JP2004297483A - Mobile station, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile station capable of coping with an interference wave from a wireless base station with which the mobile station is not in communication in the case of forming a directivity pattern by using an adaptive array antenna system to enhance communication quality. <P>SOLUTION: The mobile station is provided with: base station direction adaptive processing sections 13-1 to 13-M and reception weighting sections 3-1 to 3-M for calculating each direction of communication base stations and peripheral base stations with respect to the mobile station itself on the basis of the positional information and azimuth information of the mobile station itself and base station positional information, forming a beam pattern in the direction of the communication base station and forming null in the direction of the peripheral base stations; and a rake reception section 4 for using the beam pattern and the null to apply reception processing to a received signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

但し、Ｄｉは移動局の位置における緯度１秒当たりの距離、Ｄｋは経度１秒当たりの距離である。なお、これらの値Ｄｉ，Ｄｋは、所定の地域範囲では同じ値としてでよい。
【００２８】
そして、下記（ａ）〜（ｈ）に示す条件より、基準方向（この例では真北を基準とし、東回りを＋とする）に対する角度θｐｓを求める。条件（ａ）〜（ｈ）には移動局と通信基地局の位置関係に対応する角度θｐｓが示されている。
（ａ）移動局経度＜基地局経度、移動局緯度＜基地局緯度；θｐｓ＝θａ
（ｂ）移動局経度＜基地局経度、移動局緯度＞基地局緯度；θｐｓ＝１８０度−θａ
（ｃ）移動局経度＞基地局経度、移動局緯度＞基地局緯度；θｐｓ＝１８０度＋θａ
（ｄ）移動局経度＞基地局経度、移動局緯度＜基地局緯度；θｐｓ＝３６０度−θａ
（ｅ）移動局経度＝基地局経度、移動局緯度＜基地局緯度；θｐｓ＝０度
（ｆ）移動局経度＝基地局経度、移動局緯度＞基地局緯度；θｐｓ＝１８０度
（ｇ）移動局経度＜基地局経度、移動局緯度＝基地局緯度；θｐｓ＝９０度
（ｈ）移動局経度＞基地局経度、移動局緯度＝基地局緯度；θｐｓ＝２７０度
【００２９】
次いで、基準方向に対する通信基地局方向の角度θｐｓと移動局の方位角度θｄとから、次式により基準アンテナに対する通信基地局方向の角度θｓを算出する。
θｄ＜θｐｓの場合にはθｓ＝θｐｓ−θｄ
θｄ＞θｐｓの場合にはθｓ＝３６０度−（θｄ−θｐｓ）
θｄ＝θｐの場合にはθｓ＝０
【００３０】
次いで、基準アンテナに対する通信基地局方向の角度θｓから重み係数を算出する。以下に重み係数Ｗ１１，Ｗ１２の計算例を示す。この例の条件は、アレーアンテナのアンテナ素子数Ｎは２、アンテナ素子の間隔はλ／２、所望波の電力は１、干渉波はなしである。
Ｗ１１＝１
Ｗ１２＝ｅｘｐ（−ｊπｓｉｎθｓ）
なお、上記算出方法は一例であり、素子数、素子間隔、配置などの条件により計算式は異なる。
【００３１】
次に、通信基地局方向へのビームパターンに、干渉波に対するヌルを加味する方法を説明する。
初めに、周辺基地局の位置情報によりヌルを形成する場合を説明する。
周辺基地局２００−２の位置情報と移動局（携帯端末１００）の位置情報に基づいて、干渉波の発信源となりうる周辺基地局の方向に対してヌルを形成し、通信基地局方向へのビームパターンと合成する。干渉波の発信源となりうる周辺基地局には、例えば移動局と周辺基地局との距離が通信基地局以外で最も近い順に周辺基地局を選択する。なお、この基地局の選択は、基地局方向適応処理部の数のＭ個まで対応可能である。
【００３２】
これにより、図３に示すように、通信基地局２００−１の方向にビームパターンが形成され、且つ干渉波の発信源となりうる周辺基地局２００−２（周辺ＢＳ１）の方向にヌルが形成される。また、基地局の位置情報に基づいてビームパターン及びヌルが形成されるので、それらパターンの形成は周辺環境に影響されることがない。したがって、図４に示すように、所望波や干渉波が周囲の建物などで遮られても、ビームパターン及びヌルは常に安定して形成される。
【００３３】
これにより、例えば干渉波が建物などに遮蔽されていた状態から、移動局が移動したことにより直接に干渉波が到来する状態に変化しても、予め干渉波の発信源の方向にヌルを形成しているので、干渉波の影響は少ない。この結果、通信していない無線基地局からの干渉波に対して安定的に対応することができるので、通信品質が安定する。
【００３４】
以下に、干渉波の発信源となりうる周辺基地局の方向にヌルを形成するための重み係数の計算方法の例を説明する。
先ず、上記した通信基地局方向のビームパターンを形成するための重み係数の算出方法と同様にして、周辺基地局と移動局（携帯端末１００）のそれぞれの位置情報（経度、緯度）に基づき、基準方向に対する周辺基地局の角度θｐｉを算出する。そして、この角度θｐｉと移動局の方位角度θｄから基準アンテナに対する周辺基地局の方向の角度θｉを算出する。この角度情報θｉと、基準アンテナに対する通信基地局の方向の角度θｓとから重み係数を算出する。以下に重み係数Ｗ１１，Ｗ１２の計算例を示す。この例の条件は、アレーアンテナのアンテナ素子数Ｎは２、アンテナ素子の間隔はλ／２、所望波の電力は１、干渉波の電力は１、内部雑音の電力は０．０１（２０ｄＢ）である。

