JP3421719B2 - Array antenna device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to directivity control and waveform equalization of an antenna for a wireless communication system.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional array antenna device. (Tanaka, Miura, Karasawa, "Interference Suppression Experiment of BSCMA Adaptive Array", IEICE Technical Report, February 26, 1996, Vol.95 No.53.
5 PP. 49-54)

A plurality of antenna elements 7011 to 701n,
A / D converter 7021 connected to each antenna element
˜702n, FFs that form a plurality of beams by FFT calculation from the outputs of the A / D converters 7021 to 702n
T multi-beam forming means 703, beam selecting means 70 for selecting a beam to be weighted among the formed beams
4. Adaptive beam control means 7 for controlling the selected beam
In the array antenna apparatus configured by 05, the beam selecting unit 704 selects a beam that exceeds the set threshold value, thereby simplifying the control.

[0004]

In the conventional configuration, since the element or beam for weighting is determined only from the reception level, if the control is simplified, the communication quality may be insufficient. was there.

An object of the present invention is to provide an array antenna device which is easy to control and has good communication quality.

[0006]

The features of the present invention for achieving the above-mentioned object are: a plurality of antenna elements, weighting means for imposing complex weights on the outputs of the antenna elements, and weight control for controlling the weights of the weighting means. From the device, the branching unit for inputting the output of the antenna element to the weighting unit and the weight control unit, the reference signal generator, and the combiner for combining the signals of the plurality of antenna elements with the complex weighted signals In the array antenna device configured, there is an array antenna device that controls the number of antenna element outputs determined from the delay time distribution of incoming waves.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION All delayed waves are represented by the sum of delayed waves S (t-jT _S ) in symbol length units. Where S
(T) is a transmission waveform, j is an integer, and T _S is a symbol length. Therefore, the reception waveform X _i (t) of each antenna element is also represented by the sum of delayed waves in symbol length units.

[Equation 5] Here, when the received waveform X _i (t) is sampled once per symbol, the coefficient A _ij is a constant.

Using the complex weight W _i , the output y (t) of the array antenna apparatus is

[Equation 6] Is expressed as In order to suppress the influence of the delayed wave, only the component with the delay time of 0 should be received. Therefore, the simultaneous equations to be solved are

[Equation 7] Is. In the above equation, the number of equations to be solved becomes infinite, but the minimum delay time of the delayed wave to be suppressed is τ _min , the maximum in order to obtain the communication quality such as the bit error rate required by the receiving system. When the delay time is τ _max , the number N of equations to be solved can be finite.

Therefore, if the number of antenna elements is N, simultaneous equations can be solved. Therefore, an array antenna device is used which is characterized in that the number N of weighting means to be controlled is determined from the delay time distribution of the delayed wave.

The number N of weighting means to be controlled is as follows.

Let τ _{min be} the minimum delay time of the delayed wave to be suppressed,
The maximum delay time is τ _max , the symbol length is T _S , [·] _int
Is a signal that means rounding down below the decimal point, and L _max and L _min obtained from this are

[Equation 8] And the number N of weighting means to be controlled is

[Equation 9] And

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment,
The minimum delay time τ of the delayed wave to be suppressed in order to obtain the communication quality such as the bit error rate required by the receiving system.
_This is a configuration that optimizes the number of weighting means to be controlled when _min and the maximum delay time τ _max are known. τ _min , τ _max
Is determined, for example, according to the transmission quality such as a predetermined error rate, from the size and material of the room in the indoor propagation environment, and from the arrangement of surrounding buildings in the outdoor communication. Also, τ _min ,
τ _max can also be determined using a delay profile measuring means.

In this figure, reference numerals 1011 to 101n
Is an antenna element, for example, a planar array antenna,
Alternatively, it is realized by a plurality of horn antennas or the like. Reference numerals 1021 to 102n denote antenna elements 1011 to 101
It is a weighting means for imposing a complex weight on the output of n, and is realized by, for example, a combination of an amplifier and a phase shifter, or A / D conversion of the reception waveform of each antenna element, and then calculation by digital signal processing. Reference numeral 103 is a weight control device that determines the number N of weights to be controlled and the weights of the weighting means 1021 to 102N, for example, LMS (Leas).
t MeanSquare) algorithm, RLS (R
Ecursive Least Squares algorithm, SMI (Sample Matrix In)
The value of each weight is calculated by a version algorithm, a direction constraint algorithm, or the like. Reference numeral 104 is a reference signal generator that generates a reference signal from a known training signal or a demodulated signal. Reference numeral 105 is a combiner that combines the outputs of the complex weighting means 1021 to 102N and is realized by analog or digital signal processing.

