JP3410177B2 - Antenna coupling device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna coupling device for removing an interference wave caused by multipath fading.

[0002]

2. Description of the Related Art In land mobile communication, multipath fading occurs particularly in urban areas and deteriorates communication quality. At the time of such multipath fading, CMA (Constant Modulus Alg
The antenna coupling device to which the (orithm) is applied is, for example, “Japanese Patent Laid-Open No. 3-70216”, “Fujimoto, Kikuma, Inagaki:“ Multiple wave suppression characteristics of CMA adaptive array using Marquardt method ”, IEICE Transactions B-2, Vol. 74, No. 11, pp. 559-607, 1991 "and the like.

The antenna coupling device to which the CMA described above is applied multiplies the signal received from each antenna by a coefficient, synthesizes the multiplication results and outputs the result as an antenna output, and each coefficient is the multiplication result. Adaptive control is performed so that the combined output becomes constant. In adaptive control, a value obtained by multiplying a signal based on an error from a constant output by a feedback coefficient μ is fed back to each coefficient.

[0004]

The above-mentioned conventional antenna coupling device has a poor convergence speed until it reaches a steady state.
Further, there is a problem that the degree of performance improvement is poor when there are multipaths of two or more waves.

It is an object of the present invention to provide an antenna coupling device having good convergence and improved performance.

[0006]

Means adopted by the present invention for solving the above-mentioned problems will be described. In an antenna combining device for combining and outputting signals received from M antennas, the received signals from the M antennas are separated into an in-phase component and a quadrature component, and each of the separated signals is multiplied by a coefficient, Beam forming means for forming N beams with different directing directions by adding multiplication results, and N signals output from the beam forming means are multiplied by a coefficient, and outputs obtained by adding the multiplication results are constant. And adaptive control means for adaptively controlling and generating each coefficient.

[0007]

The beam forming means separates the signals received from the M antennas into the in-phase component and the quadrature component.
The in-phase and quadrature component signals of the separated antennas are multiplied by a coefficient, and N beams with different directing directions are shaped and output.

The adaptive control means multiplies the N output signals output from the beam shaping means by a coefficient, adds the multiplication results and outputs the output as an antenna coupling device output, and each output becomes constant. The coefficient is adaptively controlled and generated. As described above, the signals received by the multiple antennas are separated into the in-phase component and the quadrature component, the separated signals are multiplied by the coefficient to form beams with different directing directions, and adaptive control is performed on the formed output signal. Since the output is obtained by multiplying the generated coefficient, it is possible to eliminate or reduce the simultaneous input of multiple waves as the adaptive control input by beam shaping, improving the convergence characteristics and improving the performance. Also gets better.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of the first embodiment of the present invention, FIG. 2 is a specific example of the beam shaping means of the same embodiment, and FIG. 3 is a specific example of the adaptive control means of the same embodiment.

In FIG. 1, 1 is an antenna, 2 is a frequency converter, 3 is a local oscillator, 4 is a 90-degree phase shifter, 5 is an analog-digital converter, 6 is beam shaping means, and 7 is adaptive control means. The embodiment shows the case where the antenna 1 is composed of four antennas, and is generally composed of M antennas.

The received signal from each antenna is split into two and input to the frequency converters 2A and 2B, respectively.
The frequency converter 2A receives the output from the local oscillator 3 and the frequency converter 2B receives the signal which is 90 degrees phased by the 90 degree phase shifter 4 to convert the frequency.

That is, the output signals from the frequency converters 2A and 2B are mutually orthogonal signals. The frequency-converted signals are converted into digital signals by analog-to-digital converters (A / D) 5A and 5B, respectively.

Hereinafter, in order to explain the signals converted by the A / Ds 5A and 5B as a pair, these will be represented by vectors. That is, S ₁ = s _1I + js _1Q (1) where S ₁ is the signal s _1I of the antenna # 1 system, the in-phase component s _1Q of the antenna # 1 system is the quadrature component of the antenna # 1 system.

As shown in FIG. 2, the beam shaping means 6 is composed of a multiplication section 61, a coefficient memory 62 and an addition section 63. That is, the output X at the beam shaping means 6
₁ outputs X ₁ by performing a calculation of X ₁ = D ₁₁ S ₁ + D ₁₂ S ₂ + D ₁₃ S ₃ + D ₁₄ S ₄ (2).

