JP2004048753A - Sector antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient radio communication with a mobile station in a sector antenna device which forms a directional sector and radio-communicates with the mobile station of the sector. <P>SOLUTION: The device is provided with a plurality of antennas T1 to T6 in round shape, a control means 1 controls each adjustment means G1 to GL according to communication situations with the mobile station such as number of the mobile station, ratio of receiving signal power to interference power of each sector and receiving signal error rate of each sector, and a directivity of the sectors (L pieces) synthesized each adjustment means G1 to GL by the antennas T1 to T6 is changed by each adjustment means G1 to GL's for adjusting amplitudes and phases of power signals applied to the antennas T1 to T6 each antenna. Synthesizers H1 to HL output the power signals of transmission object to each adjustment means G1 to GL, and synthesize the power signals received by each antenna T1 to T6 and adjusted by the adjustment means G1 to GL. <P>COPYRIGHT: (C)2004,JPO

Description

【００３１】
ここで、Ａ’ｍ・ｅｘｐ（ｊδｍ）を複素数Ａｍで置き換え、このＡｍをパラメータとすると、上記した放射電界Ｅ（φ）は式２のように示される。
【００３２】
【数２】

【００３３】
一方、（２Ｎ＋１）本のアンテナを直線状に等間隔で配置した直線状配置アレーアンテナについて、これら複数のアンテナを配置した直線の方向をφ＝０の方向としてφ＝０軸を定め、上記図１１に示した場合と同様に、当該φ＝０軸から半時計回りの方向をφの正の方向であるとする。この場合に、直線状配置アレーアンテナにより生成されるφ方向の放射電界Ｅ０（φ）は式３のように示される。なお、Ｂｎ（ｎ＝−Ｎ〜Ｎであり、それぞれ各アンテナに対応している）は各アンテナに対応したパラメータである。
【００３４】
【数３】

【００３５】
ここで、上記式３は、Ｎを無限大（∞）に近づけるとφに関するフーリエ（Ｆｏｕｒ
ｉｅｒ）級数となり、例えばサンプル数を有限で打ち切ってしまうと細かい部分の補間はできなくなるが、近似的に基となる関数を表現することは可能である。このため、直線状配置アレーアンテナでは、式４に示すＢｎをｎ番目のアンテナのパラメータとして用いることにより、所望の放射電界Ｅ０（φ）を実現するためのパラメータＢｎを推定して算出することができる。
【００３６】
【数４】

【００３７】
次に、上記式２に示した放射電界Ｅ（φ）と上記式３に示した放射電界Ｅ０（φ）とが等しいと仮定することにより、上記した円状配置アレーアンテナが生成する電界パターンを上記した直線状配置アレーアンテナが生成する電界パターンと同様のものとする場合を考える。上記式２の右辺と上記式３の右辺とが等しいと仮定すると、例えば−π≦φ≦πの範囲において式５が得られる。
【００３８】
【数５】

【００３９】
ここで、上記式５を判り易くするため、μ＝（ｍ＋１／２）として置き換え、パラメータをＡμとすると、上記式５は式６のように変形される。
【００４０】
【数６】

【００４１】
また、ψ＝（φ−２μπ／２Ｍ）として置き換え、上記式６の左辺を上記式４のＥ０（φ）に代入すると、式７及び式８が得られる。
【００４２】
【数７】

【００４３】
【数８】

【００４４】
ここで、一般に、クロネッカーのデルタ（Ｋｒｏｎｅｃｋｅｒ’ｓ　Ｄｅｌｔａ）δμμ’を用いると、式９に示す等式が成立する。なお、このデルタは、μ≠μ’の場合にδμμ’＝０となり、μ＝μ’の場合にδμμ’＝１となる記号である。
【００４５】
【数９】

【００４６】
上記した直線状配置アレーアンテナのアンテナ数（２Ｎ＋１）が上記した円状配置アレーアンテナのアンテナ数（２Ｍ）より１本多いとすると、Ｍ＝Ｎとなり、上記式７は式１０のように変形される。
【００４７】
【数１０】

