KR100698996B1 - Adaptive control apparatus - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide an adaptive control apparatus which adaptively controls the directivity of an array antenna so that it can continuously follow each of the mobile terminals. According to the present invention, an adaptive control device for changing the directivity of an array antenna of a wireless device, the adaptive control device comprising: a distance between a receiver receiving a radio frequency signal transmitted from the wireless device and a distance between the wireless device and the relative of the receiver to the wireless device; Setting means for setting parameters including a moving speed and a moving direction, evaluation means for evaluating how much the received power of the receiver or the wireless device changes after a predetermined period of time, and a plurality of antenna elements included in the array antenna Weighting control means for adjusting the plurality of weighting coefficients for. The directivity is varied so that the amount of change in the received power is within a certain range that does not depend on the distance between the receiver and the wireless device.

Cellular Communication Systems, Mobile Terminals, Array Antennas, Adaptive Control Devices, Directional

Description

Adaptive control device {ADAPTIVE CONTROL APPARATUS}

TECHNICAL FIELD The present invention relates to the technical field of mobile communications, and more particularly, to an adaptive control device for adaptively controlling the directivity of an array antenna.

In this kind of technical field represented by cellular communication, the communication band is widening in response to requests such as high speed and high quality of communication. In order to sufficiently transmit a wideband radio signal through the cell, more power is required than in the narrowband case. However, since the transmission capability of the mobile terminal has a stricter limit than that of the radio base station, it is not possible to simply increase the transmission power. On the other hand, if the cell radius is reduced, the problem of transmission power itself can be overcome, but the number of wireless base stations installed in a wide range of service areas is greatly increased, which is disadvantageous from the viewpoint of facility investment and system management. These problems are not all solved even if the transmission bands of the uplink and downlink are asymmetric.

From this point of view, there is a technique of maintaining the cell radius largely by sharply forming the antenna's directivity and adaptively omitting radio waves in a desired direction. There are two methods in this technique, one is the beamforming method (that is, the method of increasing the S of SINR = S / (N + I)), which adaptively controls the directivity to adapt the direction of the main beam to the desired wave, The other is a null forming method (ie, a method of suppressing I of SINR = S / (N + I)) which adaptively controls the directivity to fit a null to an interference wave. Either way, in these adaptive control methods, the direction of arrival (DoA) of the path is estimated, and a plurality of weighting coefficients for a plurality of antenna elements are sequentially updated by using a convergence algorithm such as a steepest descent method. In the desired direction, a highly directional beam (pre-fixed narrow beam width beam) is directed. The beam width is set to ensure that the received power at the cell edge is above the system design value.

By the way, in a communication system employing a spread spectrum method, transmission power control (TCP) is performed, so that transmission power of a mobile terminal is increased so that a signal received from a wireless base station has a communication quality (especially, reception level) of a certain level or more. Controlled. More specifically, the transmission power of the mobile terminal is increased or decreased in accordance with the distance between the radio base station and the mobile terminal.

1 is a conceptual diagram illustrating antenna gain in conventional beam control. As shown in Fig. 1A, it is assumed that the mobile terminal located at the cell end moves at a speed v in the circumferential direction with respect to the radio base station. The mobile terminal transmits at the transmit power P _T1 , and the receive power at the radio base station is P _R1 (P _T1 , P _G , r ₁ ). When the mobile terminal moves, the angular change (angular velocity) per unit time for the radio base station becomes Δθ ₁ , during which the power gain changes by ΔP _G1 = P _G (0) −P _G (Δθ ₁ ). Thus, the power received at the wireless base station after the move is

P _R1 = P _T1 + P _G (Δθ ₁ ) -P _ATT (r ₁ )

= P _T1 + P _G (0) -ΔP _G1 -P _ATT (r ₁ )

Becomes Here, P _G (θ) represents the beam gain at the phase angle θ, and P _ATT (r) represents the distance attenuation of radio waves with respect to the distance r.

