JP3958218B2 - CDMA adaptive antenna array base station design method and apparatus, CDMA adaptive antenna array base station design program, and recording medium recording the program - Google Patents

Description

により計算される。更にアレイ素子水平パタンGs(y)は例えば、パタン計算部2-2にθeとｍ'(有効角計算パラメータ）、ＦＧ、ＦＢが入力され、±θeの有効角範囲内の各方位角では
【数２】

が計算され、それ以外の方位角では
Gs(y)＝ＦＧ−ＦＢ [dB] for （−π≦ｙ≦−θe,θe≦ｙ≦π）
が計算される。このアレイ素子水平パタン計算結果Gs(y)は例えば図５(B)に示すようにＢＷをパラメータとし、横軸に方位角度180y/π（度）を縦軸にGs(y)をとって例えば表示画面に表示される。なおこのアレイ素子水平パタン計算式は、多数ある計算式の１つの例である。
【００１２】
図６はアレイ素子垂直パタン計算手段４の処理概念とアレイ素子垂直パタンの計算例を示す図である。
条件設定手段１から(d)素子垂直パラメータ（スタック数Ｂ、チルト角Ｔ）と(e)アレイ素子垂直パタン計算式Gvs(z)（補助式や場合分け条件も含む）が入力されて、アレイ素子垂直パタン計算結果Gvs(z)を出力する。アレイ素子垂直パタン計算式Gvs(z)は、俯角ｚの関数として与えられ、素子垂直パラメータを代入して俯角ｚごとに式計算を行うことで、アレイ素子垂直パタンが計算される。
図６(A)においてはまずスタック数Ｂを用いてGvs'(z)
【数３】

が計算される。更にアレイ素子垂直パタンGvs(z)は例えばチルト角Ｔを用いて
Gvs(z)＝max[−25,Gvs'(z−T)] [dB] for (−π/２≦ｚ≦π/２)
のように計算される。このアレイ素子垂直パタンは例えば図６(B)に示すように、横軸に俯角180y/π（度）を、縦軸にGvs(z)をとって例えば表示画面に表示される。この例はＢ＝８、Ｔ＝０である。なお、このアレイ素子垂直パタン計算式は、多数ある計算式の１つの例である。
【００１３】
図７は適応アンテナアレイアンテナパタン計算手段３の処理概念と計算結果を示す図である。
条件設定手段１から設定される(c)アレイパラメータ（アレイ素子数Ａ、波長λ、素子間隔Ｄ）とアレイ素子水平パタン計算手段２からのアレイ素子水平パタン計算結果Gs(y)が入力され、希望波方向ｘと方位角ｙを変数とする適応アンテナアレイアンテナパタン計算結果Ga(x,y)を出力する。
【００１４】
図８は適応アンテナアレイアンテナパタン計算手段３の機能を説明する図である。
(c)アレイパラメータ（アレイ素子数Ａ、使用波長λ、素子間隔Ｄ）と、アレイ素子水平パタンGs(y)を真値変換部3-1で真値表現に変換したものGsn(y)＝10^Gs(y)/10および計算精度を決定する内部条件Nuを用いて計算を行う。Nuは内部的に半固定的に設定される値で、通常10以上であり、一般的には100を設定し、この値が大きいほど高精度な適応アンテナアレイパタンを得ることができる。これらを用いて、干渉波アレイ入力計算部3-2で干渉波アレイ入力ベクトルが、希望波アレイ入力計算部3-3で希望波アレイ入力ベクトルがそれぞれ計算される。干渉波アレイ入力ベクトル[au_k1・・・au_ki・・・au_kA]^Tはｋ＝１,・・・,Nuについて次式より求める。（[]^Tは転置ベクトルを表す。）
【数４】

希望波アレイ入力ベクトル[ax1・・・axi・・・axA]^Tは 希望波方向ｘの関数であり、ｉ＝１,・・・,Aについて希望波アレイ入力計算部3-3で次式により計算する。
【数５】

全てのｋについて干渉アレイ入力ベクトルとある方向ｘにおける希望波アレイ入力ベクトルのベクトル和をベクトル生成部3-4でとってアレイ入力ベクトルX(x)を生成する。つまりアレイベクトルX(x)のｉ番目の要素Xi(x)は次式で表せる。
【数６】

【００１５】
相関計算部3-5でアレイ入力ベクトルとそのハミルトニアンの積X(x)・X(x)^Tをとって相関行列R_xxが計算される。ハミルトニアンとは行列の各要素を複素共役化した後、転置行列化することである。一方、相関ベクトル計算部3-6で希望波方向ｘの関数である相関ベクトルr_xr(x)を次式により、ｉ＝１,・・・,Ａについて計算して求める。
r_xr＝Gsn(x)・exp(−j(2π/λ)D(i−1)sin(x))
相関行列R_xxの逆行列と相関ベクトルr_xr(x)を用いて、重み決定部3-7で適応アンテナアレイアンテナパタンを決定する最適ウエイト（重み）
【数７】

を求める。最適ウエイトを計算する式中のεはゼロでない内部定数であり通常は１が設定される。
【００１６】
伝搬ベクトル計算部3-8でｉ＝１,・・・,Ａ（A：アレイ素子数）について
V(y)＝exp(−j(2π/λ)Ｄ(i−1)sin(y))
を計算してアレイ伝搬ベクトルV(y)を求める。
このアレイ伝搬ベクトルV(y)と最適ウエイトW_opt(x)のハミルトニアンを用いてパタン計算部3-9で適応アンテナアレイアンテナパタン（真値）
【数８】

を求め、これをデシベル変換部3-10でデシベル変換して適応アンテナアレイアンテナパタンGa(x,y)＝10 log₁₀(Gan(x,y))を得る。適応アンテナアレイアンテナパタンGa(x,y)を図７(B)に示す。適応アンテナアレイアンテナパタンの計算方法は他の手法に拠ってもよい。
【００１７】
図９は伝搬損失及びジオメトリ計算手段５の処理概念と、伝搬損失とジオメトリ計算例を示す図である。伝搬損失及びジオメトリ計算手段５は伝搬損失計算部5-1とジオメトリ計算部5-2から構成される。
条件設定手段１から設定される(g)伝搬損失パラメータ（周波数freq、基地局アンテナ高hb、移動局アンテナ高hm）、(h)伝搬損失計算式L(r)（補助式や場合分け条件を含む）、(i)セル配置パラメータ（セル半径Ｒ、周辺基地局数Nc、基地局位置Position）、伝搬損失計算式L(r)（補助式や場合分け条件を含む）とアレイ素子垂直パタン計算手段４の出力であるアレイ素子垂直パタン計算結果Gvs(z)が入力され、伝搬損失計算結果L(r)とジオメトリ計算結果g^-1(r)を出力する。パラメータを固定した場合には伝搬損失は基地局と移動局の距離ｒの関数となる。
伝搬損失補正項a(hm)
a(hm)＝(1.1 log(freq)−0.7)hm−(1.56 log(freq)−0.8)
の計算結果を用いると、伝搬損失L(r)は

で表される。
【００１８】
ジオメトリは各基地局がある送信電力で送信している場合に、注目移動局における接続基地局からの受信電力とその他すべての基地局Ncからの受信電力の総和の比を、注目移動局・接続基地局間の距離特性で定義したものである。基地局BSiから注目移動局への距離をr＿iとし接続基地局をBS0とすると、各基地局が同一の送信電力であるとしてジオメトリは
【数９】