Similarly, the outputs X ₂ , X ₃ and X ₄ are multiplied by different coefficients. The value of the coefficient D is Dnξ = cos (nξ) −j sin (nξ) (3) where omnidirectional antennas are installed on a straight line at equal intervals, where ξ = Kπ / (2N + 1) By setting K = ± 1, ± 3, ..., ± 2N−1 or K = 0, ± 2, ..., ± 2N, beam forming is performed so that the pointing directions are at equal intervals.

FIG. 7 shows 5 inputs (S _{1 to} S ₅ ) and 5 outputs (X
The calculation result of the formula (3) in the case of _{1 to} X ₅ ) is shown. Next, adaptive control of CMA coefficients will be described with reference to FIG. In FIG. 3, reference numeral 70 denotes a coefficient generation unit, which includes a coefficient memory 71, a subtractor 72, and a multiplier 73. Further, 74 is a multiplication unit, and 75 is an addition unit.

There are four systems corresponding to the respective inputs X _{1 to} X ₄ , but since the operations are the same, only one system will be described.
The multiplier 74 multiplies the signal X ₁ (k) represented by the equation (2) by the coefficient H ₁ (k) recorded in the coefficient memory 71 and outputs the product to the adder 75. That is, X ₁ (k) H ₁ (k) = [Y ₁ (k)] (4) where X ₁ (k) is the kth sample value H ₁ (k) is the coefficient value for the kth Multiply and output [Y ₁ (k)].

The adder 75 combines the results of multiplication by the multiplier 74. That is, Y (k) = [Y ₁ (k)] + [Y ₂ (k)] + [Y ₃ (k)] + [Y ₄ (k)] (5) ) Is output.

Y (k) shown in the equation (5) is output as a reception signal of the antenna. The output Y (k) of the adder 75 expressed by the equation (5) is taken into the feedback signal generator 76. The feedback signal generator 76 first performs a square operation on each of the in-phase component y _I and the quadrature component y _Q of Y (k) to perform addition.

That is, | Y (k) | ² = (y _I (k)) ² + (y _Q (k)) ² (6) is performed and the amplitude of the signal Y (k) is squared. Value | Y
(K) | ² is calculated. Next, 1 is subtracted from the addition output to calculate an error e (k) from the constant value output. That is, e (k) = (y _I (k)) ² + (y _Q (k)) ² −1 = [| Y (k) | ² −1] (7) is calculated.

Then, the error e (k) is multiplied by Y (k). That, [| Y (k) | 2 -1] Y (k) = e (k) Y (k) ... (8) comprising performing a calculation.

On the other hand, the conjugate of the input signal X ₁ (k) is taken.
^{_{That, X 1 c (k) =}} [x 1I (k) + jx 1Q (k)] c = x 1I (k) -jx 1Q (k) ... (9) However, X ^c represents the conjugate of X. Is processed,
The sign of the orthogonal component is inverted.

The feedback signal generator 76 multiplies the result of equation (8) and the result of equation (9) and outputs a feedback signal. That is, A ₁ (k) = e (k) Y (k) X ₁ ^c (k) (10) is output.

For the second system, X in equation (10) is used.₁ ^c
X replaced with (k)₂ ^c(K) is multiplied by A₂(K) is
Is output. The k + th coefficient of the coefficient memory 71 of the coefficient generator 70
First coefficient value H₁(K + 1) is H ₁From (k), the formula (1
The feedback signal A shown in 0) is multiplied by the feedback coefficient μ in the multiplier 73.
It is rewritten to the value obtained by subtracting the result.

[0025] That _{is, H 1 (k + 1)} = H 1 (k) -μe (k) Y (k) X 1 c (k) ... (11) becomes H ₁ (k + ₁₎ by rewriting is the value of the next Data X
The multiplication with ₁ (k + 1) is repeated.

As is clear from the equation (11), the coefficient H is such that when the feedback coefficient μ is set to a small value, the second term of the equation (11) becomes small, and the value of the coefficient H reaches a steady state. Since it has to be repeated many times, the convergence becomes poor. However, if the feedback coefficient μ is reduced, e
Even if the values of (k), Y (k), and ^Xc (k) change greatly, the change in the value of the coefficient H is small and the operation is stable.

