刻の設定について、詳細に説明する。図１７はパイロットウインドウのフレームを示すもので、通信に先だって送信する車両の通信用ＩＤコードは、その第１の桁の値に応じてパイロットスロットの開始位置が決められている。したがって、受信した車両の通信用ＩＤコードの値が分かると、パイロットスロットの通信開始位置（時刻）を推定できるようになり、自車と他車との時刻（時計）を合わせることができ、これによって同期の準備を整えることができるようになる。
【０１０８】
この図では、例えば、自車が他の車両である通信用ＩＤコードの値が「２３４５」であるものについて、第１の桁の値が「２」であるから、パイロットスロット２でデータが受信されている。ここで、パイロットスロットとは、基準時刻から測定して、２．００〜２．９９秒の間の時間間隔を示している。車両の通信用ＩＤコードの第１の桁の値が「２」の車両は、パイロットスロット２を構成するイニシャルスロット部に、時刻２．０１から２．０５になるまでのユニット間時間内に送信を開始することとする。同期捕捉前には確定されていなかった通信用の時計が、データ受信により暫定的に設定され、基準時刻が推定されるようになる。
【０１０９】
説明を簡単にするために、パイロットスロット用の時間を１０タイムユニット、各通信スロットも１０タイムユニットとすると、パイロットウインドウが開始し、１０個の通信スロットが完了するまでに１１０タイムユニットを要することになる。各車両とも、パイロットウインドウ（パイロットスロット）と通信ウインドウ（通信スロット）への送信タイミングが車両の通信用ＩＤコードにより設定されている。よって、車両の通信用ＩＤコードが決まれば、パイロットスロットへの信号を送り始めた時刻と次に通信スロットへ送信する時刻とが決定されることになる。
【０１１０】
通信用ＩＤコードの第１の桁の値が「５」の車両は、パイロットスロット５に通信用ＩＤコードに関連したデータを送った後、通信スロット５にデータを送信するようになる。したがって、パイロットスロットへの信号が無ければ、車両は通信データも無いと予測判定することができる。
【０１１１】
例えば、通信用ＩＤコードが「２３４５」である車両は、第１の桁の値が「２」であるから、タイムユニット２．０１から２．０５の間にパイロットスロットへの通信を開始し、通信スロットへは、
［パイロットウインドウ］＋［通信スロット］×２＝３０タイムユニット
であるから、基準時刻から３０タイムユニット後に通信用ＩＤコード「２３４５」の車両の通信データが送信されることになる。
【０１１２】
また、通信用ＩＤコードが「３４５６」であるときには、タイムユニット３．０１から３．０５の間にパイロットスロットへの通信を開始し、通信スロットへは、
［パイロットウインドウ］＋［通信スロット］×３＝４０タイムユニット
であるから、基準時刻から４０タイムユニット後に通信用ＩＤコード「３４５６」の車両の通信データが送信されることになる。
【０１１３】
パイロットスロットは、前述のように、イニシャルスロットと１０個のリカバリスロットとから構成されており、各車両からは、通信用ＩＤコードの第１の桁の値と同じ番号のパイロットスロットのイニシャルスロットに通信用ＩＤコードが送信され、第２の桁の値と同じ番号のリカバリスロットにも通信用ＩＤコードが送信される。第１の桁の値が同じで、互いに衝突する場合でも、第２の桁の値が異なることにより、受信した車両の通信用ＩＤコードを認識することができるようになる。
【０１１４】
次に、通信タイミング設定について説明する。車両が複数になった場合には、相互の基準時刻を合わせないと、通信衝突が起こって通信ができなくなるおそれがある。また、基準時刻を合わせても、車両の通信用ＩＤコードの第１の桁の値が同じとなる可能性もあるので、その場合の通信タイミングの設定を調整する必要がある。以下は、その手順を規定したものである。
【０１１５】
図１９は、合計７台の車両が走行して、相互に通信を行う場合の例を示したものである。各車両に付されている通信用ＩＤコードは、例えば図示のように設定されている。いま、通信用ＩＤコードが「２３４５」と「０３４５」の２台の車両に着目して通信の行われ方について説明する。通信用ＩＤコードが「２３４５」の車両の通信エリアは図示の破線で示す領域である。この車両が通信できる車両は通信用ＩＤコードが「０３４５」、「２９８８」、「９８５４」の３台である。一方、通信用ＩＤコードが「０３４５」の車両が通信できる車両は通信用ＩＤコードが「２３４５」、「２６９２」、「２８５４」及び「９８５４」の４台である。
【０１１６】
送信タイミングの決定ルールを以下のように決めておく。車両の通信用ＩＤコードの第１の桁の値が重複する場合（ＩＤの１桁めを仮にｉとする）は、パイロットウインドウ内のｉ番目のパイロットスロットのイニシャルスロットに通信用ＩＤコードが送信される。次に、ｉ番目のパイロットスロットのリカバリスロット（ＩＤコードの第２の桁をｊとする）のｊ番目のスロットにも通信用ＩＤコードが送信される。
【０１１７】
通信用ＩＤコードの第１の桁の値が同じで、第２の桁の値が異なる場合は、第２の桁の値が小さい方の通信用ＩＤコードを有するものについて優先的に通信スロットを割り当て、大きい方の通信用ＩＤコードを有するものについては空きの通信スロットを順次割り当てる。例えば、通信用ＩＤコードの第１の桁の値が同じで「８」の車両が３台（例えば「８２６６」、「８４７０」、「８９３２」）存在するときに、そのときの空きスロットが０，２，３，４，７，９であるときに、通信用ＩＤコードが「８２６６」のものが最初にスロット８で、次に「８４７０」のものがリカバリスロット９で、そして、「８９３２」のものがリカバリスロット０で送信を行うように構成されている。
【０１１８】
各車両はパイロットスロットへの通信をモニタして、自車の通信エリア内にある他の車両の周辺車両の状況や、各車両が車車間通信にどのスロットを用いているかを判断できる。図１４及び図１５は各車両の通信タイミングの設定のフローを示している。
【０１１９】
まず、０時刻つまり基準時刻の設定を行い（ステップＲ１）、続いて、自車の通信用ＩＤコードを読出して取得し（ステップＲ２）、取得した通信用ＩＤコードの第１の桁及び第２の桁の数を個別に記憶する（ステップＲ３）。次に、基準時刻に基づいてパイロットスロットを開始する（ステップＲ４）。このとき、既に周囲に存在する車両との間で同期が取れた状態となっていることを前提としている。ここで、各スロットの通信衝突回数を記録するための分類データ（フラグ）を初期化する。
【０１２０】
次に、パイロットスロットタイミングの計測を開始する（ステップＲ５）。続いて、他車のパイロットスロットタイミングになったか否かをチェックし（ステップＲ６）、「ＹＥＳ」の場合には、他車のパイロット信号が出されるタイミングにデータが受信されたか否かをチェックする（ステップＲ７）。データが受信されたときには、「ＹＥＳ」と判断して受信したデータの解析を行う（ステップＲ８）。通常受信があると、各パイロットスロットの番号を第１の桁にもつ車両の通信用ＩＤコードが読まれる。
【０１２１】
受信した他車の通信用ＩＤコードの第１の桁の値が、自車の第１の桁の値と同じ値である場合には、自車と同じ通信スロットに通信を行って干渉を起こす可能性があるので、自車か他車の通信スロットを変更する必要がある。通信スロットパイロットスロットのリカバリスロットへの通信結果（１回目は、第２の桁の通信用ＩＤコードの番号のリカバリスロットへ各車がデータ送信）により選択される。リカバリスロットへの送信が早い方（第２の桁の値が小さい方）は、通信スロットを変更せず、遅い方が空いている次の通信スロットを選択してそこへ通信を行うようにする。
【０１２２】
自車の通信用ＩＤコードの第１の桁の値と同じ値の他車の通信用ＩＤコードを複数受信した場合には、受信信号の状態によるが、通常、データが衝突して読めないおそれがある。この場合でも、自車と同じ通信スロットに通信して干渉する可能性があるため、自車が他車の通信スロットを変更する必要がある。この場合も、同様に、通信スロットは、パイロットスロットのリカバリスロットへの通信結果（１回目は、第２の桁の値のリカバリスロットへ各車がデータ送信）により選択される。リカバリスロットへの送信が早い方（第２の桁の値が小さい方）は、通信スロットを変更せず、リカバリスロットへの送信が次に遅い方が空いている次の通信スロットを選択してそこへ通信を行うようにする。
【０１２３】
次に、受信したデータを記憶する（ステップＲ９）。もし解析したデータにエラーがあれば、データは廃棄もしくは誤り補正される。また、ステップＲ６あるいはＲ７にて「ＮＯ」と判断した場合には、パイロットスロットタイミングを計測する（ステップＲ１０）。続いて、自車のパイロットスロットタイミングになったかどうかをチェックし（ステップＲ１１）、「ＹＥＳ」の場合には、データｉを「０」にセットすると同時にイニシャルスロットへ送信を行う（ステップＲ１２）。
【０１２４】
このとき、送信した自車のイニシャルスロットと同じスロットに信号が受信されていないかをチェックする（ステップＲ１３）。ここで受信データが検出されたときには、自車の通信用ＩＤコードと第１の桁の値が同じ通信用ＩＤコードを持つ車両が存在することが判定される（ステップＲ１４）。ここで、Ｊ（Ｉ）はＪ（Ｉ）＋１に変更される。次に、リカバリスロットタイミングで送信を行う（ステップＲ１５）。また、ステップＲ１３で「ＮＯ」と判断した場合つまり、同じイニシャルスロットの受信データがないときには、リカバリスロットタイミングで送信するようになる（ステップＲ１６）。
【０１２５】
続いて、リカバリスロットへの送信のときに、同じスロットに受信データが無いかをチェックする（ステップＲ１７）。受信データがあった場合には、通信用ＩＤコードの第１及び第２の桁の値が同じであると判定して第２の桁の衝突があったことを記録する（ステップＲ１８）。そして、次回のリカバリスロットへ送信する桁数Ｊ（Ｉ）＋１をセットする（ステップＲ１９）。なお、このときイニシャルスロットへは常に通信用ＩＤコードの第１の桁の値を送信する。そして次のパイロットスロットタイミングを待つ。
【０１２６】
次に、ステップＲ１１において「ＮＯ」と判断した場合には、パイロットスロットタイミングを計測し（ステップＲ２０）、続いてパイロットスロット時間が終了したかをチェックし（ステップＲ２１）、パイロットスロット時間がまだ終了していない場合にはステップＲ５に戻ってパイロットスロットタイミングを計測し、終了している場合には（図中ａで示す分岐）図１５に示す通信スロット制御のフローに移行する。