で表すことができ、ジオメトリ計算結果としてはジオメトリの逆数ｇ^-1(r)を出力する。なお、基地局の配置（図中では「基地局位置 position＝正則セル配置」）や周辺基地局数（図中ではNc＝７）はセル配置パラメータで決定される。
【００１９】
図１０は通信品質・収容ユーザ数推定手段の処理概念と計算例を示す図である。
(f)システムパラメータ（セクタ分割数Ｓ、α（１−直交化率）、セグメント分割数Ｍ、半径分割数N'、処理利得pg、有音率VA、受信機熱雑音電力Ｎ、基地局総送信電力Pt_total、基地局共通制御チャンネル送信電力Pt_control）、(i)セル配置パラメータ（セル半径Ｒ）、アレイ素子水平パタン計算手段２からのアレイ素子水平パタン計算結果Gs(y)、適応アンテナアレイアンテナパタン計算手段３からの適応アンテナアレイアンテナパタン計算結果Ga(x,y)、伝搬損失及びジオメトリ計算手段５からの伝搬損失計算結果L(r)とジオメトリ計算結果g^-1(r)が入力され、通信品質・収容ユーザ数計算結果SIR・C又はＣ或いはSIRを求める。
【００２０】
図１１は通信品質・収容ユーザ数推定手段の機能を説明する図である。
(f)システムパラメータ、(i)セル配置パラメータ、ジオメトリ計算結果g^-1(r)、伝搬損失計算結果L(r)、アンテナ素子水平パターンGs(y)、適応アンテナアレイアンテナパタンGa(x,y)から、干渉低減率推定部6-1での積分計算を行うことにより、自セル内通信チャンネルに対する干渉低減率Aes(φ_m)、他セル内通信チャンネルに対する干渉低減率Aeo(φ_m)、自セル内共通制御チャンネルに対する干渉低減率Aes＿cont(φ_m)、他セル内共通制御チャンネルに対する干渉低減率Aeo＿cont(φ_m)を、それぞれ自セル内通信チャンネル推定部6-11、他セル内通信チャンネル推定部6-12、自セル内共通制御チャンネル推定部6-13、他セル内共通制御チャンネル推定部6-14で求める。求まった各干渉低減率を用いて、品質・ユーザ数決定部6-2で通信品質と収容ユーザ数SIR・Ｃを求める。これらの処理は図１２のような一般的な基地局を設計するためのシステムモデルを用いて以下のように説明される。
【００２１】
平面状に基地局(BS ＃p)とセクタ(SECT ＃q)、および移動局(MS ＃r)が一様に分布すると仮定する。すなわち基地局の相対位置関係は規定せず、注目する基地局(BS ＃i)から見て、他の基地局は全方位に均等に存在している。また、移動局はその属する基地局とのセル内での相対位置関係が全てのセルで共通的に繰り返すとしている。なお、セグメント(SEG m,n)はセル内の部分領域を表している。このような仮定は、最も一般的な基地局を設計するときの前提条件として妥当である。このとき、基地局(BS ＃i),セクタ(SECT ＃j)に所属する特定の注目移動局(MS ＃k：以下簡単にi,j,k)の下り回線における信号電力対干渉電力比SIR^i,j,kは（１）式で与えられる。
【数１０】

ただし、Pt^i,j,kを注目移動局への、Pt^i,j,rを自セクタに属する移動局(MS i,j,r)への基地局(BS ＃i)セクタ(SECT ＃j)からの通信チャンネルの送信電力とし、Pt^i,q,rを自セルの他セクタに属する移動局(MS i,q,r)への基地局(BS ＃i)セクタ(SECT ＃q)からの通信チャンネルの送信電力とし、Pt^p,q',r'を他セルに属する移動局(MS p,q',r')への基地局(BS ＃p)セクタ(SECT ＃q')からの通信チャンネルの送信電力とし、Pt_contol ^i,jを基地局(BS ＃i)セクタ(SECT ＃j)から送信される共通制御チャンネルの送信電力とし、Pt_contol ^i,qを基地局(BS ＃i)セクタ(SECT ＃q)から送信される共通制御チャンネルの送信電力とし、Pt_contol ^p,q'を基地局(BS ＃p)セクタ(SECT ＃q')から送信される共通制御チャンネルの送信電力とする。
また、（L_i,j,k ⁱ)^-1を注目移動局への基地局 (BS ＃i)からの、（L_i,j,k ^p)^-1を注目移動局への基地局(BS ＃p)からのアンテナパタンの垂直利得を含めた伝搬損失の逆数とする。
【００２２】
Ga_i,j,k ^i,j,kを基地局(BS ＃i)セクタ(SECT ＃j)において注目移動局(MS ＃k)に向けて形成した適応アンテナアレイアンテナパタンの注目移動局への水平パタン利得とし、Ga_i,j,k ^i,q,rを基地局(BS ＃i)セクタ(SECT ＃q)において自セル内他セクタ移動局(MS ＃r)に向けて形成した適応アンテナアレイパタンの注目移動局への水平パタン利得とし、Ga_i,j,k ^p,q',r'を基地局(BS ＃p)セクタ(SECT ＃q')において他セル内移動局(MS ＃r')に向けて形成した適応アンテナアレイパタンの注目移動局への水平パタン利得とする。
Gs_i,j,k ^i,j,kを基地局(BS ＃i)セクタ(SECT ＃j)においてセクタ化パタンの注目移動局への水平パタン利得とし、Gs_i,j,k ^i,q,rを基地局(BS ＃i)セクタ(SECT ＃q)においてセクタ化パタンの注目移動局への水平パタン利得とし、Gs_i,j,k ^p,q',r'を基地局(BS ＃p)セクタ(SECT ＃q')においてセクタ化パタンの注目移動局への水平パタン利得とする。
pgを拡散利得、αを（１−直交率）、ＶＡを有音率、Ｎを受信機における拡散帯域内の熱雑音電力（受信機の雑音指数によるレベル上昇分を含む）、Ｃをセル当たりの収容移動局数（以下セル容量）、Ｓをセル当たりのセクタ分割数、Ncを周辺基地局数としている。（１）式を注目移動局における受信電力Pt^i,j,k・（L_i,j,k ⁱ)^-1・Ga_i,j,k ^i,j,k・Gs_i,j,k ^i,j,kで約分し、なおかつ、移動局とその属する基地局とのセル内での相対位置関係が、全てのセルで共通的に繰り返すことから、基地局での受信電力の対称性を考慮しながら式展開を行うとSIR^i,j,kは（２）式で与えられる。ただし、共通制御チャンネルの送信電力は全セルで同一、すなわちPt_contol＝Pt_contol ^i,j＝Pt_contol ^i,q＝Pt_contol ^p',qとしている。
【数１１】

【００２３】
次に、図１２に示すように基地局を中心としたＭの扇状のセグメントにセクタを分割し、更に基地局からの距離方向にセグメントをN'分割する。セグメント(m,n)内でのSIRを一定値(SIR^i,j,k)^m,nであるとし、ＭとN'を十分に大きくすれば、同一セグメント内において、
Pt^i,q,r＝Pt^i,j,k （３）
Pt^i,j,r＝Pt^i,j,k （４）
が成り立つ。また、セグメント(m,n)で代表させた(SIR)^m,nを用いて、（２）式は
【数１２】

と変形できる。ただし、(Lⁱ _i,j,k)_n ^-1は基地局(BS ＃i)から距離方向にｎ番目のセグメントにおける基地局(BS ＃i)からのアンテナパタンの垂直利得を含めた伝搬損失の逆数であり、(L_i,j,k ^p)_n ^-1は基地局(BS ＃i)から距離方向にｎ番目のセグメントにおける基地局(BS ＃p)からのアンテナパタンの垂直利得を含めた伝搬損失の逆数である。また、Ｃ_m,nはセグメント(m,n)をセル内全体に拡張したときのセル容量である。
ところで、セグメント(m,n)毎のアンテナパタンによる自セル内通信チャネルに対する干渉低減率Array＿effect＿self_m,n ^i,j,kと他セル通信チャンネルに対する干渉低減率Array effect＿other_m,n ^i,j,k、および、自セル内共通制御チャンネルに対する干渉低減率Array＿effect＿self＿cont_m,n ^i,j,kと他セル共通制御チャンネルに対する干渉低減率Array＿effect＿other＿cont_m,n ^i,j,k、他セル基地局受信電力と自セル基地局受信電力の比（ジオメトリの逆数）相当g_n ^-1は以下のように定義できる。
【数１３】