Further, when the output from the antenna is directly input to the adaptive control means without performing beam forming, the input signal is a composite signal of the main wave and a plurality of reflected waves.
The amplitude of the input signal fluctuates, and H (k) shown in equation (11)
Must be repeated many times before reaching a steady value, but if the beamforming output is input, the number of wave of the input signal is reduced, the fluctuation of the amplitude is reduced, the number of repetitions can be reduced, and the error value is also reduced. Is also improved.

In generating the coefficient H, equation (7)
As indicated by, the difference e (k), which is the difference between the amplitude of the output signal and the constant value, is fed back. That is, the control of the CMA is performed so that the output value becomes constant. Therefore,
The input signal may be any signal as long as it has a constant carrier wave amplitude, such as FM, GMSK, PSK, or π / 4 shift PSK.

The reason why the reflected wave is removed by the above-described operation is that the multiplication unit 74 adaptively controls the coefficient H and multiplies the received signal by each received signal to synthesize the received signal in the arrival directions of a plurality of reflected waves. A Noor point is created, and the reflected wave is removed by equivalently reducing the gain in the reflected wave direction.

In the first embodiment described above, the equation (11) is calculated corresponding to the signals X ₁ (k) to X ₄ (k) to obtain the coefficient H ₁ (for the k + 1th signal). k
Since +1) to H ₄ (k + 1) are generated, the calculation processing time is long. The second embodiment shortens the generation processing time of the coefficient H. For the (k + 1) th, H ₁ (k + 1) = H ₁ (k) −μA ₁ (k) H ₂ (k + 1) = H ₂ (K) H ₃ (k + 1) = H ₃ (k) H ₄ (k + 1) = H ₄ (k) For number k + 2, H ₁ (k + 2) = H ₁ (k + 1) H ₂ (k + 2) = H ₂ (k + 1) -μA ₂ (k + 1) H ₃ (k + 2) = H ₃ (k + 1) H ₄ (k + 2) = H ₄ (k + 1): (12), and a coefficient is sequentially input every time one signal is input. Is generated and no other coefficient is generated.

By doing so, the coefficient generation processing time is shortened. Further, in the case where only one coefficient is sequentially generated and operated in this way, the result of simulation shows that the convergence time is slightly longer. Further, in the first embodiment, the multiplication unit 74 in the adaptive control means 7 performs the multiplication as the complex multiplication as shown by the equation (7). That, [Y (k)] = X (k) H (k) = [x I (k) + jx Q (k)] [h I (k) + jh Q (k)] = [x I (k) h _{I (k) -x Q (k} ) h Q (k)] + j [ had done _{x I (k) h Q (} k) + x Q (k) h I (k) ... (13) made operation.

Therefore, for the multiplication of one sequence, the expression (1
As shown in 3), four multiplications and two additions were required. In the third embodiment, the multiplication in the multiplication unit 74 is performed by [Y (k)] → x _I (k) h _I (k) + jx _Q (k) h _Q (k) (14) Y (k)] is output.

According to the simulation result, the equation (1
Even if the result of 4) is output as [Y (k)], the result that stable operation is obtained although the convergence is slightly slower is obtained.
The multiplication processing time in 4 can be shortened. Also,
In the beam shaping means 6 of the first embodiment, the multiplication and addition shown in the equation (2) are performed and X is output. That is, the results of performing the complex multiplication four times were added.

As described above, complex multiplication requires four multiplications and two additions, which results in a long arithmetic processing time. In the fourth embodiment, the processing is executed as follows. The coefficient D for multiplication is, as shown in FIG.
The absolute values of D ₁₁ and D ₁₅ , and D ₁₂ and D ₁₄ are equal.

Therefore, D ₁₁ S ₁ + D ₁₅ S ₅ = (D _11I + jD _11Q ) (s _1I + js _1Q ) + (D _15I + jD _15Q ) (s _5I + js _5Q ) = (D _11I + jD _11Q ) (s _1I + js _{1Q) + (D 11I -jD 11Q} ) (s 5I + js 5Q) = (s 1I + s 5I) D 11I - (s 1Q -s 5Q) D 11Q + j (s 1I -s 5I) D 11Q + j (s 1Q + s _5Q ) D _11I (15), the number of operations can be reduced by performing complex addition on the signal and then multiplying by the coefficient. That is, eight multiplications and four additions can be performed by four additions and four multiplications.

Further, the calculation of D ₁₂ S ₂ + D ₁₄ S ₄ can be similarly performed. Next, a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 4, the beam shaping means 6 and the application control means 7 are as described in FIGS.

