JP3570572B2 - 3D delay dispersion estimation method - Google Patents

Description

となる。ｚは観測面１３と垂直なｚ軸上の観測面１３からの距離、ξはｚ軸に対する方位角、ηはｚ軸に対する仰角である。
【０００７】
このＩ（ξ，η）は観測面１３から各方向を見た時の振幅と、位相とが求まり、電波源像が再生されたことになる。この再生波源像の一次波源である放射器１２の波動に対する各伝搬遅延時間をその波源の位相から求める。即ち一次波源である放射器１２の位置を（ξ_０ ，η_０ ）、放射器１２の観測面１３からの距離をγ_０ とし、電波の速度をｃ、ω_１ ＝２πｆ_１ 、ω_２ ＝２πｆ_２ とすると再生波源像、つまり観測面から見た二次波源および一次波源の伝搬遅延時間Ｄ（ξ，η）は次式より求まる。

更に上記再生波源像Ｉ（ξ，η）ｅｘｐ（ｊθ（ξ，η））と、伝搬遅延時間Ｄ（ξ，η）と、推定したい周波数２πｆ＝ωにより観測された波源の位相とを用いて各波源を３次元空間に再配置する。つまり各波源の絶対座標は次式で与えられる。
【０００８】
γ（ξ，η）＝Ｄ（ξ，η）・ｃとすると、
Ｘ（ξ，η）＝γ（ξ，η）・ξ・ｃｏｓ（ｓｉｎ^−１（η）） …（４） Ｙ（ξ，η）＝γ（ξ，η）・η・ｃｏｓ（ｓｉｎ^−１（ξ）） …（５） Ｚ（ξ，η）＝√（γ（ξ，η）^２ −Ｘ（ξ，η）^２ −Ｙ（ξ，η）^２ …（６） この時の各波源の放射強度と位相は次式となる。
【０００９】
Ｉ′（ξ，η，ω）＝γ（ξ，η）・Ｉ（ξ，η，ω） …（７）
θ′（ξ，η，ω）＝θ（ξ，η，ω）＋２πγ（ξ，η）ｆ …（８）
再生像の座標（ξ，η）で決る３次元空間の各位置つまり（４），（５），（６）式で与えられる座標Ｘ，Ｙ，Ｚ上に（７）式及び（８）式で与えられる波源が存在することになる。
【００１０】
ここで３次元空間の任意の位置（ｘ′，ｙ′，ｚ′）における遅延平均値τ_ｍ 、遅延の標準差τ_ｒｍｓ は、その位置（ｘ′，ｙ′，ｚ′）から各波源までの距離γ′（ξ，η）に応じた遅延時間γ′（ξ，η）／ｃと強度（Ｉ′（ξ，η，ω）／ｒ（ξ，η））^２とからそれぞれ次式により求まる。

【００１１】
【数１】

（９），（１０）式でΣΣはそれぞれξ，ηの各値についての加算であり、

このようにしてホログラム観測面１３から見える３次元空間の任意の位置（ｘ′，ｙ′，ｚ′）における遅延平均τ_ｍ 、遅延の標準偏差τ_ｒｍｓ をそれぞれ（９），（１０）式を演算することにより求めることができる。上述の処理手順を図２に示す。なお遅延波分散量は（９）式において開平演算を行うものであるが、（９）式を遅延分散と呼ぶこともある。
【００１２】
通常の電波による通信においては有限の周波数帯域で行われる。従って有限帯域ω±Δωの範囲では各波源の強度Ｉ′（ξ，η，ω）位相θ′（ξ，η，ω）は変化が小さいと考えられ、それぞれをＩ′（ξ，η）、θ′（ξ，η）とし、アンテナ指向特性をＡ（ξ，η）とすると、任意の位置（ｘ′，ｙ′，ｚ′）における伝搬路の周波数応答を次式で求めることができる。
【００１３】