【００４８】
そして、上記式１０に上記式９を適用して整理すると、式１１に示すようにパラメータＡμを得ることができる。
【００４９】
【数１１】

【００５０】
以上に示されるように、上記した円状配置アレーアンテナでは、各アンテナに印加される電流の振幅成分Ａ’ｍ及び位相成分δｍを調整して、上記式１１に示されるパラメータＡμを調整することにより、これら複数のアンテナにより合成されるセクタの指向性のパターン（すなわち、放射電界Ｅ（φ））を種々なものに変化させることができる。
【００５１】
また、上記のように、上記した直線状配置アレーアンテナでは、各アンテナに印加される電流の振幅成分等を調整して、上記式４に示されるパラメータＢｎを調整することにより、これら複数のアンテナにより合成されるセクタの指向性のパターン（すなわち、放射電界Ｅ０（φ））を種々なものに変化させることができる。
【００５２】
なお、以上では、複数のアンテナを直線状に配置した場合と円状に配置した場合との例を示したが、所望のセクタ指向性パターンを生成するために各アンテナに印加される電気信号の振幅や位相を制御する仕方は、例えば各アンテナの配置の仕方や、例えば固定配置された各アンテナと指向性を向ける方向（セクタを形成させる向き）との間の絶対角度等に依存し、これらの条件に基づいて振幅等の制御が行われる。
【００５３】
また、一般に、アンテナから無線信号を送信する場合の指向性と、当該アンテナにより無線信号を受信する場合の指向性とは同じであるため、本発明に係るセクタアンテナ装置では、上記のような電気信号の振幅及び位相の制御を無線信号の送受信に際して行うことにより、送信及び受信に対して同様なセクタの指向性を実現することができる。
【００５４】
【発明の実施の形態】
本発明の第１実施例に係るセクタアンテナ装置を図面を参照して説明する。
なお、本例では、本発明に係るセクタアンテナ装置が例えば携帯電話システム等の基地局に備えられているとし、当該セクタアンテナ装置が指向性を有するセクタを形成して当該セクタの複数の移動局と無線通信する場合を示す。
図１には、本発明に係るセクタアンテナ装置の一例を示してあり、このセクタアンテナ装置は、複数（本例では６本）のアンテナＴ１〜Ｔ６を円周上に配置したサーキュラアレイ（円状配置アダプティブアレイアンテナ）の構成を有している。
【００５５】
同図に示したセクタアンテナ装置には、上記した６本のアンテナＴ１〜Ｔ６と、セクタ数（本例ではＬとする）と同数の重み付け部Ｇ１〜ＧＬと、セクタ数と同数の合成器Ｈ１〜ＨＬと、上記した各重み付け部Ｇ１〜ＧＬを制御する重み制御部１とが備えられている。また、各重み付け部Ｇ１〜ＧＬは６本のアンテナＴ１〜Ｔ６と接続されているとともに、それぞれ１つの合成器Ｈ１〜ＨＬと接続されている。
【００５６】
各重み付け部Ｇ１〜ＧＬは、例えば位相器等から構成されており、重み制御部１による制御に従って６本のアンテナＴ１〜Ｔ６に印加される電気信号の振幅及び位相を各アンテナ毎に調整する機能を有している。
具体的には、例えばアンテナＴ１〜Ｔ６から無線信号を送信する場合には、各重み付け部Ｇ１〜ＧＬではそれぞれの合成器Ｈ１〜ＨＬから入力された送信対象となる電気信号の振幅や位相を各アンテナ毎に調整して、調整した電気信号を各アンテナＴ１〜Ｔ６から無線送信させる。また、例えばアンテナＴ１〜Ｔ６により無線信号を受信する場合には、各重み付け部Ｇ１〜ＧＬでは各アンテナＴ１〜Ｔ６により受信されて得られた電気信号の振幅や位相を各アンテナ毎に調整して、調整した複数（本例では６つ）の電気信号をそれぞれの合成器Ｈ１〜ＨＬへ出力する。
【００５７】
各合成器Ｈ１〜ＨＬは、複数の電気信号を１つの電気信号に合成する機能を有している。
具体的には、例えばアンテナＴ１〜Ｔ６から無線信号を送信する場合には、各合成器Ｈ１〜ＨＬでは送信対象となる電気信号を例えば６つの電気信号に分配してそれぞれの重み付け部Ｇ１〜ＧＬへ出力する。また、例えばアンテナＴ１〜Ｔ６から無線信号を受信する場合には、各合成器Ｈ１〜ＨＬではそれぞれの重み付け部Ｇ１〜ＧＬから入力された複数（本例では６つ）の電気信号を合成する。
【００５８】
重み制御部１は、移動局との通信状況に応じて上記した各重み付け部Ｇ１〜ＧＬによる電気信号の振幅及び位相の調整を制御する機能を有しており、この制御は、例えば各重み付け部Ｇ１〜ＧＬに対して制御信号を送信して振幅や位相の重み付けの係数を指示することにより行われる。このような制御を行うことにより、例えば各重み付け部Ｇ１〜ＧＬ毎に異なるセクタの指向性を形成することができ、また、これら各セクタの指向性を変化させることができる。
【００５９】
なお、所望のセクタ指向性を実現するために各アンテナＴ１〜Ｔ６に印加される電気信号の振幅や位相を変化させる仕方としては、その具体例を上記「課題を解決するための手段」において示したため、本例では説明を省略する。本例の重み制御部１では、例えば、当該具体例に示した理論式と同様なものを用いて各アンテナＴ１〜Ｔ６毎に調整する振幅や位相の値を決定する。
【００６０】
本例では、上記した各重み付け部Ｇ１〜ＧＬにより、複数のアンテナに印加される電気信号の振幅及び位相を各アンテナ毎に調整することによりこれらのアンテナにより合成されるセクタの指向性を変化させる調整手段が構成されている。また、本例では、複数の調整手段（本例では、重み付け部Ｇ１〜ＧＬ）が備えられており、各調整手段毎にセクタが形成される。
また、本例では、上記した重み制御部１により、移動局との通信状況に応じて調整手段による調整を制御することによりセクタの指向性を変化させる制御手段が構成されている。
【００６１】
以上の構成により、本例のセクタアンテナ装置では、指向性を有する複数のセクタを形成して各セクタの移動局と無線通信するに際して、移動局との種々な通信状況に応じて各セクタの指向性を変化させることができ、これにより、移動局との無線通信の効率化を図ることができる。
【００６２】
なお、本発明に係るセクタアンテナ装置により行われる上記した電気信号の振幅及び位相の調整処理の制御は、例えばプロセッサやメモリ等を備えたハードウエア資源においてプロセッサが制御プログラムを実行することにより行われてもよく、また、例えば当該処理を実行するための各機能手段が独立したハードウエア回路から構成されてもよい。
【００６３】
また、図２には、本発明に係るセクタアンテナ装置の他の構成例を示してあり、このセクタアンテナ装置は、複数（本例では７本）のアンテナＵ１〜Ｕ７を直線状に配置したリニアアレイ（直線状配置アダプティブアレイアンテナ）の構成を有している。ここで、同図に示したセクタアンテナ装置には、各アンテナＵ１〜Ｕ７に印加される電気信号の振幅及び位相を各アンテナ毎に調整するセクタ数と同数の重み付け部Ｖ１〜ＶＬや、複数の電気信号を合成するセクタ数と同数の合成器Ｗ１〜ＷＬや、上記した各重み付け部Ｖ１〜ＶＬを制御する重み制御部１１が備えられており、このセクタアンテナ装置の構成や動作は、アンテナＵ１〜Ｕ７の数及びその配置が異なっていることや各重み付け部Ｖ１〜ＶＬにより行われる電気信号の振幅及び位相の調整の仕方が異なっているといった点を除いては、上記図１に示した装置の場合と同様である。
【００６４】
次に、本例のセクタアンテナ装置により上記した電気信号の振幅及び位相の調整処理を制御する態様の具体例を示す。なお、以下では、上記図１に示したセクタアンテナ装置を代表させてその動作の具体例を示すが、上記したように、例えば上記図２に示したセクタアンテナ装置を用いた場合の動作についてもほぼ同様である。
【００６５】
また、本例のセクタアンテナ装置には、例えば各セクタの移動局数を検出する移動局数検出手段が備えられているとし、本例では、移動局数に基づいて上記調整処理を制御する態様を示す。なお、各セクタの移動局数の検出は、例えば各セクタ毎の送受信処理回路（本例では、１つの重み付け部Ｇ１〜ＧＬ及び１つの合成器Ｈ１〜ＨＬから成る各処理回路）で無線通信している移動局の数を検出することにより行われる。
【００６６】
一例として、本例のセクタアンテナ装置と移動局との間でＴＤＭＡ方式やＦＤＭＡ方式を用いて無線通信が行われる場合を示す。
この場合、本例のセクタアンテナ装置に備えられた重み制御部１では、例えば各セクタの移動局数を監視しており、いずれかのセクタの移動局数が最大許容多元接続数を超えたことに応じて、当該セクタに対応する重み付け部Ｇ１〜ＧＬを制御することで当該セクタの幅を狭める等することにより当該セクタの移動局数を最大許容多元接続数以下に減少させる一方、当該セクタがカバーする範囲から外されたエリアを当該セクタに隣接するセクタの幅を広める等してカバーする。
【００６７】
ここで、上記のようなセクタの制御を図３及び図４を用いて更に具体的に説明する。
上記図３や図４には、本例のセクタアンテナ装置が形成するセクタを概念的に示してあり、これらの図中の円の中心点に本例のセクタアンテナ装置（すなわち、本例では基地局）が設置されており、当該セクタアンテナ装置が６つのセクタ（“セクタ１”〜“セクタ６”）を形成することにより３６０度のサービスエリア（セル）をカバーしている。また、図３中の黒丸及び白丸や図４中の黒丸はそれぞれ１つの移動局を示している。
【００６８】
例えば本例のセクタアンテナ装置が形成する各セクタの最大許容多元接続数が等しく３であるとして、もしも上記図３に示した通信状況が生じてしまった場合には、“セクタ１”や“セクタ５”の移動局数が最大許容多元接続数（３）を超えてしまっていることから、本例のセクタアンテナ装置では、例えば白丸で示した移動局との間で無線通信することができない。
【００６９】
そこで、本例のセクタアンテナ装置では、例えば、まず“セクタ１”の幅を狭めるとともに当該“セクタ１”に隣接する“セクタ２”や“セクタ６”の幅を広めることにより“セクタ１”の移動局数を最大許容多元接続数以下に減少させ、次に、“セクタ２”について同様な制御を行い、次いで、他の各セクタについても同様な制御を順次行うこと等により、セル全体をカバーしながら各セクタの指向性を変化させていき、これにより結果として、上記図４に示されるように、各セクタの移動局数を最大許容多元接続数以下に減少させる。
【００７０】
このような制御を行う本例のセクタアンテナ装置の効果を従来のものと比較すると、例えば従来では上記図３に示されるセクタ構成のままであるため、セル全体として通信可能な移動局の数は１５となり、３つの移動局（白丸で示した移動局）とは１セクタ当たりの最大許容多元接続数の制約によって通信不可能となってしまうが、本例のセクタアンテナ装置では、上記図４に示したセクタ構成に変化させることができるため、セル全体として１セル当たりの最大許容多元接続数である１８つの移動局との間で無線通信することができ、これにより、通信容量を有効に活用することができる。
【００７１】
なお、以上では、通信方式としてＴＤＭＡ方式やＦＤＭＡ方式が用いられる場合を示したが、例えば本例のセクタアンテナ装置と移動局との間でＣＤＭＡ方式を用いて無線通信が行われる場合には、上記した１セクタ当たりの最大許容多元接続数としては、当該セクタの移動局とセクタアンテナ装置とにより行われる無線通信の品質を要求される程度に確保することができる移動局数が設定される。すなわち、セクタの移動局数が当該最大許容多元接続数を超えると当該セクタにおける通信品質が悪くなるが、本例のセクタアンテナ装置では、上記と同様な制御により、当該セクタの移動局数を減少させることにより、当該セクタにおける通信品質を要求される程度に確保することができる。
【００７２】
また、図５には、本例のセクタアンテナ装置により行われる処理の手順の一例を示してある。
すなわち、本例のセクタアンテナ装置では、各セクタｉ（ｉ＝１〜Ｌ）の移動局数（ユーザ数）を適時検出しており（ステップＳ１）、例えばセクタ１（ｉ＝１）からセクタＬ（ｉ＝Ｌ）へと順に（ステップＳ２）、各セクタｉの移動局数（検出ユーザ数）が１セクタ当たりの最大許容数を超えているか否かを判定する（ステップＳ３）。
【００７３】
この結果、検出したセクタｉの移動局数が最大許容数を超えていることが判定された場合には、セクタアンテナ装置では、例えば当該セクタｉの幅を狭めることにより当該セクタｉの移動局数を最大許容数以下に減少させるとともに、当該セクタｉに隣接する２つのセクタ（セクタ（ｉ−１）とセクタ（ｉ＋１））の移動局数を比較して（ステップＳ４）、比較したこれらのセクタの内で移動局数が少ない方のセクタを広めることにより（ステップＳ５、ステップＳ８）、セル全体をＬ個のセクタでカバーできるようにする。そして、セクタアンテナ装置では、同様な処理を他のセクタについても順次行うことにより（ステップＳ６、ステップＳ７）、１セクタ当たりの最大許容数の制限によって通信不可能となってしまう移動局の数を減少させる。
【００７４】
一方、上記の判定処理により（ステップＳ３）、検出したセクタｉの移動局数が最大許容数以下であることが判定された場合には、セクタアンテナ装置では、以降の他のセクタについても順次上記と同様な判定処理を行っていき（ステップＳ６、ステップＳ７）、上記と同様に必要な場合には各セクタの幅等を変化させることにより通信不可能となってしまう移動局の数を減少させることを行う。
【００７５】
以上のように、本例のセクタアンテナ装置では、上記した重み制御部１から成る制御手段等によって、セクタの移動局数が最大許容数を超えた場合に当該セクタの指向性を変化させることにより当該セクタの移動局数を当該最大許容数以下に減少させることが行われるため、セクタの移動局数といった通信状況に応じて効率的な無線通信を実現することができる。
【００７６】
次に、本発明の第２実施例に係るセクタアンテナ装置を図面を参照して説明する。なお、本例のセクタアンテナ装置の構成や動作は、重み制御部１が各重み付け部Ｇ１〜ＧＬを制御する態様が異なっているといった点を除いては、例えば上記第１実施例で示した装置の構成等と同様であるため、以下では、主として本例の重み付け部１による制御態様について詳しく説明する。
【００７７】
本例のセクタアンテナ装置に備えられた重み制御部１では、例えば各セクタの移動局数を監視しており、いずれかのセクタの移動局数が平均的な移動局数（平均移動局数）を超えたことに応じて、当該セクタに対応する重み付け部Ｇ１〜ＧＬを制御することで当該セクタの幅を狭める等することにより当該セクタの移動局数を減少させる一方、当該セクタがカバーする範囲から外されたエリアを当該セクタに隣接するセクタの幅を広める等してカバーする。なお、上記した平均的な移動局数とは、１セクタ当たりの平均的な移動局数のことであり、例えば（全セクタの移動局数）／（セクタ数Ｌ）で表される。
【００７８】
ここで、このようなセクタの制御を上記第１実施例で用いた図３及び図４を用いて更に具体的に説明する。
上記したように、図３や図４には本例のセクタアンテナ装置が形成するセクタを概念的に示してあり、これらの図中の円の中心点に本例のセクタアンテナ装置（すなわち、本例では基地局）が設置されており、当該セクタアンテナ装置が６つのセクタ（“セクタ１”〜“セクタ６”）を形成することにより３６０度のサービスエリア（セル）をカバーしている。また、図３中の黒丸及び白丸や図４中の黒丸はそれぞれ１つの移動局を示している。
【００７９】
例えば本例のセクタアンテナ装置が形成する各セクタの最大許容数が等しく３であるとして、もしも上記図３に示した通信状況が生じてしまった場合には、各セクタの移動局数が均等でないことから、このままでは移動局との無線通信に不具合が生じてしまうことがある。
【００８０】
具体的には、例えば通信方式としてＴＤＭＡ方式やＦＤＭＡ方式が用いられる場合には、“セクタ１”や“セクタ５”の移動局数が最大許容多元接続数（３）を超えてしまっていることから、このままでは例えば白丸で示した移動局との間で無線通信することができないといったことが生じる。また、例えば通信方式としてＣＤＭＡ方式が用いられる場合には、同様に、このままでは例えば“セクタ１”や“セクタ５”における通信品質が悪くなってしまうことが生じる。
【００８１】
そこで、本例のセクタアンテナ装置では、例えば、まず“セクタ１”の幅を狭めるとともに当該“セクタ１”に隣接する“セクタ２”や“セクタ６”の幅を広めることにより“セクタ１”の移動局数を平均移動局数以下に減少させ、次に、“セクタ２”について同様な制御を行い、次いで、他の各セクタについても同様な制御を順次行うこと等により、セル全体をカバーしながら各セクタの指向性を変化させていき、これにより結果として、上記図４に示されるように、各セクタの移動局数を平均移動局数以下に減少させる。
【００８２】
例えばＴＤＭＡ方式やＦＤＭＡ方式を用いて無線通信を行う場合における本例のセクタアンテナ装置の効果を従来のものと比較すると、例えば従来では上記図３に示されるセクタ構成のままであるため、セル全体として通信可能な移動局の数は１５となり、３つの移動局（白丸で示した移動局）とは１セクタ当たりの最大許容多元接続数の制約によって通信不可能となってしまうが、本例のセクタアンテナ装置では、上記図４に示したように各セクタの移動局数を均等化することができるため、セル全体として１セル当たりの最大許容多元接続数である１８つの移動局との間で無線通信することができ、これにより、通信容量を有効に活用することができる。
【００８３】
また、例えば本例のセクタアンテナ装置と移動局との間でＣＤＭＡ方式を用いて無線通信が行われる場合についても同様に、例えば従来では上記図３に示されるセクタ構成のままであるため、“セクタ１”や“セクタ５”における通信品質が悪くなってしまうが、本例では、上記図４に示したように各セクタの移動局数を均等化することができるため、各セクタにおける受信信号電力対干渉電力比や通信品質をほぼ均等化することができ、これにより、従来に比べて通信容量を有効に活用することができる。
【００８４】
また、図６には、本例のセクタアンテナ装置により行われる処理の手順の一例を示してある。
すなわち、本例のセクタアンテナ装置では、各セクタｉ（ｉ＝１〜Ｌ）の移動局数（ユーザ数）を適時検出するとともに（ステップＳ１１）、１セクタ当たりの平均移動局数（ＡＶＥ）を算出しており（ステップＳ１２）、例えばセクタ１（ｉ＝１）からセクタＬ（ｉ＝Ｌ）へと順に（ステップＳ１３）、各セクタｉの移動局数（検出ユーザ数）が平均移動局数を超えているか否かを判定する（ステップＳ１４）。
【００８５】
この結果、検出したセクタｉの移動局数が平均移動局数を超えていることが判定された場合には、セクタアンテナ装置では、例えば当該セクタｉの幅を狭めることにより当該セクタｉの移動局数を平均移動局数以下に減少させるとともに、当該セクタｉに隣接する２つのセクタ（セクタ（ｉ−１）とセクタ（ｉ＋１））の移動局数を比較して（ステップＳ１５）、比較したこれらのセクタの内で移動局数が少ない方のセクタを広めることにより（ステップＳ１６、ステップＳ１９）、セル全体をＬ個のセクタでカバーできるようにする。そして、セクタアンテナ装置では、同様な処理を他のセクタについても順次行うことにより（ステップＳ１７、ステップＳ１８）、各セクタの移動局数を均等化する。
【００８６】
一方、上記の判定処理により（ステップＳ１４）、検出したセクタｉの移動局数が平均移動局数以下であることが判定された場合には、セクタアンテナ装置では、以降の他のセクタについても順次上記と同様な判定処理を行っていき（ステップＳ１７、ステップＳ１８）、上記と同様に必要な場合には各セクタの幅等を変化させることにより各セクタの移動局数を均等化することを行う。
【００８７】
以上のように、本例のセクタアンテナ装置では、上記した重み制御部１から成る制御手段が各重み付け部Ｇ１〜ＧＬを制御することにより、セクタ間の移動局数の差を減少させて各セクタの移動局数を均等化することが行われるため、セクタの移動局数といった通信状況に応じて効率的な無線通信を実現することができる。
【００８８】
次に、本発明の第３実施例に係るセクタアンテナ装置を図面を参照して説明する。なお、本例のセクタアンテナ装置の構成や動作は、重み制御部１が各重み付け部Ｇ１〜ＧＬを制御する態様が異なっているとともに、通信方式として特にＣＤＭＡ方式が用いられる場合に有効であるといった点を除いては、例えば上記第１実施例で示した装置の構成等と同様であるため、以下では、主として本例の重み付け部１による制御態様について詳しく説明する。
【００８９】
上記したように、本例のセクタアンテナ装置と移動局との間ではＣＤＭＡ方式を用いて無線通信が行われているとする。
また、本例のセクタアンテナ装置には、各セクタの移動局からの受信信号電力対干渉電力比を検出するＳＩＲ検出手段が備えられている。ここで、受信信号電力対干渉電力比とは、受信を希望する信号の電力（希望信号電力、すなわち通信相手となる特定の移動局から受信する信号の電力）と干渉信号の電力（すなわち通信相手としていない移動局等から受信する干渉信号の電力）との比である。
【００９０】
なお、受信信号電力対干渉電力比の測定方法としては、例えば一般の送信電力制御の際に用いられるのと同様な方法を用いることができ、具体的には、希望信号中のパイロットシンボルの平均電力を検出することで当該検出値を当該希望信号の電力とみなして用いることができ、また、当該パイロットシンボルの平均電力からの各パイロットシンボルの電力の分散により干渉信号の電力を擬制して決定することができる。
【００９１】
本例のセクタアンテナ装置に備えられた重み制御部１では、例えば各セクタにおける受信信号電力対干渉電力比を監視しており、いずれかのセクタの受信信号電力対干渉電力比が平均的な受信信号電力対干渉電力比（平均ＳＩＲ）を超えたことに応じて、当該セクタに対応する重み付け部Ｇ１〜ＧＬを制御することで当該セクタの幅を狭める等する一方、当該セクタがカバーする範囲から外されたエリアを当該セクタに隣接するセクタの幅を広める等してカバーする。なお、上記した平均的な受信信号電力対干渉電力比とは、１セクタ当たりの平均的な受信信号電力対干渉電力比のことであり、例えば（全セクタの受信信号電力対干渉電力比の総和）／（セクタ数Ｌ）で表される。
【００９２】
ここで、図７には、一例として、セクタの幅と受信信号電力対干渉電力比との関係を概念的に示してあり、同図（ａ）や同図（ｂ）には図中の円の中心点にセクタアンテナ装置Ｔが配置されている場合に形成される１つのセクタの例を示してある。同図（ａ）に示されるようにセクタの幅が広い場合と同図（ｂ）に示されるようにセクタの幅が狭い場合とでは、例えば特定の移動局から受信する希望信号の電力は同じである。この場合、セクタアンテナ装置では、セクタの幅を広めるに従って他の移動局等から多くの干渉波を受信することとなるため受信信号電力対干渉電力比は小さくなって通信品質が悪くなり、一方、セクタの幅を狭めるに従って他の移動局等からの干渉波が少なくなるため受信信号電力対干渉電力比は大きくなって通信品質が向上する。
【００９３】
また、図８には、本例のセクタアンテナ装置により行われる処理の手順の一例を示してある。
すなわち、本例のセクタアンテナ装置では、各セクタｉ（ｉ＝１〜Ｌ）の受信信号電力対干渉電力比（ＳＩＲ）を適時検出するとともに（ステップＳ２１）、１セクタ当たりの平均ＳＩＲ（ＡＶＥ）を算出しており（ステップＳ２２）、例えばセクタ１（ｉ＝１）からセクタＬ（ｉ＝Ｌ）へと順に（ステップＳ２３）、各セクタｉの受信信号電力対干渉電力比（ＳＩＲ測定値）が平均ＳＩＲを超えているか否かを判定する（ステップＳ２４）。
【００９４】
この結果、検出したセクタｉの受信信号電力対干渉電力比が平均ＳＩＲ未満であることが判定された場合には、セクタアンテナ装置では、例えば当該セクタｉの幅を狭めることにより当該セクタｉの受信信号電力対干渉電力比を平均ＳＩＲ以上に増加させるとともに、当該セクタｉに隣接する２つのセクタ（セクタ（ｉ−１）とセクタ（ｉ＋１））の受信信号電力対干渉電力比を比較して（ステップＳ２５）、比較したこれらのセクタの内で受信信号電力対干渉電力比が大きい方のセクタを広めることにより（ステップＳ２６、ステップＳ２９）、セル全体をＬ個のセクタでカバーできるようにする。そして、セクタアンテナ装置では、同様な処理を他のセクタについても順次行うことにより（ステップＳ２７、ステップＳ２８）、各セクタの受信信号電力対干渉電力比を均等化する。
【００９５】
一方、上記の判定処理により（ステップＳ２４）、検出したセクタｉの受信信号電力対干渉電力比が平均ＳＩＲ以上であることが判定された場合には、セクタアンテナ装置では、以降の他のセクタについても順次上記と同様な判定処理を行っていき（ステップＳ２７、ステップＳ２８）、上記と同様に必要な場合には各セクタの幅等を変化させることにより各セクタの受信信号電力対干渉電力比を均等化することを行う。
【００９６】
以上のように、本例のセクタアンテナ装置では、上記した重み制御部１から成る制御手段が各重み付け部Ｇ１〜ＧＬを制御することにより、セクタ間の受信信号電力対干渉電力比の差を減少させて各セクタの受信信号電力対干渉電力比を均等化することが行われるため、セクタの受信信号電力対干渉電力比といった通信状況に応じて効率的な無線通信を実現することができる。具体的には、本例のセクタアンテナ装置では、ＣＤＭＡ方式を用いて移動局と無線通信を行う場合に、各セクタの受信信号電力対干渉電力比を均等化することにより各セクタにおける通信品質をほぼ均等化することができ、これにより、通信容量を有効に活用することができる。
【００９７】
なお、本例のように受信信号電力対干渉電力比に基づいてセクタの指向性を制御する構成では、例えば上記第２実施例に示したように移動局数に基づいて制御を行う場合に比べて、通常、各セクタにおける通信品質をより正確に均等化することができる。
【００９８】
次に、本発明の第４実施例に係るセクタアンテナ装置を図面を参照して説明する。なお、本例のセクタアンテナ装置の構成や動作は、重み制御部１が各重み付け部Ｇ１〜ＧＬを制御する態様が異なっているとともに、通信方式として特にＣＤＭＡ方式が用いられる場合に有効であるといった点を除いては、例えば上記第１実施例で示した装置の構成等と同様であるため、以下では、主として本例の重み付け部１による制御態様について詳しく説明する。
【００９９】
上記したように、本例のセクタアンテナ装置と移動局との間ではＣＤＭＡ方式を用いて無線通信が行われているとする。
また、本例のセクタアンテナ装置には、各セクタの移動局からの受信信号の誤り率を検出する誤り率検出手段が備えられている。ここで、受信信号の誤り率としては、例えばビット誤り率やフレーム誤り率を用いることができる。
【０１００】
なお、ビット誤り率やフレーム誤り率の測定方法としては、例えば移動局から無線送信される信号にパリティチェック用の符号を付加しておく方法を用いることができ、この場合、本例のセクタアンテナ装置では、一例として、移動局から受信した信号中で誤りが発生した信号の個数や当該誤りを訂正した回数を所定の時間幅で平均化して得られる値を誤り率として用いることを行う。
【０１０１】
本例のセクタアンテナ装置に備えられた重み制御部１では、例えば各セクタにおける受信信号誤り率を監視しており、いずれかのセクタの受信信号誤り率が平均的な受信信号誤り率（平均誤り率）を超えたことに応じて、当該セクタに対応する重み付け部Ｇ１〜ＧＬを制御することで当該セクタの幅を狭める等する一方、当該セクタがカバーする範囲から外されたエリアを当該セクタに隣接するセクタの幅を広める等してカバーする。なお、平均的な受信信号誤り率とは、１セクタ当たりの平均的な受信信号誤り率のことであり、例えば（全セクタの受信信号誤り率の総和）／（セクタ数Ｌ）で表される。
【０１０２】
なお、通常、セクタの幅を広めるに従って他の移動局等から多くの干渉波を受信することとなるため受信信号誤り率は大きくなって通信品質が悪くなる一方、セクタの幅を狭めるに従って他の移動局等からの干渉波が少なくなるため受信信号誤り率は小さくなって通信品質が向上する。
【０１０３】
また、図９には、本例のセクタアンテナ装置により行われる処理の手順の一例を示してある。
すなわち、本例のセクタアンテナ装置では、各セクタｉ（ｉ＝１〜Ｌ）の受信信号誤り率を適時検出するとともに（ステップＳ３１）、１セクタ当たりの平均誤り率（ＡＶＥ）を算出しており（ステップＳ３２）、例えばセクタ１（ｉ＝１）からセクタＬ（ｉ＝Ｌ）へと順に（ステップＳ３３）、各セクタｉの受信信号誤り率（誤り率測定値）が平均誤り率を超えているか否かを判定する（ステップＳ３４）。
【０１０４】
この結果、検出したセクタｉの受信信号誤り率が平均誤り率を超えていることが判定された場合には、セクタアンテナ装置では、例えば当該セクタｉの幅を狭めることにより当該セクタｉの受信信号誤り率を平均誤り率以下に減少させるとともに、当該セクタｉに隣接する２つのセクタ（セクタ（ｉ−１）とセクタ（ｉ＋１））の受信信号誤り率を比較して（ステップＳ３５）、比較したこれらのセクタの内で受信信号誤り率が小さい方のセクタを広めることにより（ステップＳ３６、ステップＳ３９）、セル全体をＬ個のセクタでカバーできるようにする。そして、セクタアンテナ装置では、同様な処理を他のセクタについても順次行うことにより（ステップＳ３７、ステップＳ３８）、各セクタの受信信号誤り率を均等化する。
【０１０５】
一方、上記の判定処理により（ステップＳ３４）、検出したセクタｉの受信信号誤り率が平均誤り率以下であることが判定された場合には、セクタアンテナ装置では、以降の他のセクタについても順次上記と同様な判定処理を行っていき（ステップＳ３７、ステップＳ３８）、上記と同様に必要な場合には各セクタの幅等を変化させることにより各セクタの受信信号誤り率を均等化することを行う。
【０１０６】
以上のように、本例のセクタアンテナ装置では、上記した重み制御部１から成る制御手段が各重み付け部Ｇ１〜ＧＬを制御することにより、セクタ間の受信信号誤り率の差を減少させて各セクタの受信信号誤り率を均等化することが行われるため、セクタの受信信号誤り率といった通信状況に応じて効率的な無線通信を実現することができる。具体的には、本例のセクタアンテナ装置では、ＣＤＭＡ方式を用いて移動局と無線通信を行う場合に、各セクタの受信信号誤り率を均等化することにより各セクタにおける通信品質を均等化することができ、これにより、通信容量を有効に活用することができる。
【０１０７】
ここで、以上の第１実施例〜第４実施例では、上記図１に示したサーキュラアレイの構成や上記図２に示したリニアアレイの構成を有したセクタアンテナ装置を例示したが、本発明のセクタアンテナ装置としては、必ずしもこれらの実施例の態様に限られず、種々な装置構成が用いられてもよい。
具体的には、例えばアンテナの数や配置等としては種々なものが用いられてもよく、要は、各アンテナに印加される電気信号の振幅や位相を各アンテナ毎に調整することでこれらのアンテナにより合成されるセクタの指向性を変化させることができる構成であればよい。
【０１０８】
また、セクタの数や大きさ等としても、種々な態様が用いられてもよい。
また、本発明のセクタアンテナ装置の適用分野としても、特に限定はなく、例えば上記第１実施例〜第４実施例に示したように複数の移動局と無線通信する移動通信システムの基地局等といったもののアンテナ装置として本発明を用いることができる。
【０１０９】
【発明の効果】
以上説明したように、本発明に係るセクタアンテナ装置によると、指向性を有するセクタを形成して当該セクタの移動局と無線通信するに際して、例えばセクタの移動局数や受信信号電力対干渉電力比や受信信号誤り率といった移動局との通信状況に応じて、通信に用いる複数のアンテナに印加される電気信号の振幅及び位相を各アンテナ毎に調整することによりこれらのアンテナにより合成されるセクタの指向性を変化させるようにしたため、種々な通信状況に対応して移動局との無線通信の効率化を図ることができる。
【図面の簡単な説明】
【図１】本発明に係るセクタアンテナ装置の構成例を示す図である。
【図２】本発明に係るセクタアンテナ装置の他の構成例を示す図である。
【図３】セクタの構成及び各セクタの移動局を概念的に示す図である。
【図４】セクタの構成及び各セクタの移動局を概念的に示す図である。
【図５】セクタアンテナ装置による処理の手順の一例を示すフローチャートである。
【図６】セクタアンテナ装置による処理の手順の一例を示すフローチャートである。
【図７】セクタの幅と受信信号電力対干渉電力比との関係を説明するための図である。
【図８】セクタアンテナ装置による処理の手順の一例を示すフローチャートである。
【図９】セクタアンテナ装置による処理の手順の一例を示すフローチャートである。
【図１０】従来例に係るセクタの構成を説明するための図である。
【図１１】円状配置８素子アレーアンテナの一例を示す図である。
【符号の説明】
１、　１１・・重み制御部、　Ｔ１〜Ｔ６、Ｕ１〜Ｕ７・・アンテナ、
Ｇ１〜ＧＬ、Ｖ１〜ＶＬ・・重み付け部、
Ｈ１〜ＨＬ、Ｗ１〜ＷＬ・・合成器、[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sector antenna device that forms a sector having directivity and wirelessly communicates with a mobile station of the sector, and more particularly, to a sector antenna device that changes the directivity of a sector according to a communication state with a mobile station.
[0002]
[Prior art]
For example, in a mobile telephone system, a mobile telephone system (cellular system), and the like, wireless communication is performed between a base station and a mobile station (user). In such a system, communication is performed between a base station and a plurality of mobile stations by using a multiple access method (multiple access) as a communication method. As a typical multiple access method, time is set for each channel. TDMA (Time Division Multiple Access) method for dividing, FDMA (Frequency Division Multiple Access) method for dividing frequency for each channel, and CDMA (Code Division Multiple) method for dividing code for each channel.
[0003]
When wireless communication is performed between a base station and a mobile station using such a communication method, it is required to improve the use efficiency of radio frequencies. Sectoring is known. Here, a cell is a service area covered by one base station (performs wireless communication), and a sector is each area when the cell is divided into a plurality of areas. By performing cell sectorization, co-channel interference can be reduced, thereby increasing communication capacity.
[0004]
As a method of realizing the above-described sector configuration, for example, a method of providing a base station with a sector antenna having directivity is known. An example of the sector configuration in this case is shown with reference to FIG.
The figure shows an example of a sector configuration in a base station when the number of sectors is 6, and as shown in the figure, the base station has six antennas 21 around one point (the center point of a circle). Are radially arranged, and a reflector 22 is provided around each antenna 21 so that the aperture angles of the antennas 21 are equally divided, for example.
[0005]
With the above configuration, each antenna 21 is spatially separated from the adjacent antenna 21 by the reflection plate 22, whereby the directivity of the transmission / reception signal is realized for each antenna 21. When the aperture angle is equally divided as described above, the angle at which the sector (“sector 1” to “sector 6”) formed for each antenna 21 faces around the above one point is 60 degrees (360 degrees / 360 degrees). 6), and the amount of interference can be reduced to 1/6.
Although the case where the number of sectors is set to 6 has been described above, in general, when one cell is divided into L (L is plural) sectors, the angle facing each sector is fixed to 360 degrees / L. Is done.
[0006]
[Problems to be solved by the invention]
However, in the sector configuration of the base station as described above, since each sector is fixed, for example, the directivity of the sector is changed in accordance with various communication conditions that change due to, for example, a plurality of mobile stations moving. Therefore, there is a problem that the wireless communication cannot be efficiently performed depending on the communication status with the mobile station.
[0007]
Here, a specific example of the above-described problem will be described.
For example, when the TDMA method or the FDMA method is used as the communication method, the maximum number of mobile stations (the maximum allowable multiple access number per sector) that the base station can simultaneously perform wireless communication by one sector is generally ( Since the number is limited to the maximum number of multiple access per cell / (the number of sectors), if a large number of mobile stations are concentrated in one sector and exceed the maximum allowable multiple access per sector. However, there is a problem that a mobile station that cannot perform wireless communication occurs even though the maximum allowable number of multiple access per cell does not reach the entire cell (that is, a call loss occurs). there were.
[0008]
Further, for example, when a CDMA system is used as a communication system, different codes are assigned to the respective mobile stations. Therefore, even when a large number of mobile stations are concentrated in one sector, the radio communication between the base station and the mobile stations is performed. Is not impossible at all, but since all mobile stations share the same frequency band and the same time to perform wireless communication with the base station, the quality of wireless communication in each sector is For example, if a large number of mobile stations are concentrated in one sector, the communication quality between the mobile station in the sector and the base station deteriorates, and the base station receives signals from the mobile station. However, there is a problem that the error rate of the signal becomes worse than required.
[0009]
A configuration is also conceivable in which the base station changes the directivity of each sector by changing the angle of the reflector 22 of the sector antenna shown in FIG. 10, for example, so that the number of mobile stations in each sector is maintained at about the same number. However, in such control of the reflector 2, the reflection angle of the beam (signal) by the reflector 22 changes, and the shape of the sector is deformed, so that the desired beam shape and antenna gain cannot be obtained well. There were many problems. For this reason, in such control of the reflector 22, co-channel interference increases in both downlink communication from the base station to the mobile station and uplink communication from the mobile station to the base station, and the communication quality deteriorates. However, it was not suitable for practical use.
[0010]
The present invention has been made in order to solve such a conventional problem, and when forming a sector having directivity and performing wireless communication with a mobile station of the sector, the sector according to a communication state with the mobile station is determined. It is an object of the present invention to provide a sector antenna device capable of improving the efficiency of wireless communication with a mobile station by changing the directivity of the sector antenna.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a sector antenna device according to the present invention includes a plurality of antennas, forms a sector having directivity as follows, and wirelessly communicates with a mobile station of the sector.
That is, the control unit controls the adjusting unit according to the communication status with the mobile station, and the adjusting unit adjusts the amplitude and phase of the electric signal applied to the plurality of antennas for each antenna, thereby controlling these. Change the directivity of the sector synthesized by the antenna.
[0012]
Therefore, the sector antenna apparatus can perform wireless communication by changing the directivity of the sector in accordance with the communication state with the mobile station, and thereby can perform wireless communication with the mobile station in various communication states. Efficiency can be improved.
As a method of changing the directivity of a sector, for example, a method of changing the size of a sector, a method of changing the direction of the sector while keeping the size of the sector constant, or a method of changing the size and direction of the sector And how to change both.
[0013]
As a specific example of the control described above, in the sector antenna device according to the present invention, when the number of mobile stations detecting means detects the number of mobile stations in the sector, and the control means described above determines that the number of mobile stations in the sector exceeds the maximum allowable number, The number of mobile stations in the sector is reduced to the maximum allowable number or less by changing the directivity of the sector.
Here, the maximum allowable number means the maximum allowable number of multiple access per sector when, for example, the TDMA system or the FDMA system is used as the communication system, and when the CDMA system is used as the communication system, for example. Refers to the maximum number of mobile stations per sector that can ensure the required communication quality (allowable error rate).
[0014]
In general, the TDMA method is a method in which time is divided by the number of channels to give exclusive time to each channel (each mobile station). Similarly, the FDMA method is a method in which the frequency is divided by the number of channels and each channel (each mobile station). In this method, for example, the number of channels per sector is the maximum allowable multiple access number of the sector. Further, in these systems, since each mobile station monopolizes time and frequency, the number of mobile stations in a sector hardly affects the quality of wireless communication in the sector.
[0015]
In general, the CDMA system is a system in which a code is divided by the number of channels to give an exclusive code to each channel (each mobile station). Although it may be infinite (however, it is actually limited to, for example, the number of types of codes), the maximum allowable number is set based on a request for ensuring communication quality. That is, in this method, the communication quality in the sector tends to deteriorate as the number of mobile stations in the sector increases, and thus the maximum allowable number that can maintain such communication quality to the required level is usually set. Setting is performed.
[0016]
Therefore, for example, when the TDMA scheme or the FDMA scheme is used, even if the number of mobile stations in a certain sector exceeds the maximum allowable number, the present control mode allows the maximum number of mobile stations in the sector. While the number of mobile stations is reduced to less than or equal to the number, mobile stations that have fallen out of the sector are covered by other sectors. This can be suppressed from occurring.
Further, for example, when the CDMA system is used, communication quality with the mobile station in the sector can be guaranteed by keeping the number of mobile stations in the sector to the maximum allowable number or less by this control mode.
[0017]
Also, as a specific example, in the sector antenna device according to the present invention, a plurality of the above-described adjusting units are provided, a sector is formed for each of the adjusting units, and the mobile station number detecting unit detects the number of mobile stations in each sector. The control means controls the adjusting means to reduce the difference in the number of mobile stations between sectors.
[0018]
Therefore, for example, when the TDMA system or the FDMA system is used, the number of mobile stations in each sector can be kept approximately the same by reducing the difference in the number of mobile stations between sectors. Although the number of mobile stations in any one of the sectors exceeds the maximum allowable number of multiple access per sector even though the number of mobile stations is less than the maximum allowable number of multiple access per cell, a mobile station that cannot communicate occurs. It is possible to suppress occurrence of such a situation.
[0019]
Further, for example, when the CDMA system is used, the communication quality in each sector can be maintained at the same level by maintaining the number of mobile stations in each sector at the same number in the same manner as described above. It is possible to avoid a situation in which the mobile station concentrates only on the mobile station and the communication quality in the sector deteriorates.
[0020]
As a specific example, in the sector antenna apparatus according to the present invention, a CDMA system is used as a communication system with a mobile station, a plurality of the above-described adjusting units are provided, a sector is formed for each of the adjusting units, and a SIR (Signal power to signal) is formed. (Interference Ratio: signal power to interference power ratio) detecting means detects the ratio of received signal power to interference power from the mobile station in each sector, and the control means controls the adjusting means to control the received signal power between sectors. Reduce the difference in interference power ratio. In general, in wireless communication using the CDMA method, there is a tendency that the larger the ratio of received signal power to interference power, the better the communication quality.
[0021]
Therefore, by reducing the difference between the signal power to interference power ratio between the sectors in the uplink communication from the mobile station to the sector antenna device by the present control mode, for example, it is possible to maintain the same communication quality in each sector, As a result, it is possible to avoid a situation in which the ratio of the received signal power to the interference power in only one of the sectors increases and the communication quality in the sector deteriorates.
[0022]
Further, as a specific example, in the sector antenna apparatus according to the present invention, a CDMA system is used as a communication system with the mobile station, a plurality of the above-described adjusting units are provided, and a sector is formed for each adjusting unit. The error rate of the signal received from the mobile station in each sector is detected, and the control means controls the adjusting means to reduce the difference in error rate between the sectors.
[0023]
Therefore, by reducing the difference between the bit error rate and the frame error rate in the uplink communication from, for example, the mobile station to the sector antenna apparatus between the sectors by the present control mode, the communication quality in each sector can be maintained at the same level. Thus, it is possible to avoid a situation in which the bit error rate or the like of only one of the sectors increases and the communication quality in the sector deteriorates.
[0024]
In the above description, when the CDMA system is used, the directivity of the sector is changed based on the number of mobile stations in the sector, the ratio of received signal power to interference power, or the reception error rate, and the communication quality in each sector is substantially the same. However, it is usually preferable to perform control based on the reception error rate because the communication quality can be most directly adjusted. However, when constructing an actual device, since control based on the received signal power to interference power ratio is generally simpler than control based on the reception error rate, control based on the received signal power to interference power ratio is adopted. In some cases, the communication quality can be adjusted with almost the same accuracy as in the case of the control based on the reception error rate. Similarly, it may be preferable to adopt such control also for control based on the number of slave stations. In this case, too, the communication quality is adjusted with almost the same accuracy as control based on the reception error rate. be able to.
[0025]
Here, a specific example of a method of adjusting the amplitude and phase of an electric signal according to the present invention will be described. As described above, in the present invention, the directivity of the sector combined by these antennas is changed by adjusting the amplitude and phase of the electric signal applied to the plurality of antennas for each antenna. Note that the electric signal applied to a plurality of antennas is, for example, in the case of wireless transmission, a current signal or the like applied to the plurality of antennas to radiate a wireless signal from the plurality of antennas. In the case of reception, it means a current signal or the like applied to these antennas by an electromagnetic field generated by a signal wirelessly transmitted from the mobile station.
[0026]
As a specific example, “Basic study of variable zone configuration system using array antenna” (Kubota, Iwama, Yokoyama, IEICE RCS95-76, pp.53-58, September 1995) An example is described in which a desired sector is formed by adjusting the amplitude and phase of an electric signal applied to a plurality of antennas arranged in a circle (circular array antenna) for each antenna. This example will be described.
[0027]
First, for a circular array antenna in which (2M) antennas are arranged at equal angular intervals on a circumference having a radius a from the origin, the angle of each antenna from the φ = 0 axis with respect to the origin as θm ( m = (− M) to (M−1), each corresponding to each antenna). Here, the φ = 0 axis is such that φ of the M antennas and φ of the remaining M antennas are respectively symmetric, as in the case of (2M) = 8 exemplified in FIG. 11 described later. Stipulated in
[0028]
Here, FIG. 11 shows a configuration example of a circularly arranged eight-element array antenna when (2M) = 8 as a specific example of the above-described circularly arranged array antenna. The array antenna is configured by arranging eight antennas Z1 to Z8 at equal angular intervals (45 ° intervals) on the circumference. The φ = 0 axis is defined so as to pass through the midpoint between the antennas Z1 and Z8 and the midpoint between the antennas Z4 and Z5, and φ of the four antennas Z1 to Z4 and the remaining four Φ of the antennas Z8 to Z5 are symmetrical (positive and negative are opposite).
[0029]
Hereinafter, description will be made again assuming that the total number of antennas is (2M).
For example, if k = (2π / λ) (λ is the wavelength), the radiated electric field E (φ) in the φ direction can be calculated by using the amplitude component A′m and the phase component δm of the current applied to each antenna. As shown. Note that j in Expression 1 represents a complex part.
[0030]
(Equation 1)

[0031]
Here, if A′m · exp (jδm) is replaced by a complex number Am, and this Am is used as a parameter, the above-mentioned radiated electric field E (φ) is expressed by Expression 2.
[0032]
(Equation 2)

[0033]
On the other hand, for a linear array antenna in which (2N + 1) antennas are linearly arranged at equal intervals, the direction of the straight line on which the plurality of antennas are arranged is defined as φ = 0, and the φ = 0 axis is determined. Similarly to the case shown in FIG. 11, the direction counterclockwise from the φ = 0 axis is the positive direction of φ. In this case, the radiated electric field E0 (φ) in the φ direction generated by the linearly arranged array antenna is expressed by Expression 3. Bn (n = −N to N, each corresponding to each antenna) is a parameter corresponding to each antenna.
[0034]
[Equation 3]

[0035]
Here, Equation 3 shows that when N approaches infinity (∞), Fourier (Four)
ier) series. For example, if the number of samples is cut off to a finite number, it is not possible to interpolate a fine portion, but it is possible to approximately express the underlying function. Therefore, in the linear array antenna, the parameter Bn for realizing the desired radiated electric field E0 (φ) can be estimated and calculated by using Bn shown in Expression 4 as the parameter of the nth antenna. it can.
[0036]
(Equation 4)

[0037]
Next, by assuming that the radiation electric field E (φ) shown in the above equation 2 is equal to the radiation electric field E0 (φ) shown in the above equation 3, the electric field pattern generated by the above-mentioned circular array antenna is calculated. Consider a case where the electric field pattern is similar to the electric field pattern generated by the linear array antenna described above. Assuming that the right side of Equation 2 is equal to the right side of Equation 3, Equation 5, for example, is obtained in the range of -π ≦ φ ≦ π.
[0038]
(Equation 5)

[0039]
Here, in order to make Equation 5 easier to understand, μ is replaced by μ = (m + 置 き 換 え), and when the parameter is Aμ, Equation 5 is transformed into Equation 6.
[0040]
(Equation 6)

[0041]
Further, when ψ = (φ−2μπ / 2M) and the left side of Expression 6 is substituted into E0 (φ) of Expression 4, Expressions 7 and 8 are obtained.
[0042]
(Equation 7)

[0043]
(Equation 8)

[0044]
Here, in general, when Kronecker's Delta δμμ ′ is used, the equation shown in Expression 9 is established. Note that this delta is a sign that δμμ ′ = 0 when μ ≠ μ ′ and δμμ ′ = 1 when μ = μ ′.
[0045]
(Equation 9)

[0046]
Assuming that the number of antennas (2N + 1) of the linear array antenna is one greater than the number of antennas (2M) of the circular array antenna, M = N, and the above equation (7) is transformed into the equation (10). You.
[0047]
(Equation 10)

[0048]
Then, by rearranging the above equation 9 by applying the above equation 9, the parameter Aμ can be obtained as shown in equation 11.
[0049]
[Equation 11]

[0050]
As described above, in the above-described circular array antenna, the parameter Aμ shown in the above equation 11 is adjusted by adjusting the amplitude component A′m and the phase component δm of the current applied to each antenna. Accordingly, the pattern of the directivity of the sector (that is, the radiation electric field E (φ)) synthesized by the plurality of antennas can be changed to various patterns.
[0051]
Further, as described above, in the above-described linear array antenna, the plurality of antennas are adjusted by adjusting the amplitude component of the current applied to each antenna and adjusting the parameter Bn shown in the above equation (4). Can be changed to various patterns of the directivity of the sector (that is, the radiation electric field E0 (φ)).
[0052]
In the above description, an example in which a plurality of antennas are arranged in a straight line and an example in which a plurality of antennas are arranged in a circle has been described. However, in order to generate a desired sector directivity pattern, an electric signal applied to each antenna is generated. How to control the amplitude and phase depends on, for example, the way of arranging the antennas and, for example, the absolute angle between each of the fixedly arranged antennas and the direction of directivity (the direction of forming a sector). Is controlled based on the above condition.
[0053]
Further, in general, the directivity when transmitting a radio signal from an antenna is the same as the directivity when receiving a radio signal with the antenna, and therefore, in the sector antenna device according to the present invention, the electric power as described above is used. By controlling the amplitude and phase of a signal when transmitting and receiving a wireless signal, it is possible to realize the same sector directivity for transmission and reception.
[0054]
BEST MODE FOR CARRYING OUT THE INVENTION
A sector antenna device according to a first embodiment of the present invention will be described with reference to the drawings.
In this example, it is assumed that the sector antenna apparatus according to the present invention is provided in a base station such as a mobile phone system, and that the sector antenna apparatus forms a sector having directivity and a plurality of mobile stations in the sector are provided. It shows the case of wireless communication with.
FIG. 1 shows an example of a sector antenna device according to the present invention. This sector antenna device has a circular array (circular shape) in which a plurality (six in this example) of antennas T1 to T6 are arranged on a circumference. (Disposed adaptive array antenna).
[0055]
The sector antenna device shown in the figure includes the above-described six antennas T1 to T6, the same number of weighting sections G1 to GL as the number of sectors (L in this example), and the same number of combiners H1 as the number of sectors. To HL, and a weight control unit 1 for controlling each of the weighting units G1 to GL described above. Each of the weighting units G1 to GL is connected to six antennas T1 to T6, and is connected to one combiner H1 to HL, respectively.
[0056]
Each of the weighting units G1 to GL includes, for example, a phase shifter, and has a function of adjusting the amplitude and the phase of the electric signals applied to the six antennas T1 to T6 for each of the antennas under the control of the weight control unit 1. have.
Specifically, for example, when transmitting a radio signal from the antennas T1 to T6, each of the weighting units G1 to GL determines the amplitude and phase of the electric signal to be transmitted input from each of the combiners H1 to HL. Adjustment is performed for each antenna, and the adjusted electric signal is wirelessly transmitted from each of the antennas T1 to T6. For example, when a wireless signal is received by the antennas T1 to T6, each of the weighting units G1 to GL adjusts the amplitude and phase of the electric signal received and received by each of the antennas T1 to T6 for each antenna. The adjusted (six in this example) electrical signals are output to the respective combiners H1 to HL.
[0057]
Each of the combiners H1 to HL has a function of combining a plurality of electric signals into one electric signal.
Specifically, for example, when transmitting a wireless signal from the antennas T1 to T6, each of the combiners H1 to HL divides the electric signal to be transmitted into, for example, six electric signals and divides each of the weighting sections G1 to GL. Output to For example, when receiving a wireless signal from the antennas T1 to T6, each of the combiners H1 to HL combines a plurality (six in this example) of electric signals input from the respective weighting units G1 to GL.
[0058]
The weight control unit 1 has a function of controlling the adjustment of the amplitude and phase of the electric signal by each of the weighting units G1 to GL according to the communication status with the mobile station. This is performed by transmitting a control signal to G1 to GL and instructing amplitude and phase weighting coefficients. By performing such control, for example, the directivity of a different sector can be formed for each of the weighting units G1 to GL, and the directivity of each of these sectors can be changed.
[0059]
A specific example of how to change the amplitude and the phase of the electric signal applied to each of the antennas T1 to T6 in order to realize the desired sector directivity is shown in the above-mentioned “Means for Solving the Problems”. Therefore, the description is omitted in this example. The weight control unit 1 of the present example determines the amplitude and phase values to be adjusted for each of the antennas T1 to T6 using, for example, the same formula as the theoretical formula shown in the specific example.
[0060]
In this example, the weights G1 to GL adjust the amplitude and phase of the electric signal applied to the plurality of antennas for each antenna, thereby changing the directivity of the sector combined by these antennas. Adjusting means is configured. In this example, a plurality of adjusting means (in this example, weighting units G1 to GL) are provided, and a sector is formed for each adjusting means.
Further, in this example, the weight control section 1 constitutes a control means for changing the directivity of the sector by controlling the adjustment by the adjustment means according to the communication status with the mobile station.
[0061]
With the configuration described above, in the sector antenna apparatus of the present example, when a plurality of sectors having directivity are formed and wireless communication is performed with the mobile station in each sector, the direction of each sector is adjusted according to various communication situations with the mobile station. , The efficiency of wireless communication with the mobile station can be improved.
[0062]
The control of the amplitude and phase adjustment processing of the electric signal performed by the sector antenna device according to the present invention is performed, for example, by the processor executing a control program in a hardware resource including a processor and a memory. Alternatively, for example, each functional means for executing the processing may be constituted by an independent hardware circuit.
[0063]
FIG. 2 shows another configuration example of the sector antenna device according to the present invention. This sector antenna device has a linear configuration in which a plurality of (seven in this example) antennas U1 to U7 are linearly arranged. It has an array (linearly arranged adaptive array antenna) configuration. Here, in the sector antenna device shown in the figure, the same number of weighting units V1 to VL as the number of sectors for adjusting the amplitude and phase of the electric signal applied to each antenna U1 to U7 for each antenna, and a plurality of The same number of synthesizers W1 to WL as the number of sectors for synthesizing electric signals and the weight control unit 11 for controlling the weighting units V1 to VL described above are provided. 1 except that the numbers and arrangements of U7 to U7 are different and that the manner of adjusting the amplitude and phase of the electric signal performed by each of the weighting units V1 to VL is different. Is the same as
[0064]
Next, a specific example of a mode in which the above-described adjustment processing of the amplitude and phase of the electric signal is controlled by the sector antenna device of the present example will be described. In the following, a specific example of the operation is shown on behalf of the sector antenna device shown in FIG. 1, but as described above, for example, the operation in the case of using the sector antenna device shown in FIG. It is almost the same.
[0065]
Further, it is assumed that the sector antenna device of the present example is provided with, for example, a mobile station number detecting means for detecting the number of mobile stations in each sector. In this example, the mode in which the adjustment process is controlled based on the number of mobile stations Is shown. The number of mobile stations in each sector is detected, for example, by wireless communication using a transmission / reception processing circuit (each processing circuit including one weighting unit G1 to GL and one combiner H1 to HL in this example) for each sector. This is performed by detecting the number of mobile stations that are in use.
[0066]
As an example, a case is described in which wireless communication is performed between the sector antenna apparatus of the present example and a mobile station using the TDMA scheme or the FDMA scheme.
In this case, the weight control unit 1 provided in the sector antenna apparatus of the present example monitors the number of mobile stations in each sector, for example, and determines that the number of mobile stations in any sector exceeds the maximum allowable multiple access number. In response to the above, the number of mobile stations in the sector is reduced to or below the maximum allowable multiple access number by controlling the weighting units G1 to GL corresponding to the sector to reduce the width of the sector, etc. The area outside the range to be covered is covered by increasing the width of the sector adjacent to the sector.
[0067]
Here, the control of the sector as described above will be described more specifically with reference to FIGS.
FIGS. 3 and 4 conceptually show the sectors formed by the sector antenna device of the present example. The sector antenna device of the present example (that is, the base station in this example) is located at the center of the circle in these figures. Station), and the sector antenna device covers sixty-three degree of service area (cell) by forming six sectors ("sector 1" to "sector 6"). Further, the black circle and white circle in FIG. 3 and the black circle in FIG. 4 each indicate one mobile station.
[0068]
For example, assuming that the maximum allowable multiple access number of each sector formed by the sector antenna apparatus of this example is equal to three, if the communication situation shown in FIG. 3 occurs, “sector 1” or “sector 1” Since the number of mobile stations of 5 ″ exceeds the maximum allowable multiple access number (3), the sector antenna apparatus of this example cannot perform wireless communication with, for example, the mobile stations indicated by white circles.
[0069]
Therefore, in the sector antenna device of the present example, for example, the width of “sector 1” is first reduced, and the width of “sector 2” and “sector 6” adjacent to “sector 1” is increased. The number of mobile stations is reduced to the maximum allowable multiple access number or less, then the same control is performed for “sector 2”, and then the same control is sequentially performed for the other sectors to cover the entire cell. While changing the directivity of each sector, as a result, as shown in FIG. 4, the number of mobile stations in each sector is reduced to the maximum allowable multiple access number or less.
[0070]
Comparing the effect of the sector antenna apparatus of the present example that performs such control with that of the conventional one, for example, since the conventional one has the sector configuration shown in FIG. 15 and cannot be communicated with the three mobile stations (mobile stations indicated by white circles) due to the restriction on the maximum allowable number of multiple connections per sector. However, in the sector antenna apparatus of this example, FIG. Since the sector configuration can be changed to the one shown, wireless communication can be performed between the entire cell and 18 mobile stations, which is the maximum allowable number of multiple access per cell, thereby effectively utilizing the communication capacity. can do.
[0071]
Although the case where the TDMA system or the FDMA system is used as the communication system has been described above, for example, when wireless communication is performed using the CDMA system between the sector antenna apparatus of this example and the mobile station, As the maximum allowable number of multiple access per sector described above, the number of mobile stations capable of ensuring the required quality of the wireless communication performed by the mobile station of the sector and the sector antenna device is set. That is, if the number of mobile stations in the sector exceeds the maximum allowable multiple access number, communication quality in the sector deteriorates. However, in the sector antenna device of this example, the number of mobile stations in the sector is reduced by the same control as described above. By doing so, the communication quality in the sector can be secured to the required degree.
[0072]
FIG. 5 shows an example of a procedure of a process performed by the sector antenna device of the present example.
That is, in the sector antenna device of this example, the number of mobile stations (the number of users) of each sector i (i = 1 to L) is detected at appropriate times (step S1), and, for example, from sector 1 (i = 1) to sector L In order (i = L) (step S2), it is determined whether or not the number of mobile stations (the number of detected users) of each sector i exceeds the maximum allowable number per sector (step S3).
[0073]
As a result, when it is determined that the detected number of mobile stations in the sector i exceeds the maximum allowable number, the sector antenna apparatus reduces the number of mobile stations in the sector i by, for example, reducing the width of the sector i. And the number of mobile stations of two sectors (sector (i-1) and sector (i + 1)) adjacent to the sector i are compared (step S4), and the compared sectors are compared. By spreading the sector having the smaller number of mobile stations among them (steps S5 and S8), the entire cell can be covered by L sectors. Then, the sector antenna apparatus sequentially performs the same process for other sectors (steps S6 and S7) to determine the number of mobile stations that cannot be communicated due to the limitation of the maximum allowable number per sector. Decrease.
[0074]
On the other hand, when it is determined that the number of mobile stations of the detected sector i is equal to or less than the maximum allowable number by the above determination process (step S3), the sector antenna apparatus sequentially performs the above-mentioned operations on other sectors. (Steps S6 and S7), and if necessary, the number of mobile stations that cannot be communicated is reduced by changing the width of each sector if necessary. Do that.
[0075]
As described above, in the sector antenna device of the present example, the directivity of the sector is changed by the control means including the weight control unit 1 when the number of mobile stations in the sector exceeds the maximum allowable number. Since the number of mobile stations in the sector is reduced to the maximum allowable number or less, efficient wireless communication can be realized according to the communication status such as the number of mobile stations in the sector.
[0076]
Next, a sector antenna device according to a second embodiment of the present invention will be described with reference to the drawings. The configuration and operation of the sector antenna device of this example are the same as those of the device shown in the first embodiment, except that the weight control unit 1 controls the weighting units G1 to GL differently. Since the configuration is the same as that described above, the control mode by the weighting unit 1 of the present embodiment will be mainly described in detail below.
[0077]
The weight control unit 1 provided in the sector antenna device of this example monitors the number of mobile stations in each sector, for example, and the number of mobile stations in any sector is the average number of mobile stations (average number of mobile stations). The number of mobile stations in the sector is reduced by controlling the weighting units G1 to GL corresponding to the sector in response to the number of mobile stations, thereby reducing the number of mobile stations in the sector. The area removed from the sector is covered by increasing the width of a sector adjacent to the sector. The average number of mobile stations described above is an average number of mobile stations per sector, and is represented by, for example, (number of mobile stations in all sectors) / (number of sectors L).
[0078]
Here, such sector control will be described more specifically with reference to FIGS. 3 and 4 used in the first embodiment.
As described above, FIG. 3 and FIG. 4 conceptually show the sectors formed by the sector antenna device of the present embodiment, and the sector antenna device of the present embodiment (that is, In this example, a base station is installed, and the sector antenna device covers a 360-degree service area (cell) by forming six sectors ("sector 1" to "sector 6"). Further, the black circle and white circle in FIG. 3 and the black circle in FIG. 4 each indicate one mobile station.
[0079]
For example, assuming that the maximum allowable number of each sector formed by the sector antenna device of the present example is equal to 3, if the communication situation shown in FIG. 3 occurs, the number of mobile stations in each sector is not equal. As a result, a problem may occur in the wireless communication with the mobile station.
[0080]
Specifically, for example, when the TDMA system or the FDMA system is used as a communication system, the number of mobile stations in “sector 1” or “sector 5” exceeds the maximum allowable multiple access number (3). As a result, for example, wireless communication cannot be performed with the mobile station indicated by a white circle. Further, for example, when the CDMA system is used as the communication system, similarly, the communication quality in, for example, “sector 1” or “sector 5” may be deteriorated.
[0081]
Therefore, in the sector antenna device of the present example, for example, the width of “sector 1” is first reduced, and the width of “sector 2” and “sector 6” adjacent to “sector 1” is increased. The number of mobile stations is reduced to the average number of mobile stations or less, and then the same control is performed for “sector 2”, and then the same control is sequentially performed for the other sectors to cover the entire cell. While changing the directivity of each sector, as a result, as shown in FIG. 4, the number of mobile stations in each sector is reduced below the average number of mobile stations.
[0082]
For example, when the effect of the sector antenna apparatus of the present example when performing wireless communication using the TDMA scheme or the FDMA scheme is compared with that of the related art, for example, the sector configuration shown in FIG. As a result, the number of mobile stations that can communicate with each other becomes 15, and it becomes impossible to communicate with three mobile stations (mobile stations indicated by white circles) due to the restriction on the maximum allowable number of multiple connections per sector. In the sector antenna apparatus, since the number of mobile stations in each sector can be equalized as shown in FIG. 4, the maximum number of mobile stations per cell, which is the maximum allowable multiple access number per cell, is 18 for the entire cell. Wireless communication can be performed, whereby the communication capacity can be effectively used.
[0083]
Also, for example, in the case where wireless communication is performed using the CDMA method between the sector antenna apparatus of the present example and the mobile station, similarly, for example, the sector configuration shown in FIG. Although the communication quality in “sector 1” and “sector 5” deteriorates, in this example, the number of mobile stations in each sector can be equalized as shown in FIG. The power-to-interference power ratio and the communication quality can be substantially equalized, so that the communication capacity can be used more effectively than in the past.
[0084]
FIG. 6 shows an example of a procedure of a process performed by the sector antenna device of the present example.
That is, in the sector antenna apparatus of this example, the number of mobile stations (the number of users) in each sector i (i = 1 to L) is detected as appropriate (step S11), and the average number of mobile stations per sector (AVE) is determined. For example, in order from sector 1 (i = 1) to sector L (i = L) (step S13), the number of mobile stations (the number of detected users) of each sector i is the average number of mobile stations. Is determined (step S14).
[0085]
As a result, when it is determined that the number of mobile stations detected in the sector i exceeds the average number of mobile stations, the sector antenna apparatus reduces the width of the sector i to reduce the number of mobile stations in the sector i. The number of mobile stations is reduced to not more than the average number of mobile stations, and the number of mobile stations in two sectors (sector (i-1) and sector (i + 1)) adjacent to the sector i is compared (step S15). By spreading the sector having the smaller number of mobile stations among the sectors (steps S16 and S19), the entire cell can be covered by L sectors. Then, in the sector antenna apparatus, the same processing is sequentially performed on other sectors (steps S17 and S18), thereby equalizing the number of mobile stations in each sector.
[0086]
On the other hand, when it is determined that the number of mobile stations of the detected sector i is equal to or smaller than the average number of mobile stations by the above determination process (step S14), the sector antenna apparatus sequentially performs the other sectors thereafter. The same determination processing as described above is performed (steps S17 and S18), and if necessary, the number of mobile stations in each sector is equalized by changing the width and the like of each sector, if necessary. .
[0087]
As described above, in the sector antenna device of the present example, the control means including the weight control unit 1 controls each of the weighting units G1 to GL, thereby reducing the difference in the number of mobile stations between sectors, and Since the number of mobile stations is equalized, efficient wireless communication can be realized according to the communication status such as the number of mobile stations in a sector.
[0088]
Next, a sector antenna device according to a third embodiment of the present invention will be described with reference to the drawings. Note that the configuration and operation of the sector antenna device of this example are different in the manner in which the weight control unit 1 controls each of the weighting units G1 to GL, and is effective especially when a CDMA system is used as a communication system. Except for this point, the configuration is the same as the configuration of the device shown in the first embodiment, for example. Therefore, the control mode mainly by the weighting unit 1 of the present embodiment will be described below in detail.
[0089]
As described above, it is assumed that wireless communication is performed between the sector antenna device of this example and the mobile station using the CDMA method.
Further, the sector antenna device of this example is provided with SIR detection means for detecting the ratio of the received signal power to the interference power from the mobile station in each sector. Here, the ratio of the received signal power to the interference power refers to the power of a signal desired to be received (desired signal power, that is, the power of a signal received from a specific mobile station as a communication partner) and the power of an interference signal (that is, the power of a communication partner). (Power of an interference signal received from a mobile station or the like that has not been set).
[0090]
As a method of measuring the ratio of received signal power to interference power, for example, a method similar to that used in general transmission power control can be used. Specifically, the average of pilot symbols in a desired signal is averaged. By detecting the power, the detected value can be used as the power of the desired signal, and the power of the interference signal is determined by simulating the power of each pilot symbol from the average power of the pilot symbol. can do.
[0091]
The weight control unit 1 provided in the sector antenna apparatus of the present example monitors, for example, the ratio of the received signal power to the interference power in each sector. In response to exceeding the signal power to interference power ratio (average SIR), the weighting units G1 to GL corresponding to the sector are controlled to reduce the width of the sector, etc. The removed area is covered by, for example, increasing the width of a sector adjacent to the sector. The average received signal power to interference power ratio is an average received signal power to interference power ratio per sector, and is, for example, (total of the received signal power to interference power ratio of all sectors). ) / (Number of sectors L).
[0092]
Here, FIG. 7 conceptually shows, as an example, the relationship between the sector width and the received signal power to interference power ratio, and FIG. 7A and FIG. 2 shows an example of one sector formed when the sector antenna device T is arranged at the center point of the sector. For example, the power of a desired signal received from a specific mobile station is the same between the case where the width of a sector is wide as shown in FIG. 7A and the case where the width of a sector is narrow as shown in FIG. It is. In this case, in the sector antenna apparatus, as the width of the sector is increased, more interference waves are received from other mobile stations and the like, so that the received signal power to interference power ratio becomes smaller and the communication quality becomes worse. As the width of the sector is reduced, interference waves from other mobile stations and the like are reduced, so that the ratio of received signal power to interference power is increased and communication quality is improved.
[0093]
FIG. 8 shows an example of a procedure of a process performed by the sector antenna device of the present example.
That is, in the sector antenna apparatus of the present example, the received signal power to interference power ratio (SIR) of each sector i (i = 1 to L) is detected as appropriate (step S21), and the average SIR per sector (AVE) is obtained. (Step S22), for example, in order from sector 1 (i = 1) to sector L (i = L) (step S23), the received signal power to interference power ratio of each sector i (SIR measurement value) Is greater than or equal to the average SIR (step S24).
[0094]
As a result, if it is determined that the detected signal-to-interference power ratio of the detected sector i is less than the average SIR, the sector antenna apparatus reduces the width of the sector i by, for example, reducing the width of the sector i. The signal power to interference power ratio is increased to an average SIR or more, and the received signal power to interference power ratio of two sectors (sector (i-1) and sector (i + 1)) adjacent to the sector i is compared ( In step S25), by spreading the sector having the larger received signal power to interference power ratio among these compared sectors (steps S26 and S29), the entire cell can be covered by L sectors. Then, in the sector antenna apparatus, the same processing is sequentially performed on the other sectors (steps S27 and S28) to equalize the received signal power to interference power ratio of each sector.
[0095]
On the other hand, when it is determined by the above determination process (step S24) that the detected signal power-to-interference power ratio of the detected sector i is equal to or more than the average SIR, the sector antenna apparatus performs the following other sectors. Also, the same determination processing as described above is sequentially performed (steps S27 and S28), and if necessary, the received signal power to interference power ratio of each sector is changed by changing the width of each sector. Do equalization.
[0096]
As described above, in the sector antenna device of this example, the control means including the weight control unit 1 controls the weighting units G1 to GL, thereby reducing the difference between the received signal power and the interference power ratio between the sectors. Since the received signal power to interference power ratio of each sector is equalized in this way, efficient wireless communication can be realized according to the communication status such as the received signal power to interference power ratio of the sector. Specifically, in the case of performing wireless communication with a mobile station using the CDMA scheme, the sector antenna apparatus of the present example improves communication quality in each sector by equalizing the ratio of received signal power to interference power in each sector. Almost equalization can be achieved, whereby the communication capacity can be used effectively.
[0097]
In the configuration in which the directivity of the sector is controlled based on the ratio of the received signal power to the interference power as in this example, for example, as compared with the case where the control is performed based on the number of mobile stations as shown in the second embodiment. Thus, the communication quality in each sector can usually be more accurately equalized.
[0098]
Next, a sector antenna device according to a fourth embodiment of the present invention will be described with reference to the drawings. Note that the configuration and operation of the sector antenna device of this example are different in the manner in which the weight control unit 1 controls each of the weighting units G1 to GL, and is effective especially when a CDMA system is used as a communication system. Except for this point, the configuration is the same as the configuration of the device shown in the first embodiment, for example. Therefore, the control mode mainly by the weighting unit 1 of the present embodiment will be described below in detail.
[0099]
As described above, it is assumed that wireless communication is performed between the sector antenna device of this example and the mobile station using the CDMA system.
Further, the sector antenna device of the present example is provided with an error rate detecting means for detecting an error rate of a signal received from a mobile station in each sector. Here, as the error rate of the received signal, for example, a bit error rate or a frame error rate can be used.
[0100]
As a method of measuring the bit error rate or the frame error rate, for example, a method of adding a code for parity check to a signal wirelessly transmitted from a mobile station can be used. In this case, the sector antenna of this example is used. As an example, the apparatus uses, as an error rate, a value obtained by averaging the number of erroneous signals in the signal received from the mobile station and the number of times the error has been corrected over a predetermined time width.
[0101]
The weight control unit 1 provided in the sector antenna apparatus of the present example monitors, for example, the received signal error rate in each sector, and the received signal error rate in any of the sectors is averaged. Rate), the width of the sector is reduced by controlling the weighting units G1 to GL corresponding to the sector, and an area outside the range covered by the sector is assigned to the sector. The width of an adjacent sector is increased to cover the sector. The average received signal error rate is an average received signal error rate per sector, and is represented by, for example, (sum of received signal error rates of all sectors) / (number of sectors L). .
[0102]
Generally, as the width of the sector is increased, more interference waves are received from other mobile stations and the like, so that the received signal error rate increases and the communication quality deteriorates. Since the number of interference waves from mobile stations and the like is reduced, the received signal error rate is reduced and communication quality is improved.
[0103]
FIG. 9 shows an example of a procedure of a process performed by the sector antenna device of this example.
That is, in the sector antenna device of this example, the reception signal error rate of each sector i (i = 1 to L) is detected at appropriate times (step S31), and the average error rate per sector (AVE) is calculated. (Step S32), for example, in order from sector 1 (i = 1) to sector L (i = L) (step S33), the received signal error rate (error rate measurement value) of each sector i exceeds the average error rate. It is determined whether or not there is (step S34).
[0104]
As a result, if it is determined that the detected signal error rate of the detected sector i exceeds the average error rate, the sector antenna apparatus reduces the width of the sector i to reduce the received signal error rate of the sector i. The error rate is reduced below the average error rate, and the received signal error rates of two sectors (sector (i-1) and sector (i + 1)) adjacent to the sector i are compared (step S35). By spreading the sector having the smaller received signal error rate among these sectors (steps S36 and S39), the entire cell can be covered by L sectors. Then, in the sector antenna apparatus, the same processing is sequentially performed on other sectors (steps S37 and S38), thereby equalizing the reception signal error rate of each sector.
[0105]
On the other hand, if it is determined that the received signal error rate of the detected sector i is equal to or less than the average error rate by the above determination process (step S34), the sector antenna apparatus sequentially performs the other sectors thereafter. The same determination processing as described above is performed (steps S37 and S38), and if necessary, the received signal error rate of each sector is equalized by changing the width of each sector, if necessary. Do.
[0106]
As described above, in the sector antenna device of the present example, the control means including the weight control unit 1 controls the weighting units G1 to GL, thereby reducing the difference in the received signal error rate between the sectors and reducing the difference. Since the received signal error rate of the sector is equalized, efficient wireless communication can be realized according to the communication status such as the received signal error rate of the sector. Specifically, in the case of performing wireless communication with a mobile station using the CDMA method, the sector antenna apparatus of the present example equalizes the communication quality in each sector by equalizing the reception signal error rate in each sector. As a result, the communication capacity can be effectively utilized.
[0107]
Here, in the first to fourth embodiments, the sector antenna device having the configuration of the circular array shown in FIG. 1 or the configuration of the linear array shown in FIG. 2 is exemplified. The sector antenna device is not necessarily limited to the embodiments described above, and various device configurations may be used.
Specifically, for example, various things may be used as the number and arrangement of the antennas, and the point is that these are adjusted by adjusting the amplitude and phase of the electric signal applied to each antenna for each antenna. Any configuration can be used as long as the directivity of the sector combined by the antenna can be changed.
[0108]
Also, various modes may be used as the number and size of the sectors.
Also, the application field of the sector antenna device of the present invention is not particularly limited. For example, as shown in the first to fourth embodiments, a base station of a mobile communication system that wirelessly communicates with a plurality of mobile stations, and the like. The present invention can be used as an antenna device having such a configuration.
[0109]
【The invention's effect】
As described above, according to the sector antenna apparatus of the present invention, when a sector having directivity is formed and radio communication is performed with the mobile station of the sector, for example, the number of mobile stations in the sector or the received signal power to interference power ratio The amplitude and phase of electric signals applied to a plurality of antennas used for communication are adjusted for each antenna according to the communication status with the mobile station, such as the reception signal error rate, and the sector synthesized by these antennas is adjusted. Since the directivity is changed, the efficiency of wireless communication with the mobile station can be increased in accordance with various communication situations.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a sector antenna device according to the present invention.
FIG. 2 is a diagram showing another configuration example of the sector antenna device according to the present invention.
FIG. 3 is a diagram conceptually showing a configuration of a sector and a mobile station of each sector.
FIG. 4 is a diagram conceptually showing a configuration of a sector and a mobile station of each sector.
FIG. 5 is a flowchart illustrating an example of a procedure of a process performed by the sector antenna device.
FIG. 6 is a flowchart illustrating an example of a procedure of a process performed by the sector antenna device.
FIG. 7 is a diagram for explaining a relationship between a sector width and a received signal power to interference power ratio.
FIG. 8 is a flowchart illustrating an example of a procedure of a process performed by the sector antenna device.
FIG. 9 is a flowchart illustrating an example of a procedure of a process performed by the sector antenna device.
FIG. 10 is a diagram for explaining a configuration of a sector according to a conventional example.
FIG. 11 is a diagram showing an example of a circularly arranged 8-element array antenna.
[Explanation of symbols]
1, 11, weight control unit, T1 to T6, U1 to U7, antenna,
G1 to GL, V1 to VL... Weighting unit,
H1 to HL, W1 to WL ...