Reference numeral 81 is an output monitoring unit, 82 is an initial value rewriting unit, and 83 is an initial value storage unit. The initial value storage unit 83 stores the initial values set in the coefficient memory 71 (H _{1 to} H ₄ ) of the adaptive control means 7. As an initial value, for example, H ₁ = 1, H ₂ = H ₃ = H ₄ = 0 H ₂ = 1, H ₁ = H ₃ = H ₄ = 0 H ₃ = 1, H ₁ = H ₂ = H _{4 = 0 H 4 = 1, H} 1 = H 2 = H 3 = 0 ... stores four sets of initial values of (16).

The output monitor 81 monitors the amplitude of the signals X _{1 to} X ₄ output from the beam shaping means 6.
That is, | X | ² = x _I ² + x _Q ² (17) is performed to obtain | X ₁ | ² , | X ₂ | ² , | X ₃ |
² and | X ₄ | ² are output.

The initial value rewriting section 82 selects the maximum value among the values | X ₁ | ² to | X ₄ | ² output from the output monitoring section 81 at the start of operation, and the selected value is If | X ₁ | ^2, it is recorded in the initial value recording unit 83. The data of the set of H ₁ = 1 and H ₂ = H ₃ = H ₄ = 0 is read and set in the coefficient memory 71 to start the operation.

If | X ₂ | ² is the maximum, then equation (16)
The second set of data is set in the coefficient memory 71. ｜ X
The reason why the coefficient value 1 is set for the system having the maximum | ² and the coefficient value 0 is set for the other systems is that the signal X having the maximum | X | ² is the main wave, Assuming that the other waves are reflected waves, the convergence is improved by performing adaptive control by the CMA on the main wave.

Although "1" and "0" are set as the initial values in the embodiment, the initial values are "1".
The value is not limited to “0” and may be any value as long as it is regarded as a main wave and the convergence of adaptive control is good. Next, a sixth embodiment of the present invention will be described with reference to FIG.

In FIG. 5, the beam shaping means 6 and the adaptive control means are as described in FIGS. 1 to 3, and the initial value storage unit 83 is as described in FIG. Also, 8
Reference numeral 4 is an initial value rewriting unit, and 85 is an output error detecting unit. The output error detection unit 85 outputs the difference in the value of the output Y from a constant value.

That is, e _a = | e (k) | + | e (k + 1) | + ... + | e (k + n) | (18) where e (k) is n number of equation (7). and outputs a e _a by adding the error e (k).

In the initial value rewriting unit 84, the output error detecting unit 8
The difference signal e _a output from the signal No. 5 is monitored, and when e _a exceeds a predetermined value, the initial value of the first set recorded in the initial value recording unit 83 is read out and the adaptive control means is read. No. 7 coefficient memory 71 is set and operated.

Even if the initial value of the first set is set and the operation is performed, if e _a is equal to or more than a predetermined value, then the second
The initial values of the set are read from the initial value storage unit 83, set in the coefficient memory 71, and operated. After that, the third and fourth sets of initial values are read and set, and if the difference signal e _a is equal to or less than _a certain value, rewriting of the initial values is stopped.

By setting different initial values as described above and stopping the rewriting when the difference signal is below a certain value, convergence can be performed in a short time. Further, the operation of the initial value rewriting unit 82 described in the fifth embodiment is started when the output e _{a of} the output error detection unit 85 described in the sixth embodiment exceeds a certain fixed value. You may allow it.

Next, a seventh embodiment of the present invention will be described with reference to FIG. In FIG. 6, the beam shaping means 6 and the adaptive control means 7 are as described in FIGS.
The output monitor 81 is as described in FIG. 4, and the output error detector 85 is as described in FIG.

Reference numeral 86 is a switching unit and 87 switching control unit. The switching unit 86 selects and outputs _{one of the} signals X _{1 to} X ₄ output from the beam shaping unit 6 and the signal Y output from the adaptive control unit 7. When the difference signal e _a output from the output error detection unit 85 exceeds a certain fixed value, the switching control unit 87 outputs the amplitude value | X ₁ shown by the equation (17) output from the output monitoring unit 81. The maximum one of | ² to | X ₄ | ² is selected, and the switching unit 86 is instructed to switch so that X _n corresponding to the selected | X _n | ² is output.