更に周波数帯域制限関数をＢ（ω）とすると、伝搬路の時間応答関数ｇ（ｔ）は次式で表すことができる。
ｇ（ｔ）＝∫Ｇ（ω）・Ｂ（ω）・ｅｘｐ（ｊωｔ）ｄω
∫は制限されている周波数範囲の積分
この時間応答関数から、任意の位置（ｘ′，ｙ′，ｚ′）における遅延平均τ_ｍ 、遅延の標準偏差τ_ｒｍｓ はそれぞれ次式で求めることができる。
【００１４】
τ_ｍ ＝∫ｔ・｜ｇ（ｔ）｜^２ ｄｔ／∫｜ｇ（ｔ）｜^２ ｄｔ …（１２）
τ_ｒｍｓ ＝√｛∫（ｔ−τ_ｍ ）^２ ｜ｇ（ｔ）｜^２ ｄｔ／∫｜ｇ（ｔ）｜^２ ｄｔ｝…（１３）
電波ホログラム（干渉データ）Ｈ（ｘ，ｙ）を得るにはスペクトル領域ではなく、時間領域での積分により求めることもできる。その例を図３に、図１と対応する部分に同一符号を付けて示す。低域通過フィルタ２９、３１よりのベースバンド信号は乗算器６４，６５ヘ供給される。一方基準となる固定アンテナ１５側の帯域通過フィルタ２５の出力は、局部発振器２８の出力を移相器６６でπ／２ずらされたものと乗算器６７で乗算され、その乗算出力は低域通過フィルタ６８によりベースバンド信号が取出される。低域通過フィルタ３１，６８の各出力はそれぞれ乗算器６４，６５へ供給される。つまり帯域通過フィルタ２５の出力は直交検波されるその検波出力の同相成分と、直交成分とが走査アンテナ１４側のベースバンド信号と乗算器６４，６５で乗算される。乗算器６４，６５の各出力は積分器７１，７２で発振器３４からのクロックによりサンプリングされ、時系列デジタル信号にされた後、それぞれ時間領域で積分され、実部Ｒ_ｅ 、虚部Ｉ_ｍ として演算部７３へ供される。この例では図に示していない固定無線機よりの電波をアンテナ１４，１５で受信すると共に、前記固定無線機との通信用送受信機７４によリ得られている受信電界強度｜Ｓ_ｒ ｜が演算部７３へ供給される。演算部７３ではＲ_ｅ ＋ｊＩ_ｍ ＝Ｓ_ｍ ・Ｓ_ｒ ^＊ を演算し、これを｜Ｓ_ｒ ｜で割算して、電波ホログラムＨ（ｘ，ｙ）を得る。またこの例では送受信機７４が受信した特定のＩＤコードを検出した時に、乗算器６４，６５の各出力を積分器７１，７２へ供給するようにすることもできる。また送受信機７４での受信電波の選択と対応して、局部発振器２３の発振周波数を自動的に制御するようにされている。
【００１５】
このようにすると、運用中の通信システムの電波を利用して、その電波の伝搬路の３次元空間の各部の遅延平均τ_ｍ と遅延標準偏差τ_ｒｍｓ を求めることにより、ビルディングの設置、取壊しなどで電波環境が変化したことにもとずく通信品質の劣化などを評価することができる。
【００１６】
【発明の効果】
以上述べたようにこの発明によれば、干渉データを観測し、その波源像を再生し、これを３次元空間の再配置し、ホログラム観測面から見ることができる任意の位置の各波源との距離に対応した減衰と遅延とを求めて遅延平均τ_ｍ と遅延標準偏差τ_ｒｍｓ とを求めているため、各位置に受信機を移動させて測定する従来技術と比較して簡単かつ短時間に求めることができ、しかも特別な変調を必要とせず、狭帯域で測定して、短かい遅延も分離することができる。
【図面の簡単な説明】
【図１】干渉データを得るための構成例を示すブロック図。
【図２】この発明による方法の処理手順を示す図。
【図３】干渉データを得る他の構成例を示すブロック図。[0001]
[Industrial applications]
The present invention relates to a method for estimating the variance of a three-dimensional multipath delay wave generated by repeating reflection and diffraction of radio waves radiated from an antenna in wireless communication.
[0002]
[Prior art]
The delay dispersion is used for evaluating communication quality. For example, the maximum communicable bit rate is determined from the value of the delay dispersion. Conventionally, for example, in IEEE Transactions on Antenas and Propagation, Vol. 42, no. 10. Oct. , 1994, PP. 1369-1376, as shown in "A New Approach for Estimating Indoor Radio Propagation Characteristics", a radio wave obtained by modulating a PN code is transmitted, and a receiver provided at a position to be measured receives the transmission wave to measure. ing.
[0003]
[Problems to be solved by the invention]
Conventionally, a receiver is installed in each place to be evaluated and measurement is performed directly, so that the measurement operation is difficult and time-consuming. Since modulation is performed using the PN code, short delays cannot be separated unless the modulation frequency bandwidth is sufficiently widened, and measurement accuracy is poor.
[0004]
[Means for Solving the Problems]
According to the present invention, two-dimensional interference data of a wave is measured at at least two frequencies at a position where the primary wave source can be seen and the wave field space to be estimated can be seen, and a wave source image is formed using the measured two-dimensional interference data. Reconstructed, the propagation delay time of the reconstructed wave source image with respect to the primary wave source is obtained from the phase of the wave source, and each wave source is three-dimensionally determined using the reproduced wave source image, the propagation delay time, and the phase of the wave source observed at the frequency to be estimated. The delay time and the intensity attenuation corresponding to the distance from the reception point to be rearranged in the space to be evaluated to each of the rearranged wave sources are obtained, and a delay average value and a delay dispersion value are calculated.