Claims (5)

In a sector antenna device that forms a sector having directivity and wirelessly communicates with a mobile station of the sector,
Multiple antennas,
Adjusting means for changing the directivity of the sector synthesized by these antennas by adjusting the amplitude and phase of the electric signal applied to the plurality of antennas for each antenna;
Control means for changing the directivity of the sector by controlling the adjustment by the adjustment means according to the communication status with the mobile station,
A sector antenna device comprising: The sector antenna device according to claim 1,
Mobile station number detecting means for detecting the number of mobile stations in a sector,
When the number of mobile stations in the sector exceeds the maximum allowable number, the control means changes the directivity of the sector to reduce the number of mobile stations in the sector to the maximum allowable number or less. . The sector antenna device according to claim 1,
Forming a sector for each adjusting means with a plurality of adjusting means,
Mobile station number detecting means for detecting the number of mobile stations in each sector,
The control means controls the adjusting means to reduce the difference in the number of mobile stations between sectors. The sector antenna device according to claim 1,
Using a CDMA system as a communication system with the mobile station,
Forming a sector for each adjusting means with a plurality of adjusting means,
SIR detection means for detecting a ratio of received signal power to interference power from the mobile station in each sector,
A sector antenna device, wherein the control means controls the adjusting means to reduce a difference in received signal power to interference power ratio between sectors. The sector antenna device according to claim 1,
Using a CDMA system as a communication system with the mobile station,
Forming a sector for each adjusting means with a plurality of adjusting means,
Sector antenna apparatus comprising: an error rate detection means for detecting an error rate of a signal received from a mobile station in each sector; and a control means for controlling an adjustment means to reduce a difference in an error rate between sectors. .

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