なお、上記算出方法は一例であり、素子数、素子間隔、配置などの条件により計算式は異なる。
【００３５】
次に、受信波適応処理部２により形成される指向性パターンに基づきヌルを形成する場合を説明する。
受信波適応処理部２により形成される指向性パターンには、干渉波の到来方向の情報が含まれている。そこで、受信波適応処理部２により算出された重み係数Ｗ０１〜Ｗ０Ｎを基地局方位適応処理部１３−１〜Ｍに渡し、その重み係数Ｗ０１〜Ｗ０Ｎに基づいて干渉波の到来方向の角度を算出する。そして、その干渉波の到来方向の角度に基づいてヌルを形成し、通信基地局の方向へのビームパターンと合成する。
【００３６】
なお、重み係数Ｗ０１〜Ｗ０Ｎから干渉波の到来方向の角度を求める際には、例えば、重み係数Ｗ０１〜Ｗ０Ｎからある角度毎に０から３６０度の受信感度の電力を計算し、その受信感度の中で一番低い感度点の角度を求めればよい。
【００３７】
これにより、図５に示すように、通信基地局２００−１の方向にビームパターンが形成され、且つ干渉波の到来方向にヌルが形成される。また、通信基地局の位置情報に基づいてビームパターンが形成されるので、そのビームパターンの形成は周辺環境に影響されることがない。したがって、図６に示すように、所望波が周囲の建物なので遮られても、指向性パターンは常に安定して形成される。さらに、実際に受信された干渉波の到来方向にヌルが形成されるので、干渉波の影響を精度よく取り除くことができる。
なお、重み係数の計算方法は上記した干渉波の発信源となりうる周辺基地局の方向にヌルを形成するための重み係数の計算方法と同様である。
なお、通信基地局（２００−１）の方向へのビームパターンと干渉波の到来方向へのヌルの方向がある範囲内で同じである場合は、どちらか一方を選択する。
【００３８】
なお、上記した通信基地局方向へのビームパターンに干渉波に対するヌルを加味する方法については、周辺基地局の位置情報によりヌルを形成し行う第１の方法または受信波適応処理部２により形成される指向性パターンに基づきヌルを形成し行う第２の方法のいずれかを実装してもよく、あるいは双方を実装するようにしてもよい。また、それら第１及び第２の方法の双方を実装する場合には、いずれかの方法を適宜選択するようにしてもよく、あるいは並列処理し、レイク受信部４により受信波を合成するようにしてもよい。
【００３９】
なお、上述した実施形態では、受信処理を例に挙げて説明したが、送信処理にも同様に適用可能である。送信時には、受信時に得られたそれぞれの指向性パターンの重み係数を元に送信周波数に対応する補正などを行う。そして、その補正された重み係数により、位相と振幅を制御して送信用の指向性パターンを形成する。
【００４０】
なお、上述した図１の実施形態においては、基地局方向適応処理部１３−１〜Ｍと受信重み付け部３−１〜Ｍが基地局方向ビームパターン形成手段及び基地局方向ヌル形成手段に対応する。また、受信波適応処理部２と受信重み付け部３−０が受信波指向性パターン（受信波ビームパターン及び受信波ヌル）形成手段に対応する。また、レイク受信部４が受信処理手段に対応する。また、ベースバンド処理部５が基地局位置情報取得手段に対応する。
【００４１】
なお、本発明の移動局としては、例えば携帯電話機やＰＤＡ（Ｐｅｒｓｏｎａｌ Ｄｉｇｉｔａｌ Ａｓｓｉｓｔａｎｔｓ：個人用情報機器）と称される携帯型の端末も含むものとする。ここで、ＰＤＡの場合、無線通信手段を内蔵しているものとする。また、ＧＰＳ機能及び電子コンパス機能などの位置や方位情報取得手段を有するカーナビゲーションシステムを備えた自動車電話機又は移動物体に搭載された様々な無線装置も同様に含まれる。
【００４２】
また、移動局の位置や方位情報については、移動局の近隣に在る外付け等で接続される外部の位置又は方位情報取得装置（例えばＧＰＳ）から取得するようにしてもよい。
【００４３】
以上、本発明の実施形態を図面を参照して詳述してきたが、具体的な構成はこの実施形態に限られるものではなく、本発明の要旨を逸脱しない範囲の設計変更等も含まれる。
【００４４】
【発明の効果】
以上説明したように、本発明によれば、通信基地局方向のビームパターン及び周辺基地局方向のヌルにより無線信号の受信が行われるので、周辺基地局からの干渉波に対応することができる。これにより、適応アレーアンテナシステムにより指向性パターンを形成し、安定して通信品質の向上を図ることができるという優れた効果が得られる。
【００４５】
また、本発明によれば、受信信号に基づき干渉波の到来方向にヌルを形成し、該ヌルと通信基地局方向のビームパターンにより無線信号の受信が行われるので、実際に受信された干渉波の到来方向にヌルが形成され、干渉波の影響を精度よく取り除くことができる。
【図面の簡単な説明】
【図１】本発明の一実施形態による携帯端末１００の構成を示すブロック図である。
【図２】本発明の一実施形態による通信制御方法を説明するための第１の図である。
【図３】本発明の一実施形態による通信制御方法を説明するための第２の図である。
【図４】本発明の一実施形態による通信制御方法を説明するための第３の図である。
【図５】本発明の一実施形態による通信制御方法を説明するための第４の図である。
【図６】本発明の一実施形態による通信制御方法を説明するための第５の図である。
【符号の説明】
１…無線送受信部、２−…受信波適応処理部、３−０〜Ｍ…受信重み付け部、４…レイク受信部、５…ベースバンド処理部、１１…位置情報処理部、１２…方位情報処理部、１３−１〜Ｍ…基地局方向適応処理部、１００…携帯端末（移動局）、２００−１…無線基地局（通信基地局）、２００−２…無線基地局（周辺基地局）、ＡＮＴ−１〜Ｎ…アンテナ素子、ＧＰＳＡＮＴ…ＧＰＳ用アンテナ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile station and a communication control method suitable for use in a code division multiple access (CDMA) wireless communication system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a mobile station (portable terminal) is provided with an adaptive array antenna system having a plurality of antenna elements, performs reception wave adaptation processing using MMSE (least square error method) or