1B illustrates a case where a mobile terminal located near the radio base station moves at a speed v in the circumferential direction with respect to the radio base station. The mobile terminal transmits at the transmit power P _T2 , and the angular change (angular velocity) per unit time for the radio base station is Δθ ₂ , during which the power gain is ΔP _G2 = P _G (0) -P _G (Δθ ₂ ). Change. Thus, the power received at the wireless base station after the move is

P _R2 = P _T2 + P _G (Δθ ₂ ) -P _ATT (r ₂ )

= P _T2 + P _G (0) -ΔP _G2 -P _ATT (r ₂ )

It becomes

In the conventional beam control method, the beam is formed with a fixed beam width without depending on the perspective of the mobile terminal, and the beam direction is appropriately adjusted. As shown in Figs. 1A, 1B and the above equation, even if the moving speed v and the moving direction (circumferential direction) of the mobile terminal are the same, if the distance from the wireless base station is large, the angular velocity Δθ ₁ If the distance is small and the distance is small, the angular velocity Δθ ₂ becomes large (Δθ ₁ <Δθ ₂ ). In addition, the change amount of the power gain is ΔP _G1 <ΔP _G2 . Therefore, with respect to the powers P _R1 and P _R2 received by the radio base station from the mobile terminal after the movement, the received power P _R1 from the far mobile terminal is not so small (it becomes as small as ΔP _G1 ), but the nearby mobile terminal The received power P _{R2 from} is very small (as small as ΔP _G2 ). Therefore, in order to make the reception level at the radio base station more than a certain level, it is necessary to request transmission with more power than the mobile terminal moved in the vicinity, or adjust the beam direction before the angular velocity becomes large.

However, since the former technique increases power even though it is located in the vicinity, it is not an advantageous technique to increase interference with other communication signals. According to the latter method, since the beam direction is adjusted before the angular velocity becomes large, high performance adaptive control is required to follow the mobile terminal at high speed, and the control burden in the system is large.

In this regard, Patent Document 1 (Japanese Patent Laid-Open No. 2002-94448) discloses a technique for performing beam control on a group basis, and classifies a plurality of mobile stations into groups of mobile stations located near each other, thereby providing one beam. It is possible to cover the area where this one group is located. This makes it possible to reduce the control burden required on the system or the base station as compared to the case of controlling the beam on a mobile station basis.

However, such group classification is not always possible in a communication system, and when group classification is difficult, it is difficult to achieve the desired purpose.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-94448

SUMMARY OF THE INVENTION An object of the present invention is to provide an adaptive control apparatus which adaptively controls the directivity of an array antenna so that it can continuously follow each of the mobile terminals. This object is solved by the following means.

According to the present invention, an adaptive control device for changing the directivity of an array antenna, which is used in a wireless device having an array antenna for transmitting and receiving radio frequency signals,

Setting means for setting a parameter including a distance between a receiver receiving a radio frequency signal transmitted from the wireless device and the wireless device, a relative moving speed and a moving direction of the receiver relative to the wireless device;

Evaluation means for evaluating how much the received power of the receiver or the wireless device changes after a predetermined period of time has elapsed;

Weighting control means for adjusting a plurality of weighting factors for a plurality of antenna elements included in the array antenna

And the directivity is changed so that the amount of change in the received power is within a certain range that does not depend on the distance between the receiver and the wireless device.

1 is a conceptual diagram showing antenna gain in conventional beam control.

2 is a conceptual diagram of an antenna system according to an embodiment of the present application;

3 is a diagram illustrating another form of the power measurement unit.

4 is a diagram illustrating another form of a Fourier transform unit.

5 is a conceptual diagram illustrating antenna gain in beam control according to an embodiment of the present application.

6 is a block diagram of an adaptive control device according to another embodiment.

7 is a conceptual diagram showing antenna gains for beams with different directivities.

8 is a block diagram of an adaptive control apparatus according to another embodiment.

9 is a conceptual diagram of a wireless base station using an adaptive control device according to an embodiment of the present invention.

2 shows a conceptual diagram of an antenna system according to an embodiment of the present application. In general, antenna system 200 has an array antenna 202 and an adaptive control device 204. For convenience of description, the antenna system 200 is described as being installed in a wireless base station, but it is also possible to install the antenna system 200 in a mobile terminal. In addition, the control method of the array antenna described below can be used for receiving beam forming or transmission beam forming.