【００２４】
移動局と基地局の配置が一様なとき、注目移動局の方向とその所属する基地局セクタの適応アンテナアレイ正面との相対角度により、所属基地局におけるセクタ化パタンと適応アンテナアレイパタンを合成したアンテナパタン、すなわち自セルからの被干渉電力が一意に決定される。同時に周辺基地局が一様なときのアンテナパタンに基づく被干渉電力低減効果も一意に決定される。また、注目移動局の基地局からの距離、周辺基地局との位置関係とあわせて考慮すれば、希望受信電力と総被干渉電力の比も一意に決定される。したがって、ｍ毎に各干渉低減率の平均値と、ｎ毎に他セル基地局受信電力と自セル基地局受信電力の比が定数として存在するという仮定に基づく上記の式展開は妥当である。
ところで、通信チャンネル当たりの送信電力と総送信電力の関係は（１１）式で定義できる。ただし、Pt_total ^i,jは基地局(BS ＃i)セクタ(SECT ＃j)の総送信電力であるが、全ての基地局セクタで同一とし、Pt_total ^i,j ＝Pt_totalが成り立つとする。
【数１４】

上記のことから、（６）式、（７）式、（８）式、（９）式、（１０）式、（１１）式を用いて、（５）式は（１２）式のように書き換えることができる。
【数１５】

【００２５】
ところで、セグメントｍをアンテナアレイ正面方向（セクタ化パタンの中心方向と一致）を基準とした方向φ_mで定義すると、Array＿effect＿self_m,n ^i,j,k、Array＿effect＿other_m,n ^i,j,k、Array＿effect＿self＿cont_m,n ^i,j,k、および、Array＿effect＿other＿cont_m,n ^i,j,kは以下で書き換えることができる。
【数１６】

ただし、Ga(x,y)は希望信号がアンテナアレイ正面方向を基準にｘ方向にあるときの適応アンテナアレイの、Gs(y)はアレイ素子の、セクタ化パタン中心方向を基準にｙ方向のアンテナ利得である。セクタの対称性を考え、φ_mの値域は−π／S≦φ_m≦π／Sとしている。
【００２６】
図１３は、自セル内の適応アンテナアレイアンテナパタンとアレイ素子によるセクタ化パタンを示している。
したがって、（１３）式、（１４）式、（１５）式（１６）式により（１２）式を（１７）式に書き換えられる。
【数１７】

更に、移動局の所要SIRをセグメント(m,n)に限らずセル全体で一定(SIR)^m,n＝(SIR)とおき、セル容量ＣはＣ_m,nの定義されるセグメント面積（Ac_m,n)の加重平均であるとすれば、（１８）式が成り立つ。
【数１８】