the like, and forms a directional pattern to form a radio base station. One that receives a radio signal from a station is known. The adaptive array antenna system forms a reception beam pattern in the arrival direction of a desired wave, and forms and suppresses a directional pattern null in the arrival direction of an interference wave such as a delayed wave, thereby improving communication quality. Is planned. In some mobile stations, a beam pattern is formed in the direction of the base station based on the position information of the wireless base station with which the mobile station is currently communicating (see, for example, Patent Documents 1 and 2).
[0003]
[Patent Document 1]
JP-A-8-139661 [Patent Document 2]
JP-A No. 14-26800
[Problems to be solved by the invention]
However, according to the above-described conventional technology, a beam pattern is formed in the direction of the currently communicating wireless base station, so that it is possible to cope with a desired wave from the communicating wireless base station, but the communication is not performed. There is a problem that it cannot cope with an interference wave from a wireless base station.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to improve the communication quality by forming a directional pattern using an adaptive array antenna system, and to improve the communication quality of peripheral wireless base stations that are not communicating. It is an object of the present invention to provide a mobile station and a communication control method capable of suppressing an interference wave from a mobile station.
[0006]
[Means for Solving the Problems]
In order to solve the above problem, the mobile station according to claim 1 is a mobile station that receives a radio signal with an array antenna having a plurality of antenna elements, a position measuring unit that measures the position of the mobile station, Azimuth measuring means for measuring the azimuth of the own mobile station, base station position information obtaining means for obtaining base station position information of a communication base station which is currently communicating and a peripheral base station which is not communicating, Pattern forming means for calculating a direction of the communication base station with respect to the own mobile station based on the position and orientation of the mobile station and the base station position information, and forming a beam pattern in the direction of the communication base station; Null forming means for calculating a direction of the peripheral base station with respect to the mobile station based on the position of the station, the azimuth, and the base station position information, and forming a null in the direction of the peripheral base station; Use down and the null is characterized by comprising a reception processing means for performing reception processing of the received signal.
[0007]
The mobile station according to claim 2 is a mobile station that receives a radio signal by an array antenna having a plurality of antenna elements. In the mobile station, a position measuring unit that measures a position of the own mobile station, and a direction in which the own mobile station is oriented. Azimuth measuring means for measuring, base station position information obtaining means for obtaining base station position information of the communication base station currently communicating, based on the position of the own mobile station, the direction and the base station position information Beam pattern forming means for calculating a direction of the communication base station with respect to the mobile station and forming a beam pattern in the direction of the communication base station; and null forming means for forming null in an arrival direction of an interference wave based on the received signal. And reception processing means for performing reception processing of the reception signal using the beam pattern and the null.
[0008]
According to a third aspect of the present invention, the mobile station includes transmission processing means for performing transmission processing of a transmission signal using the beam pattern.
[0009]
A communication control method according to claim 4 is a communication control method in a mobile station that receives a radio signal by an array antenna having a plurality of antenna elements, wherein a step of measuring a position of the own mobile station, Measuring the facing direction, obtaining the base station position information of the communication base station currently communicating and the peripheral base station not communicating, the position of the own mobile station, the direction, and the base station. Calculating the direction of the communication base station with respect to the own mobile station based on the position information, forming a beam pattern in the direction of the communication base station, the position of the own mobile station, the azimuth, the base station position information, Calculating the direction of the neighboring base station with respect to the own mobile station based on the above, forming a null in the direction of the neighboring base station, and performing the reception process of the received signal using the beam pattern and the null. It is characterized in that it comprises and.
[0010]
The communication control method according to claim 5 is a communication control method in a mobile station that receives a radio signal by an array antenna having a plurality of antenna elements, wherein a step of measuring a position of the own mobile station, Measuring the facing direction, acquiring base station position information of the communication base station currently communicating, and performing self-movement based on the position of the own mobile station, the azimuth, and the base station position information. Calculating the direction of the communication base station with respect to a station, forming a beam pattern in the direction of the communication base station, forming null in the direction of arrival of the interference wave based on the received signal, the beam pattern and the Performing a receiving process of the received signal using nulls.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of a mobile terminal 100 according to an embodiment of the present invention. The mobile terminal 100 is used as a mobile station (MS) in a code division multiple access (CDMA) wireless communication system.
In FIG. 1, the mobile terminal 100 includes an array antenna including a plurality of antenna elements ANT-1 to ANT-N, a radio transmission / reception unit 1, a reception wave adaptation processing unit 2, a plurality of reception weighting units 3-0 to M, Rake receiving unit 4, baseband processing unit 5, GPS (Global Positioning System) antenna GPSANT, position information processing unit 11, azimuth information processing unit 12, and multiple base station direction adaptation processing units 13-1 To M.
[0012]
The wireless transmission / reception unit 1 performs transmission and reception using the antenna elements ANT-1 to ANT-N. In FIG. 1, other blocks relating to the transmission function are omitted. After the signals A1 to AN of the antenna elements ANT-1 to ANT-N are received by the radio transmission / reception unit 1, they are output to the reception wave adaptation processing unit 2 and the reception weighting units 3-0 to M as reception signals B1 to BN.
[0013]
The received wave adaptation processing unit 2 performs adaptive signal processing on the input received signals B1 to BN using, for example, MMSE. By this adaptive signal processing, weight coefficients W01 to W0N for each antenna element corresponding to the received wave are calculated and output to reception weighting section 3-0. Since the directivity pattern corresponding to the received wave changes as needed due to a reflected wave or the like, the received wave adaptation processing unit 2 obtains a weight coefficient so as to follow the change.
[0014]
The reception weighting unit 3-0 multiplies the input reception signals B1 to BN by weighting factors W01 to W0N, adds the signals, and outputs the result to the rake reception unit 4. Thus, the phases and amplitudes of the received signals B1 to BN are controlled, and a directivity pattern of the received wave is formed.
[0015]
The rake receiving unit 4 performs rake reception using a plurality of received signals. By this rake reception, several desired waves having different propagation paths such as delayed waves are combined at the maximum ratio to improve the reception characteristics.
The baseband processing unit outputs a baseband signal for the received signal after rake reception. The base station position information (latitude, longitude) received from the wireless base station is output to the position information processing unit 11. The base station position information includes the position information of the wireless base station (communication base station) with which the mobile station is currently communicating and the position information of the wireless base station (peripheral base station) with which there is a possibility of communication by handoff. Including. The base station position information may be stored in advance as data.