[0005]
【Example】
Hereinafter, an embodiment in which the present invention is applied to estimation of three-dimensional delay dispersion of radio waves in a premises will be described. In this embodiment, two-dimensional interference data of an electromagnetic wave is measured at at least two frequencies at a position where the primary wave source can be seen and the electromagnetic field space to be estimated can be seen. For example radiator 12 for radiating the radio wave of the radio wave and the frequency f ₂ frequency f ₁ as the primary wave sources in the premises 11 are used as shown in FIG. 1, it can be seen the radiator 12, and want to estimate the electromagnetic field The observation surface 13 is arranged at a position overlooking the space, and the scanning antenna 14 is positioned at each point of the observation surface 13 for reception, and the signal is received by a fixed antenna 15 fixedly provided at a position relatively close to the scanning antenna 14. The respective reception outputs of the antennas 14 and 15 pass through preamplifiers 16 and 17, and after unnecessary waves are removed by filters 18 and 19, are frequency-mixed with local signals from a local oscillator 23 by frequency mixers 21 and 22. The respective difference frequency components (for example, 21.4 MHz) are taken out by band-pass filters 24 and 25, respectively, and these are further frequency-mixed by frequency mixers 26 and 27 with a local signal (for example, 22.4 MHz) of a local oscillator 28, The respective difference frequency components (for example, 1 MHz) are extracted by the low-pass filters 29 and 31, respectively. Outputs of the filters 29 and 31 are supplied to Fourier integrators 32 and 33, respectively, are sampled by a pulse (for example, 10.24 MHz) from an oscillator 34, each sample value is converted into a digital signal, and discrete Fourier integration is performed. You. These Fourier integration results S _m (x, y) and S _r are output from the hologram calculation unit 35 to the hologram calculation H (x, y) = (S _m (x, y)) based on the output S _r of the Fourier integrator 33. / S _r ) · | S _r | (1)
Is performed to obtain interference data. x and y indicate each point of the rectangular coordinates on the observation surface 13. The oscillators 23, 28 and 34 are synchronized by a stable reference signal (for example, 10 MHz) from the reference oscillator 36. By adjusting the frequency of the local oscillator 23, to measure the complex hologram when receiving a radio wave of frequency f ₁ (two-dimensional interference data), and a complex hologram at the time of receiving the radio waves of the frequency f _2. The size of the observation surface 13 is, for example, 28 × 28 cm ² , and the moving pitch of the scanning antenna 14 in each of the x and y directions is, for example, 0.45 cm.
[0006]
H (x, y) means that the amplitude and phase of the received signal with respect to the received wave of the fixed antenna 15 at each point on the observation surface 13 have been obtained. When H (x, y) is two-dimensionally Fourier-integrated,