セル当たりの収容ユーザ数を与える（１８）式の両辺に(SIR)を乗ずれば以下のようになる。
【数１９】

よって、式（１９）によりユーザ品質・収容ユーザ数SIR・Ｃが求まることがわかる。このようにして求めたユーザ品質・収容ユーザ数SIR・Ｃをアレイ素子数Ａの変化に対し、β＝１−αをパラメータとして示すと例えば図１０(B)に示すようになる。
【００２７】
以上の処理手順を図１４に示す。
先ず(a)素子水平パラメータ、(b)アレイ素子水平パタン計算式、(c)アレイパラメータ、(d)素子垂直パラメータ、(e)アレイ素子垂直パタン計算式、(f)システムパラメータ、(g)伝搬損失パラメータ、(h)伝搬損失計算式、(i)セル配置パラメータなどの条件を設定し(S10,S11)、設定された素子水平パラメータ(BW、FG、FB)を用いて設定したアレイ素子水平パタン計算式によりアレイ素子水平パタンGs(y)を計算する(S12)。次にその計算したアレイ素子水平パタンとアレイパラメータ(Ａ、λ、Ｄ)を用いて適応アンテナアレイアンテナパタンGa(x,y)を計算する(S13)。更に設定された素子垂直パラメータＢ、Ｔを用いて設定したアレイ素子垂直パタン計算式によりアレイ素子垂直パタンGvs(y)を計算する。次にその計算したアレイ素子垂直パタンと伝搬損失パラメータ(freq、hb、hm)とセル配置パラメータ(Ｒ、Nc、Position)、伝搬損失計算式によりジオメトリｇ^-1(r)と伝搬損失L(r)を計算する(S15)。この適応アンテナアレイパタンGa(x,y)、アレイ素子水平パタンGvs(y)、ジオメトリｇ^-1(r)と伝搬損失L(r)とシステムパラメータ(S、α、Ｍ、N'、pg、VA、Ｎ、pt_total、pt_control)、セル配置パラメータＲを用いて式（１８）を計算して通信品質と収容ユーザ（移動局）数の積SIR・Ｃを推定（計算）する(S16)。
【００２８】
図１４中に波線で示すように、条件設定の直後に所要品質SIRreqを設定し、通信品質・収容ユーザ数推定を行ってから、式（１９）の計算結果をSIRreqで割り算して収容ユーザ数Ｃを推定するようにしても良い。また、条件設定の直後に収容ユーザ数Creqを設定し、式（１９）の計算結果をCreqで割り算して通信品質SIRを推定しても良い。
つまり設計装置としては、図３中に波線で示すように、所要品質SIRreqを条件設定手段に入力し、割り算手段７で通信品質・収容ユーザ数推定手段よりの推定結果SIR・ＣをSIRreqで割り算して、収容ユーザ数Ｃを求め、或いは通信品質・収容ユーザ数推定手段にSIRreqを入力して収容ユーザ数Ｃを求めても良い。
また、条件設定手段１により収容ユーザ数Creqを入力して、割り算手段７においてSIR・ＣをCreqで割り算して、通信品質SIRを求め、或いは、通信品質・収容ユーザ数推定手段にCreqを入力して通信品質SIRを求めても良い。
【００２９】
図３に示した基地局の設計装置をコンピュータにより機能させても良い。この場合は図３に示した装置として機能させるためのＣＤＭＡ適応アンテナアレイ基地局プログラムを、コンピュータに、CD-ROM、可撓性磁気ディスクなどの記録媒体からインストールし、又は通信回線を介してダウンロードさせて、コンピュータにそのプログラムを実行させれば良い。
【００３０】
【発明の効果】
以上のようにこの発明によれば、ＣＤＭＡ適応アンテナアレイ基地局の設計において通信品質・収容ユーザ数あるいは通信品質または収容ユーザ数の計算を簡単に行うことができ、繰り返し収束計算を行う必要がなく、したがって、処理時間が少なくて済む。
【図面の簡単な説明】
【図１】従来の通信品質と収容ユーザ数を推定するためのシミュレーションを説明する図。
【図２】従来の通信品質と収容ユーザ数を推定するための処理手順を示す流れ図、
【図３】本発明のCDMA適応アンテナアレイ基地局の設計装置の構成例を示す概要ブロック図。
【図４】条件設定手段の概念を示す図。
【図５】アレイ素子水平パタン計算手段の処理概念とアレイ素子水平パタンの計算例を示す図。
【図６】アレイ素子垂直パタン計算手段の処理概念とアレイ素子垂直パタンの計算例を示す図。
【図７】適応アンテナアレイアンテナパタン計算手段の処理概念と計算結果のパタン例を示す図。
【図８】適応アンテナアレイアンテナパタン計算手段を説明する図。
【図９】伝搬損失及びジオメトリ計算手段の処理概念と伝搬損失とジオメトリの計算例を示す図。
【図１０】通信品質・収容ユーザ数推定手段の処理概念とアレイ素子水平パタンの計算例を示す図。
【図１１】通信品質・収容ユーザ数推定手段を説明する図。
【図１２】一般的な基地局を設計するためのシステムモデルを示す図。
【図１３】適応アンテナアレイアンテナパタンとアレイ素子水平パタンの関係を示す図。
【図１４】通信品質と収容ユーザ数を推定するための従来の処理手順を示す流れ図。
【符号の説明】
１・・・条件設定手段
２・・・アレイ素子水平パタン計算手段
３・・・適応アンテナアレイアンテナパタン計算手段
４・・・アレイ素子垂直パタン計算手段
５・・・伝搬損失及びジオメトリ計算手段
６・・・通信品質・収容ユーザ数推定手段
７・・・割り算手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a base station design method and apparatus for designing a base station by estimating the downlink communication quality and the number of accommodated mobile stations (users) of a base station equipped with an adaptive antenna array in CDMA or W-CDMA. The present invention relates to a base station design program and a recording medium on which the program is recorded.
[0002]
[Prior art]
In the conventional W-CDMA adaptive antenna array base station design, in order to estimate the downlink communication quality and the number of accommodated users, that is, the number of accommodated mobile stations, a certain number in the virtual service area (region) on the computer. A simulation as shown in FIG. 1 (A) is performed in which communication users are simulated by randomly arranging users (mobile stations). That is, the service area of the system is divided so that regular hexagonal cells CE1, CE2,... Are spread, and base stations BS1, BS2,. Further, each base station divides the service area into, for example, three sectors (120 ° sectors) S1, S2, S3, and each mobile station (user) MS1, MS2, each sector S1, S2, S3. When the MS3 is appropriately arranged, the communication base station so that the communication quality is the best for each of the arranged mobile stations MS1, MS2, and MS3. In the example shown in FIG. The antenna pattern AP4 of the adaptive antenna array is formed, and it is determined whether all mobile stations (users) MS1, MS2, and MS3 satisfy the required communication quality. ) Can be accommodated and the obtained quality is determined as communication quality, and if there is a mobile station (user) that does not satisfy it, the individual mobile station After the transmission power control to the user), in which repeatedly performs a series of trials of performing again adaptive antennas forming the antenna pattern AP4 of array communication quality determination. For example, as shown in FIG. 1 (C), the communication quality of mobile stations MS1, MS2, and MS3 that receive signals transmitted from the base station BS4 exceeds the required quality, and MS3 is just the required quality. If the mobile station MS2 is below the required quality, the base station BS4 controls the mobile station MS1 and MS2 to lower the transmission power and the latter to increase the transmission power. By controlling the antenna pattern AP4 of the array, as shown in FIG. 1 (D), each of the mobile stations MS1, MS2 and MS3 can perform transmission power control so that the signal quality from the base station BS4 becomes the required quality. The antenna pattern AP4 is repeatedly controlled (for example, Non-Patent Document 1 and Document 2).
[0003]
When transmission power control is performed on at least one of the mobile stations MS1, MS2, and MS3, the influence of interference on other mobile stations and mobile stations in other cells changes, so all mobile stations can be controlled with one transmission power control. It is rare for a station to meet the communication quality, and the antenna pattern of the adaptive antenna array and the transmission power control state at the base station for each mobile station (user) gradually become optimal values by repeating trials many times. It converges and all mobile stations (users) transition to a state that satisfies the required communication quality. However, if the required quality cannot be satisfied within the specified total transmission power (total transmission power to each mobile station) to which the base station is assigned, the set number of mobile stations (users) is determined to be unacceptable. The This operation is performed while gradually increasing the number of mobile stations (users) to be arranged, and the maximum number of users that can be accommodated is obtained as the number of accommodated users. However, even if the number of users is the same, if there is a bias in the mobile station arrangement, it may be accommodated or may not be accommodated. The possibility probability is calculated, and the number of users who can be accommodated with a certain probability or more is defined as the number of accommodated users.
[0004]
The flow of the simulation procedure is shown in FIG.
First, the number of users (mobile stations) set with specifications such as antenna and required quality is updated (initially, one mobile station is arranged in each sector) (S1, S2). Next, adaptive antenna array pattern control and base station transmission power control convergence calculation are performed (S3). As shown in FIG. 2B, this calculation places a predetermined number of users (mobile stations) at random positions (S3-1) and determines the communication partner base station of the mobile station ( In this state, the mobile station performs reception processing (S3-3), and based on the result, calculates the preferred adaptive antenna array pattern of the base station (S3-4). The communication quality of the signal from the opposite base station is calculated (S3-5), and it is determined whether the adaptive antenna array pattern has converged to the optimum value (S3-6). If not converged (S3-6: NO) Controls the transmission power to the base station (S3-7), determines whether the transmission power control result has converged to the optimum value (S3-8), and if not converged (S3-8: NO) Power control is repeated until convergence (S3-8: YES). When the transmission power control converges to the optimum value, the mobile station side reception process is performed (S3-3), and the same is repeated thereafter. When the adaptive antenna array convergence determination converges to the optimum value (S3-6): YES), this subroutine ends. In the main routine, check whether the above process has been tried N times (end determination) (S4). If not, repeat it (S4: NO). If it is N times (S4: YES), calculate the user accommodation probability. (S5), if the accommodable probability is equal to or higher than the predetermined value, that is, if the increase in the number of accommodable users can be expected (S6): NO) The number of users is updated (S2), If there is, the maximum number of users when the number is equal to or greater than the predetermined value is set as the number of accommodated users (S7).
[0005]
[Non-Patent Document 1]
ARIB, “Japan Proposal for Candidate Radio Transmission Technology on IMT-2000: W-CDMA”, September 1998
[Non-Patent Document 2]
Mori, Imai, Shingaku Sodai B-5-40, "A Study on Uplink Capacity for Adaptive Antenna Array Adaptation in W-CDMA System" March 2002
[0006]
[Problems to be solved by the invention]
However, this conventional method for designing a W-CDMA adaptive antenna array base station includes the following problems. The relationship between the antenna pattern of the adaptive antenna array formed for each user (mobile station) and the transmission power control is based on a delicate balance. Therefore, when there is a user who does not satisfy the required communication quality and an attempt is made to update the antenna pattern of the adaptive antenna array, the communication quality for the mobile station changes greatly, and therefore transmission that tries to maintain the communication quality is performed. Since power control becomes unstable, a long calculation time is required until both converge.
Also, as the number of users (mobile stations) increases, calculation processing increases, and it becomes stochastically difficult for all mobile stations (users) to simultaneously satisfy the required communication quality. It has been found that the time required increases significantly. For this reason, in designing an adaptive antenna array base station that can accommodate a larger number of mobile stations (users) than in the past, it is difficult to estimate communication quality and accommodated users at high speed using existing simulation methods.
The present invention has been made in view of the above points, and its purpose is to estimate communication quality and the number of accommodated users (mobile stations) at high speed when designing a CDMA base station to which the adaptive antenna array technology is applied to the downlink. Another object of the present invention is to provide a base station design method and apparatus for designing a base station, a base station design program, and a recording medium on which the program is recorded.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the method of the present invention, the antenna pattern of the array element and the adaptive antenna array based on the setting conditions such as the characteristics and quantity of antennas to be installed, the arrangement of surrounding base stations and the state of radio wave propagation The communication quality and the number of accommodated users (mobile stations) in the base station are estimated by calculating the antenna pattern, propagation loss, and geometry (interference state of neighboring base stations).
With this configuration, a certain number of mobile stations (users) are randomly arranged in a virtual service area on the computer, or the antennas of the adaptive antenna array so that the communication quality is best for each arranged mobile station (user). There is no need to form a pattern, the base station performs transmission power control for individual mobile stations (users), or repetitive calculations while updating the number of users to be placed. The number of users can be determined.
[0008]
According to the apparatus of the present invention, an array element horizontal pattern calculating means for calculating an array element horizontal pattern, an adaptive antenna array antenna pattern calculating means for calculating an adaptive antenna array antenna pattern based on the array element horizontal pattern calculation result, and an array Array element vertical pattern calculation means for calculating element vertical pattern, propagation loss and geometry calculation means for calculating propagation loss and geometry based on array element vertical pattern calculation result, array element horizontal pattern calculation result and adaptive antenna array antenna pattern Communication quality / accommodated user number estimation means for estimating the communication quality and the accommodated users based on the calculation result, the propagation loss, and the geometry is provided.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is a schematic block diagram of a CDMA adaptive antenna array base station design apparatus showing an embodiment of the present invention.
In the condition setting means 1, in order to estimate the communication quality and the number of accommodated users (mobile stations), the characteristics and quantity of antennas installed in the base station, the location of surrounding base stations, the state of radio wave propagation, system specifications, etc. are set can do. As shown in FIG. 4, the condition setting values input to the condition setting means 1 determine the characteristics of one antenna element (array element) constituting the adaptive antenna array. (A) Element horizontal parameter and (d) Element vertical parameter , (C) Array parameters for arraying antenna elements, (f) System parameters for determining system specifications, (i) Cell allocation parameters for determining surrounding base station location, (g) Propagation loss parameters for determining radio wave loss , Each calculation formula (b) Array element horizontal pattern calculation formula, (e) Array element vertical pattern calculation formula, (h) Propagation loss calculation formula) Is done.
The array element horizontal pattern calculation means 2 calculates the horizontal antenna pattern of the array element using the condition set value from the condition setting means 1.
The adaptive antenna array antenna pattern calculation unit 3 calculates the adaptive antenna array antenna pattern using the array element horizontal pattern calculation result and the condition setting value from the condition setting unit 1.
The array element vertical pattern calculation means 4 calculates the vertical antenna pattern of the array element using the condition set value from the condition setting means 1.
The propagation loss and geometry calculation means 5 calculates the propagation loss and geometry using the array element vertical pattern calculation result and the condition setting value from the condition setting means 1.
The communication quality / accommodated user number estimation means 6 uses the array element horizontal pattern calculation result, adaptive antenna array antenna pattern calculation result, propagation loss calculation result, geometry calculation result, and condition setting value from the condition setting means 1, Estimate the communication quality, the number of accommodated users (mobile stations), the number of accommodated users (mobile stations), or the communication quality.
[0010]
The condition setting means 1 includes: (a) element parameters such as a main beam half width BW of an array element horizontal pattern, a front gain (main beam gain) FG, a front bag gain ratio (ratio of main beam gain and rear gain) FB; (c) Array parameters such as the number of array elements A, operating wavelength λ, array element spacing D, etc. (d) Element vertical parameters such as the number of stacks (vertical stacking number of elements) B and tilt angle (vertical beam pointing direction) T (f) Sector division number S for dividing a cell into sectors, segment division number M for dividing sectors equally (calculation conditions), radius division number N ′ (calculation conditions) for dividing sectors at equal intervals in the radial direction, Processing gain (spreading gain) pg, sound rate (time rate during utterance in which radio waves are actually radiated) VA, receiver thermal noise power N in the spreading band, 1 to orthogonal rate (intra-cell by using orthogonal code) Interference reduction rate The value obtained by subtracting the alpha, base station common channel transmission power Pt_control, Base station total transmission power Pt_total(G) base station transmission frequency freq, base station antenna height hb, mobile station antenna height hm and other propagation loss parameters, (i) cell radius R, number of neighboring base stations Nc, base station position (Placement method) Cell placement parameters such as Position, (b) Array element horizontal pattern calculation formula, (e) Array element vertical pattern calculation formula, (h) Propagation loss calculation formula, etc. can be set and selected with a keyboard or mouse It has become. For each parameter, a fixed value may be substituted, or for a specific parameter, it is possible to specify a range and calculate the continuous relationship between parameter transition and communication quality / accommodating user (mobile station) number. is there. Each calculation formula set and selected by the condition setting means is composed of one or more mathematical formulas, and may include a case-specific condition and a calculation procedure.
[0011]
FIG. 5 is a diagram showing a processing concept of the array element horizontal pattern calculation means 2 and a calculation example of the array element horizontal pattern.
From the condition setting means 1 to (a) element horizontal parameters (half-value width BW, front gain FG, front bag gain ratio FB) and (b) array element horizontal pattern calculation formula Gs (y) (including auxiliary formula and case classification conditions) Is input and the array element horizontal pattern calculation result Gs (y) is output. The array element horizontal pattern calculation formula Gs (y) is given as a function of the azimuth angle y, and the array element horizontal pattern is calculated by calculating the formula for each azimuth y by substituting element parameters.
5A, first, the front bag gain ratio FB and the half-value width BW are input to the effective angle calculation unit 2-1, and the effective angle θe is, for example,
[Expression 1]

Is calculated by Further, the array element horizontal pattern Gs (y) is input, for example, by θe and m ′ (effective angle calculation parameters), FG and FB to the pattern calculation unit 2-2, and at each azimuth angle within the effective angle range of ± θe.
[Expression 2]

For all other azimuth angles
Gs (y) = FG−FB [dB] for (−π ≦ y ≦ −θe, θe ≦ y ≦ π)
Is calculated. The array element horizontal pattern calculation result Gs (y) is shown in FIG. 5B, for example, with BW as a parameter, azimuth angle 180y / π (degrees) on the horizontal axis and Gs (y) on the vertical axis. Displayed on the display screen. This array element horizontal pattern calculation formula is one example of many calculation formulas.
[0012]
FIG. 6 is a diagram showing a processing concept of the array element vertical pattern calculation means 4 and an example of calculating the array element vertical pattern.
The condition setting means 1 inputs (d) element vertical parameters (number of stacks B, tilt angle T) and (e) array element vertical pattern calculation formula Gvs (z) (including auxiliary formulas and classification conditions) The element vertical pattern calculation result Gvs (z) is output. The array element vertical pattern calculation formula Gvs (z) is given as a function of the depression angle z, and the array element vertical pattern is calculated by calculating the expression for each depression angle z by substituting the element vertical parameter.
In FIG. 6 (A), Gvs' (z)
[Equation 3]

Is calculated. Further, the array element vertical pattern Gvs (z) is obtained by using, for example, the tilt angle T.
Gvs (z) = max [−25, Gvs ′ (z−T)] [dB] for (−π / 2 ≦ z ≦ π / 2)
It is calculated as follows. For example, as shown in FIG. 6B, this array element vertical pattern is displayed on a display screen, for example, with the depression angle 180y / π (degrees) on the horizontal axis and Gvs (z) on the vertical axis. In this example, B = 8 and T = 0. This array element vertical pattern calculation formula is one example of many calculation formulas.
[0013]
FIG. 7 is a diagram showing a processing concept and calculation results of the adaptive antenna array antenna pattern calculation means 3.
(C) Array parameters (number of array elements A, wavelength λ, element spacing D) set from the condition setting means 1 and array element horizontal pattern calculation result Gs (y) from the array element horizontal pattern calculation means 2 are input, An adaptive antenna array antenna pattern calculation result Ga (x, y) with the desired wave direction x and the azimuth angle y as variables is output.
[0014]
FIG. 8 is a diagram for explaining the function of the adaptive antenna array antenna pattern calculation means 3.
(c) Array parameter (number of array elements A, wavelength used λ, element spacing D) and array element horizontal pattern Gs (y) converted to true value expression by true value conversion unit 3-1 Gsn (y) = Ten^{Gs (y) / 10}The calculation is performed using the internal condition Nu that determines the calculation accuracy. Nu is a value that is set semi-fixed internally, and is usually 10 or more. Generally, 100 is set, and the higher this value, the higher the adaptive antenna array pattern can be obtained. Using these, the interference wave array input calculation unit 3-2 calculates the interference wave array input vector, and the desired wave array input calculation unit 3-3 calculates the desired wave array input vector. Interference wave array input vector [au_k1 ... au_ki ... au_kA]^TIs obtained from the following equation for k = 1,..., Nu. ([]^TRepresents a transposed vector. )
[Expression 4]

Desired wave array input vector [ax1 ... axi ... axA]^TIs a function of the desired wave direction x, and i = 1,..., A is calculated by the desired wave array input calculation unit 3-3 according to the following equation.
[Equation 5]

The vector generation unit 3-4 generates the array input vector X (x) by taking the vector sum of the interference array input vector and the desired wave array input vector in a certain direction x for all k. That is, the i-th element Xi (x) of the array vector X (x) can be expressed by the following equation.
[Formula 6]