The array antenna 202 has, for example, a plurality of N antenna elements 206 and a combining unit 208 that adds signals from the plurality of antenna elements 206. Appropriate weighting is applied to the signals received at the antenna element 206 and synthesized at the combining section 208 to form a received signal. In the transmission, a transmission signal is transmitted from each antenna element 206 after appropriate weighting is performed. The weighting at the time of reception is performed by weighting factors W _R1 -W _RN , and the weighting at the time of transmission is performed by weighting coefficients W _T1 -W _TN . These weighting coefficients are appropriately set by the adaptive control device 204, and are controlled to follow the mobile terminal after being sequentially updated at predetermined update periods.

The adaptive control device 204 includes a setting unit 210 for setting parameters required for calculating weighting coefficients based on a received signal before or after synthesis, and a weight control unit 212 for outputting weighting coefficients based on the set parameters. Has The setting unit 210 calculates a power based on a received signal before synthesis from one or a plurality of antenna elements 206 and calculates a distance from the mobile terminal based on the calculated power. It has the distance calculating part 216 to calculate. In the distance calculator 216, for example,

P _ATT (r) = P ₀ + γ × 10log (r)

Based on a known relationship with respect to power, the distance r between the mobile terminal and the wireless base station is estimated. Here, P _ATT (r) represents the distance attenuation of radio waves, P _o represents the distance attenuation at the cell edge (end of the cell), and γ represents a predetermined integer.

This relation about distance is only an example, and it is possible to add a new correction term or use another relation as necessary. In addition, the power value used as the basis for calculating the distance can be calculated based on the signals from one antenna element 206 before synthesis, or can be calculated based on the signals from the plurality of antenna elements 206. . In the latter case, as shown in Fig. 3, a power synthesizer for combining and equalizing a plurality of signals is required. The former is preferable from the viewpoint of simplifying the circuit and the latter from the viewpoint of suppressing the influence of noise (for example, improving the S / N ratio). In addition, if the coordinates of the mobile terminal are obtained by, for example, GPS or the like without using such known relational expressions, the distance can be directly calculated based on the coordinates of the mobile terminal and the wireless base station. In this case, however, it is necessary to mount a device such as a GPS receiver in the mobile terminal, unlike in the case of using the above known relational expression.

The setting unit 210 finds a Fourier transform unit 218 for Fourier transforming a signal received by one or a plurality of antenna elements 206 before synthesis to obtain a frequency spectrum, and finds a Doppler frequency based on the frequency spectrum. And a speed calculator 220 for calculating a relative speed of the mobile terminal. When the mobile terminal moves with respect to the radio base station, a frequency shift (Doppler shift) occurs in the signal transmitted and received in the meantime, and the relative speed is calculated based on the following equation.

v = f _d × λ = f _d × c / f _c

Where v denotes the relative speed of the mobile terminal, f _d denotes the Doppler frequency, λ denotes the wavelength of radio waves, c denotes the luminous flux, and f _c denotes the carrier frequency. As in the case of the above distance calculation, the relative speed v can be calculated based on a signal from one antenna element 206 before synthesis, or can be calculated based on signals from a plurality of antenna elements 206. . In the latter case, as shown in Fig. 4, a synthesizer for performing Fourier transform on each signal and synthesizing them to form one frequency spectrum is required.

The setting unit 210 includes a direction estimating unit 222 for obtaining a moving direction or an angular velocity Δθ with respect to the wireless base station of the mobile terminal. This angular velocity can be calculated based on, for example, the direction of arrival DoA of the path from the mobile terminal. In addition, the power measuring unit 214 and the distance calculating unit 216 for estimating the distance, the Fourier transforming unit 218 and the speed calculating unit 220 for estimating the speed, and the direction estimating unit 222 are always Not all of them need to be installed. This is because parameters such as the distance r, the speed v and the angular velocity Δθ may be set by these means or based on other information inputs and provided to the weight control unit 212 at the next stage.

The weight control unit 212 evaluates how much the received power of the mobile terminal changes after a predetermined time elapses (for example, when the next weighting factor is updated) based on various parameters from the setting unit 210. It has an evaluation unit 224. The weight control unit 212 includes a procedure algorithm unit 226 that executes an algorithm for updating the weighting coefficient based on the evaluation result of the evaluation unit 224. This algorithm is, for example, a steepest descent method such as LMS (Least Mean Square), which aims to minimize or maximize the value of the evaluation function that varies depending on the weighting coefficient. For example, an electric power value relating to an error between a received signal and a known signal may be used as an evaluation function, and the weighting coefficient may be sequentially updated so that the value taken by this evaluation function is minimized. The initial value in the calculation of this algorithm is prepared and set in the initial value setting unit 227. The weight control unit 212 includes a weight adjustment unit 228 for setting the weighting coefficient calculated by the convergence algorithm unit 226 to each antenna element 206. The signal representing the weighting coefficient from the weighting adjusting unit 228 is supplied to each antenna element 206, and the weighting coefficient is actually adjusted. The weight control unit 212 has an integral value calculating unit 230 that calculates an integral value over a predetermined period of the received power received by the mobile terminal based on the parameter from the setting unit 210.

As described above, in the conventional beam control, a beam having a fixed beam width is controlled so as to be directed in a desired direction (the direction in which the mobile terminal is located) each time. The beam width was set to ensure that the received power at the cell edge is more than the system design value. In this case, when the mobile terminal distant from a wireless base station such as a cell edge moves at a speed v in the circumferential direction, the change in the received power ΔP _G1 of the mobile terminal or the wireless base station is small, The change in the received power ΔP _G2 of the mobile terminal or the wireless base station when moving at the same speed in the circumferential direction near the wireless base station is large. In general, the embodiment of the present invention controls the beam width to be narrower for the mobile terminal located far from the radio base station and to widen the beam width for the mobile terminal located in the vicinity of the radio base station, thereby moving the motion regardless of the distance perspective. It is trying to follow the beam continuously to the terminal.

5 is a conceptual diagram illustrating antenna gain in beam control according to an embodiment of the present application. As shown in Fig. 5A, it is assumed that the mobile terminal located at the cell end moves at a speed v in the circumferential direction with respect to the radio base station. For convenience of explanation, the case of moving in the circumferential direction is assumed, but the generality is not lost. The mobile terminal transmits at the transmit power P _T1 , and the receive power at the radio base station is P _R1 (P _T1 , P _G1 , r ₁ ). When the mobile terminal moves, the angular change (angular velocity) per unit time for the radio base station becomes Δθ ₁ , during which the power gain changes by ΔP _G1 = P _G1 (0) −P _G1 (Δθ ₁ ). First, the power received at the wireless base station before the move is

P _R1 = P _T1 + P _G1 (0) -P _ATT (r ₁ ) ... (a)

Becomes Here, P _G1 (θ) represents the power gain with respect to the phase angle θ, and P _ATT (r) represents the distance attenuation of the radio waves with respect to the distance r. The power received at the wireless base station after the move,

P _R1 = P _T1 + P _G1 (Δθ ₁ ) -P _ATT (r ₁ )

= P _T1 + P _G1 (0) -ΔP _G1 -P _ATT (r ₁ )

Becomes

In addition, as shown in FIG. 5B, it is assumed that a mobile terminal located near the radio base station moves at the same speed v in the circumferential direction with respect to the radio base station. The mobile terminal transmits at the transmit power P _T2 , and the angular change (angular velocity) per unit time for the radio base station is Δθ ₂ , during which the power gain is ΔP _G2 = P _G2 (0) -P _G2 (Δθ ₂ ). Change. First, the power received at the wireless base station before the move is

P _R2 = P _T2 + P _G2 (0) -P _ATT (r ₂ ) ... (c)

It becomes The power received at the wireless base station after the move,

P _R2 = P _T2 + P _G2 (Δθ ₂ ) -P _ATT (r ₂ )

= P _T2 + P _G2 (0) -ΔP _G2 -P _ATT (r ₂ )

It becomes

In the embodiment of the present application, control is performed so that the reception power is the same regardless of the distance perspective. Specifically, control is performed such that P _R1 = P _R2 is established. Unlike the prior art, it should be noted that the power gains P _G1 and P _G2 are not necessarily the same in the present embodiment. In order to satisfy P _R1 = P _R2 ,

P _T1 + P _G1 (0) -P _ATT (r ₁ )

= P _T2 + P _G2 (0) -P _ATT (r ₂ )

Needs to be established. As for the transfer,

P _T1 + P _G1 (0) -ΔP _G1 -P _ATT (r ₁ )

= P _T2 + P _G2 (0) -ΔP _G2 -P _ATT (r ₂ )

Needs to be established. therefore,

ΔP _G1 = ΔP _G2 (e)

Control is performed so that is satisfied.

As described above, when the beam control is performed under the condition that the amount of change in the power gain becomes constant, as shown in Figs. 5A and 5B, the beam width is narrower and directivity becomes stronger for the far-end mobile terminal. For a mobile terminal in the vicinity, the beam width becomes wider. For this reason, even if the mobile terminal in the vicinity moves in the circumferential direction at high speed v, the power does not suddenly decrease (the decrease amount is ΔP _G2 ), and it is possible to follow the mobile terminal as well as in the far mobile terminal. do. In this case, the transmission power of the mobile terminal can also be made constant regardless of the distance (P _T1 = P _T2 ). The directional beam depending on the distance of such a mobile terminal can assume the specific shape of the directionality from the beginning and adjust the weighting coefficient, or apart from assuming such a specific shape, the conditions of (e), etc. It is also possible to obtain the desired directivity as a result of the control to satisfy the. Either way, in the present embodiment, control is performed to satisfy the condition (e) for each update step of the weighting coefficient.

In addition, the control performed to satisfy the condition (e) may be controlled such that the error between ΔP _G1 and ΔP _G2 is smaller than the predetermined value D (ε <D, ε = | ΔP _G1 -ΔP _G2 |), Or you may control so that (DELTA) P _G1 and (DELTA) P _G2 may become smaller than predetermined margin M ((DELTA) P _G1 <M, (DELTA) P _G2 <M).

By the way, from the viewpoint of the stability of the system control, the weighting coefficient is calculated every time a received sample is obtained, not actually updated each time a received sample is obtained, but the weighting coefficient is updated by the weight adjusting unit 228. Is preferably performed for a predetermined number of received samples. In addition, "stability" in this case is corresponded to the gentleness of the change of the directivity realized by the weighting factor updated continuously.

For example, whenever the weighting coefficient is updated (every update period T1), the condition of (e) is satisfied, but for each weighting coefficient calculated for a plurality of samples in between, (e) It is to calculate and average without imposing conditions. In this way, a weighting factor that does not satisfy the condition of (e) can be calculated instantaneously, but by averaging over a plurality of samples, it is possible to stably calculate the weighting coefficient for each update period T1.

Alternatively, the weighting coefficient can be more stably calculated by calculating a weighting coefficient calculated within the update period T1 by applying a certain restriction. For example, it is possible to control the integral value of the received power over a period of time to be constant regardless of the distance. That is, the total received power of S _1, while the change in phase angle is 0, the far side of the mobile terminal ₁ to Δθ as shown in (A) of Figure 5,

This corresponds to an area indicated by diagonal lines in FIG. 5A. Similarly, the total received power S ₂ for the phase angle of the mobile terminal in the vicinity of the base station is changing from O to ₂ is Δθ,

This corresponds to an area indicated by diagonal lines in FIG. 5B. And, it is possible to perform these total received power is updated to be the same period in the _{T1 (S 1 = S 2)} , control. In this way, in addition to satisfying the condition (e) for each update period, the total received power is controlled to be constant even for the samples obtained therebetween, so that the weighting coefficient can be calculated more stably.

6 is a block diagram of an adaptive control apparatus according to another embodiment. The adaptive control device 600 includes a first setting unit 602 for setting a first parameter required for calculating a weighting coefficient based on a received signal before or after synthesis, and a first based on the set first parameter. And a first weight control unit 604 for outputting weighting coefficients. These are the same as the adaptive control device of FIG. The adaptive control device 600 also has a storage unit 606 which sequentially stores parameters such as the distance r, the speed v, and the angular velocity Δθ used to calculate the weighting coefficient. The adaptive control apparatus 600 has the 2nd setting part 608 which estimates a future parameter using the past parameter stored in the memory | storage part 606. FIG. For example, the second setting unit 608 estimates the parameters such as the current distance r, the speed v, the angular velocity Δθ and the like based on the parameters such as the distance r, the speed v, the angular velocity Δθ at two past viewpoints. The type and number of parameters referred to in the second setting unit 608 may be appropriately changed as necessary. The adaptive control apparatus 600 has the 2nd weight control part 610 which outputs a 2nd weighting coefficient based on the 2nd parameter set by this 2nd setting part 608. FIG. The first and second weight control units 604 and 610 are common in terms of outputting weighting coefficients, but the parameters on which the calculation is based differ.

The adaptive control apparatus 600 determines the difference between the main direction of directivity that can be realized by the first weighting factor (the direction in which the peak of the beam is directed) and the main direction of directivity that can be realized by the second weighting coefficient. The angle of arrival comparison unit 612 is provided. The adaptive control device 600 can be received when the power that can be received when the first directivity by the first weighting factor could be realized and when the second directivity by the second weighting factor could be realized. And a power comparison section 614 for determining the amount of power difference. In addition, the adaptive control device 600 selects either the first weighting factor or the second weighting factor based on the output from the angle of arrival comparator 612 and / or the output from the power comparator 614. Has a selection unit 616.

As described above, the first and second weight controllers 604 and 610 are common in terms of outputting weighting coefficients, and the parameters on which the calculation is based differ. Therefore, if the parameters set by the first and second setting units are the same, the weighting coefficients calculated by the first and second weight controllers 604 and 610 are also the same. However, there is a case where the first parameter obtained at the present time point t = t _n and the second parameter estimated based on the parameters at the past time points t = t _n-1 , t _n-2 ,... have. For example, when the mobile terminal is moving at a high speed, since the change in the moving speed and the moving direction is small, the second parameter more accurately reflects the situation than the first parameter. In such a case, it is difficult to sufficiently follow the mobile terminal only with the first parameter. In the present embodiment, the angle of arrival comparison unit 612 determines an amount of difference between the main direction of directivity that can be realized by the first weighting factor and the main direction of directivity that can be realized by the second weighting coefficient. When the difference amount ΔΘ exceeds a predetermined threshold, the angle of arrival comparison unit 612 now determines that the first weighting factor calculated by the first parameter cannot follow the mobile terminal. Then, the angle of arrival comparison unit 612 instructs the selection unit 616 to output the second weighting coefficient from the adaptive control device 600 instead of the latest first weighting coefficient as the initial value of the next weighting coefficient calculation. Give a signal. This makes it possible to follow the mobile terminal moving at a high speed by making the above difference amount ΔΘ small.

FIG. 7A shows a first directivity 702 and a second directivity 704 that may be formed for a mobile terminal (not shown) remote to the wireless base station. The first directivity 702 can be realized by the above first parameter and the first weighting coefficient. The second directivity 704 can be realized by the above second parameter and the second weighting factor. In each directivity case, the difference in power received by the receiver is represented by ΔP ₁ . Similarly, FIG. 7B shows a first directivity 706 and a second directivity 708 that may be formed for a mobile terminal (not shown) in the vicinity of the wireless base station. In each directivity case, the difference in power received by the receiver is represented by ΔP ₂ .

As shown in Figs. 7A and 7B, the difference in the received power between the two directivity depends on the perspective of the distance between the radio base station and the mobile terminal,

ΔP ₁ > ΔP ₂

Relationship is established. This means that the influence of changing the directivity is great for the mobile terminal in the far side, but the influence is small for the mobile terminal in the vicinity. That is, when the difference amount ΔΘ of the angle of arrival becomes large, it is already difficult to follow the far mobile terminal, but it is still possible to follow the near mobile terminal because the beam width is wide. Therefore, the power comparison unit 614 calculates the difference amounts ΔP ₁ , ΔP ₂ of the powers for the two directivity, and when the difference amount exceeds a predetermined threshold, an instruction signal is given to the selection unit 616, and the It is advantageous to choose two weighting factors.

In the present embodiment, the angle of arrival comparison unit 612 and the power comparison unit 614 are provided, but the power comparison unit 614 can be omitted from the viewpoint of reducing the processing burden. However, if both are provided, the initial value of the weight calculation can be forcibly set only when it is truly necessary, such as when it cannot follow the far mobile terminal. In view of this, it is because introducing such discontinuity should be avoided as much as possible).

8 is a block diagram of an adaptive control apparatus according to another embodiment. The adaptive control device 800 includes a first setting unit 802 for setting a first parameter required for calculating a weighting coefficient based on a received signal before or after synthesis, and a first based on the set first parameter. And a first weight control unit 804 for outputting weighting coefficients. These are the same as the adaptive control device of FIG. The adaptive control device 800 has a storage unit 806 that sequentially stores parameters such as a distance r, a speed v, and an angular velocity Δθ used to calculate the weighting coefficient. The adaptive control device 800 has a second setting unit 808 which estimates future parameters using past parameters stored in the storage unit 806. The adaptive control apparatus 800 has the 2nd weight control part 810 which outputs a 2nd weighting coefficient based on the 2nd parameter set by this 2nd setting part 808. FIG. The adaptive control apparatus 800 determines the difference between the main direction of directivity that can be realized by the first weighting factor and the main amount of directivity that can be realized by the second weighting factor. Has The adaptive control device 800 can be received when the power that can be received when the first directivity by the first weighting factor could be realized and when the second directivity by the second weighting factor could be realized. And a power comparison section 814 that determines the amount of power difference. The above element is the same as each element described above in FIG.

In the present embodiment, a correction unit 816 that outputs a correction signal A based on the first weighting factor and the second weighting factor and the instruction signal from the angle of arrival comparison unit 812 and / or the power comparison unit 814 is provided. It is installed. The correction signal A is fed back to the first weight control unit 804. The weighting coefficient output from the adaptive control device 800 of this embodiment is the first weighting coefficient output from the first weight control unit 804.

As described above, when the upper amount ΔΘ of the angle of arrival and / or the upper amount ΔP of the received power, which is calculated with respect to the directivity that can be realized by the first and second weighting factors, respectively, exceeds a predetermined value, the correction unit 816 The purpose is to be notified. In response to this notification, the correction unit 816 outputs a correction signal A calculated in dependence on the difference amount between the first and second weighting coefficients. The content of the correction signal A is intended to correct the content of the next time calculation of the first parameter, and does not forcibly set the initial value of the calculation of the next time weighting factor as the second weighting coefficient, for example, an offset amount to a parameter or weighting coefficient. Add to this. If you forcibly change the initial value to discontinuity, there is a risk of the beam moving away from the mobile terminal. However, by introducing a feedback signal such as the correction signal A as in the present embodiment, when the first weighting coefficient is gradually updated, for example, the weighting coefficient can be smoothly changed to some extent even for a mobile terminal moving at high speed. do.

9 shows wireless base stations 902 and 904 using an adaptive control device in accordance with an embodiment of the present application. The first wireless base station 902 has a first array antenna 906 and a first adaptive control device 908. The first adaptive control device 908 includes a first setting unit 910 for setting a first parameter required for calculating a weighting coefficient based on a received signal before or after synthesis, and a first based on the set first parameter. And a first weight control unit 912 for outputting one weighting coefficient. The first adaptive control device 908 has a storage unit 914 that sequentially stores parameters such as the distance r, the speed v, the angular velocity Δθ, and the like used to calculate the weighting coefficient. The first adaptive control device 908 has a second setting unit 916 for estimating future parameters using past parameters stored in the storage unit 914. These elements are the same as that shown in FIG.

The second wireless base station 904, like the first wireless base station 902, also has a second array antenna 918 and a second adaptive control device 920. The second adaptive control device 920 includes a first setting unit 922 for setting a first parameter required to calculate a weighting coefficient based on a received signal before or after synthesis, and a first based on the set first parameter. And a first weight control unit 924 for outputting one weighting coefficient. An initial value setting unit 926 is shown in the first weight control unit 924. The second adaptive control device 920 has the same elements as the first adaptive control device 908, but for the sake of simplicity, other elements are not shown.

Assume that a mobile terminal exists in a cell of the first wireless base station 902 and is communicating using a directional beam that is adaptively controlled by the first wireless base station 902. It is assumed that this mobile terminal reaches the end of the cell and transitions (hands over) into the cell of the second radio base station 904 while continuing communication. At this handover, the first adaptive control device 908 provides the parameters related to the mobile terminal to the wireless base station 904 at the transition destination. Specifically, the parameter is input to the initial value setting unit 926. The parameters provided generally include a distance r, a speed v and an angular velocity Δθ, but if the distance r is known at the time of handover, for example, it is possible to omit it. By passing the parameters together with the handover in this manner, it is possible to quickly prepare an appropriate directional beam in the wireless base station 904 at the transition destination, thereby making it possible to shorten the initial lead-in time of beam formation. In the illustrated example, the current parameter estimated based on the past parameter is provided for the handover, but the current parameter can be provided instead of or in addition thereto.

As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation and a change are possible within the scope of the summary of this invention.

Claims (14)

An adaptive control device for changing the directivity of an array antenna, for use in a wireless device having an array antenna for transmitting and receiving radio frequency signals, comprising: Setting means for setting a parameter including a distance between the receiver receiving the radio frequency signal transmitted from the wireless device and the wireless device, and a relative moving speed and direction of movement of the receiver relative to the wireless device; Evaluation means for evaluating how much the received power of the receiver or the wireless device will change after a predetermined period of time; Weighting control means for adjusting a plurality of weighting factors for a plurality of antenna elements included in the array antenna; Integrating means for calculating an integral value over a predetermined period of the received power; And the directivity is changed so that the amount of change of the received power and the integral value are within a certain range that does not depend on the distance between the receiver and the wireless device. delete The method of claim 1, The setting means has a distance calculating means for calculating the distance by using a known relationship between the received power value received at the array antenna and the amount of propagation attenuation of radio waves. Device. The method of claim 3, And the distance calculating means is configured to calculate the distance based on the received power value received by one antenna element. The method of claim 3, And the distance calculating means is configured to calculate the distance based on the received power values received by the plurality of antenna elements. The method of claim 1, The setting means, Fourier transform means for obtaining a frequency spectrum of the signal received by the array antenna; Velocity estimation means for obtaining the relative velocity by determining a Doppler frequency shift based on the frequency spectrum Adaptive control device having a. The method of claim 6, And the Fourier transforming means of the setting means is configured to obtain a frequency spectrum based on a signal received by one antenna element. The method of claim 6, And the Fourier transforming means of the setting means is configured to obtain a frequency spectrum based on signals received from a plurality of antenna elements. The method of claim 1, The setting means, A first parameter including a distance between the receiver and a wireless device that receives a radio frequency signal transmitted from the wireless device based on a received signal from an array antenna, and a relative moving speed and direction of movement of the receiver relative to the wireless device First setting means for setting a; Storage means connected to an output of said first setting means and storing past parameters used for determining weight factors to be sequentially updated; Second setting means for outputting the second parameter estimated as the current parameter by using the parameter stored in the storage means. With The weighting control means calculates a first weighting factor based on the first parameter, and a second weighting factor based on the second parameter, The weighting control means has a higher difference amount between the main direction of the first directivity that can be realized by the first weighting factor and the main direction of the second directivity that can be realized by the second weighting coefficient than a predetermined value; And calculate the next weighting coefficient by using the second weighting coefficient as an initial value. The method of claim 9, The weighting control means includes a power that can be received by the receiver when the directivity of the array antenna is a first directivity and power that can be received by the receiver when the directivity of the array antenna is a second directivity. And when the difference amount is larger than a predetermined value, the next weighting coefficient is calculated as the initial value using the second weighting coefficient. The method of claim 1, The setting means, Based on a received signal from an array antenna, a first including a distance between the receiver and a wireless device receiving a radio frequency signal transmitted from the wireless device, a relative moving speed and direction of movement of the receiver relative to the wireless device; First setting means for setting a parameter, Storage means connected to an output of said first setting means and storing past parameters used for determining weight factors to be sequentially updated; Second setting means for estimating the current parameter and outputting it as a second parameter by using the parameter stored in the storage means; With The weighting control means calculates a first weighting coefficient based on the first parameter and a second weighting coefficient based on the second parameter, When the adaptive control device differs from the main direction of directivity that can be realized by the first weighting coefficient and the main direction of directivity that can be realized by the second weighting coefficient, the above-mentioned value is greater than the predetermined value. And correction means for feeding back information on the second weighting coefficient to the first setting means to correct the first parameter. The method of claim 11, The correcting means is configured to determine the power that the receiver can receive when the directivity of the array antenna is the first directivity and the power that the receiver can receive when the directivity of the array antenna is the second directivity. And when the difference amount is larger than a predetermined value, the information relating to the second weighting coefficient is fed back to the first setting means to correct the first parameter. The method of claim 1, And the receiver is a mobile terminal used in a cellular communication system, and the wireless device is a wireless base station provided for each cell. The method of claim 13, And when the mobile terminal handovers between cells, the parameters related to the mobile terminal are also delivered.

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