The weight control device 103 determines the number N of weighting means to be controlled based on the equation (2). The weighting means to be controlled is determined, for example, by selecting from the largest A _i0 value to the Nth, or from the highest reception level to the Nth.

By controlling the determined weighting means in this way, it is possible to reduce the number of controlled objects while ensuring a predetermined quality.

For example, τ _min = 0.2T _S , τ _max =
At 4.2T _S , L _min = 0 and L _max = 5, and the number N of control targets is N = L _max −L _min + 1 = 6.

In the figure, the antenna element 101n is not weighted.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a view showing the second embodiment,
Minimum delay time tau _{mi n} of delayed waves to be suppressed, the maximum delay time tau
Weighting means 1 for controlling even when _max is unknown
This is a configuration for optimizing the number N of 021 to 102N. The same components as those described in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 201 denotes a delay means having a variable delay time, which is realized by, for example, storing a signal obtained by sampling an input signal by an A / D converter in a memory and then reading it again after a predetermined delay time has elapsed. To be done. Reference numeral 202 indicates the output of the delay means 201 and each antenna element 10.
It is a correlator that obtains a correlation value with the outputs of 11 to 101n, and is realized by, for example, A / D converting two input signals, multiplying the complex conjugate of one input with the other input, and integrating. Reference numeral 203 is L for determining L _max and L _min
It is a means for determining _max and L _min , and is realized by using the output of the correlator as an input, and setting the minimum delay time when exceeding the threshold level as L _min and the maximum delay time as L _max . Reference numeral 204 is a control target determining means for determining the weight to be controlled, and the number N of weighting means to be controlled from the input values of L _max and L _min is

[Equation 10] Determined by

Reference numeral 205 is a weighting means 102 for controlling.
Is a weight calculation means for obtaining a weight value of 1 to 102N,
For example, LMS algorithm, RLS algorithm, SM
The value of each weight is calculated by the I algorithm or the like.

By using this control method, even when the minimum delay time τ _min and the maximum delay time τ _max are unknown, the number N of weighting means 1021 to 102N to be controlled is optimized.

Next, a third embodiment of the present invention will be described.

FIG. 3 is a view showing the third embodiment,
Weighting means 10 for controlling when the delay time distribution of the delayed wave to be suppressed is distributed more than a symbol apart
This is a configuration for optimizing the number N of 21 to 102N. In addition,
The same components as those described in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

The output of the correlator 202 is directly input to the controlled object determining means 204. The controlled object determining means determines the number M of the outputs of the correlator 202 that exceeds the threshold value, and sets the number of controlled objects as N = M + 1 (4). By using this method, when the delay time distribution of the delay wave is discretely distributed with the symbol length or more apart on the time axis, the weighting means 1021-1 for control targets
Optimize the number N of 02N.

Next, a fourth embodiment of the present invention will be described.

FIG. 4 is a diagram showing the fourth embodiment,
This is a configuration that simplifies the determination of the controlled object by using the selection means. The same components as those described in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted.

In this figure, reference numeral 401 is a selecting means. In the selection means 401, the output of the antenna element whose output exceeds the threshold value or the output of the antenna element having the maximum output is input to the correlator 202, so that L _max ,
Simplify the determination of L _min .

Next explained is the fifth embodiment of the invention.

FIG. 5 is a view showing the fifth embodiment,
This is a configuration that simplifies the determination of the control target using the multi-beam forming means. The same components as those described in FIGS. 1 to 4 are designated by the same reference numerals and the description thereof will be omitted.

In this figure, reference numeral 501 is a multi-beam forming means. The multi-beam forming means is, for example, F
It is realized by the FT algorithm or the Butler matrix. Inside the weight controller 103, the beam whose output exceeds the threshold value or the beam whose maximum output is maximum is output to the correlator 20.
The input of 2 simplifies the determination of L _max and L _min .