【０１２７】
通信スロット制御の動作では、まず、通信スロットタイミングを計測し（ステップＲ２２）、他車の通信スロットタイミングか否かを判断する（ステップＲ２３）。ここで、他車の通信スロットタイミングである場合には、その通信スロットに他車データがあるかをチェックする（ステップＲ２４）。
【０１２８】
そして、データがある場合には、他車のスロットデータを解析し（ステップＲ２５）、他車の通信スロットデータを記憶し（ステップＲ２６）、空いている通信スロットを確認する（ステップＲ２７）。この確認結果から自車の通信スロットが使用可能か否かを判断し（ステップＲ２８）、使用不可の場合には、空き通信スロットをルールに従って選択する（ステップＲ２９）。
【０１２９】
次に、空き通信スロットを選択した場合や、ステップＲ２３で「ＮＯ」と判断した場合や、ステップＲ２８で「ＮＯ」と判断した場合には、通信スロットタイミングを計測し（ステップＲ３０）、自車の通信スロットタイミングである場合には（ステップＲ３１で「ＹＥＳ」と判断）、自車のデータを通信スロットに送信する（ステップＲ３２）。
【０１３０】
続いて、自車と同じ通信スロットのタイミングで受信データがあるか否かをチェックする（ステップＲ３３）。これは、新たな車両が通信エリア内に存在して通信を開始しようとしているか否かを判断するもので、「ＹＥＳ」の場合には、受信したデータを解析し（ステップ３４）、新規車両である場合には（ステップＲ３５）、新規車両データが記憶されるようになり（ステップＲ３６）、新規車両ではない場合にはその受信データは暫定的に記録されるようになる（ステップＲ３７）。なお、ここで暫定的としたのは、時間がたてば自動的にこれを消去することを意味している。
【０１３１】
この後、再びステップＲ２２に戻って上述の処理を繰り返すことになる。また、前述のステップＲ３１にて「ＮＯ」と判断された場合、つまり自車の通信スロットタイミングではない場合には、次ぎの通信スロットタイミングを計測し（ステップ３８）、通信スロットが終了したか否かを判断し（ステップＲ３９）、終了していない場合には再びステップＲ２２に戻って上述の処理を繰り返し実行し、通信スロットが終了した場合にはパイロットスロット制御（図１４参照）に戻るようになる。
【０１３２】
さて、上述のようにして通信処理を行う過程において、前述の通信用ＩＤコードが「２３４５」の車両と「０３４５」の車両との受信および送信タイミングの制御結果の例について、図１９ないし図２２を参照して、いくつかの具体的ケースを上げて説明する。
【０１３３】
図１９は、４桁の数字に設定された通信用ＩＤコードを有する場合で、例えば、通信用ＩＤコードの値が「２３４５」の車両の通信エリア１８内に、通信用ＩＤコードが「０３４５」、「２９８８」、「９８４５」の３台が存在し、そのうちの通信用ＩＤコードが「０３４５」の車両の通信エリア内に「２３４５」、「９８５４」、「２６９２」、「２８４５」の４台が存在する場合を示している。
【０１３４】
各車両においては、通信用ＩＤコードを用いて前述したフローチャートにしたがって通信を開始すると、それぞれの通信エリア内では、通信データに認識できた通信車両の通信用ＩＤコードのデータを送信し、この結果に基づいて自車の通信スロットの選択変更を行うようになる。ここでは、図２０に示すように通信フレームの中において干渉する通信用ＩＤコードを有する車両同士が調整を行うことにより衝突を回避して通信処理を確実に達成するようになる。
【０１３５】
また、図２１に示す例では、通信用ＩＤコードが「２３４５」の車両の通信エリア内に「０３４５」、「２９８８」、「９８４５」、「２６９２、「２８５４」の５台が存在し、通信用ＩＤコードが「０３４５」の車両の通信エリア内に「２３４５」、「９８５４」、「２６９２」、「２８４５」の４台が存在する場合を示している。
【０１３６】
この場合には、通信用ＩＤコードの第１の桁の値が「２」となる車両が全部で４台あり、通信用ＩＤコードの値の小さいものから順に、空き通信スロットを選択して通信処理を実行するようになる。また、通信を行っているグループから車両が離脱した場合（通信用ＩＤコードが「２６９２」，「２８５４」が離脱）や、車両が新たに入ってきた場合には、そのときの状況に応じて動的に通信スロットが変更されるようになる。
【０１３７】
なお、通信データには、位置座標データ、道路マーカデータ、位置ＩＤデータなどが含まれており、各車両のディスプレイには、それらの位置データに基づいた各車両の位置が表示されるようになっている。車両に車両の型式などの車両形状データを参照できるデータが入っていれば、ディスプレイには、実際に走行している状況を俯瞰しているような表示を行うことができる。また、これらのデータを車両に搭載されたＣＣＤカメラデータと比較することもできる。
【０１３８】
（第２の実施形態）
図２２は、本発明の第２の実施形態を示すもので、第１の実施形態と異なるところは、車両１に設けるＤＳＲＣ通信機の数を４個にしたところである。すなわち、４個のＤＳＲＣ通信機２ａ〜２ｄは、車両１の前後左右の４か所に配置され、前方、後方、左方、右方の各検出エリア２１ａ〜２１ｄを合成して矩形状の通信エリア２１を形成しており、この通信エリア２１内の他車と通信処理を行うように構成されている。
【０１３９】
このような第２の実施形態においても、第１の実施形態と同様の作用効果を得ることができ、この場合には、通信エリアの範囲設定の自由度が第１の実施形態の場合よりも小さいが、必要に応じてＤＳＲＣ通信機の設置個数を減らすことでコストの上昇を防止することができるようになる。
【０１４０】
（第３の実施形態）
図２３及び図２４は本発明の第３の実施形態を示すもので、第１の実施形態と異なるところは、前席左、右及び後部の３つの表示装置２２ａ〜２２ｃの構成を、画像生成器１０、表示データ制御器１１を含んだ構成としたものを使用している。なお、データベース１２については、これを一体に設ける構成としても良いし、共通に利用する構成とすることもできる。
【０１４１】
これにより、各表示装置２２ａ〜２２ｃにそれぞれ個別に使用者の要求する表示画面を表示させることもでき、使用者は周辺状況を多角的に把握することができるようになる。
【０１４２】
（他の実施形態）
本発明は、上記実施形態にのみ限定されるものではなく、次のように変形また拡張できる。
ＤＳＲＣ通信機を１個のみ設ける簡単な構成とすることもできる。この場合には、位置情報は、他車から送信される位置検出信号に基づいて判断することになるが、位置検出信号の検出精度が向上することにより十分実用上利用することができるものとすることができる。
【０１４３】
アンテナの配置は適宜の個数と位置を選択することができる。車両の周囲に存在する他車の位置情報をどの範囲まで認識することが安全性の点で良いかということも考慮して、矩形状に限らず特定の範囲を検出するように設定することもできる。
【０１４４】
移動体用通信装置は、車両に搭載するものに限らず、人が携帯するようなものでも良いし、あるいはロボットや無人搬送車などの移動体とすることもできる。その位置情報の利用の可能性は、人の場合には、歩行したり車両に搭乗したりする場合にも利用することができる。また、ロボットや無人搬送車などの使用者や運転者などが存在しない場合でも、遠隔的に位置情報を認識することに利用したり、あるいは装置間での移動制御や走行制御などに利用することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態を示すシステム構成図
【図２】電気的ブロック構成図
【図３】通信エリアの設定状態を示す平面図
【図４】自己の車両と周辺の車両とを道路上での平面図で示した図
【図５】アンテナの設置状態を示す図
【図６】検出信号による位置特定の説明図
【図７】他の車両の存在を推定するための作用説明図
【図８】図４の表示装置への表示画面を切り換えて示す車両の表示画面を生成する
【図９】表示装置による表示例を示す図
【図１０】通信フレームの構成を示す図
【図１１】同期信号を含んだデータ信号の構成と同期信号の検出用フィルタの対応を示す作用説明図
【図１２】通信処理の基本動作のプログラムのフローチャート
【図１３】同期捕捉処理過程のプログラムのフローチャート
【図１４】通信タイミングの設定処理のプログラムのフローチャート（その１）
【図１５】通信タイミングの設定処理のプログラムのフローチャート（その２）
【図１６】受信信号のパターンと通信エリア内での個別の通信状態を示す具体例の図
【図１７】パイロットウインドウへの通信用ＩＤコードの送信タイミングを説明するための作用説明図
【図１８】パイロットスロットの構成を説明する作用説明図
【図１９】通信処理過程の第１の具体例を示す車両の位置関係を示す図
【図２０】通信処理過程での干渉に対する通信スロットの割り当ての説明図
【図２１】通信処理過程の第２の具体例を示す車両の位置関係を示す図と通信処理過程での干渉に対する通信スロットの割り当ての説明図
【図２２】本発明の第２の実施形態を示す図３相当図
【図２３】本発明の第３の実施形態を示す図２相当図
【図２４】表示装置のブロック構成図
【符号の説明】
１は自動車（車両、移動体）、２ａ〜２ｆはＤＳＲＣ通信機、４ａ〜４ｄ，２２ａ〜２２ｃは表示装置、５はＧＰＳ受信器（位置検出手段）、６は広域通信機、７ａ〜７ｄはＣＣＤカメラ（撮像手段）、９はデータ制御器、１０は画像生成器、１１は表示データ制御器、１２はデータベース、１３は表示制御器、１４はディスプレイ、１５はユーザ入出力制御器、１６はデータ判定車内ＬＡＮ制御器、１７は外部機器制御器、１８は通信エリア（狭域通信エリア）、２０は道路である。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a narrow-area communication method for a mobile communication device that communicates with another mobile communication device that exists in its own communication area.To the lawRelated.
[0002]
[Problems to be solved by the invention]
There are the following configurations for preventing a rear-end collision with a vehicle ahead when the vehicle is running, or for keeping the inter-vehicle distance above a certain level. That is, for example, there is a forward vehicle detection type radar that transmits electromagnetic waves, measures the reflection time thereof, and measures the distance from the forward vehicle. Moreover, the same method is used, and an attempt is made to detect a plurality of vehicles using reflection of electromagnetic waves.
[0003]
The method using the reflected wave can detect front and rear vehicles, but cannot grasp the positions of surrounding vehicles. In order to exchange information between vehicles on ordinary roads, it is necessary to overcome various noise factors and to communicate with multiple vehicles. There is no way to reliably know what vehicle is traveling in which position. Therefore, it is insufficient as safe driving information (automatic driving information) for the driver.
[0004]
In addition, in order to realize communication between vehicles in this way, it is necessary to provide some kind of relay equipment on the road or on the road side. Therefore, a large amount of capital investment is required to realize this, and it may be difficult to achieve this.
[0005]
  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a narrow area communication method capable of reliably communicating with each other without causing collisions between the mobile bodies, and to transfer position information of the mobile bodies. Narrow-area communication method for mobile communication devices that can automatically recognize other moving objects that are approaching while movingThe lawIt is to provide.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, when performing communication processing with respect to another mobile communication device existing in its own communication area, a communication frame to be used is divided into a plurality of communication windows and the plurality of communication. It consists of a pilot window for allocating to the window, and in the process of starting communication, the communication ID code is transmitted into its own communication area and the signal transmitted from other mobile communication devices is received. Waiting, in the timing processing process, when there is reception from another mobile communication device, synchronization acquisition is performed to set the start time of the communication frame, and then the communication frame obtained in the communication processing process The communication data is transmitted / received in correspondence with the start time of.
[0007]
  This enables communication between mobile communication devices using communication frames that are free of a plurality of communication windows using communication frames without using communication relay facilities fixed at other fixed positions. Can be done. Further, by increasing the number of communication windows, it becomes possible to perform communication between three or more mobile communication devices. As a result, communication with other mobile communication devices in the communication area can be performed without interfering with each other.
  Then, the communication ID code is set in accordance with a rule that can be ordered with respect to any other, and in the timing process, the communication ID code of the self and the other mobile communication device received Since the communication window of the communication frame determined by ordering with the communication ID code is set, not only when there is one other mobile communication device, but also when there are two or more devices, Since the communication ID code and the own communication ID code can be ordered with each other, the communication frame communication window can be set according to the result of ordering the received communication I codes.
  This can be carried out in the same manner in other mobile communication devices, and can communicate with each other in accordance with the set communication window, resulting in a large number of mobile communication devices. Even in a situation where the two communicate with each other, it is possible to reliably perform communication in a self-aligned manner without providing a separate arbitration means for mediating the collision, and without causing a transmission / reception communication window to collide. become.
  Also, since the communication ID code is set to a value consisting of a multi-digit number or an orderable character, for example, when a communication ID code is set using a multi-digit number, other mobile units Can be ordered by comparing the size relationship with the communication ID code of the communication device, and when it is set to a value consisting of characters, for example, characters that can be ordered, such as alphabets, An order can be added by setting a character that can be expressed by a coded number or a character string that has been previously set in correspondence as a communication ID code.
  And when setting the communication ID code by numbers, when the communication ID code is received, it can be ordered by directly comparing the size without performing conversion processing, etc. In order to set the communication ID code, it is necessary to set the ordering rules and go through the ordering process, but as a character string including the name associated with the user of the mobile communication device Since the communication ID code can be set, it can be handled as a communication ID code that is meaningful and easy to remember for the user, and the communication partner can be recognized by looking at the communication ID code. It becomes like this.
  Then, the communication frame is set by providing more communication windows than can be set in the first digit for determining the order of the communication ID code, and the first communication ID code is set in the mobile communication device during communication. Since transmission is performed using a communication window corresponding to the value of the digit, communication is quickly performed between mobile communication devices having different values set in the first digit of the communication ID code. By assigning windows, communication processing can proceed without collision in different communication windows.
  Further, the pilot window of the communication frame is composed of a plurality of pilot slots, and the communication ID code to be transmitted to the mobile communication device in the process of starting communication is set to the value of the first digit for determining its rank. Since it is made to transmit to the corresponding pilot slot, in the communication start process, it is for the mobile body which communicates by receiving the communication ID code transmitted from the other mobile communication apparatus transmitted to the pilot window. An order for communication ID codes of communication devices can be added, and communication windows can be assigned based on the result.
  The pilot slot is composed of an initial slot followed by a plurality of recovery slots, and the mobile communication device is caused to transmit its own communication ID code to the initial slot of the pilot slot. When another communication ID code is received in the same initial slot, the order of its own communication ID code The communication ID code is transmitted again to the recovery slot corresponding to the value of the second digit for column determination, and in the timing process, another communication ID received in the recovery slot of the pilot slot Since the order is determined based on the code, a communication ID code consisting of a plurality of digits is set, and the pilot slot is determined by the first digit for order determination, so that the order can be easily and quickly handled. The pilot slot can be specified, and the order of the order can be determined using the recovery slot based on the second digit only when the pilot slot competes. Communication window designation processing based on the code can be performed.
[0008]
According to the invention of claim 2, in the invention of claim 1 above, in the communication start process by the mobile communication device, the communication ID code is transmitted at predetermined time intervals. Even if another mobile communication device enters, it is detected by starting communication by receiving a transmission signal from the other mobile communication device that has entered without detecting this separately. Will be able to.
[0009]
According to a third aspect of the present invention, in the first aspect of the invention, the mobile communication device transmits a communication ID code when there is another mobile communication device in the communication area in the communication start process. Therefore, when there is no other mobile communication device in the communication area, useless transmission power can be eliminated, and by confirming that there is another mobile communication device in the communication area by some means Thus, it becomes possible to quickly start communication with the mobile communication device.
[0014]
  Claim 4According to the invention of the aboveClaims 1 to 3In the timing process, the timing process is performed based on a signal for setting a reference time for synchronization. Therefore, when starting communication, a time signal corresponding to the reference time from the outside. The communication timing of the communication frame can be ensured by performing the timing processing by setting the reference time for synchronization internally between the mobile communication devices that communicate with each other and performing the timing processing. Communication processing can be carried out without being caught and colliding.
[0015]
In this case, in order to obtain the reference time externally, for example, a time signal output by a GPS satellite or a facility for outputting a time signal on the road side is provided, for example, for all mobile objects that perform communication. By receiving the communication device, it can be used as a common reference time. Also, in order to obtain the reference time internally, a predetermined reference time setting rule is determined between mobile communication devices in the communication area, so that an independent system can be used without obtaining a synchronization signal externally. Communication processing can be performed without setting a reference time and colliding.
[0016]
  Claim 5According to the invention of the aboveClaim 4In the invention, the mobile communication device is provided with a synchronization base ID code having a specific number of communication ID codes, and in the communication start process, the synchronization base ID code is transmitted together with the communication ID code. In the process, since the reference time is set based on the reception timing of the synchronization base ID code, it is possible to set the reference time internally between the mobile communication devices that perform communication and perform the timing process. become able to.
[0017]
In this case, the mobile communication device is provided with a synchronization base ID code for setting a reference time for synchronization with a specific number of communication ID codes. In addition, in the mobile communication device to which the synchronization base ID code is attached, it becomes possible to perform the timing process by setting the reference time by itself.
[0018]
  Claim 6According to the invention of the aboveClaim 5In the timing processing process, when there is no mobile communication device that transmits the synchronization base ID code, the communication ID code order determination of the mobile communication devices that are about to start communication is performed. Since the reference time is set based on the reception timing of the communication ID code transmitted by the first digit value that is positioned at the head of the order, communication is performed even when the synchronization base ID code is not received. Since the reference time can be set between the mobile communication devices, the time adjustment process can be surely performed and the communication process can be performed in a synchronized state.
[0019]
  Claim 7According to the invention ofClaims 1 to 3In the timing process, the communication ID code of the other mobile communication device received at the start of communication and the communication ID code of the mobile device are ranked in order to obtain the most dominant communication ID code. Since the timing of receiving the ID code for communication of the mobile communication device is set as the reference time and the timing processing is performed, the mobile communication devices that perform communication in a self-aligned manner in any case Can reliably communicate with each other.
[0020]
  Claim 8According to the invention of the aboveClaims 1 to 7In the invention, in the communication processing process, the synchronization tracking process is performed in parallel so as to maintain the synchronization state based on the reference time obtained in the timing processing process. Even in such a case, since it is possible to proceed while maintaining the synchronization state initially set in the course of progress, it is possible to reliably achieve the communication processing.
[0024]
  Claim 9According to the invention of the aboveClaims 1 to 8In the present invention, in the timing processing process, when another communication ID code is received in the recovery slot of the pilot slot, the communication ID received in the communication slot and recovery slot corresponding to the own communication ID code Since the communication slot corresponding to the code is designated as the communication window corresponding to the pilot slot, the communication slot corresponding to the code is designated as the communication window corresponding to the pilot slot, and the communication processing is performed. Even when pilot slots compete, it is possible to easily specify other vacant communication windows based on the order of precedence and perform communication processing, thus preventing mutual interference as much as possible and ensuring reliable communication processing. Will be able to do.
[0025]
  Claim 10According to the invention, in each of the above-described inventions, the communication method of the mobile communication device is the spread spectrum communication method. Therefore, when performing communication processing with other adjacent mobile communication devices, Communication can be performed promptly and reliably without interference.
[0033]
According to the invention of claim 22, in the invention of claim 21, when the position determination means obtains the relative position of another moving body based on the position detection signal, the position detection of the plurality of antennas is performed. Since the position information of the antenna that received the signal is also referenced, even if the position detection signal contains an error, the position is determined after recognizing that there is a moving object in the detection area of the antenna that received the signal. Since it can be determined, it is possible to prevent erroneous detection and improve position detection accuracy.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a radar mounted on an automobile will be described with reference to FIGS.
FIG. 1 schematically shows an overall configuration, and a vehicle 1 such as an automobile which is a moving body is illustrated by taking a passenger car as an example. DSRC (Dedicated Short-Range Communication) communication devices 2a to 2f are arranged at six locations on the front and rear, left and right corners and both sides of the vehicle 1. The six DSRC communication devices 2a to 2f are for performing narrow-area communication. For example, a communication area that is a communicable range is set to about 30 m. These six DSRC communication devices 2a to 2f are connected to the vehicle-to-vehicle communication controller 3, and the communication control is integrated.
[0046]
Display devices 4 a to 4 d are arranged at four locations in the passenger compartment 1 a of the vehicle 1. In addition, a GPS receiver 5 and a wide area communication device 6 as a position detector are disposed in the dashboard 1b portion. Further, four CCD cameras 7a to 7d capable of photographing the front, rear, left and right are arranged on the ceiling portion of the passenger compartment 1a. These CCD cameras 7a to 7d are connected to an image controller 8 to control output of captured image data.
[0047]
Next, the electrical configuration will be described with reference to FIG. The data controller 9 for comprehensively controlling the narrow area communication includes a storage unit such as a CPU, a ROM, and a RAM, an input / output control interface, and the like. This is a configuration having functions such as a determination means. The data controller 9 is connected to the DSRC communication devices 2a to 2f via the vehicle-to-vehicle communication controller 3 described above, is connected to the GPS receiver 5 and the wide area communication device 6, and is connected to the CCD via the image controller 8. Cameras 7a to 7d are connected.
[0048]
In addition, display devices 4 a to 4 d are connected to the data controller 9 via an image generator 10 and a display data controller 11. A database 12 is connected to the image generator 10 so that data relating to various images can be read out. The database 12 includes a road shape database 12a, a contour line database 12b, a three-dimensional vehicle shape database 12c, and a texture database 12d.
[0049]
The image generator 10 uses road shape data for generating an image stored in the database 12, contour map, vehicle shape data traveling around, and textures such as plant vegetation as data, and displays them. The virtual image data is generated. At this time, the virtual image to be generated is created by a three-dimensional projection method, and the data that is insufficient at this time can be downloaded from the outside through, for example, the wide-area communication device 6. .
[0050]
As will be described later, the position of the vehicle is the position coordinate, the vehicle shape is the model data of the vehicle, the road is extracted from the captured images of the CCD cameras 7a to 7d, or the road image data is read, and the relationship between the road and the vehicle is simply determined. Can be displayed. In addition, if the positional relationship between the vegetation of trees, the position of structures, rivers, lakes, etc. can be determined from the results of sampling the surrounding conditions from the images taken by the CCD cameras 7a-7d or digital map data, the roads in the landscape It is possible to simulate how each vehicle is running. For the generation of an image, a ray tracing method, a von shading method, a Z buffer method, or the like is used.
[0051]
The image generator 10 can extract a road shape, vehicle shape, vegetation, and the like from the captured images of the CCD cameras 7a to 7d and replace them with shape data to generate an image three-dimensionally. The image generator 10 is configured such that a similar image generator 10 can be easily added when the processing capacity becomes insufficient.
[0052]
The display data controller 11 performs processing such as switching the generated image (or a plurality of processes) to a live-action image, superimposing, partly taking a photograph, and partly making a composite image. Thereby, it is possible to create a bird's-eye view by transitioning from an actual photograph of the CCD cameras 7a to 7d to a landscape created with various shape data while superimposing an image (composition image). Thereby, the user can see the display result of the surrounding situation radar without feeling uncomfortable, and can easily grasp the surrounding situation.
[0053]
The display devices 4a to 4d include a display controller 13 and a display 14, and the display controller 13 displays an image corresponding to the display data when the display data is supplied from the display data controller 11. It has become.
[0054]
These display devices 4a to 4d can display different images by transferring different data from the data controller 9 to each of the display devices 4a to 4d. It is possible to grasp from various perspectives.
[0055]
The data controller 9 is connected to the user input / output controller 15 through an interface, and monitors the user's operation to perform the operation desired by the user. Further, an external device controller 17 is connected to the data controller 9 via a data determination in-vehicle LAN controller 16, and the operation of other external devices disposed in the vehicle based on the detected position information is controlled. It also has a configuration to control.
[0056]
Note that the data controller 9 is provided with a plurality of data controllers 9 in order to prevent the processing capability from being lowered even when a communication device or other device connected thereto is added. It is configured to work.
[0057]
FIG. 3 shows a narrow communication area 18 set in a square shape around the vehicle 1, and the narrow detection areas 18a to 18f set by the DSRC communication devices 2a to 2f described above are shown as a whole. Is the range that can be obtained as the communication area 18. In this case, for example, the communication area 18 is set as an area that can be detected up to a range of about 30 m for each of the front, rear, left, and right sides of the vehicle 1.
[0058]
Each of the DSRC communication devices 2a to 2f has a detection area that can be communicated by increasing the antenna output with respect to the detection areas 18a to 18f set as a reliably communicable range. It can be expanded.
[0059]
Next, the operation of this embodiment will be described. In the description of the operation, the outline of the radar detection operation will be described first, and then the narrow area communication method applied in the present embodiment will be described in detail.
[0060]
[Description of radar operation]
FIG. 4 is a diagram showing a relationship between the communication area 18 of the vehicle 1 on the road 20 and other vehicles. The road 20 is a driving lane 20a and an overtaking lane 20b on which the vehicle 1 is traveling, and an opposite driving lane. 20c and the overtaking lane 20d facing each other are separated by a separation band 20e. Around the vehicle 1, vehicles A to G, which are other moving bodies (vehicles), are traveling. What is indicated by a broken line in the vicinity of each of the vehicles A to G is a communication vicinity area.
[0061]
Vehicles A to C traveling in the same direction as the vehicle 1 and vehicles D and E traveling opposite to each other exist in the communication area 18 and can directly communicate with each other. The vehicles F and G are traveling in the same direction, but are out of the communication area 18 and can communicate with the vehicle F via the vehicle B, and can communicate with the vehicle G via the vehicle F. It has become.
[0062]
When communication processing is started, communication data such as position information is exchanged in a self-aligned state while applying a communication method described later to prevent mutual interference. Here, the signal transmitted in the communication area includes a position detection signal and a signal indicating the installation position of the DSRC communication devices 2a to 2f that transmit the signal in addition to the communication ID code. Yes.
[0063]
The relative positions of other vehicles existing in the communication area are estimated as follows. Since the antennas of the DSRC communication devices 2a to 2f are arranged as shown in FIG. 5 with respect to the vehicle 1, the positions of other vehicles can be estimated from the signals received by the antennas. For example, assuming that the front right antenna has received a signal from another vehicle, the position of the vehicle can be estimated as follows based on the information of the antenna that transmitted the received signal (see FIGS. 6 and 7).