It becomes. z is the distance from the observation plane 13 on the z axis perpendicular to the observation plane 13, ξ is the azimuth angle with respect to the z axis, and η is the elevation angle with respect to the z axis.
[0007]
The amplitude and phase of this I (ξ, η) when viewing each direction from the observation surface 13 are obtained, and the radio wave source image is reproduced. Each propagation delay time for the wave of the radiator 12, which is the primary wave source of the reproduced wave source image, is obtained from the phase of the wave source. That is, the position of the radiator 12 as the primary wave source is (ξ ₀ , η ₀ ), the distance of the radiator 12 from the observation surface 13 is γ ₀ , the speed of the radio wave is c, ω ₁ = 2πf ₁ , ω ₂ = 2πf. _Assuming that ₂ , the reproduced wave source image, that is, the propagation delay time D (ξ, η) of the secondary wave source and the primary wave source viewed from the observation surface is obtained by the following equation.

Further, using the reproduced wave source image I (ξ, η) exp (jθ (ξ, η)), the propagation delay time D (ξ, η), and the phase of the wave source observed at the frequency 2πf = ω to be estimated. Each wave source is rearranged in a three-dimensional space. That is, the absolute coordinates of each wave source are given by the following equations.
[0008]
If γ (ξ, η) = D (ξ, η) · c,
X (ξ, η) = γ (ξ, η) · ξ · cos (sin ⁻¹ (η)) (4) Y (ξ, η) = γ (ξ, η) · η · cos (sin ⁻¹⁾ (Ξ)) ... (5) Z (ξ, η) = √ (γ (ξ, η) ² -X (ξ, η) ² -Y (ξ, η) ² … (6) The radiation intensity and phase are as follows.
[0009]
I ′ (ξ, η, ω) = γ (ξ, η) · I (・, η, ω) (7)
θ ′ (ξ, η, ω) = θ (ξ, η, ω) + 2πγ (ξ, η) f (8)
Equations (7) and (8) on each position in the three-dimensional space determined by the coordinates (ξ, η) of the reproduced image, that is, coordinates X, Y, and Z given by equations (4), (5), and (6) There will be a wave source given by
[0010]
Here, the delay average value τ _m and the standard delay τ _{rms at} an arbitrary position (x ′, y ′, z ′) in the three-dimensional space are calculated from the position (x ′, y ′, z ′) to each wave source. From the delay time γ ′ (ξ, η) / c and the intensity (I ′ (ξ, η, ω) / r (ξ, η)) ² according to the distance γ ′ (ξ, η) of I get it.

[0011]
(Equation 1)

In equations (9) and (10), ΣΣ is an addition for each value of ξ and η, respectively.

In this way, the delay average τ _m and the standard deviation τ _rms of the delay at an arbitrary position (x ′, y ′, z ′) in the three-dimensional space viewed from the hologram observation surface 13 are expressed by the following equations (9) and (10). It can be obtained by calculation. The above processing procedure is shown in FIG. The amount of delay wave dispersion is obtained by performing square root calculation in equation (9), but equation (9) may be referred to as delay dispersion.
[0012]
Normal radio wave communication is performed in a finite frequency band. Therefore, in the range of the finite band ω ± Δω, the intensity I ′ (位相, η, ω) and the phase θ ′ (波, η, ω) of each wave source are considered to have a small change. Assuming that θ ′ (ξ, η) and the antenna directivity characteristic is A (ξ, η), the frequency response of the propagation path at an arbitrary position (x ′, y ′, z ′) can be obtained by the following equation.
[0013]