[0015]
Correlation calculator 3-5 calculates array input vector and its Hamiltonian product X (x) ・ X (x)^TTaking the correlation matrix R_xxIs calculated. Hamiltonian means that each element of a matrix is complex-conjugated and then transposed. On the other hand, correlation vector r which is a function of desired wave direction x in correlation vector calculation unit 3-6_xr(x) is calculated for i = 1,..., A by the following equation.
r_xr= Gsn (x) · exp (−j (2π / λ) D (i−1) sin (x))
Correlation matrix R_xxInverse matrix and correlation vector r_xrThe optimal weight (weight) for determining the adaptive antenna array antenna pattern by the weight determination unit 3-7 using (x)
[Expression 7]

Ask for. In the formula for calculating the optimum weight, ε is an internal constant that is not zero, and is normally set to 1.
[0016]
Propagation vector calculator 3-8 for i = 1, ..., A (A: number of array elements)
V (y) = exp (−j (2π / λ) D (i−1) sin (y))
To obtain the array propagation vector V (y).
This array propagation vector V (y) and optimum weight W_optAdaptive antenna array antenna pattern (true value) in pattern calculation unit 3-9 using Hamiltonian of (x)
[Equation 8]

, And the decibel transform unit 3-10 decibel transforms the adaptive antenna array antenna pattern Ga (x, y) = 10 log_TenGet (Gan (x, y)). The adaptive antenna array antenna pattern Ga (x, y) is shown in FIG. The calculation method of the adaptive antenna array antenna pattern may be based on other methods.
[0017]
FIG. 9 is a diagram showing a processing concept of the propagation loss and geometry calculation means 5, and an example of propagation loss and geometry calculation. The propagation loss and geometry calculation means 5 includes a propagation loss calculation unit 5-1 and a geometry calculation unit 5-2.
(G) Propagation loss parameter (frequency freq, base station antenna height hb, mobile station antenna height hm) set from condition setting means 1, (h) propagation loss calculation formula L (r) (I) Cell placement parameters (cell radius R, number of neighboring base stations Nc, base station position Position), propagation loss calculation formula L (r) (including auxiliary formulas and case classification conditions) and array element vertical pattern calculation The array element vertical pattern calculation result Gvs (z), which is the output of the means 4, is input, the propagation loss calculation result L (r) and the geometry calculation result g^-1(r) is output. When the parameter is fixed, the propagation loss is a function of the distance r between the base station and the mobile station.
Propagation loss correction term a (hm)
a (hm) = (1.1 log (freq) −0.7) hm− (1.56 log (freq) −0.8)
Using the calculation result, the propagation loss L (r) is

It is represented by
[0018]
The geometry indicates the ratio of the sum of the received power from the connected base station and the received power from all other base stations Nc in the mobile station of interest when each base station is transmitting at a certain transmission power. It is defined by the distance characteristics between base stations. If the distance from the base station BSi to the target mobile station is r_i and the connected base station is BS0, the geometry is assumed that each base station has the same transmission power.
[Equation 9]

The result of geometry calculation is the reciprocal of geometry g^-1(r) is output. Note that the arrangement of base stations (“base station position position = regular cell arrangement” in the figure) and the number of neighboring base stations (Nc = 7 in the figure) are determined by cell arrangement parameters.
[0019]
FIG. 10 is a diagram showing a processing concept and a calculation example of the communication quality / accommodated user number estimation means.
(f) System parameters (sector division number S, α (1-orthogonalization rate), segment division number M, radius division number N ′, processing gain pg, sound rate VA, receiver thermal noise power N, base station total Transmission power Pt_total, Base station common control channel transmission power Pt_control), (I) Cell arrangement parameter (cell radius R), array element horizontal pattern calculation result Gs (y) from array element horizontal pattern calculation means 2, adaptive antenna array antenna pattern calculation from adaptive antenna array antenna pattern calculation means 3 Result Ga (x, y), propagation loss and propagation loss calculation result L (r) from geometry calculation means 5, and geometry calculation result g^-1(r) is input, and the communication quality / accounted user count calculation result SIR · C or C or SIR is obtained.
[0020]
FIG. 11 is a diagram for explaining the function of the communication quality / accommodated user number estimation means.
(f) System parameter, (i) Cell placement parameter, Geometry calculation result g^-1(r), the propagation loss calculation result L (r), the antenna element horizontal pattern Gs (y), and the adaptive antenna array antenna pattern Ga (x, y) must be integrated in the interference reduction rate estimator 6-1. The interference reduction rate Aes (φ_m), Interference reduction rate for other intra-cell communication channels Aeo (φ_m), Interference reduction rate Aes_cont (φ for common control channel in own cell)_m), Interference reduction rate Aeo_cont (φ for the common control channel in other cells_m) In the own cell communication channel estimation unit 6-11, the other cell communication channel estimation unit 6-12, the own cell common control channel estimation unit 6-13, and the other cell common control channel estimation unit 6-14. Ask. Using the obtained interference reduction rates, the quality / user number determination unit 6-2 determines the communication quality and the number of accommodated users SIR · C. These processes are described as follows using a system model for designing a general base station as shown in FIG.
[0021]
Assume that base stations (BS #p), sectors (SECT #q), and mobile stations (MS #r) are uniformly distributed in a plane. In other words, the relative positional relationship between the base stations is not defined, and other base stations exist equally in all directions as viewed from the base station (BS #i) of interest. In addition, the mobile station assumes that the relative positional relationship in the cell with the base station to which the mobile station belongs is repeated in common in all cells. The segment (SEG m, n) represents a partial region in the cell. Such an assumption is reasonable as a precondition when designing the most common base station. At this time, the signal power-to-interference power ratio SIR in the downlink of the mobile station of interest (MS #k: hereinafter simply i, j, k) belonging to the base station (BS #i) and sector (SECT #j)^{i, j, k}Is given by equation (1).
[Expression 10]

However, Pt^{i, j, k}Pt to attention mobile station^{i, j, r}Is the transmission power of the communication channel from the base station (BS #i) sector (SECT #j) to the mobile station (MS i, j, r) belonging to its own sector, and Pt^{i, q, r}Is the transmission power of the communication channel from the base station (BS #i) sector (SECT #q) to the mobile station (MS i, q, r) belonging to another sector of the own cell, and Pt^{p, q ', r'}Is the transmission power of the communication channel from the base station (BS #p) sector (SECT #q ′) to the mobile station (MS p, q ′, r ′) belonging to another cell, and Pt_contol ^{i, j}Is the transmission power of the common control channel transmitted from the base station (BS #i) sector (SECT #j), and Pt_contol ^{i, q}Is the transmission power of the common control channel transmitted from the base station (BS #i) sector (SECT #q), and Pt_contol ^{p, q '}Is the transmission power of the common control channel transmitted from the base station (BS #p) sector (SECT #q ′).
Also, (L_{i, j, k} ⁱ)^-1From the base station (BS #i) to the mobile station of interest, (L_{i, j, k} ^p)^-1Is the reciprocal of the propagation loss including the vertical gain of the antenna pattern from the base station (BS #p) to the mobile station of interest.
[0022]
Ga_{i, j, k} ^{i, j, k}Is the horizontal pattern gain of the adaptive antenna array antenna pattern formed for the target mobile station (MS #k) in the base station (BS #i) sector (SECT #j) to the target mobile station, and Ga_{i, j, k} ^{i, q, r}Is the horizontal pattern gain of the adaptive antenna array pattern formed toward the other sector mobile station (MS #r) in its own cell in the base station (BS #i) sector (SECT #q)_{i, j, k} ^{p, q ', r'}Is the horizontal pattern gain of the adaptive antenna array pattern formed toward the mobile station (MS #r ′) in the other cell in the base station (BS #p) sector (SECT #q ′).
Gs_{i, j, k} ^{i, j, k}Is the horizontal pattern gain of the sectorized pattern to the mobile station of interest in the base station (BS #i) sector (SECT #j), and Gs_{i, j, k} ^{i, q, r}Is the horizontal pattern gain of the sectorized pattern to the mobile station of interest in the base station (BS #i) sector (SECT #q), and Gs_{i, j, k} ^{p, q ', r'}Is the horizontal pattern gain of the sectorized pattern to the target mobile station in the base station (BS #p) sector (SECT #q ′).
pg is spread gain, α is (1-orthogonal rate), VA is the sound rate, N is the thermal noise power in the spread band in the receiver (including the level rise due to the noise figure of the receiver), and C is per cell Where S is the number of sector divisions per cell, and Nc is the number of neighboring base stations. Equation (1) is the received power Pt at the target mobile station.^{i, j, k}・ (L_{i, j, k} ⁱ)^-1・ Ga_{i, j, k} ^{i, j, k}・ Gs_{i, j, k} ^{i, j, k}Since the relative positional relationship in the cell between the mobile station and the base station to which the mobile station belongs is repeated in common in all cells, the equation considering the symmetry of the received power at the base station is taken into account. SIR with deployment^{i, j, k}Is given by equation (2). However, the transmission power of the common control channel is the same in all cells, that is, Pt_contol= Pt_contol ^{i, j}= Pt_contol ^{i, q}= Pt_contol ^{p ', q}It is said.
## EQU11 ##