[0064]

[0065]
Further, assuming that the front left antenna receives a signal of another vehicle, the position of the vehicle can be estimated as follows based on the information of the antenna that transmitted the received signal.
[0066]

[0067]
Note that the receiving antenna may not have directivity as long as it only estimates the position. On the other hand, in order to prevent contact, since it is necessary to measure the distance to the vehicle in each direction, directionality is required.
[0068]
When communicating with other vehicles, if the vehicle receives a strong radio wave of the other vehicle, that is, a radio wave whose electric field strength is larger than the set value, it is assumed that the other vehicle is present at a close range. Therefore, the display devices 4a to 4d are used for the driver, or a warning is issued by a buzzer or voice output to prevent contact with other vehicles.
[0069]
In addition, when the number of vehicles existing in the own communication area 18 increases so much that the communication processing is burdened, or when quick communication with a vehicle at a close distance is necessary, the DSRC communication device 2a The range of the communication area 18 can be changed as necessary by adjusting the reception sensitivity and transmission intensity of ˜2f. In addition, the communication area 18 can be changed in conjunction with the travel speed of the host vehicle and the distance to the partner vehicle that requires communication.
[0070]
When the relative position of other vehicles existing in the communication area 18 is determined as described above, this is displayed on the display devices 4a to 4d. For example, when the vehicle is present on the road 20 as shown in FIG. 4, the display screen S is shown as seen from above as shown in FIG. Here, in order to make the position of the own vehicle 1 easy to understand, the color of the vehicle is changed or blinked.
[0071]
In addition, this display screen S can display presence of the vehicle ahead or back rather than the own communication area 18 by operating the scroll bar B provided in the screen lower part. This is based on the fact that the upper part of a wide range of vehicles can be detected by linking the communication areas to each other due to the occurrence of traffic jams. It is possible to display the head position of a vehicle that travels at a speed (for example, a speed of about 50 km / h and a speed that is assumed to be free of traffic). In addition, an enlarged display button M, a reduced display button N, and the like are also displayed so that it is convenient to see the relative position with respect to the other vehicle in detail or to see the whole in an overhead view.
[0072]
Thus, not only the range of the communication area 18 of the own vehicle, but also a wide range of vehicle position information obtained by relaying the communication area of other vehicles can be obtained. Etc. can be grasped in real time, route search to avoid traffic congestion can be performed quickly and accurately, and the time to escape from traffic congestion can be predicted to some extent, so the driver's frustration due to traffic congestion etc. Can also be relaxed.
[0073]
When displaying the relative position of other vehicles, it is also possible to display an image as shown in FIG. 9A using image information from the CCD cameras 7a to 7d. In this case, by receiving the vehicle type of the other vehicle as communication processing data, the three-dimensional information of the vehicle and the surrounding map information (terrain information) are read from the database 12, and the relative position between the own vehicle and the other vehicle is read. Based on the detection result, the three-dimensional model of the vehicle and the terrain is arranged and drawn according to the measurement result in real time, and can be displayed on the display devices 4a to 4d as a realistic virtual image.
[0074]
And in the display of the virtual image generated in this way, it is possible to display the state from the viewpoint moved freely by moving the viewpoint. For example, the operation lever L is displayed on a part of the display screen S, and the viewpoint can be moved by operating the operation lever L in the desired direction of up, down, left, and right. When the viewpoint is moved upward (see Fig. 7 (b)), the whole situation can be grasped in a three-dimensional manner from a high position, and the presence of the vehicle in front that could not be seen in the shadow of the previous vehicle is three-dimensionally displayed. Can be confirmed. Further, when the viewpoint is moved to a position as seen from the side of the road (see (c) in the figure), it is possible to objectively display the state of the vehicle and other vehicles existing before and after the vehicle. It becomes like this.
[0075]
[Description of narrow area communication method]
Next, the narrow area communication method by the DSRC communication devices 2a to 2f in the communication area 18 will be described in detail. The communication method achieved in this embodiment is characterized in that the vehicle-to-vehicle communication can be directly controlled between vehicles without providing a repeater on the roadside or the like. The mobile communication device mounted on each vehicle 1 can exchange signal data with each other without causing interference with the mobile communication device of another vehicle 1 existing in its own communication area 18. It is configured as follows.
[0076]
As is well known, electromagnetic wave signals are used in various applications and cannot occupy a wide frequency band for inter-vehicle communication. Therefore, a communication system that has a narrow frequency band and is resistant to noise and radio wave interference is required. Also, since there are a plurality of vehicles around the vehicle, it is necessary to control communication so that interference and communication collisions do not occur. In this embodiment, in order to solve these problems, for example, a spread spectrum communication method is adopted, and a communication method as described below is adopted so that communication collision can be avoided in vehicle-to-vehicle communication. Yes.
[0077]
In describing the communication method, the preconditions will be described. The timing at which each vehicle communicates is determined based on the value of the vehicle or communication ID code. Here, the communication ID code set for each vehicle uses a multi-digit number. In this embodiment, for the sake of simplicity, a case where a 4-digit number is set as a communication ID code will be described as an example.
[0078]
Of the communication ID codes indicated by four-digit numbers, the vehicle 1 in which the number of the first first digit is “0” is set as the synchronization base ID vehicle. This is because the communication sequence starts from a vehicle whose first digit is “0”. Further, in the group of vehicles whose first digit number is not “0”, the vehicle having the smallest communication ID code is set as the synchronization base vehicle.
[0079]
The configuration of a communication frame used for communication is as shown in FIG. That is, a communication frame having a reference time, which will be described later, as a start time is composed of a pilot window WP located at the head and ten communication windows WC following the first window. ing. The pilot window WP is composed of ten pilot slots SP from “0” to “9”. Each pilot slot SP is further composed of an initial slot followed by 10 recovery slots SR.
[0080]
A vehicle whose first digit value of the communication ID code is “0” transmits its own communication ID code and synchronization base ID code to the slot of the pilot window number “0”. In addition, the vehicle whose first digit value of the communication ID code is “0” transmits the communication data to the 0th communication slot.
[0081]
When the number of slots is variable, transmission is performed including the number of used communication slots. For example, when the number of communication slots is increased from 10 to 16, the number obtained by dividing the last two digits by 16 becomes the slot number for communication.
[0082]
In the above-described case, the synchronization base ID code indicates the vehicle ID code that determines the reference time of the synchronization time when a plurality of vehicles travel in a collective manner. As described above, the synchronization-based vehicle is normally set to a vehicle whose first digit value of the communication ID code is “0”. If there is no vehicle for which the reference time of the synchronization time is set, that is, the vehicle whose first digit value is “0” among the vehicles of the group to be communicated, the first digit value is “ The vehicle closer to “0” will function as a synchronous base ID vehicle. The slot number and communication slot number in the pilot window are selected and set independently for each vehicle according to the value of the first digit of the communication ID code.
[0083]
In order to perform communication, it is necessary to know the start position of communication data, that is, the reference time for timing. Here, a delay line matched filter F is used for data demodulation processing. FIG. 11 shows the configuration of the signal, in which the data portion is sent following the synchronization signal. A plurality of synchronization signals are set in order to increase the possibility of matching.
[0084]
In the figure, the delay matching filter F is configured such that data is output only when a designated signal is received, and the reference time (0 time) can be calculated from the matched timing. In addition, the phase (time) is controlled (the time is adjusted) so that the synchronization correction with another vehicle (this is called synchronization acquisition) matches the reference time. Further, when synchronization is established, synchronization tracking called a phase lock loop (PLL) is performed so as not to deviate from the condition, and control is performed so as not to cause a deviation in communication timing.
[0085]
Next, a basic communication flow will be described with reference to FIG. When the communication process is started (step S1), first, buffer initialization, control parameter setting, counter stability check, and the like are executed. Subsequently, a communication ID code is transmitted as the ID data of the own vehicle (step S2). Here, a case where a communication ID code is periodically transmitted is shown as an example. In this method, if the transmission interval becomes longer, a delay occurs in the time from when another vehicle enters the communication area 18 until communication is started. Therefore, an appropriate time interval is set so as not to adversely affect the transmission interval. It is preferable to transmit the communication ID code.
[0086]
Also, instead of the above case, the communication ID code is transmitted when any of the CCD cameras 7a to 7d detects that a vehicle to be communicated exists in the communication area 18. Also good. In this case, since data can be received unless the other vehicle is incapable of communication, step S3 is not necessary, but a step of detecting the presence of the other vehicle is added at the start of this communication processing flow. Will be.
[0087]
Next, it is checked whether other vehicle data has been received (step S3). This is to determine whether or not a communication ID code has been received from another vehicle. If there is no received data, the process returns to step S2 and the process of periodically transmitting the communication ID code is repeated. . If there is received data, the timing process (synchronization acquisition) is subsequently executed (step S4). When synchronization acquisition is completed, synchronization tracking and user communication processing are performed in parallel (steps S5 and S6). Thereby, the communication process performed with the other vehicle which exists in the communication area 18 is complete | finished.
[0088]
Next, in the basic flow of the above communication processing, the DSRC communication devices 2a to 2f of the vehicle 1 are configured to perform full-duplex communication, that is, transmission and reception simultaneously. In this case, in receiving, the data processing can be executed whenever data is received. Since the received data is modulated as described above, it is decoded through a demodulation filter. When there is an output from the demodulation filter, it is determined that there is reception. On the other hand, when there is no output, it is processed as noise reception.