Further, assuming that the frequency band limiting function is B (ω), the time response function g (t) of the propagation path can be expressed by the following equation.
g (t) = ∫G (ω) · B (ω) · exp (jωt) dω
∫ is the integral of the limited frequency range From this time response function, the average delay τ _m and the standard deviation τ _rms of the delay at an arbitrary position (x ′, y ′, z ′) can be obtained by the following equations. .
[0014]
τ _m = ∫t · | g (t) | ² dt / ∫ | g (t) | ² dt (12)
τ _rms = {(t−τ _m ) ² | g (t) | ² dt / ∫ | g (t) | ² dt} (13)
In order to obtain the radio wave hologram (interference data) H (x, y), it is also possible to obtain the radio wave hologram (integration data) in the time domain instead of the spectral domain. An example is shown in FIG. 3 by attaching the same reference numerals to parts corresponding to FIG. The baseband signals from the low-pass filters 29 and 31 are supplied to multipliers 64 and 65. On the other hand, the output of the band-pass filter 25 on the fixed antenna 15 side serving as the reference is multiplied by the multiplier 67 with the output of the local oscillator 28 shifted by π / 2 by the phase shifter 66, and the multiplied output is low-passed. The baseband signal is extracted by the filter 68. Outputs of the low-pass filters 31 and 68 are supplied to multipliers 64 and 65, respectively. That is, the output of the band-pass filter 25 is subjected to quadrature detection. The in-phase component of the detection output and the quadrature component are multiplied by the baseband signal on the scanning antenna 14 side by the multipliers 64 and 65. Each output of the multiplier 64 and 65 is sampled by the clock from the oscillator 34 by the integrator 71 and 72, when after being series digital signals are integrated respectively in the time domain, the real part R _e, as an imaginary part I _m It is provided to the calculation unit 73. In this example, the radio waves from the fixed wireless device not shown are received by the antennas 14 and 15, and the received electric field strength | S _r | obtained by the transceiver 74 for communication with the fixed wireless device is obtained. The data is supplied to the calculation unit 73. The arithmetic unit 73 in _{R e + jI m = S m} · S r * is calculated, this | _{S r} | and divided by, obtaining radio wave hologram H (x, y). Further, in this example, when the transceiver 74 detects the specific ID code received, the outputs of the multipliers 64 and 65 can be supplied to the integrators 71 and 72. Further, the oscillation frequency of the local oscillator 23 is automatically controlled in response to the selection of the received radio wave in the transceiver 74.
[0015]
In this way, by using the radio wave of the operating communication system and obtaining the delay average τ _m and the delay standard deviation τ _rms of each part in the three-dimensional space of the propagation path of the radio wave, the building is installed, demolished, etc. Thus, it is possible to evaluate the deterioration of the communication quality based on the change in the radio wave environment.
[0016]
【The invention's effect】
As described above, according to the present invention, interference data is observed, its wave source image is reproduced, and this is rearranged in a three-dimensional space. Since the delay average τ _m and the delay standard deviation τ _rms are obtained by calculating the attenuation and the delay corresponding to the distance, it is easier and faster than the conventional technology in which the receiver is moved to each position and measured. It can be determined, and requires no special modulation, and can be measured in a narrow band to isolate short delays.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example for obtaining interference data.
FIG. 2 is a diagram showing a processing procedure of a method according to the present invention.
FIG. 3 is a block diagram showing another configuration example for obtaining interference data.

Claims (2)

Measuring the two-dimensional interference data of the wave at at least two frequencies at a position where the primary wave source can be seen and the wave field space to be estimated can be seen;
A wave source image is reproduced using the measured two-dimensional interference data,
The propagation delay time of the reproduced wave source image with respect to the primary wave source is obtained from the phase of the wave source,
Using the reproduced wave source image, the propagation delay time, and the phase of the wave source observed at the frequency to be estimated, rearrange each wave source in a three-dimensional space,
3D delay variance estimation, wherein a delay time and an intensity attenuation amount according to a distance from a reception point to be evaluated to each of the rearranged wave sources are obtained, and a delay average value and a standard deviation of delay are calculated. Method. The frequency band of the wave is limited, and the intensity and phase of the rearranged wave source are constant in the frequency band, and the frequency response of the propagation path is determined in consideration of the attenuation of the intensity according to the distance and the delay. 2. The method according to claim 1, wherein a time response function is obtained from the frequency response function, and the delay average and the standard deviation of the delay are calculated from the time response function.

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