[0023]
Next, as shown in FIG. 12, the sector is divided into M fan-shaped segments with the base station as the center, and the segments are further divided into N ′ in the distance direction from the base station. SIR within segment (m, n) is constant (SIR^{i, j, k})^{m, n}If M and N ′ are sufficiently large, within the same segment,
Pt^{i, q, r}= Pt^{i, j, k}        (3)
Pt^{i, j, r}= Pt^{i, j, k}        (4)
Holds. Also represented by segment (m, n) (SIR)^{m, n}Using equation (2),
[Expression 12]

And can be transformed. However, (Lⁱ _{i, j, k})_n ^-1Is the reciprocal of the propagation loss including the vertical gain of the antenna pattern from the base station (BS #i) in the n-th segment in the distance direction from the base station (BS #i)._{i, j, k} ^p)_n ^-1Is the reciprocal of the propagation loss including the vertical gain of the antenna pattern from the base station (BS #p) in the n-th segment in the distance direction from the base station (BS #i). C_{m, n}Is the cell capacity when the segment (m, n) is extended to the entire cell.
By the way, the interference reduction rate for the intra-cell communication channel by the antenna pattern for each segment (m, n) Array_effect_self_{m, n} ^{i, j, k}And interference reduction rate array for other cell communication channels effect_other_{m, n} ^{i, j, k}, And interference reduction rate for common control channel in own cell Array_effect_self_cont_{m, n} ^{i, j, k}And interference reduction rate for other cell common control channel Array_effect_other_cont_{m, n} ^{i, j, k}, Equivalent to the ratio of the received power of other cell base stations to the received power of the own cell base station (reciprocal of geometry) g_n ^-1Can be defined as:
[Formula 13]

[0024]
When the arrangement of mobile stations and base stations is uniform, the sectorized pattern and adaptive antenna array pattern at the base station are combined based on the relative angle between the direction of the mobile station of interest and the adaptive antenna array front of the base station sector to which the mobile station belongs. The antenna pattern, that is, the interfered power from the own cell is uniquely determined. At the same time, the interference power reduction effect based on the antenna pattern when the surrounding base stations are uniform is also uniquely determined. Further, when considering the distance from the base station of the mobile station of interest and the positional relationship with the neighboring base stations, the ratio of the desired received power and the total interfered power is also uniquely determined. Therefore, the above equation development based on the assumption that the average value of each interference reduction rate for each m and the ratio of the received power of the other cell base station and the own cell base station for each n exists as a constant is reasonable.
By the way, the relationship between the transmission power per communication channel and the total transmission power can be defined by equation (11). However, Pt_total ^{i, j}Is the total transmission power of the base station (BS #i) sector (SECT #j), and is the same for all base station sectors, and Pt_total ^{i, j} = Pt_totalSuppose that
[Expression 14]

From the above, using Equation (6), Equation (7), Equation (8), Equation (9), Equation (10), and Equation (11), Equation (5) becomes Equation (12) Can be rewritten.
[Expression 15]

[0025]
By the way, the direction φ with the segment m as a reference from the front direction of the antenna array (coincident with the center direction of the sectorization pattern)_m, Array_effect_self_{m, n} ^{i, j, k}, Array_effect_other_{m, n} ^{i, j, k}, Array_effect_self_cont_{m, n} ^{i, j, k}, And Array_effect_other_cont_{m, n} ^{i, j, k}Can be rewritten as:
[Expression 16]

Where Ga (x, y) is the adaptive antenna array when the desired signal is in the x direction relative to the front direction of the antenna array, and Gs (y) is the y direction relative to the center direction of the sectorization pattern of the array element. Antenna gain. Considering the symmetry of the sector, φ_mThe range of is -π / S ≦ φ_m≦ π / S.
[0026]
FIG. 13 shows a sectorization pattern by an adaptive antenna array antenna pattern and an array element in the own cell.
Therefore, Expression (12) can be rewritten to Expression (17) by Expression (13), Expression (14), Expression (15), Expression (16).
[Expression 17]

Furthermore, the required SIR of the mobile station is not limited to the segment (m, n), but is constant throughout the cell (SIR)^{m, n}= (SIR) and cell capacity C is C_{m, n}Segment area defined by (Ac_{m, n}), The equation (18) is established.
[Expression 18]

Multiplying both sides of equation (18) giving the number of accommodated users per cell by (SIR) yields the following.
[Equation 19]

Therefore, it can be seen that the user quality and the number of accommodated users SIR · C are obtained from the equation (19). FIG. 10B shows the user quality and the number of accommodated users SIR · C obtained as described above, with β = 1−α as a parameter with respect to the change in the number A of array elements.
[0027]
The above processing procedure is shown in FIG.
First, (a) Element horizontal parameter, (b) Array element horizontal pattern calculation formula, (c) Array parameter, (d) Element vertical parameter, (e) Array element vertical pattern calculation formula, (f) System parameter, (g) Array elements set with conditions such as propagation loss parameters, (h) propagation loss calculation formula, (i) cell placement parameters (S10, S11) and set element horizontal parameters (BW, FG, FB) The array element horizontal pattern Gs (y) is calculated by the horizontal pattern calculation formula (S12). Next, an adaptive antenna array antenna pattern Ga (x, y) is calculated using the calculated array element horizontal pattern and array parameters (A, λ, D) (S13). Further, the array element vertical pattern Gvs (y) is calculated by the array element vertical pattern calculation formula set using the set element vertical parameters B and T. Next, the geometry g is calculated from the calculated array element vertical pattern, propagation loss parameters (freq, hb, hm), cell arrangement parameters (R, Nc, Position), and propagation loss calculation formula.^-1(r) and propagation loss L (r) are calculated (S15). This adaptive antenna array pattern Ga (x, y), array element horizontal pattern Gvs (y), geometry g^-1(r), propagation loss L (r) and system parameters (S, α, M, N ′, pg, VA, N, pt_total, Pt_control), Equation (18) is calculated using the cell allocation parameter R, and the product SIR · C of the communication quality and the number of accommodated users (mobile stations) is estimated (calculated) (S16).
[0028]
As indicated by the wavy line in FIG. 14, the required quality SIRreq is set immediately after setting the conditions, the communication quality and the number of accommodated users are estimated, and the calculation result of Expression (19) is divided by SIRreq to obtain the number of accommodated users. C may be estimated. Alternatively, the number of accommodated users Creq may be set immediately after setting the conditions, and the communication quality SIR may be estimated by dividing the calculation result of Expression (19) by Creq.
In other words, as shown by the wavy line in FIG. 3, the design device inputs the required quality SIRreq to the condition setting means, and the dividing means 7 divides the estimation result SIR · C from the communication quality / accommodated user number estimating means by SIRreq. Then, the number of accommodated users C may be obtained, or the number of accommodated users C may be obtained by inputting SIRreq to the communication quality / accommodated user number estimation means.
Further, the number of accommodated users Creq is input by the condition setting means 1, and the SIR / C is divided by Creq in the dividing means 7 to obtain the communication quality SIR, or the Creq is input to the communication quality / accepted user number estimating means. Then, the communication quality SIR may be obtained.
[0029]
The base station design apparatus shown in FIG. 3 may function by a computer. In this case, the CDMA adaptive antenna array base station program for functioning as the device shown in FIG. 3 is installed on a computer from a recording medium such as a CD-ROM or a flexible magnetic disk, or downloaded via a communication line. And let the computer execute the program.
[0030]
【The invention's effect】
As described above, according to the present invention, in the design of a CDMA adaptive antenna array base station, communication quality / number of accommodated users or communication quality or number of accommodated users can be easily calculated, and it is not necessary to perform repeated convergence calculations. Thus, less processing time is required.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a simulation for estimating conventional communication quality and the number of accommodated users.
FIG. 2 is a flowchart showing a processing procedure for estimating conventional communication quality and the number of accommodated users;
FIG. 3 is a schematic block diagram showing a configuration example of a design apparatus for a CDMA adaptive antenna array base station according to the present invention.
FIG. 4 is a diagram showing a concept of condition setting means.
FIG. 5 is a diagram showing a processing concept of an array element horizontal pattern calculation means and an example of calculating an array element horizontal pattern.
FIG. 6 is a diagram showing a processing concept of an array element vertical pattern calculation means and an example of calculating an array element vertical pattern.
FIG. 7 is a diagram showing a processing concept of an adaptive antenna array antenna pattern calculation unit and a pattern example of a calculation result.
FIG. 8 is a diagram for explaining adaptive antenna array antenna pattern calculation means.
FIG. 9 is a diagram showing a processing concept of propagation loss and geometry calculation means, and a calculation example of propagation loss and geometry.
FIG. 10 is a diagram showing a processing concept of communication quality / accommodated user number estimation means and an example of calculating an array element horizontal pattern.
FIG. 11 is a diagram for explaining communication quality / accommodated user number estimation means;
FIG. 12 is a diagram showing a system model for designing a general base station.
FIG. 13 is a diagram showing a relationship between an adaptive antenna array antenna pattern and an array element horizontal pattern.
FIG. 14 is a flowchart showing a conventional processing procedure for estimating communication quality and the number of accommodated users.
[Explanation of symbols]
1 ... Condition setting means
2 ... Array element horizontal pattern calculation means
3 ... Adaptive antenna array antenna pattern calculation means
4 ... Array element vertical pattern calculation means
5 ... Propagation loss and geometry calculation means
6: Communication quality / accommodated user number estimation means
7: Division means