The difference signal e from the output error detector 85
_{When a} becomes equal to or less than _a certain value, the switching unit 86 is instructed to output Y and switched. As described above, the time until the adaptive control means 7 converges is such that the beam forming output is maximized, and when the convergence is completed, the adaptively controlled output is output to demodulate the demodulation connected to the antenna coupling device. It is possible to supply a continuous optimum signal to the container.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made according to the gist of the invention.

[0051]

As described above, according to the present invention, the following effects can be obtained. The signals received by multiple antennas are separated into in-phase components and quadrature components, the separated signals are multiplied by a coefficient to form beams with different pointing directions, and the generated output signals are adaptively controlled to generate the generated coefficients. Since the output is obtained by multiplication, the multiple waves are not simultaneously input as the adaptive control input due to the beam forming, the convergence characteristic is improved, and the performance is improved.

Since the coefficient generated by adaptive control is generated for one input signal and sequentially repeated, the coefficient generation processing time can be shortened. Since the complex multiplication in the adaptive control is output as the real number and the multiplication result of the real number and the multiplication result of the imaginary number as the imaginary number, the complex multiplication processing time can be shortened.

Since the multiplication in the beam forming is performed after the complex addition of the signals, the processing time can be shortened. Since the initial value of the coefficient of the adaptive control means is determined by the output value of the beam shaping means, the adaptive control can be converged in a short time.

Since the initial value of the coefficient of the adaptive control means is switched based on the output value of the adaptive control means, the convergence of adaptive control can be performed in a short time. When the error of the adaptive control output is equal to or more than a certain value, the beam forming output is directly output, so that a continuous optimum signal can be output.

[Brief description of drawings]

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

FIG. 2 is a specific example of a beam shaping unit of the same embodiment.

FIG. 3 is a specific example of adaptive control means of the same embodiment.

FIG. 4 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 5 is a configuration diagram of a sixth embodiment of the present invention.

FIG. 6 is a configuration diagram of a seventh embodiment of the present invention.

FIG. 7 is a specific example of coefficient values in a coefficient memory of the beam shaping unit of the embodiment.

[Explanation of symbols]

1 antenna 2 frequency converter 3 local oscillator 4 90 degree phaser 5 Analog-to-digital converter 6 Beam shaping means 7 Adaptive control means 62 ', 71 coefficient memory 72 Subtractor 73 Multiplier 61,74 Multiplier 63,75 adder 70 coefficient generator 76 Feedback signal generator 81 Output monitoring unit 82,84 Initial value rewriting section 83 initial value storage 85 Output error detector 86 switching unit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-70216 (JP, A) JP-A-3-276903 (JP, A) JP-A-3-70221 (JP, A) JP-A-5- 145454 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 3/26

Claims (7)

(57) [Claims] 1. An antenna combining device for combining and outputting signals received from M antennas, wherein the received signals from the M antennas are separated into an in-phase component and a quadrature component, and each of the separated signals is separated. A beam forming unit that multiplies a coefficient and adds the multiplication results to form N beams with different directing directions, and N signals that are output from the beam forming unit are multiplied by a coefficient to obtain a multiplication result. An antenna coupling device comprising: an adaptive control unit that adaptively controls and generates each coefficient so that the added output becomes constant. 2. Updating the coefficient values in the adaptive control means,
The coefficient values corresponding to the N signals output from the beam shaping means are updated by one coefficient each time a signal is sequentially input, and the cycle is repeated by N times of signal input. The antenna coupling device according to claim 1. 3. The multiplication of the coefficient in the adaptive control means is such that the multiplication result of the real part of the coefficient and the in-phase component is output as a real number, and the imaginary part of the coefficient is output as the multiplication result of the orthogonal component as an imaginary result. The antenna coupling device according to claim 1, wherein: 4. The antenna coupling device according to claim 1, wherein the multiplication of each coefficient of the beam shaping means and the signal is performed by multiplying the coefficient after complex addition of the signals. 5. The antenna coupling device according to claim 1, wherein the initial value of each coefficient of the adaptive control means is determined from the output of the beam shaping means. 6. The antenna coupling device according to claim 1, wherein the initial value of each coefficient of the adaptive control means is switched and set based on the error value of the output from the adaptive control means. 7. If the error value of the output from the adaptive control means is a certain value or more, one of the signals output from the beam shaping means is output as the output of the antenna coupling device. The antenna coupling device according to claim 1, wherein: