JP6142451B2 - Tracking antenna device - Google Patents

Description

  The present invention relates to a tracking antenna apparatus that tracks a mobile body, and more particularly, to a tracking antenna apparatus that performs MIMO (Multi-Input Multi-Output) communication with a plurality of mobile bodies. .

  In a system that performs wireless communication with a mobile unit, in order to achieve high-speed and stable communication with a mobile unit at a limited frequency, the directivity of the beam from the base station is adapted to the position of the mobile unit. Is controlled.

  For example, with respect to an in-vehicle mobile terminal, a plurality of antenna elements are used to direct radio waves in a desired direction so as not to be affected by unnecessary radio waves, and the beam is limited to the position where the terminal moving from the base station exists. An adaptive array antenna technology that communicates with the antenna is known (see Patent Document 1).

  In the technique disclosed in Patent Document 1, a base station that communicates with a mobile terminal that moves at high speed receives position information and mobility information of the mobile terminal from the mobile terminal, and new position information or mobility information is input. Until the current position information of the mobile terminal is sequentially estimated and calculated based on the position information and mobility information input so far, antenna control parameters for the estimated current position information are determined, and an antenna for the mobile terminal is determined. The beam is formed using a plurality of antenna series.

  In addition, when communicating between a flying object that circulates in a predetermined orbit and a ground base station, such as satellite communication, the tracking antenna device on the base station side receives various sensor information and communication from the other party. There is a case where the pointing direction estimation or the pointing direction error amount is detected from the signal, and the pointing direction (elevation angle and azimuth angle) of the directional antenna is mechanically controlled (Non-Patent Document 1).

  Further, Patent Document 2 discloses that the tracking antenna device is coupled to the configuration of the tracking antenna device that performs such mechanical control, so that the tracking antenna device can be mechanically directed to each directional antenna. A high tracking performance can be obtained by performing a directivity control that adjusts the excitation phase and amplitude of each antenna, and a directivity direction that is roughly adjusted for each directional antenna. A tracking antenna device is disclosed. In this case, in the tracking antenna device, the mechanism that mechanically tracks the directivity direction of each directional antenna does not require a high-resolution tracking function with high resolution, and can be handled only by coarse adjustment, thus reducing the weight with a simple configuration. In addition, cost reduction can be achieved.

JP 2006-217228 A JP 2012-44596 A

Inoue et al., Marine Antenna System for Realization of Next Generation Broadband, Journal of the JIME vol.41, No.6 (2006)

  However, although the invention disclosed in Patent Document 1 is intended for communication with a mobile terminal moving at high speed, multi-user MIMO communication is performed in a situation where interference between mobile terminals becomes large. Not assumed. Rather, when a plurality of mobile terminals are gathered in a limited area and move in substantially the same way, by virtually estimating the position as a representative terminal and performing antenna control with the same parameters, the plurality of mobile terminals This is a technology that follows a mobile terminal with a beam even in an environment where the vicinity of a base station moves at a high speed all at once.

  Also, the technology disclosed in Patent Document 2 basically assumes a phased array for control for tracking one satellite, and does not assume multi-user MIMO communication.

  FIG. 12 is a diagram illustrating the concept of the configuration of multiuser MIMO.

  FIG. 12 shows an example of multi-user MIMO in which the base station transmits and the mobile station receives.

At this time, the transmission signals S ₁ and S _{2 of} the base station and the reception signals R ₁ and R ₂ of the mobile station are expressed by the following relational expressions.

ここで、送信信号を受信信号の関係を規定する行列Ｈは、「伝搬路行列」（または「チャネル応答行列」）と呼ばれる。

Here, the matrix H that defines the relationship between the transmission signal and the reception signal is called a “propagation channel matrix” (or “channel response matrix”).

When transmission signals S ₁ and S ₂ are transmitted (transmission precoding) so as to have values represented by the following equations, transmission information T ₁ and T ₂ are received without interference at the mobile station on the reception side.

ここで、送信情報Ｔ₁，Ｔ₂は、それぞれ、各移動局（ユーザ）に対する送信ストリームである。上式のようなプリコーディングは、ゼロフォーシング法と呼ばれる方式である。プリコーディングの手法は、これに限られないが、原理的には、送信情報Ｔ₁，Ｔ₂に対して、重み行列を乗算することで送信信号を生成し、受信側の移動局での、送信情報Ｔ₁，Ｔ₂の間の干渉が小さくなるように、所定の規範に基づいて重み行列が算出される。

Here, each of the transmission information T ₁ and T ₂ is a transmission stream for each mobile station (user). Precoding like the above equation is a method called a zero forcing method. The precoding method is not limited to this, but in principle, a transmission signal is generated by multiplying the transmission information T ₁ and T ₂ by a weighting matrix. A weight matrix is calculated based on a predetermined standard so that interference between the transmission information T ₁ and T ₂ is reduced.

  FIG. 13 is a conceptual diagram showing the relationship between the temporal change of the elements of the matrix H and the predicted value when the mobile station moves.

  As shown in FIG. 13A, the elements of the matrix H vary with time due to movement of the mobile station.

  At this time, for example, in the case of a TDD (Time Division Duplex) system, the base station detects the matrix H from the received signal at the reception timing from the mobile station.

In TDD, since reception and transmission cannot be performed at the same time, a propagation path matrix H at a transmission timing is predicted from a past received signal, and an inverse matrix H ⁻¹ of the matrix H is obtained at the time of base station transmission.

  As shown in FIG. 13B, the prediction method in this case is generally linear prediction or polynomial approximation.

  In this case, for example, when the mobile station is moving along a predetermined trajectory such as a road or a track, such prediction is often appropriate.

  However, when the mobile station moves in a free trajectory like an airplane and performs multiuser MIMO communication as described above, the prediction of the propagation path matrix is not possible with simple extrapolation values from the past. It may be enough. For example, even when the mobile station is moving along a predetermined trajectory as described above, for example, a plurality of mobile stations are moving in different directions with respect to intersecting trajectories. It can also occur in such cases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to perform multiuser MIMO communication with a plurality of mobile terminals while suppressing interference between the terminals. It is providing the tracking antenna device which can be performed.

  According to one aspect of the present invention, there is a tracking antenna device, a plurality of tracking antennas, directivity direction tracking means for controlling the directivity directions of the plurality of tracking antennas to track a plurality of mobile stations, and a plurality of tracking antenna devices Transmission means for multiplying a stream of transmission information corresponding to each mobile station by a weight matrix for individually transmitting to and from a plurality of mobile stations, and transmitting from a plurality of tracking antennas, Mobile object position estimating means for estimating the position of the station, a propagation path matrix detected from received signals from the plurality of tracking antennas, and a plurality of tracking antennas calculated based on the estimated position of the mobile station The propagation matrix for predicting the channel matrix of the timing at which signals are transmitted from the plurality of tracking antennas is estimated based on the expected angle at which each mobile station is expected and the distance between each of the plurality of tracking antennas and the mobile station. Including a road predicting means, based on the predicted channel matrix, and a weighting coefficient control means for calculating a weight matrix.

  Preferably, the propagation path predicting means has a first value at a first timing at which the propagation path matrix is detected from the distance reception signal with respect to a product of the expected angle dependence function of the directivity characteristic of the tracking antenna and the propagation characteristic function with respect to the distance. And a change amount of the propagation path is estimated by a ratio of the second value at the second timing at which signals are transmitted from the plurality of tracking antennas, and from the change amount and the propagation path matrix detected at the first timing, A propagation path matrix at the second timing is predicted.

  Preferably, when the mobile station antenna of the mobile station has directivity, the propagation path predicting means calculates the ratio value by adding the directivity characteristics of the mobile station antenna according to the angle at which the mobile station antenna looks at the tracking antenna. .

Preferably, the propagation path predicting unit has a first value at a first timing at which a propagation path matrix is detected from the received signal, with respect to a product of the expected angle dependence function of the directivity characteristic of the tracking antenna and the propagation characteristic function with respect to the distance. The virtual change amount of the propagation path is estimated based on the ratio of the second value when the directivity direction of the plurality of tracking antennas is changed by the virtual angle at the second timing at which signals are transmitted from the plurality of tracking antennas. A channel matrix at the second timing is calculated from the quantity and the channel matrix detected at the first timing, and the evaluation function representing the communication quality with the mobile station satisfies a predetermined angle satisfying a predetermined condition. Deriving and predicting a propagation matrix corresponding to the sufficiency angle as a propagation path matrix at the second timing, and the directivity direction tracking means changes the directivity direction by a plurality of tracking antennas by the sufficiency angle.

  Preferably, when the mobile station antenna of the mobile station has directivity, the propagation path predicting means calculates the ratio value by adding the directivity characteristics of the mobile station antenna according to the angle at which the mobile station antenna looks at the tracking antenna. .

  According to another aspect of the present invention, there is a tracking antenna device, a plurality of tracking antennas, directing direction tracking means for controlling the directivity directions of the plurality of tracking antennas to track a plurality of mobile stations, and a plurality of tracking antenna devices The reception signal from the tracking antenna is multiplied by a weight matrix for individually receiving signals from a plurality of mobile stations, and received to separate reception information streams respectively corresponding to the plurality of mobile stations. Means, a mobile object position estimating means for estimating the position of the mobile station, a propagation path matrix detected from received signals from a plurality of tracking antennas, and a plurality of positions calculated based on the estimated position of the mobile station A channel matrix of timing for separating signals from a plurality of tracking antennas according to an estimated angle at which each of the tracking antennas expects a mobile station and a distance between each of the plurality of tracking antennas and the mobile station It includes a channel prediction means for predicting, based on the predicted channel matrix, and a weighting coefficient control means for calculating a weighting factor.

Preferably, the propagation path predicting unit has a first value at a first timing at which a propagation path matrix is detected from the received signal, with respect to a product of the expected angle dependence function of the directivity characteristic of the tracking antenna and the propagation characteristic function with respect to the distance. The virtual change amount of the propagation path is estimated by the ratio of the second value when the directivity direction of the plurality of tracking antennas is changed by the virtual angle at the second timing at which the signals are separated from the plurality of tracking antennas. A channel matrix at the second timing is calculated from the quantity and the channel matrix detected at the first timing, and the evaluation function representing the communication quality with the mobile station satisfies a predetermined angle satisfying a predetermined condition. Deriving and predicting a propagation matrix corresponding to the sufficiency angle as a propagation path matrix at the second timing, and the directivity direction tracking means changes the directivity direction by a plurality of tracking antennas by the sufficiency angle.

  According to the tracking antenna apparatus of the present invention, it is possible to perform multiuser MIMO communication with a plurality of mobile terminals while suppressing interference between the terminals.

1 is a conceptual diagram illustrating a configuration of a wireless communication system including a tracking antenna device according to a first embodiment. It is a figure which shows the change of the positional relationship of a base station and a mobile station. It is a figure which shows the time change of a propagation path matrix when a mobile station moves with respect to a base station. 2 is a functional block diagram for explaining the configuration of a base station 200. FIG. It is a conceptual diagram which shows the parameter used for the process which the propagation path prediction part 42 performs. It illustrates predicted channel matrix elements of the predictive value h _'mn to (T _b). FIG. 6 is a functional block diagram for explaining a configuration of a base station 200 'of the second embodiment. 6 is a conceptual diagram illustrating a configuration of a wireless communication system including a tracking antenna device according to Embodiment 3. FIG. FIG. 11 is a functional block diagram for explaining a configuration of a base station 200 ″ of a third embodiment. It is a conceptual diagram for demonstrating the process of the propagation path estimation part 42 '. 10. Directional antenna by tracking antenna control unit 20 ' It is a figure for demonstrating control of the directivity direction of m. It is a figure which shows the concept of a structure of multiuser MIMO. It is a conceptual diagram which shows the relationship between the time change of the element of the matrix H when a mobile station moves, and a predicted value.

Hereinafter, a radio communication system including a tracking antenna apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, components and processing steps given the same reference numerals are the same or equivalent, and the description thereof will not be repeated unless necessary.
[Embodiment 1]
FIG. 1 is a conceptual diagram showing a configuration of a wireless communication system including the tracking antenna device of the first embodiment.

  When wireless communication is performed in an area where the base station has a good view, such as in the air or at sea, the reach can be increased by tracking the mobile station with a high-gain directional antenna. Here, although not particularly limited, for example, mobile stations 100.1 and 100.2 are assumed to be airplanes.

  In FIG. 1, a base station 200 having a tracking antenna device and capable of directing an antenna in the direction of a mobile station includes a plurality of directional antennas 10. Multi-user MIMO communication is performed with the mobile station 100.1 and the mobile station 100.2 by m (m: natural number).

For example, the base station 200 includes two directional antennas 10.1 and 10.2, and each of the mobile stations 100.1 and 100.2 includes one antenna 2.
(If a simple extrapolation from the past is not sufficient for channel matrix prediction)
In the following, in the configuration as shown in FIG. 1, a case where simple extrapolation values from the past are not sufficient for prediction of the channel matrix will be described.

  FIG. 2 is a diagram illustrating a change in the positional relationship between the base station and the mobile station.

  FIG. 3 is a diagram showing a time change of the propagation path matrix when the mobile station moves relative to the base station.

As shown in FIG. 2A, from time T ₁ to time T ₂ , the mobile stations 100.1 and 100.2 move in the approaching direction. h ₁₂ and h ₂₁ increase as shown in FIG.

However, as shown in FIG. 2 (b), the mobile station 100.1 and 100.2 at the time T _2, is the after closest approach, time T _2, and later go away. Therefore, after time T ₂ , the elements h ₁₂ and h ₂₁ representing interference decrease as shown in FIG.

Thus, when the tendency of fluctuations in the elements of the propagation path matrix changes suddenly, the prediction error based on the past propagation path information increases the prediction error.
(Operation of base station 200)
The base station 200 operates as follows in order to suppress an increase in the prediction error as described above.

  That is, the base station 200 stores information related to the moving path of the mobile station in advance in a storage device or the like in order to determine the direction of tracking the mobile station, and the tracking antenna control unit 20 follows the information on the moving path. Control the directivity direction of the directional antennas 10.1 and 10.2. Such directivity control can use the mechanical control as described above. However, the mechanical control may be configured as coarse movement, and more accurate directivity may be controlled by electronic control such as a phased array.

  In this case, the tracking antenna control unit 20 of the base station knows in advance the position of each mobile station in the future and the pointing direction of the tracking antenna that is driven so as to point in the direction of the mobile station correspondingly. become. The propagation path prediction unit 42 of the base station can accurately predict the following information from the movement path information from the tracking antenna control unit 20 and the pointing direction of the tracking antenna, as will be described later.

i) Change in angle at which each mobile station is viewed from each tracking antenna ii) Change in distance between each tracking antenna and each mobile station Assuming that the base station 200 also operates in TDD, these information and the previously acquired tracking Using the antenna directivity, it is possible to improve the accuracy of prediction of the amplitude and phase of the propagation path at the transmission timing.

  FIG. 4 is a functional block diagram for explaining the configuration of base station 200.

  Referring to FIG. 4, base station 200 includes first to m-th directional antennas 10.1-10. m, transmission devices 30.1 and 30.2, weight control unit 40, and reception devices 50.1 and 50.2. As described above, although not particularly limited here, for convenience of explanation, it is assumed that the number m of directional antennas is two, and the multi-user between the two mobile stations 100.1 and 100.2. A description will be given assuming that MIMO communication is performed.

  Directional directions of the directional antennas 10.1 to 10.2 are controlled by drive mechanisms 12.1 and 12.2 controlled by the tracking antenna control unit 20, respectively. The tracking antenna control unit 20 is based on the information on the movement path of the mobile station stored in the storage unit 48, and the directional antennas 10.1 to 10.10 according to the position of the moving body estimated by the moving body position estimation unit 46. .2 Directivity is controlled.

Transmitting device 30.1 is a multi-user MIMO modulating section 32.1 for modulating transmission information T ₁ is the first transmission stream transmitted in the communication, the transmission of the output and below the modulation section 32.1 device 30. Among the processes of multiplying the outputs of the modulation unit 32.2 included in 2 by the weight matrices w _{11 to} w ₂₂ calculated by the weight control unit 40, the transmission signal S ₁ is generated from the directional antenna 10.1. And a multiplication processing unit 34.1 related to.

  The output from the multiplication processing unit 34.1 is sent from the directional antenna 10.1.

Transmitting device 30.2, modulates transmission information T ₂ in a multi-user MIMO communication is a second transmission streams to be transmitted to multiplied by the weight matrix, is sent from the directional antenna 10.2, the transmitter It has the same configuration as 30.1.

The receiving apparatus 50.1 separates the signal received from the mobile station 100.1 by multiplying the signal received by the directional antennas 10.1 to 10.2 by the weight matrix calculated by the weight control unit 40. And a demodulator 54.1 that outputs the _first received stream as the received signal R1 by demodulating the output of the multiplier 52.1. The reception device 50.2 separates the signal from the mobile station 100.2 by multiplying the signal received by the directional antennas 10.1 to 10.2 by the weight matrix calculated by the weight control unit 40. In order to output the second reception stream as the reception signal R ₂ by demodulating, the configuration is the same as that of the reception device 50.1.

The weight control unit 40 estimates the propagation path matrix H at the reception timing Ta from the signals received by the directional antennas 10.1 to 10.2, and uses the information from the tracking antenna control unit 20 as described below. In addition, a propagation path prediction unit 42 that predicts a propagation path matrix at the transmission timing T _b is included.

  FIG. 5 is a conceptual diagram showing parameters used for processing performed by such a propagation path prediction unit 42.

Here, the detection of the channel matrix H at the reception timing T _a is assumed to be able to run in the same manner as the prior art.

  Further, the propagation path predicting unit 42 predicts the amount of change in the propagation path from the moving path and the tracking antenna directivity.

That is, the propagation path prediction unit 42 is estimated by the mobile body position estimation unit 46 and given to the mobile station 100. n (n = 1, 2) position information and tracking antenna directivity direction information from the tracking antenna control unit 20 based on the directional antenna 10. m (m = 1, 2) relative to the pointing direction of the mobile station 100. n, the angle θ _mn (t) where n is expected, and the directional antenna 10. m and the mobile station 100. A distance D _mn (t) between n is calculated.

Further, the propagation path prediction unit 42 includes the directional antenna 10. The directional characteristics of m and G _m (theta), and the propagation characteristics for the distance P (D), a channel time detected time the the H T _a, when the transmission timing and the time T _b, the directional antenna 10. m and the mobile station 100. A change amount Δ _mn of the propagation path between n is calculated as follows.

これら変数のうち、θ_mn(t)およびＤ_mn(t)は移動経路から、Ｇ_m(θ)およびＰ（Ｄ）は理論式や運用に先立って別途行う測定などから、予め知り得るものである。

Of these variables, θ _mn (t) and D _mn (t) can be known in advance from the movement route, and G _m (θ) and P (D) can be obtained in advance from theoretical formulas or measurements performed separately prior to operation. is there.

The propagation path prediction unit 42 multiplies each element h _mn (T _a ) of the propagation path information detected at time T _a by the change amount Δ _mn, thereby predicting the predicted value of the element of the propagation path matrix at time T _b . h ′ _mn (T _b ) is obtained as follows.

図６は、このようにして予測された伝搬路行列の要素の予測値ｈ’_mn（Ｔ_b）を示す図である。

FIG. 6 is a diagram showing predicted values h ′ _mn (T _b ) of elements of the propagation path matrix predicted in this way.

Unlike the case of FIG. 3, the use of the predicted change amount _Δmn improves the prediction accuracy.

The weighting coefficient control unit 44, based on the propagation path information predicted value h ′ _mn (T _b ) calculated by the propagation path prediction unit 42, gives weight matrices w _{11 to} w ₂₂ to the transmission devices 30.1 and 30.2. Is calculated. The calculation of the weight matrix is not particularly limited, but can be performed by the zero forcing method as described above.

  With the configuration and operation of the tracking antenna apparatus as described above, multi-user MIMO communication can be performed with a plurality of mobile terminals while suppressing interference between the terminals. In particular, it is possible to effectively suppress interference even in the case where the aspect of the temporal change of the elements of the propagation path matrix changes greatly, such as when the mobile objects move away after approaching each other.

Note that the calculation method of the predicted value h ′ _mn (T _b ) of the element of the propagation path matrix is not limited to the method described above, and for example, the following method may be used.

i) Predicted value of the element of the propagation path matrix by linear prediction (or prediction by polynomial approximation) and the predicted value h ′ _mn (T _b ) of the element of the propagation path matrix using the predicted variation Δ _mn as described above. Is used as the predicted value.

ii) In the case of a specific condition, the predicted value h ′ _mn (T _b ) of the element of the propagation path matrix using the predicted change amount Δ _mn is used as the predicted value, otherwise linear prediction (or polynomial) Predicted values of propagation path matrix elements by (prediction by approximation) are used.

Here, as an example of the “specific condition”, for example, any of the following conditions can be used:
a) The predicted value of the element of the channel matrix by linear prediction (or prediction by polynomial approximation) and the predicted value h ′ _mn (T _b ) of the element of the channel matrix using the predicted change amount Δ _mn (large) B) When the predicted change _Δmn is greater than a predetermined threshold value c) Either one of the conditions a) or b) is satisfied In the case where the antenna of the mobile station also has directivity, a method that considers the antenna directivity on the mobile station side in addition to the prediction of the change amount Δ _mn as described above is preferable.

That is, the mobile station 100. n (n = 1, 2) based on the traveling direction of the directional antenna 10. m is an angle φ _nm (t), and the mobile station 100. n antenna directivity is the directivity U _n (φ), the directional antenna 10. m and the mobile station 100. The change amount Δ _mn of the propagation path between n is expressed as follows:

ここで、φ_nm(t) は移動経路から、Ｕn(φ) は理論式や運用に先立って別途行う測定などから、予め知り得るものである。

Here, φ _nm (t) can be known in advance from the movement path, and Un (φ) can be known in advance from theoretical formulas or measurements separately performed prior to operation.

Therefore, by using such a predicted change amount Δ _mn , the channel prediction unit 42 obtains the predicted value h ′ _mn (T _b ) of the element of the channel matrix in the same manner as described above, The weight coefficient control unit 44 may calculate a weight matrix.
[Embodiment 2]
FIG. 7 is a functional block diagram for explaining the configuration of base station 200 ′ of the second embodiment.

  In base station 200 of the first embodiment, mobile body position estimation unit 46 estimates the position of the mobile body (mobile station) based on path information stored in advance in storage unit 48.

  On the other hand, in the mobile station 200 ′ of the second embodiment, the movement path of the mobile station is not set in advance, and the mobile stations 100.1 and 100.2 are controlled by the control signal from the base station 200 ′. A moving body control unit 60 is provided for controlling the moving direction and speed. That is, the control signal from the mobile control unit 60 is transmitted from the directional antennas 10.1 and 10.2 via the modulation units 32.1 and 32.2. In this case, since the control amount is known on the base station 200 'side, the mobile body position estimation unit 46 predicts the mobile station position after the control.

  Therefore, in mobile station 200 ′ of the second embodiment, in the configuration of base station 200 of the first embodiment, mobile unit control unit 60 is provided instead of storage unit 48 that stores the information on the movement path. Since it is the same as that of the structure of base station 200 of Embodiment 1 except being described, the description about the same part is not repeated.

Effects similar to those of the base station 200 of the first embodiment can also be obtained by the configuration and operation of the base station 200 ′ of the second embodiment.
[Embodiment 3]
FIG. 8 is a conceptual diagram showing a configuration of a wireless communication system including the tracking antenna device of the third embodiment.

  In the first embodiment or the second embodiment, the directional antenna 10. m predicted the propagation path on the premise that it is driven to point in the direction of the mobile station.

  As described below, the base station 200 ″ according to the third embodiment has a configuration in which the optimal directivity direction of the tracking antenna is determined based on the movement path and the tracking antenna is driven in this direction from the viewpoint of communication quality.

  In particular, when the mobile stations are close to each other, the communication quality is improved by directing the direction in which the directivity gain is reduced with respect to other mobile stations receiving interference rather than directing the mobile station direction itself. There is.

  Therefore, base station 200 ″ of Embodiment 3 is configured to control the pointing direction of the tracking antenna so that the index related to communication quality is maximized or larger than a predetermined value based on the moving path of the mobile station.

  For this reason, the tracking antenna control unit 20 controls the directivity direction of the antenna based on not only the information on the moving path of the moving object but also the information from the propagation path predicting unit 42 ′.

  FIG. 9 is a functional block diagram for explaining a configuration of base station 200 ″ according to the third embodiment.

  As described below, in the configuration of the base station 200 of the first embodiment or the configuration of the base station 200 ′ of the second embodiment, except for the configuration of the transmission path prediction unit 42 ′ and the configuration of the tracking antenna control unit 20 ′ Since it is the same as the configuration of base station 200 of Embodiment 1 or the configuration of base station 200 ′ of Embodiment 2, description of the same parts will not be repeated.

  In FIG. 9, the configuration of the base station 200 ″ of the third embodiment is described based on the configuration of the base station 200 of the first embodiment.

  First, it is assumed that an evaluation function E (H) representing communication quality between the base station and the mobile station is determined in advance depending on the channel matrix H.

  Here, as an example of the evaluation function E (H), an average value or minimum value of C / (N + I) in each mobile station (where C: signal power, N: noise power, I: interference power), or propagation The average value or minimum value of the eigenvalues of the correlation matrix determined by the path matrix H can be mentioned.

  Here, for example, a case where the average value of C / (N + I) is used as the evaluation function will be specifically described.

  If C / (N + I) of the nth mobile station is CNRn, CNRn and E (H) are expressed by the following equations.

CNRn = | hmm | ² / (Σ | hmn | ² + Nn)
E (H) = average (CNRn)
Here, Σ means to take a sum when m ≠ n, and average (CNRn) means to take an average of CNRn mobile stations. Nn is noise power related to the nth mobile station, which can be separately known.

  FIG. 10 is a conceptual diagram for explaining the processing of the propagation path prediction unit 42 ′.

The propagation path predicting unit 42 ′ includes the directional antenna 10. Assuming that the angle m is rotated by δ _m (m = 1, 2) from the direction of the mobile station at time T _a to time T _b , the propagation path change amount (virtual change amount) in that case is Predict. That is, the directional antenna 10. m and the mobile station 100. The virtual change amount εmn of the propagation path between n is expressed by the following equation:

ただしγ_mは、時刻Ｔ_aにおける指向性アンテナ１０．ｍの指向方向と移動局の方向との差である。また、θ_mn(t)およびＤ_mn(t)、Ｇ_m(θ)およびＰ（Ｄ）は、実施の形態１と同様である。

However gamma _m is a directional antenna 10 at time T _a. The difference between the directivity direction of m and the direction of the mobile station. Also, θ _mn (t) and D _mn (t), G _m (θ) and P (D) are the same as those in the first embodiment.

The propagation path predicting unit 42 ′ multiplies each element h _mn (T _a ) of the propagation path information detected at time T _a by the virtual change amount ε _mn , so that the virtual propagation path matrix element h at time T _b is obtained. ” _Mn (T _b , δ _m ) is obtained.

また、ｈ”_mn(Ｔ_b, δ_m)で構成される伝搬路行列を仮想伝搬路行列Ｈ”とする。

Further, a propagation path matrix composed of h ″ _mn (T _b , δ _m ) is assumed to be a virtual propagation path matrix H ″.

For the virtual propagation path matrix H ″, an evaluation function E (H ″) is obtained, and an angle δ _m (satisfaction angle) at which this is maximized or larger than a predetermined value is searched for to be an angle δ _{m, opt} . In FIG. 10, for the sake of simplicity of explanation, the antenna directivity direction is shown in two dimensions, but in reality, the virtual rotation angle δ _m has two elevation angles and azimuth angles. Contains elements.

Here, when obtaining C / (N + I) from the matrix H ″, the above h _mn etc. may be replaced with h ″ _mn etc.

Based on the propagation path matrix H ″ corresponding to the calculated angle δ _{m, opt} , the weight coefficient control unit 44 calculates a weight matrix in the same manner as in the first embodiment, and transmits the transmitters 30.1 and 30.2. Output to.

Channel prediction unit 42 ', the searched angle [delta] _{m, opt} tracking antenna control unit 20' passes to the tracking antenna control unit 20 'over the time T _b, the directional antenna 10. angle from the direction of the mobile station a directivity direction of m at time T _a [delta] _{m, opt} simply by rotating.

  FIG. 11 shows a directional antenna 10. It is a figure for demonstrating control of the directivity direction of m.

By the direction of the mobile station at the time T _a is rotated by an angle [delta] _{m, opt,} orientation of the tracking antenna at time T _b is determined.

  Even with the configuration and operation as described above, multi-user MIMO communication can be performed with a plurality of mobile terminals while suppressing interference between the terminals. In particular, it is possible to effectively suppress interference even in the case where the aspect of the temporal change of the elements of the propagation path matrix changes greatly, such as when the mobile objects move away after approaching each other.

Note that it is desirable to limit the search range of the virtual rotation angle δ _{m in} order to prevent a situation in which the pointing direction of the tracking antenna is greatly deviated from the direction of the mobile station due to error accumulation or the like.

Further, when the mobile station antenna has directivity, a method that considers the antenna directivity on the mobile station side in addition to the prediction of the change amount ε _mn as described above is preferable.

That is, the mobile station 100. n (n = 1, 2) based on the traveling direction of the directional antenna 10. m is an angle φnm (t), and the mobile station 100. n antenna directivity is the directivity U _n (φ), the directional antenna 10. m and the mobile station 100. The virtual change amount ε _mn of the propagation path between n is expressed as follows:

したがって、このような予測した仮想変化量εmnを用いることで、前述の方法と同様にして、伝搬路予測部４２’が、伝搬路行列の要素の予測値h”_mn（Ｔ_b）を得て、重み係数制御部４４が重み行列を算出することとしてもよい。

Therefore, by using the predicted virtual change amount εmn, the propagation path prediction unit 42 ′ obtains the predicted value h ″ _mn (T _b ) of the element of the propagation path matrix in the same manner as described above. The weight coefficient control unit 44 may calculate a weight matrix.

  In the above description using FIGS. 4, 7, and 9, the propagation path prediction units 42, 42 ′, the weight coefficient control unit 44, and the like are used in weight matrix multiplication processing at transmission timing in MIMO communication. It demonstrated as what performs the following processes.

  That is, the propagation path prediction units 42 and 42 ′ have a plurality of directional antennas 10. a propagation path matrix detected by a received signal from m, and a predicted angle at which each of a plurality of tracking antennas calculated based on the estimated positions of mobile stations 100.1 to 100.2 expects the mobile station, and a plurality of Directional antennas 10.1-10. Based on the distance between each of m and the mobile stations 100.1 to 100.2, a channel matrix of timing at which signals are transmitted from a plurality of tracking antennas is predicted.

  Thereby, the weight coefficient control unit 44 calculates a weight matrix at the time of signal transmission based on the propagation path matrix predicted in this way, and the multiplication processing units 34.1 to 34. m, and multiplying the transmission signal by the weight matrix calculated in this way, the directional antennas 10.1-10. A signal transmitted from m is generated.

  However, as shown in FIGS. 4, 7, and 9, the tracking antenna apparatus performs MIMO communication even during reception. Therefore, in the same way as at the time of transmission, the propagation path prediction units 42 and 42 ′, the weight coefficient control unit 44, and the multiplication processing units 52.1 to 52.2 are used in the weight matrix multiplication processing at the reception timing in MIMO communication. The following processing can be performed.

  That is, the propagation path prediction units 42 and 42 ′ have a plurality of directional antennas 10. a propagation path matrix detected by a received signal from m, and a predicted angle at which each of a plurality of tracking antennas calculated based on the estimated positions of mobile stations 100.1 to 100.2 expects the mobile station, and a plurality of Directional antennas 10.1-10. Based on the distance between each of m and the mobile stations 100.1 to 100.2, a channel matrix of timing for separating signals from a plurality of tracking antennas is predicted.

  The weight coefficient control unit 44 calculates a weight matrix for signal separation at the time of reception based on the propagation path matrix thus predicted, and the multiplication processing units 52.1 to 52.2 do in this way. The directional antennas 10.1-10. The received signal is separated by multiplying the signal from m.

  In addition, the propagation path prediction unit 42 ′ uses the first value at the first timing at which the propagation path matrix is detected from the received signal with respect to the product of the expected angle dependence function of the directivity characteristic of the tracking antenna and the propagation characteristic function with respect to the distance. And the virtual change amount of the propagation path is estimated by the ratio of the second values when the directivity directions of the plurality of antennas are changed by the virtual angle at the second timing for separating the signals from the plurality of tracking antennas. The evaluation function representing the communication quality with the mobile station by calculating the propagation path matrix at the second timing from the amount and the propagation path matrix detected at the first timing is the predetermined condition as described above. The satisfaction angle that satisfies is derived. The propagation path prediction unit 42 ′ may be configured to predict the propagation matrix corresponding to the satisfaction angle as the propagation path matrix at the second timing.

  Embodiment disclosed this time is an illustration of the structure for implementing this invention concretely, Comprising: The technical scope of this invention is not restrict | limited. The technical scope of the present invention is shown not by the description of the embodiment but by the scope of the claims, and includes modifications within the wording and equivalent meanings of the scope of the claims. Is intended.

  10.1, 10.2 Directional antenna, 12.1, 12.2 Drive mechanism, 20 Tracking antenna controller, 30.1, 30.2 Transmitter, 32.1, 32.2 Modulator, 34.1 , 34.2 Multiply processing unit, 40 Weight control unit, 42 Propagation path prediction unit, 44 Weight coefficient control unit, 46 Mobile object position estimation unit, 48 Storage unit, 50.1, 50.2 Receiver, 52.1, 52.2 multiplication processing unit, 54.1, 54.2 demodulation unit, 60 mobile control unit, 100.1, 100.2 mobile station, 200 base station.

Claims (7)

Multiple tracking antennas,
Directivity direction tracking means for controlling the directivity direction of the plurality of tracking antennas to track a plurality of mobile stations;
Transmission for transmitting from the plurality of tracking antennas by multiplying a stream of transmission information corresponding to each of the plurality of mobile stations by a weight matrix for individually transmitting to and from the plurality of mobile stations Means,
Mobile object position estimating means for estimating the position of the mobile station;
A propagation path matrix detected by signals received from the plurality of tracking antennas, an expected angle at which each of the plurality of tracking antennas calculated based on the estimated position of the mobile station expects the mobile station, and Propagation path prediction means for predicting a propagation path matrix of the timing of sending signals from the plurality of tracking antennas according to the distance between each of the tracking antennas and the mobile station;
A tracking antenna apparatus comprising: weight coefficient control means for calculating the weight matrix based on the predicted propagation path matrix. The propagation path prediction means includes
A first value at a first timing at which the propagation path matrix is detected from the distance received signal with respect to a product of an expected angle dependence function of a directivity characteristic of the tracking antenna and a propagation characteristic function with respect to the distance; The amount of change of the propagation path is estimated by the ratio of the second value at the second timing at which the signal is transmitted from the tracking antenna of the tracking antenna, and from the amount of change and the propagation path matrix detected at the first timing, The tracking antenna apparatus according to claim 1, wherein the propagation path matrix at a second timing is predicted. The propagation path prediction means includes
3. When the mobile station antenna of the mobile station has directivity, the directivity characteristic of the mobile station antenna corresponding to an angle at which the mobile station antenna expects the tracking antenna is added to calculate the ratio value. The tracking antenna device described. The propagation path prediction means includes
A first value at a first timing at which the propagation path matrix is detected from the received signal, as a product of a prospective angle dependence function of a directivity characteristic of the tracking antenna and a propagation characteristic function with respect to the distance, and the plurality of tracking A virtual change amount of a propagation path is estimated from a ratio of a second value when a directivity direction of the plurality of tracking antennas is changed by a virtual angle at a second timing at which a signal is transmitted from the antenna; The propagation path matrix detected at the first timing is used to calculate the propagation path matrix at the second timing, and the evaluation function representing the communication quality with the mobile station satisfies a predetermined condition. Deriving an angle, predicting the propagation matrix corresponding to the sufficiency angle as the propagation path matrix at the second timing,
The tracking antenna device according to claim 1, wherein the directivity direction tracking unit changes the directivity direction of the plurality of tracking antennas by the sufficiency angle. The propagation path prediction means includes
5. When the mobile station antenna of the mobile station has directivity, the directivity characteristic of the mobile station antenna according to an angle at which the mobile station antenna looks at the tracking antenna is added to calculate the ratio value. The tracking antenna device described. Multiple tracking antennas,
Directivity direction tracking means for controlling the directivity direction of the plurality of tracking antennas to track a plurality of mobile stations;
The received signals from the plurality of tracking antennas are multiplied by a weight matrix for individually receiving signals from the plurality of mobile stations, and separated into reception information streams respectively corresponding to the plurality of mobile stations. Receiving means for
Mobile object position estimating means for estimating the position of the mobile station;
A propagation path matrix detected by signals received from the plurality of tracking antennas, an expected angle at which each of the plurality of tracking antennas calculated based on the estimated position of the mobile station expects the mobile station, and A channel prediction means for predicting a channel matrix of timing for separating signals from the plurality of tracking antennas according to the distance between each of the plurality of tracking antennas and the mobile station;
A tracking antenna apparatus comprising: weight coefficient control means for calculating the weight matrix based on the predicted propagation path matrix. The propagation path prediction means includes
A first value at a first timing at which the propagation path matrix is detected from the received signal, as a product of a prospective angle dependence function of a directivity characteristic of the tracking antenna and a propagation characteristic function with respect to the distance, and the plurality of tracking A virtual change amount of a propagation path is estimated by a ratio of a second value when a directivity direction of the plurality of tracking antennas is changed by a virtual angle at a second timing for separating a signal from the antenna; The propagation path matrix detected at the first timing is used to calculate the propagation path matrix at the second timing, and the evaluation function representing the communication quality with the mobile station satisfies a predetermined condition. Deriving an angle, predicting the propagation matrix corresponding to the sufficiency angle as the propagation path matrix at the second timing,
The tracking antenna device according to claim 6, wherein the directivity direction tracking unit changes the directivity direction of the plurality of tracking antennas by the sufficiency angle.

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