[0016]
The position information processing unit 11 has a position measurement function such as GPS, and measures position information (latitude, longitude) of the mobile terminal 100 based on a signal received from the antenna GPSANT. Then, based on the position information of the own mobile terminal (MS) 100 and the base station position information, the positional relationship with the radio base station (BS) is grasped, and the angle information (θp) with respect to a reference direction (for example, true north) is obtained. Is calculated. In FIG. 2, the mobile terminal 100 is communicating with a communication base station (communication BS) 200-1 and calculates angle information (θps) of the communication base station 200-1 with respect to a reference direction. In addition, angle information (θpi) with respect to the reference direction for the peripheral base station (peripheral BS) 200-2 is calculated. In the example of FIG. 2, the mobile terminal 100 includes four antenna elements ANT-1 to ANT-4, and uses the antenna element ANT-1 as a reference antenna.
[0017]
The azimuth information processing unit 12 has an azimuth measuring function such as an electronic compass, measures the azimuth of the mobile terminal 100, and calculates angle information (θd) with respect to the reference direction (see FIG. 2). This angle information is obtained with reference to one predetermined reference antenna (antenna element ANT-1 in the example of FIG. 2) from among a plurality of antenna elements.
[0018]
The base station direction adaptation processing unit 13 calculates angle information of the base station direction with respect to the mobile terminal 100 based on the angle information (θp, θd) obtained by the position information processing unit 11 and the direction information processing unit 12. As shown in FIG. 2, the angle θs of the direction of the communication base station 200-1 with respect to the mobile terminal 100 is calculated from the angle θps of the communication base station 200-1 with respect to the reference direction and the angle θd. Further, the angle θi of the direction of the peripheral base station 200-2 with respect to the mobile terminal 100 is calculated from the angle θpi of the peripheral base station 200-2 with respect to the reference direction and the angle θd.
[0019]
The base station direction adaptation processing units 13-1 to 13-M form a beam pattern in the direction of the communication base station 200-1 from the angles θs and θi of the base station direction with respect to the mobile terminal 100, and generate the interference wave. .., WM1 to WMN are calculated for each antenna element for forming a null in the direction of the peripheral base station 200-2 that can be a transmission source. These weighting factors are output to the reception weighting units 3-1 to M, respectively.
[0020]
Further, the weighting factors W01 to W0N of the respective antenna elements corresponding to the received waves are input from the received wave adaptation processing unit 2 to the base station direction adaptation processing units 13-1 to 13-M. The base station direction adaptation processing units 13-1 to 13-M can calculate the direction of the interference wave based on the weighting factors W01 to W0N, and can form a null in the arrival direction of the interference wave.
[0021]
The reception weighting units 3-1 to M multiply the input reception signals B1 to BN by respective weighting coefficients and add the signals to the rake reception unit 4. As a result, the phases and amplitudes of the received signals B1 to BN are respectively controlled, a beam pattern is formed in the direction of arrival of the desired wave from the communication base station 200-1, and a null is formed in the direction of arrival of the interference wave.
[0022]
Next, the operation of the mobile terminal 100 (mobile station) shown in FIG. 1 will be described.
First, the basic operation will be described.
First, the position information processing unit 11 measures the position information (latitude, longitude) of the own mobile station, and further receives the base station position information (latitude, longitude) received from the radio base station from the baseband processing unit 5. The position information of each of the communication base station 200-1 and the peripheral base station 200-2 is obtained from the base station position information. Then, angle information (θps, θpi) in each base station direction with respect to the reference direction is calculated from the position information of the own mobile station and the position information.
[0023]
Further, the azimuth information processing unit 12 measures azimuth information indicating the azimuth (own azimuth) of the reference antenna element. Then, angle information (θd) of its own direction with respect to the reference direction is calculated.
[0024]
The base station direction adaptation processing unit 13 receives the angle information (θps, θpi, θd) from the position information processing unit 11 and the direction information processing unit 12, respectively, and calculates the angles θs, θi of each base station direction with respect to the reference antenna element. . Next, weighting factors W11 to W1N, W21 to W2N,..., WM1 to WMN are calculated based on these angles θs and θi, and output to the reception weighting units 3-1 to M, respectively. The phases and amplitudes of the received signals B1 to BN are controlled by the reception weighting units 3-1 to M based on these weighting factors, and the beam pattern toward the communication base station 200-1 and the direction toward the peripheral base station 200-2 are controlled. A null to is formed.