Next, a sixth embodiment of the present invention will be described.

FIG. 6 is a view showing the sixth embodiment,
The weight calculation is performed using the output of the correlator 202. The same components as those described with reference to FIGS. 1 to 5 are designated by the same reference numerals and the description thereof will be omitted.

The output of the i-th antenna element and the output A _ij when the reference signal delayed by j symbols is input to the correlator 202, and the weight calculation means 205 connects it to the i-th antenna element 101i. The weight value W _i of the weighting means is a simultaneous equation.

[Equation 11] Decide to meet. The equation solved here is L _max ,
When L _min is obtained, j = 0, L _min , ...
.., L _max , and weighting means 1021-1 for controlling
When the delay time (jT _S ) of the reference signal for inputting the number N of 02N to the correlator is changed in the unit of symbol length, if the output of the correlator is the number +1 which exceeds the threshold value, the output of the correlator is For all j and j = 0 above the threshold.

By using this method to determine the weight value, the weight calculation algorithm is simplified.

[0037]

In the array antenna apparatus of the present invention, the number of weighting means for obtaining the correlation value of the output of the antenna element and the reference signal delayed by the symbol length unit and controlling according to the number exceeding the predetermined threshold value. Can be optimized. Therefore, it is possible to reduce the number of antenna elements or beams for weighting while maintaining a predetermined communication quality.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a fifth embodiment of the present invention.

FIG. 6 is a diagram showing a sixth embodiment of the present invention.

FIG. 7 is a diagram showing an example of a conventional array antenna apparatus that reduces the number of controlled objects.

[Explanation of symbols]

1011~101n antenna element 1021~102n weighting means 103 weight control unit 104 reference signal generator 105 synthesizer 201 delay means 202 correlator 203 L _max, L _min determining unit 204 control target determination unit 205 weighting calculation means 401 selecting means 501 Multi Beam forming means 601 Weight calculating means 7011 to 701n Antenna elements 7021 to 702n A / D converter 703 FFT multi-beam forming means 704 Beam selecting means 705 Adaptive beam control means

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-116868 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 3/26

Claims (6)

(57) [Claims] 1. A plurality of antenna elements, a weighting means for imposing a complex weight on the output of the antenna element, a weight control device for controlling the weight of the weighting means, and an output of the antenna element to the weighting means and the weight control device. In the array antenna device including the branching means for causing the reference signal generator, and the combiner for combining the signals of the plurality of antenna elements with the complex weighted signals, it is determined from the delay time distribution of the incoming wave. An array antenna device characterized in that it controls the number of antenna element outputs. 2. The array antenna apparatus according to claim 1, wherein the minimum delay time of the delayed wave to be suppressed is τ _min , the maximum delay time is τ _max , the symbol length is T _S , and [.] _Int is rounded down after the decimal point. the signal, which means, from now obtained L _max, [number 1] the L _min Then, the number N of weighting means to be controlled is given by An array antenna device characterized by the following. 3. The array antenna device according to claim 1, wherein a delay means for delaying the reference signal in units of one symbol, and a correlator for correlating the output of the antenna element with the output of the delay means. A weight control device comprising: L _max and L _min determining means for determining L _max and L _min with the output of the correlator as input, control target determining means for determining weights to be controlled, and weight calculating means for determining weight values. And the number N of weighting means for controlling is An array antenna device characterized in that 4. The array antenna apparatus according to claim 3, wherein the output of the correlator is directly input to the control target determining means, and the number of weighting means to be controlled is N = M + 1 from the number M exceeding the threshold value. Array antenna device characterized by. 5. The array antenna apparatus according to claim 3, further comprising a selecting unit inside the weight controller for selecting one of the outputs of the antenna element that exceeds a threshold value, and the output of the selecting unit. Is an input to the correlator. 6. The array antenna apparatus according to any one of claims 2 to 4, further comprising weight calculation means for inputting an output of the correlator inside the weight controller, wherein the correlator outputs the output of the i-th antenna element. Using the output A _ij when the reference signal delayed by j symbols is input,
The weight value W _i of the weighting means connected to the i-th antenna element by the weight calculating means is expressed by the simultaneous equations An array antenna device, characterized in that it is determined so as to satisfy.