[0089]
The received data includes the communication ID code of the other vehicle that transmitted the data and the data of the vehicle (synchronization base ID code) that is the base of the synchronization timing that is used to synchronize the transmitted other vehicle. ing. As an option, when the number of communication slots is variable, the number of slots is also included in the data. If these data cannot be read from the received data, the reception process is continued as a reception error.
[0090]
Next, the timing process (synchronization acquisition) process will be described. This timing process will be described from the time when the vehicle starts operating. If the vehicle travels in a group, the vehicle travels while synchronizing to communicate with the group. If the vehicle travels independently, it is necessary to synchronize to communicate with another vehicle. Communication patterns include the following.
[0091]
Single ← → Single
Single ← → Group When a single vehicle is included in the group
Group ← → Group Group vs. group
Group ← → Single When leaving the group
[0092]
In any case, the communication vehicle ID code and the synchronization base ID code are set, and the timing of the synchronization base vehicle is used for the synchronization time setting. The synchronization timing is performed by adjusting the synchronization time by each vehicle looking at the synchronization base vehicle data of the other vehicle and comparing it with the synchronization base ID code of the own vehicle. In this case, the basis of synchronization is person-by-person. Thereby, even if it cannot communicate directly with the synchronization base vehicle, it can be synchronized with the group. For setting the synchronization base vehicle, for example, a vehicle having the smallest value of the first digit of the communication ID code in the group is selected. By selecting the synchronization base vehicle in this way, group-to-group synchronization can be performed smoothly.
[0093]
In addition, general vehicles and special vehicles (for example, ambulances, fire trucks, police cars, special work vehicles, dangerous goods vehicles, etc.) can be set as a small number or a number with “0” at the time of registration. . The general vehicle can be synchronized with the special vehicle in synchronization with the timing.
[0094]
In the following, an example of a received signal will be specifically shown and described. FIG. 16A shows the temporal transition of data received before synchronization acquisition, that is, in a state where the reference time is not fixed. A portion indicated by a rectangle indicates a portion where a signal is present. In this figure, in the pilot slot, there should be a small size signal containing the vehicle communication ID code and the synchronization base ID code.
[0095]
On the other hand, another form of signal (communication data) is received in the communication window determined according to the vehicle communication ID code. This communication data includes at least a vehicle communication ID code and a communication slot number. Since each piece of data is modulated independently, each piece is individually decoded.
[0096]
Now, the result of performing the synchronization acquisition process from the above-described temporal transition of the received data is shown in FIG. In the figure, the upper part shows the flow of the entire signal data, and the lower part shows the flow of the individual signal data of each vehicle. After synchronization acquisition, the time determined from the reception timing of the signal data is obtained, and the timing of each slot is determined. Here, in the individual signal data flow shown in the lower part, the numbers indicate the communication ID codes (four-digit numbers) of the respective vehicles, and the communication ID codes of the synchronization base vehicle are shown in parentheses. .
[0097]
Here, the filter F described above is used to read out individual signals. The presence or absence of a signal and the content of signal data are read for each detected data. Whether the data is for a pilot slot or a communication slot can be determined by checking the data content (data header). As a result, a rough communication frame window is set. Thereafter, detailed synchronization acquisition is performed based on the reception timing of the communication ID code from another vehicle output in the pilot frame.
[0098]
Detailed synchronization acquisition is performed as follows. FIG. 13 shows the flow, and the vehicle-mounted device performs reading processing of signals transmitted from the surroundings of the vehicle (step P1). Since the spread spectrum signal is difficult to distinguish from noise, the received radio wave is constantly monitored while the vehicle is running. The data reading process of the received radio signal is performed using the synchronization filter.
[0099]
Next, when the received radio wave signal can be decoded, the filter output outputs a data presence signal, so it is determined that there is an output (step P2). The time when the data is read is recorded as the time measurement origin, and the data is read. In this case, the time measurement and the data processing are configured to be performed independently. Also, here, the timer is also set for provisional time processing and fixed time processing so that the provisional time processing can be changed by one command.
[0100]
Next, it is checked whether the received data is for a pilot slot (step P3). The pilot slot data includes a vehicle communication ID code and a synchronization base ID code. On the other hand, the communication data is composed of a communication slot number, a vehicle communication ID code, and data (data tag + data), and can be distinguished from the pilot slot data because the configuration is different. Or you may make it distinguish by adding tag data for recognition to data.
[0101]
Subsequently, when the data received from the other vehicle is for the pilot slot, the vehicle having the communication ID code of the other vehicle and the vehicle having the synchronization base ID code that the other vehicle uses as the synchronization reference time is read (step P4). Next, the value of the first digit of the communication ID code of the other vehicle is stored among the received data of the other vehicle that can be read (step P5). The value of the first digit of the communication ID code usually indicates the number of the communication slot used by another vehicle. Therefore, the value of the first digit of the communication ID code is the same as the communication slot number. However, when there are a plurality of vehicles having the same value of the first digit of the communication ID code, the value of the first digit of the communication ID code may not match the communication slot number. This point will be described in detail later. Then, information (position information, speed information, etc.) relating to the communication ID code is transmitted to the communication slot determined by the value of the first digit of the vehicle communication ID code.
[0102]
Next, preparation for communication timing setting is performed (step P6). Here, the communication reference time is provisionally set. The description regarding the setting rule will be described later. The time setting is controlled so that the time set first is prioritized and the reference time is not set by a signal to the pilot window received accidentally later. Here, the signal to the pilot window determined not to be synchronized is stored if the signal can be read.
[0103]
Next, communication timing setting processing is performed (step P7). Here, the method for setting the timing for each received data is shown. However, when multiple signals with consistent reception timing are received in the pilot window, the reception time is statistically calculated. It is also possible to improve the time accuracy of the slot timing by processing automatically. If the timing is shifted and there is data extending between the slots, extra time is required for the data determination process. When the communication timing is set by the received data of the pilot slot and the set time elapses, the communication slot is started next.
[0104]
When the communication slot time is reached and data is received in the data reception mode, it is checked whether the received data is correct communication slot data (step P8). Since the communication start time is set for each communication slot number, data corresponding to the communication ID code is received at the specified time. Next, when the received data is communication slot data, it is checked whether the data is started at the set timing (step P9). If “YES”, the communication slot data is set at the set timing (expected time). If received, the data is stored in a list of synchronization base ID codes (step P10). Subsequently, when the data can be received at the set timing, the synchronization acquisition is completed (step P11), and the setting of the 0 time, that is, the reference time is determined (step P12).
[0105]
On the other hand, when “NO” is determined in step P8, that is, when it is determined that the data is not in the set form, the received data is processed as noise (step P13). In this case, as another method, the data received in the pilot window may be used based on the read data, or the data may be corrected using a normal error correction method.
[0106]
Further, when “NO” is determined in Step P9, that is, when communication does not start at the set timing, the communication ID code included in the data is read, and it is checked whether or not it is a new communication ID code. (Step P14). If it is a communication ID code for a new vehicle, it is stored in the list as an asynchronous communication ID code (step P15). If "NO" is determined in step P14, it is determined as noise. The process returns to P1 (step P16).
[0107]
Next, the communication timing setting preparation, that is, the setting of the reference time, performed in step P6 described above will be described in detail. FIG. 17 shows a pilot window frame. The starting position of the pilot slot is determined according to the value of the first digit of the vehicle communication ID code transmitted prior to communication. Therefore, if the value of the communication ID code of the received vehicle is known, the communication start position (time) of the pilot slot can be estimated, and the time (clock) between the own vehicle and the other vehicle can be adjusted. Allows you to prepare for synchronization.
[0108]
In this figure, for example, when the value of the communication ID code whose own vehicle is another vehicle is “2345”, since the first digit value is “2”, data is received in pilot slot 2. Has been. Here, the pilot slot indicates a time interval between 2.00 and 2.99 seconds as measured from the reference time. A vehicle whose first digit value of the vehicle ID code is “2” is transmitted to the initial slot portion constituting the pilot slot 2 within the inter-unit time from time 2.01 to 2.05. Let's start. A communication clock that has not been determined before synchronization acquisition is provisionally set by data reception, and a reference time is estimated.
[0109]
To simplify the explanation, if the time for the pilot slot is 10 time units and each communication slot is also 10 time units, the pilot window starts and it takes 110 time units to complete 10 communication slots. become. In each vehicle, the transmission timing to the pilot window (pilot slot) and the communication window (communication slot) is set by the vehicle communication ID code. Therefore, when the vehicle communication ID code is determined, the time at which the signal to the pilot slot is started and the time at which the signal is next transmitted to the communication slot are determined.
[0110]
A vehicle whose first digit value of the communication ID code is “5” transmits data related to the communication ID code to the pilot slot 5 and then transmits data to the communication slot 5. Therefore, if there is no signal to the pilot slot, it can be predicted that the vehicle has no communication data.
[0111]
For example, a vehicle whose communication ID code is “2345” starts communication to the pilot slot between time units 2.01 to 2.05 because the value of the first digit is “2”. To the communication slot
[Pilot window] + [Communication slot] x 2 = 30 time units
Therefore, the communication data of the vehicle with the communication ID code “2345” is transmitted 30 time units after the reference time.
[0112]
When the communication ID code is “3456”, the communication to the pilot slot is started between the time units 3.01 to 3.05.
[Pilot window] + [Communication slot] x 3 = 40 time units
Therefore, the communication data of the vehicle with the communication ID code “3456” is transmitted after 40 time units from the reference time.
[0113]
As described above, the pilot slot is composed of an initial slot and 10 recovery slots. From each vehicle, the pilot slot has the same number as the first digit of the communication ID code. The communication ID code is transmitted, and the communication ID code is also transmitted to the recovery slot having the same number as the value of the second digit. Even when the values of the first digit are the same and they collide with each other, the communication ID code of the received vehicle can be recognized because the values of the second digit are different.
[0114]
Next, communication timing setting will be described. When there are a plurality of vehicles, a communication collision may occur and communication may not be possible unless the mutual reference times are set. In addition, even if the reference time is set, the value of the first digit of the vehicle communication ID code may be the same, so it is necessary to adjust the setting of the communication timing in that case. The following defines the procedure.
[0115]
FIG. 19 shows an example in which a total of seven vehicles travel and communicate with each other. The communication ID code attached to each vehicle is set as shown in the figure, for example. Now, how to perform communication will be described by paying attention to two vehicles whose communication ID codes are “2345” and “0345”. The communication area of the vehicle whose communication ID code is “2345” is an area indicated by a broken line in the figure. The vehicles that can communicate with this vehicle are three communication ID codes “0345”, “2988”, and “9854”. On the other hand, vehicles with communication ID code “0345” can communicate with four vehicles with communication ID codes “2345”, “2692”, “2854”, and “9854”.
[0116]
The transmission timing decision rule is determined as follows. If the value of the first digit of the vehicle communication ID code overlaps (if the first digit of the ID is i), the communication ID code is transmitted to the initial slot of the i-th pilot slot in the pilot window. Is done. Next, the communication ID code is also transmitted to the j-th slot of the recovery slot of the i-th pilot slot (j is the second digit of the ID code).
[0117]
If the value of the first digit of the communication ID code is the same and the value of the second digit is different, the communication slot is preferentially assigned to the one having the communication ID code having the smaller value of the second digit. For those having a larger communication ID code, empty communication slots are sequentially assigned. For example, when there are three vehicles (for example, “8266”, “8470”, “8932”) having the same first digit value of the communication ID code and “8”, the empty slot at that time is 0. , 2, 3, 4, 7 and 9, the communication ID code “8266” is the slot 8 first, the next “8470” is the recovery slot 9, and “8932”. Are configured to transmit in recovery slot 0.
[0118]
Each vehicle can monitor the communication to the pilot slot to determine the situation of surrounding vehicles of other vehicles in the communication area of the own vehicle and which slot each vehicle uses for inter-vehicle communication. 14 and 15 show the flow of setting the communication timing of each vehicle.
[0119]
First, the time 0, that is, the reference time is set (step R1), and then the communication ID code of the own vehicle is read and acquired (step R2), and the first digit and the second digit of the acquired communication ID code are obtained. Are stored individually (step R3). Next, a pilot slot is started based on the reference time (step R4). At this time, it is premised that the vehicle is already in a synchronized state with a vehicle that already exists in the vicinity. Here, the classification data (flag) for recording the number of communication collisions in each slot is initialized.
[0120]
Next, measurement of pilot slot timing is started (step R5). Subsequently, it is checked whether or not the pilot slot timing of the other vehicle has come (step R6). If “YES”, it is checked whether or not data is received at the timing when the pilot signal of the other vehicle is issued. (Step R7). When data is received, “YES” is determined and the received data is analyzed (step R8). When there is normal reception, the communication ID code of the vehicle having the number of each pilot slot in the first digit is read.
[0121]
If the value of the first digit of the communication ID code of the received other vehicle is the same value as the value of the first digit of the own vehicle, communication is performed in the same communication slot as the own vehicle to cause interference. Because there is a possibility, it is necessary to change the communication slot of the own vehicle or other vehicles. The communication slot is selected based on the communication result to the recovery slot of the pilot slot (the first time each car transmits data to the recovery slot with the number of the communication ID code of the second digit). If the transmission to the recovery slot is faster (the second digit is smaller), the communication slot is not changed, and the later communication slot is selected and communication is performed there. .
[0122]
When a plurality of communication ID codes for other vehicles having the same value as the first digit of the communication ID code of the own vehicle are received, depending on the state of the received signal, there is usually a risk that data may not be read due to a collision. There is. Even in this case, there is a possibility that the vehicle communicates with and interferes with the same communication slot as the own vehicle, and therefore the own vehicle needs to change the communication slot of the other vehicle. In this case as well, the communication slot is selected in accordance with the result of communication to the recovery slot of the pilot slot (the first time each car transmits data to the recovery slot of the second digit value). If the transmission to the recovery slot is faster (the value of the second digit is smaller), do not change the communication slot, and select the next communication slot that has the next slower transmission to the recovery slot. Communicate there.
[0123]
Next, the received data is stored (step R9). If there is an error in the analyzed data, the data is discarded or corrected. If “NO” is determined in step R6 or R7, the pilot slot timing is measured (step R10). Subsequently, it is checked whether or not the pilot slot timing of the host vehicle has come (step R11). If “YES”, the data i is set to “0” and transmitted to the initial slot (step R12).
[0124]
At this time, it is checked whether or not a signal is received in the same slot as the transmitted initial slot (step R13). When the received data is detected here, it is determined that there is a vehicle having a communication ID code whose first digit value is the same as the communication ID code of the own vehicle (step R14). Here, J (I) is changed to J (I) +1. Next, transmission is performed at the recovery slot timing (step R15). If “NO” is determined in step R13, that is, if there is no reception data in the same initial slot, transmission is performed at the recovery slot timing (step R16).
[0125]
Subsequently, at the time of transmission to the recovery slot, it is checked whether there is no received data in the same slot (step R17). If there is received data, it is determined that the values of the first and second digits of the communication ID code are the same, and the fact that there has been a collision of the second digit is recorded (step R18). Then, the number of digits J (I) +1 to be transmitted to the next recovery slot is set (step R19). At this time, the value of the first digit of the communication ID code is always transmitted to the initial slot. It then waits for the next pilot slot timing.
[0126]
Next, if “NO” is determined in step R11, the pilot slot timing is measured (step R20), and then it is checked whether the pilot slot time has ended (step R21). If not, the process returns to step R5 to measure the pilot slot timing, and if completed (branch indicated by a in the figure), the flow proceeds to the communication slot control flow shown in FIG.
[0127]
In the operation of the communication slot control, first, the communication slot timing is measured (step R22), and it is determined whether it is the communication slot timing of another vehicle (step R23). Here, if it is the communication slot timing of another vehicle, it is checked whether there is other vehicle data in that communication slot (step R24).
[0128]
If there is data, the slot data of the other vehicle is analyzed (step R25), the communication slot data of the other vehicle is stored (step R26), and an empty communication slot is confirmed (step R27). From this confirmation result, it is determined whether or not the communication slot of the own vehicle can be used (step R28). If it cannot be used, an empty communication slot is selected according to the rule (step R29).
[0129]
Next, when an empty communication slot is selected, when “NO” is determined in step R23, or when “NO” is determined in step R28, the communication slot timing is measured (step R30), and the vehicle If it is the communication slot timing ("YES" is determined in step R31), the vehicle data is transmitted to the communication slot (step R32).
[0130]
Subsequently, it is checked whether or not there is received data at the same communication slot timing as the own vehicle (step R33). This is to determine whether or not a new vehicle exists in the communication area and is about to start communication. If “YES”, the received data is analyzed (step 34), and the new vehicle In some cases (step R35), new vehicle data is stored (step R36), and if it is not a new vehicle, the received data is provisionally recorded (step R37). Note that provisional here means that it is automatically deleted as time passes.
[0131]
Thereafter, the process returns to step R22 again and the above-described processing is repeated. If “NO” is determined in step R31 described above, that is, if it is not the communication slot timing of the own vehicle, the next communication slot timing is measured (step 38), and whether or not the communication slot has ended. (Step R39), if not completed, return to step R22 again to repeat the above process, and if the communication slot is completed, return to pilot slot control (see FIG. 14). Become.
[0132]
Now, in the process of performing the communication process as described above, examples of reception and transmission timing control results of the vehicle having the communication ID code “2345” and the vehicle “0345” will be described with reference to FIGS. With reference to the above, some specific cases will be described.
[0133]
FIG. 19 shows a case where the communication ID code is set to a 4-digit number. For example, the communication ID code is “0345” in the communication area 18 of the vehicle whose communication ID code value is “2345”. , “2988”, “9845”, and four of them are “2345”, “9854”, “2692”, “2845” in the communication area of the vehicle whose communication ID code is “0345”. Is shown.
[0134]
In each vehicle, when communication is started according to the above-described flowchart using the communication ID code, the communication vehicle ID code data of the communication vehicle recognized in the communication data is transmitted in each communication area. Based on this, the selection change of the communication slot of the own vehicle is performed. Here, as shown in FIG. 20, vehicles having communication ID codes that interfere with each other in the communication frame make adjustments to avoid collision and reliably achieve communication processing.
[0135]
In the example shown in FIG. 21, there are five units “0345”, “2988”, “9845”, “2692”, “2854” in the communication area of the vehicle whose communication ID code is “2345”. This shows a case where there are four “2345”, “9854”, “2692”, and “2845” in the communication area of the vehicle whose ID code is “0345”.
[0136]
In this case, there are four vehicles in which the value of the first digit of the communication ID code is “2” in total, and communication is performed by selecting an empty communication slot in ascending order of the value of the communication ID code. Processing will be executed. Also, if the vehicle leaves the group that is communicating (communication ID codes “2692” and “2854” are left) or if a new vehicle enters, depending on the situation at that time The communication slot is dynamically changed.
[0137]
The communication data includes position coordinate data, road marker data, position ID data, and the like, and the position of each vehicle based on the position data is displayed on the display of each vehicle. ing. If the vehicle contains data that can refer to vehicle shape data such as the model of the vehicle, the display can display a bird's-eye view of the actual driving situation. Also, these data can be compared with CCD camera data mounted on the vehicle.
[0138]
(Second Embodiment)
FIG. 22 shows a second embodiment of the present invention. The difference from the first embodiment is that the number of DSRC communication devices provided in the vehicle 1 is four. That is, the four DSRC communication devices 2a to 2d are arranged at four locations on the front and rear, left and right of the vehicle 1, and the rectangular, communication is performed by combining the front, rear, left and right detection areas 21a to 21d. An area 21 is formed, and communication processing is performed with other vehicles in the communication area 21.
[0139]
In the second embodiment as described above, the same effect as that of the first embodiment can be obtained. In this case, the degree of freedom in setting the range of the communication area is larger than that in the case of the first embodiment. Although it is small, an increase in cost can be prevented by reducing the number of installed DSRC communication devices as necessary.
[0140]
(Third embodiment)
FIGS. 23 and 24 show a third embodiment of the present invention. The difference from the first embodiment is that the configurations of the three display devices 22a to 22c on the left, right and rear of the front seat are used for image generation. A device including a device 10 and a display data controller 11 is used. In addition, about the database 12, it is good also as a structure which provides this integrally, and can also be set as the structure utilized in common.
[0141]
As a result, the display screens requested by the user can be individually displayed on the display devices 22a to 22c, and the user can grasp the surrounding situation from various perspectives.
[0142]
(Other embodiments)
The present invention is not limited to the above embodiment, and can be modified or expanded as follows.
A simple configuration in which only one DSRC communication device is provided may be employed. In this case, the position information is determined based on the position detection signal transmitted from the other vehicle. However, the position information can be used practically sufficiently by improving the detection accuracy of the position detection signal. be able to.
[0143]
An appropriate number and position of antennas can be selected. Considering to what extent the position information of other vehicles existing around the vehicle should be recognized in terms of safety, it may be set to detect a specific range as well as a rectangular shape it can.
[0144]
The mobile communication device is not limited to the one mounted on the vehicle, but may be one carried by a person, or may be a mobile body such as a robot or an automatic guided vehicle. In the case of a person, the possibility of using the position information can also be used when walking or boarding a vehicle. Also, even when there are no users or drivers such as robots or automatic guided vehicles, it can be used for remotely recognizing position information, or used for movement control and travel control between devices. Can do.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing a first embodiment of the present invention.
FIG. 2 is an electrical block configuration diagram.
FIG. 3 is a plan view showing a setting state of a communication area
FIG. 4 is a plan view of the own vehicle and surrounding vehicles on a road.
FIG. 5 is a diagram showing an antenna installation state;
FIG. 6 is an explanatory diagram of position specification based on a detection signal.
FIG. 7 is an operation explanatory diagram for estimating the presence of another vehicle.
8 generates a vehicle display screen by switching the display screen to the display device of FIG.
FIG. 9 is a diagram showing a display example by a display device
FIG. 10 is a diagram showing a configuration of a communication frame
FIG. 11 is an operation explanatory diagram showing the correspondence between a configuration of a data signal including a synchronization signal and a filter for detecting the synchronization signal.
FIG. 12 is a flowchart of a program for basic operation of communication processing;
FIG. 13 is a flowchart of a program of a synchronization acquisition process
FIG. 14 is a flowchart of a communication timing setting process program (part 1);
FIG. 15 is a flowchart of a communication timing setting processing program (part 2);
FIG. 16 is a specific example showing a pattern of a received signal and an individual communication state within a communication area.
FIG. 17 is an operation explanatory diagram for explaining the transmission timing of the communication ID code to the pilot window.
FIG. 18 is an operation explanatory diagram illustrating the configuration of a pilot slot.
FIG. 19 is a diagram showing a positional relationship of vehicles showing a first specific example of a communication processing process;
FIG. 20 is an explanatory diagram of allocation of communication slots for interference in the communication processing process.
FIG. 21 is a diagram showing a positional relationship of vehicles showing a second specific example of the communication processing process, and an explanatory diagram of allocation of communication slots with respect to interference in the communication processing process;
FIG. 22 is a view corresponding to FIG. 3, showing a second embodiment of the present invention.
FIG. 23 is a view corresponding to FIG. 2, showing a third embodiment of the present invention.
FIG. 24 is a block diagram of a display device.
[Explanation of symbols]
1 is an automobile (vehicle, moving body), 2a to 2f are DSRC communication devices, 4a to 4d and 22a to 22c are display devices, 5 is a GPS receiver (position detecting means), 6 is a wide area communication device, and 7a to 7d are CCD camera (imaging means), 9 a data controller, 10 an image generator, 11 a display data controller, 12 a database, 13 a display controller, 14 a display, 15 a user input / output controller, 16 Data determination in-vehicle LAN controller, 17 is an external device controller, 18 is a communication area (narrow area communication area), and 20 is a road.

Claims (10)

In a narrow area communication method of a mobile communication device that communicates with another mobile communication device existing in its own communication area,
A communication frame used for communication between the mobile communication devices is composed of a plurality of communication windows and a pilot window for performing allocation to the plurality of communication windows,
Communication processing by the mobile communication device,
A communication start process in which a communication ID code set to a value consisting of a multi-digit number or an orderable character is transmitted to its own communication area and reception of a signal transmitted from another mobile communication device is awaited When,
When setting the start time of a communication frame by performing synchronization acquisition when receiving from another mobile communication device , the own communication ID code and the received communication ID code of the other mobile communication device A timing process for setting a communication window of a communication frame determined by ranking with
It is configured to execute from the data communication processing process of transmitting and receiving communication data corresponding to the start time of the obtained communication frame,
The communication frame has a number of communication windows that can be set in the first digit for determining the order of the communication ID code, and the pilot window includes an initial slot as a plurality of pilot slots and a plurality of subsequent windows. A recovery slot and
The mobile communication device transmits the communication ID code transmitted in the communication start process to the pilot slot corresponding to the value of the first digit for determining the order, and at the time of communication Transmitting using a communication window corresponding to the value of the first digit of the ID code, transmitting the own communication ID code to the initial slot of the pilot slot, and other communication in the same initial slot of the same pilot slot When the communication ID code is received, the communication ID code is transmitted again to the recovery slot corresponding to the value of the second digit for determining the order of the communication ID code. in, configured to perform ranking determined based on other communication ID code received in the recovery slot of the pilot slot Short range communication method of the mobile-body communication device, characterized in that. In the narrow area communication method of the mobile communication device according to claim 1,
The mobile communication device transmits a communication ID code at a predetermined time interval in the communication start process, wherein the mobile communication device has a narrow area communication method. In the narrow area communication method of the mobile communication device according to claim 1,
The mobile communication device transmits the communication ID code when there is another mobile communication device in the communication area in the communication start process. Narrow communication method. In the narrow area communication method of the mobile communication device according to any one of claims 1 to 3,
In the time adjustment process, the time adjustment process is performed based on a signal for setting a reference time for synchronization . In the narrow area communication method of the mobile communication device according to claim 4,
The mobile communication device is attached with a synchronization base ID code for a specific number of communication ID codes,
In the communication start process, a synchronization base ID code is transmitted together with the communication ID code,
In the time adjustment process, the reference time is set based on the reception timing of the synchronization base ID code . In the narrow area communication method of the mobile communication device according to claim 5 ,
In the timing process , when there is no mobile communication device that transmits the synchronization base ID code , the first ID for determining the order of communication ID codes among the mobile communication devices that are about to start communication . A narrow-area communication method for a mobile communication device, characterized in that the reference time is set based on a reception timing of a communication ID code transmitted by a digit value located at the head of an order . In the narrow area communication method of the mobile communication device according to any one of claims 1 to 3 ,
In the timing process, the mobile body having the most dominant communication ID code by ranking the communication ID code of the other mobile communication apparatus received at the start of communication and its own communication ID code. A narrowband communication method for a mobile communication device, characterized in that a timing process is performed by setting the reception timing of the communication ID code of the communication device as a reference time . In the narrow area communication method of the mobile communication device according to any one of claims 1 to 7 ,
In the communication processing process, a synchronization tracking process is performed in parallel so as to maintain a synchronization state based on the reference time obtained in the timing processing process. Communication method. In the narrow area communication method of the mobile communication device according to any one of claims 1 to 8 ,
In the timing process , when another communication ID code is received in the recovery slot of the pilot slot, the communication ID code received in the communication slot corresponding to the own communication ID code and the recovery slot is used. The movement characterized by designating the corresponding communication slot as the communication window corresponding to the pilot slot, and assigning the remaining communication window to the unused communication window to perform communication processing. A narrow area communication method for a body communication device. In the narrow area communication method of the mobile communication device according to any one of claims 1 to 9,
A communication method of the mobile communication device is a spread spectrum communication method, wherein the mobile communication device has a narrow area communication method.

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