Claims (10)

A design method of a CDMA base station in which an adaptive antenna array technology is applied to a downlink,
The array element horizontal pattern is calculated by the array element horizontal pattern calculation means based on the element horizontal parameter,
Based on the array element horizontal pattern and the array parameter, an adaptive antenna array antenna pattern is calculated by an adaptive antenna array antenna pattern calculation means,
The array element vertical pattern is calculated by the array element vertical pattern calculation means based on the element vertical parameter,
Based on the above array element vertical pattern, propagation loss parameter and cell placement parameter, propagation loss and geometry are calculated by propagation loss and geometry calculation means,
Based on the array element horizontal pattern, the antenna array antenna pattern, the propagation loss, the geometry, and the system parameter and cell arrangement parameter, the product of the number of mobile stations (users) and the communication quality of the mobile station A CDMA adaptive antenna array base station design method, characterized in that the calculation is performed by a number estimation means. The CDMA adaptive antenna array base station design method according to claim 1,
The product of the number of accommodated mobile stations (users) and the communication quality of the mobile station is set by the base station based on the array element horizontal pattern, the adaptive antenna array antenna pattern, and α which is a value obtained by subtracting the orthogonal rate from 1. Reduction rate Aes against interference caused by radio waves of the communication channel to the mobile station other than the target mobile station in the target cell (own cell), and in cells other than the above cell (other cells) ) Reduction rate Aeo against the interference of the communication channel to the mobile station in the target cell and the common control channel radio to all mobile stations in the cell The reduction rate Aes_cont for the interference given and the reduction rate Aeo_cont for the interference given to the target mobile station by the radio waves of the common control channel to the mobile stations in the other cells are calculated, and the interference reduction rates Aes, Aeo, Aes are calculated. _Cont, Aeo_cont and the propagation loss, the geometry, the system parameter, and the cell arrangement parameter are used to calculate the product of the number of mobile stations accommodated and the communication quality of the mobile station, CDMA adaptive antenna array base station Design method. In the CDMA adaptive antenna array base station design method according to claim 1 or 2,
The communication quality required for the mobile station is used to calculate the number of accommodated mobile stations (users) from the product of the communication quality and the number of accommodated users (mobile stations) by the communication quality / accommodated user number estimation means. CDMA adaptive antenna array base station design method. In the CDMA adaptive antenna array base station design method according to claim 1 or 2,
Using the number of mobile stations (users) accommodated in the cell of the base station, the communication quality of the mobile station is calculated by the communication quality / accommodated user number estimation means from the product of the communication quality and the number of accommodated users. A CDMA adaptive antenna array base station design method characterized. An array element horizontal pattern calculating means for inputting an element horizontal parameter and calculating a horizontal pattern of the array element;
An adaptive antenna array antenna pattern calculation means for receiving an array parameter and the array element horizontal pattern and calculating an antenna pattern of the adaptive antenna array;
An array element vertical calculation means for inputting an element vertical parameter and calculating a vertical pattern of the array element;
Propagation loss and geometry calculation means for inputting propagation loss parameter and cell arrangement parameter and the above array element vertical pattern and calculating propagation loss and geometry;
System parameters and cell arrangement parameters, the array element horizontal pattern, the adaptive antenna array antenna pattern, the propagation loss and the geometry are input, and the product of downlink communication quality and the number of accommodated mobile stations (mobile stations) is estimated. A CDMA adaptive antenna array base station designing apparatus, comprising: communication quality / accommodated user number estimating means. In the CDMA adaptive antenna array base station design apparatus according to claim 5,
The communication quality / accommodated user number estimation means receives the array element horizontal pattern, the adaptive antenna array antenna pattern, and α, which is a value obtained by subtracting the orthogonal rate from 1, and within the cell in which the base station is installed ( A communication channel estimator in the own cell that calculates a reduction rate Aes for interference caused by radio waves of the communication channel to the mobile station other than the target mobile station of the own cell),
The array element horizontal pattern and the adaptive antenna array antenna pattern are inputted, and the reduction rate Aeo given to the target mobile station by the radio wave of the communication channel to the mobile station in a cell other than the cell (other cell) is calculated. Another intra-cell communication channel estimation unit;
The array element horizontal pattern, the adaptive antenna array antenna pattern, and α which is a value obtained by subtracting the orthogonal rate from 1, are input, and the radio waves of the common control channel to all mobile stations in the own cell A common control channel estimator in its own cell for calculating a reduction rate Aes_cont for interference given to the station;
The array element horizontal pattern and the adaptive antenna array antenna pattern are input, and the reduction rate Aeo_cont for the interference given to the target mobile station by the radio waves of the common control channel to all the mobile stations in the other cells is calculated An intra-cell common channel estimator;
The interference reduction rate Aes, Aeo, Aes_cont, Aeo_cont and the propagation loss, the geometry, the system parameter, and the cell arrangement parameter are input, and the communication quality for calculating the product of the number of mobile stations (users) and the communication quality is calculated. An apparatus for designing a CDMA adaptive antenna array base station, comprising an accommodation user number determination unit. In the CDMA adaptive antenna array base station design apparatus according to claim 5 or 6,
The CDMA adaptive antenna array base station designing apparatus, wherein the communication quality / accommodated user number estimating means includes means for estimating the number of accommodated mobile stations (users) by inputting the communication quality required for the mobile station. In the CDMA adaptive antenna array base station design apparatus according to claim 5 or 6,
The CDMA adaptive antenna array base station characterized in that the communication quality / accommodated user number estimation means has means for estimating the communication quality of a mobile station, to which the number of mobile stations (users) accommodated in the base station is also inputted. Design equipment. A CDMA adaptive antenna array base station design program for causing a computer to execute the CDMA adaptive antenna array base station design method according to any one of claims 1 to 4. The recording medium which recorded the CDMA adaptive antenna array base station design program of Claim 9.

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