[0025]
The received wave adaptation processing unit 2 forms a beam pattern in the direction of arrival of the received wave based on the received reference signal of the desired wave, and forms a weighting coefficient so as to form null in the direction of arrival of the interference wave. W01 to W0N are calculated and output to reception weighting section 3-0. The phases and amplitudes of the reception signals B1 to BN are controlled by the reception weighting unit 3-0 based on the weighting coefficients, and a beam pattern in the arrival direction of the reception wave and a null in the arrival direction of the interference wave are formed. .
[0026]
The rake receiving unit 4 receives desired waves by combining the above-formed beam patterns and nulls, and performs rake reception.
[0027]
Next, an example of a method of calculating a weight coefficient for forming a beam pattern in the direction of the communication base station will be described.
First, an angle θps in the direction of the communication base station with respect to the reference direction with respect to the mobile station is calculated from the position information (longitude and latitude) of each of the communication base station and the mobile station (portable terminal 100). Here, the angle θa is defined by the following equation.

Here, Di is the distance per second of latitude at the position of the mobile station, and Dk is the distance per second of longitude. Note that these values Di and Dk may be the same values in a predetermined area range.
[0028]
Then, the angle θps with respect to the reference direction (in this example, based on true north and + on the eastward direction) is determined from the following conditions (a) to (h). Conditions (a) to (h) indicate the angle θps corresponding to the positional relationship between the mobile station and the communication base station.
(A) mobile station longitude <base station longitude, mobile station latitude <base station latitude; θps = θa
(B) mobile station longitude <base station longitude, mobile station latitude> base station latitude; θps = 180 degrees−θa
(C) mobile station longitude> base station longitude, mobile station latitude> base station latitude; θps = 180 degrees + θa
(D) mobile station longitude> base station longitude, mobile station latitude <base station latitude; θps = 360 degrees−θa
(E) mobile station longitude = base station longitude, mobile station latitude <base station latitude; θps = 0 degrees (f) mobile station longitude = base station longitude, mobile station latitude> base station latitude; θps = 180 degrees (g) Station longitude <base station longitude, mobile station latitude = base station latitude; θps = 90 degrees (h) mobile station longitude> base station longitude, mobile station latitude = base station latitude; θps = 270 degrees
Next, from the angle θps in the direction of the communication base station with respect to the reference direction and the azimuth angle θd of the mobile station, the angle θs in the direction of the communication base station with respect to the reference antenna is calculated by the following equation.
When θd <θps, θs = θps−θd
If θd> θps, θs = 360 degrees− (θd−θps)
θs = 0 when θd = θp
[0030]
Next, a weight coefficient is calculated from the angle θs in the direction of the communication base station with respect to the reference antenna. A calculation example of the weight coefficients W11 and W12 is shown below. The condition of this example is that the number N of antenna elements of the array antenna is 2, the interval between the antenna elements is λ / 2, the power of the desired wave is 1, and there is no interference wave.
W11 = 1
W12 = exp (-jπsinθs)
Note that the above calculation method is an example, and the calculation formula varies depending on conditions such as the number of elements, element spacing, and arrangement.
[0031]
Next, a method of adding null to an interference wave to a beam pattern toward a communication base station will be described.
First, a case where a null is formed based on the position information of the peripheral base station will be described.
Based on the position information of the peripheral base station 200-2 and the position information of the mobile station (portable terminal 100), a null is formed in the direction of the peripheral base station that can be a source of an interference wave, and Combine with beam pattern. As the peripheral base station that can be a source of the interference wave, for example, the peripheral base station is selected in the order of the shortest distance between the mobile station and the peripheral base station other than the communication base station. The selection of the base station can correspond to up to M base station direction adaptation processing units.
[0032]
Thereby, as shown in FIG. 3, a beam pattern is formed in the direction of communication base station 200-1, and a null is formed in the direction of peripheral base station 200-2 (peripheral BS1) which can be a source of an interference wave. You. Further, since the beam pattern and the null are formed based on the position information of the base station, the formation of these patterns is not affected by the surrounding environment. Therefore, as shown in FIG. 4, even if a desired wave or an interference wave is blocked by a surrounding building or the like, the beam pattern and the null are always formed stably.
[0033]
By this, for example, even if the interference wave changes from a state where the interference wave is blocked by a building or the like to a state where the interference wave directly arrives due to the movement of the mobile station, a null is formed in the direction of the source of the interference wave in advance. Therefore, the influence of the interference wave is small. As a result, it is possible to stably cope with an interference wave from a wireless base station that is not performing communication, so that communication quality is stabilized.
[0034]
Hereinafter, an example of a method of calculating a weight coefficient for forming a null in the direction of a peripheral base station that may be a source of an interference wave will be described.
First, based on the position information (longitude and latitude) of the peripheral base station and the mobile station (portable terminal 100), in the same manner as the above-described method of calculating the weighting coefficient for forming the beam pattern in the direction of the communication base station, The angle θpi of the peripheral base station with respect to the reference direction is calculated. Then, the angle θi in the direction of the peripheral base station with respect to the reference antenna is calculated from the angle θpi and the azimuth angle θd of the mobile station. A weight coefficient is calculated from the angle information θi and the angle θs of the direction of the communication base station with respect to the reference antenna. A calculation example of the weight coefficients W11 and W12 is shown below. The condition of this example is that the number N of antenna elements of the array antenna is 2, the interval between the antenna elements is λ / 2, the power of the desired wave is 1, the power of the interference wave is 1, and the power of the internal noise is 0.01 (20 dB). It is.

Note that the above calculation method is an example, and the calculation formula varies depending on conditions such as the number of elements, element spacing, and arrangement.
[0035]
Next, a case where a null is formed based on the directivity pattern formed by the received wave adaptation processing unit 2 will be described.
The directivity pattern formed by the reception wave adaptation processing unit 2 includes information on the arrival direction of the interference wave. Therefore, the weighting factors W01 to W0N calculated by the received wave adaptation processing unit 2 are passed to the base station direction adaptation processing units 13-1 to 13-M, and the angle of arrival of the interference wave is calculated based on the weighting factors W01 to W0N. I do. Then, a null is formed based on the angle of the direction of arrival of the interference wave, and is combined with a beam pattern toward the communication base station.
[0036]
When calculating the angle in the direction of arrival of the interference wave from the weight coefficients W01 to W0N, for example, the power of the reception sensitivity of 0 to 360 degrees is calculated for each angle from the weight coefficients W01 to W0N, and the power of the reception sensitivity is calculated. What is necessary is just to find the angle of the lowest sensitivity point among them.
[0037]
Thereby, as shown in FIG. 5, a beam pattern is formed in the direction of communication base station 200-1, and a null is formed in the direction of arrival of the interference wave. Further, since the beam pattern is formed based on the position information of the communication base station, the formation of the beam pattern is not affected by the surrounding environment. Therefore, as shown in FIG. 6, even if the desired wave is blocked because it is a surrounding building, the directivity pattern is always formed stably. Further, since a null is formed in the arrival direction of the actually received interference wave, the influence of the interference wave can be accurately removed.
The method of calculating the weight coefficient is the same as the method of calculating the weight coefficient for forming a null in the direction of the neighboring base station that can be a source of the interference wave.
If the beam pattern in the direction of the communication base station (200-1) and the null direction in the direction of arrival of the interference wave are the same within a certain range, either one is selected.
[0038]
In addition, regarding the method of adding null to the interference wave to the above-mentioned beam pattern toward the communication base station, the first method of forming null based on the position information of the peripheral base station or the reception wave adaptation processing unit 2 is used. Either of the second methods for forming a null based on a directivity pattern may be implemented, or both may be implemented. When both the first and second methods are implemented, either one of the methods may be appropriately selected, or the rake receiving unit 4 may combine the received waves by performing parallel processing. You may.
[0039]
Note that, in the above-described embodiment, the receiving process is described as an example, but the present invention can be similarly applied to the transmitting process. At the time of transmission, correction corresponding to the transmission frequency is performed based on the weight coefficient of each directivity pattern obtained at the time of reception. Then, the phase and the amplitude are controlled by the corrected weight coefficient to form a directivity pattern for transmission.
[0040]
In the above-described embodiment of FIG. 1, the base station direction adaptation processing units 13-1 to 13-M and the reception weighting units 3-1 to M correspond to a base station direction beam pattern forming unit and a base station direction null forming unit. . Further, the reception wave adaptation processing unit 2 and the reception weighting unit 3-0 correspond to a reception wave directivity pattern (reception wave beam pattern and reception wave null) forming unit. Further, the rake receiving unit 4 corresponds to a reception processing unit. Further, the baseband processing unit 5 corresponds to a base station position information acquisition unit.
[0041]
Note that the mobile station of the present invention includes, for example, a portable terminal called a mobile phone or a PDA (Personal Digital Assistants). Here, it is assumed that the PDA has a built-in wireless communication unit. In addition, various wireless devices mounted on a mobile phone or a moving object equipped with a car navigation system having position and direction information acquisition means such as a GPS function and an electronic compass function are also included.
[0042]
Further, the position and direction information of the mobile station may be acquired from an external position or direction information acquisition device (for example, GPS) connected by an external device near the mobile station.
[0043]
As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a design change or the like without departing from the gist of the present invention.
[0044]
【The invention's effect】
As described above, according to the present invention, since a radio signal is received based on the beam pattern toward the communication base station and the null toward the peripheral base station, it is possible to cope with the interference wave from the peripheral base station. As a result, an excellent effect that a directivity pattern is formed by the adaptive array antenna system and communication quality can be stably improved can be obtained.
[0045]
Further, according to the present invention, a null is formed in the arrival direction of the interference wave based on the received signal, and the radio signal is received based on the null and the beam pattern toward the communication base station. , A null is formed in the arrival direction, and the influence of the interference wave can be accurately removed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a mobile terminal 100 according to an embodiment of the present invention.
FIG. 2 is a first diagram illustrating a communication control method according to an embodiment of the present invention.
FIG. 3 is a second diagram illustrating a communication control method according to an embodiment of the present invention.
FIG. 4 is a third diagram illustrating a communication control method according to an embodiment of the present invention.
FIG. 5 is a fourth diagram illustrating a communication control method according to an embodiment of the present invention.
FIG. 6 is a fifth diagram illustrating the communication control method according to the embodiment of the present invention;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wireless transmission / reception part, 2 -... Reception wave adaptation processing part, 3-0-M ... Reception weighting part, 4 ... Rake receiving part, 5 ... Baseband processing part, 11 ... Position information processing part, 12 ... Direction information processing , 13-1 to M: base station direction adaptation processing unit, 100: portable terminal (mobile station), 200-1: radio base station (communication base station), 200-2: radio base station (peripheral base station), ANT-1 to ANT-N: Antenna element, GPSANT: GPS antenna

Claims (5)

In a mobile station receiving a radio signal by an array antenna having a plurality of antenna elements,
Position measuring means for measuring the position of the own mobile station,
Azimuth measuring means for measuring the azimuth of the mobile station,
Base station position information acquisition means for acquiring base station position information of a communication base station that is currently communicating and a peripheral base station that is not communicating,
Pattern forming means for calculating the direction of the communication base station with respect to the own mobile station based on the position and orientation of the own mobile station and the base station position information, and forming a beam pattern in the direction of the communication base station;
Null forming means for calculating the direction of the surrounding base station with respect to the own mobile station based on the position, direction and base station position information of the own mobile station, and forming a null in the surrounding base station direction,
Reception processing means for performing reception processing of the reception signal using the beam pattern and the null,
A mobile station comprising: In a mobile station receiving a radio signal by an array antenna having a plurality of antenna elements,
Position measuring means for measuring the position of the own mobile station,
Azimuth measuring means for measuring the azimuth of the mobile station,
Base station position information obtaining means for obtaining base station position information of a communication base station that is currently communicating,
A beam pattern forming unit that calculates a direction of the communication base station with respect to the own mobile station based on the position, the direction, and the base station position information of the own mobile station, and forms a beam pattern in the communication base station direction,
Null forming means for forming a null in the arrival direction of the interference wave based on the received signal,
Reception processing means for performing reception processing of the reception signal using the beam pattern and the null,
A mobile station comprising: The mobile station according to claim 1, further comprising a transmission processing unit that performs transmission processing of a transmission signal using the beam pattern. A communication control method in a mobile station that receives a radio signal by an array antenna having a plurality of antenna elements,
Measuring the position of the mobile station;
Measuring the heading of the mobile station;
A step of obtaining base station position information of a communication base station that is currently communicating and a peripheral base station that is not communicating,
Calculating the direction of the communication base station with respect to the own mobile station based on the position of the own mobile station, the azimuth, and the base station position information, forming a beam pattern in the direction of the communication base station;
Calculating the direction of the surrounding base station with respect to the own mobile station based on the position, direction, and base station position information of the own mobile station, and forming a null in the surrounding base station direction;
Performing a reception process of the reception signal using the beam pattern and the null,
A communication control method comprising: A communication control method in a mobile station that receives a radio signal by an array antenna having a plurality of antenna elements,
Measuring the position of the mobile station;
Measuring the heading of the mobile station;
A step of acquiring base station position information of a communication base station with which communication is currently being performed,
Calculating the direction of the communication base station with respect to the own mobile station based on the position of the own mobile station, the azimuth, and the base station position information, forming a beam pattern in the direction of the communication base station;
A step of forming a null in the arrival direction of the interference wave based on the received signal,
Performing a reception process of the reception signal using the beam pattern and the null,
A communication control method comprising:

Images