JP2008092062A - Beam controller, array antenna system and radio apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the time variation of the average SINR from being reduced caused by a fixed output level difference among antenna elements when causing the time variation of the average SINR on the reception side by controlling the phase amount of signals radiated from respective antenna elements. <P>SOLUTION: The beam controller is provided with a beam control part 16 for calculating a phase control amount for varying the phase amount timewise to the signals of the antenna element 11a-2 and also calculating a level control amount for varying a level timewise to the signals of the antenna element 11a-2. The beam control part 16 calculates the level control amount for varying a level difference between the signals of the respective antenna elements 11a-1 and 11a-2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a beam control apparatus, an array antenna system, and a radio apparatus.

As a conventional beam control device, for example, the one described in Patent Document 1 is known. In the prior art described in Patent Document 1, in a beam control device that controls the radiation pattern of an array antenna having a plurality of antenna elements, the angular velocity with respect to the phase amount of the signal radiated from each antenna element with reference to a fixed angular velocity A fluctuation amount that varies with time is given by the fluctuation function. Thus, in a mobile communication system that performs scheduling and adaptive channel assignment based on SINR (Signal to Interference plus Noise power Ratio) in the mobile station, the base station varies the gain of the combined beam for each mobile station over time. Thus, fading can be artificially generated. Further, by using an array antenna that can arbitrarily generate different gains for each direction, it is possible to generate fading having different time variations between mobile stations. As a result, even if the mobile station or an object around the mobile station is stationary or moving at a low speed and the instantaneous fluctuation of the propagation path due to multipath fading does not occur sufficiently, artificially between the mobile stations By generating fading having different time variations, it is possible to actively vary the average SINR over time, and to prevent the transmission throughput of each mobile station from being biased. Further, the phase variation amount is temporally varied by the angular velocity fluctuation function so that the SINR time variation characteristic of each mobile station does not have periodicity, and the SINR time variation characteristic is biased between the mobile stations. At the same time, a sufficient amount of instantaneous fluctuation of the SINR time fluctuation characteristic is secured.
JP 2006-196978 A

  However, in the above-described prior art, the phase amount is controlled. However, if there is a fixed output level difference between antenna elements due to the mutual coupling amount between the antenna elements, synthesis is performed even if the phase amount is controlled. There is a case where the gain of the combined beam does not change so much because it is not sufficiently reflected in the beam. As a result, the time variation of the average SINR on the receiving side cannot be sufficiently caused. As a method for dealing with this, it is conceivable to introduce a calibration device for calibrating the output level difference between antenna elements into each base station device, but there are problems such as a complicated device configuration. is there.

  The present invention has been made in consideration of such circumstances, and its object is to control the phase amount of a signal radiated from each antenna element to cause a variation in time of the average SINR on the receiving side. An object of the present invention is to provide a beam control apparatus, an array antenna system, and a radio apparatus capable of preventing the temporal variation of the average SINR from being reduced due to a fixed output level difference between elements.

  In order to solve the above-described problems, a beam control apparatus according to the present invention is a beam control apparatus that controls a radiation pattern of an array antenna having a plurality of antenna elements. A phase control amount calculating means for calculating a phase control amount for changing the level control amount, and a level control amount calculating means for calculating a level control amount for changing the level in time with respect to the signal of the antenna element. The amount calculation means calculates a level control amount that varies a level difference between the signals of the antenna elements.

  An array antenna system according to the present invention includes an array antenna having a plurality of antenna elements, the beam control apparatus according to claim 1, and a phase of a signal of the antenna element based on a phase control amount obtained by the beam control apparatus. Phase adjustment means for adjusting the amount, and level adjustment means for adjusting the signal level of the antenna element based on the level control amount obtained by the beam control device are provided.

  A radio apparatus according to the present invention is a radio apparatus that performs time slot scheduling and adaptive channel allocation based on a state of a radio propagation path, and includes the array antenna system according to claim 2.

  According to the present invention, when the level difference between the signals of the antenna elements fluctuates, the time variation of the average SINR on the receiving side is caused by controlling the phase amount of the signal radiated from each antenna element. The influence of the fixed output level difference between the antenna elements can be almost ignored, and the control result of the phase amount is sufficiently reflected in the combined beam. As a result, the gain of the combined beam for each receiving station can be sufficiently varied in time, and the time variation of the average SINR on the receiving side can be prevented from being reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an array antenna system 10 according to an embodiment of the present invention. In FIG. 1, the array antenna unit 11 has two antenna elements 11a-1 and 11a-2. The beam forming unit 12 includes a distributor 13, a phase shift adjustment unit 14, and a level adjustment unit 15. The phase shift adjustment unit 14 and the level adjustment unit 15 are provided for the antenna element 11a-2.

  The distributor 13 distributes the input transmission signal to the antenna elements 11a-1 and 11a-2 at the time of transmission, and synthesizes and outputs the reception signals of the antenna elements 11a-1 and 11a-2 at the time of reception.

  The phase shift adjustment unit 14 can arbitrarily change the phase amount of the signal transmitted via the antenna element 11a-2. By manipulating this phase amount, the phase difference between signals transmitted through the antenna elements 11a-1 and 11a-2 can be adjusted.

  The level adjusting unit 15 can arbitrarily change the level (amplitude) of a signal transmitted via the antenna element 11a-2. By this level operation, the level difference between signals transmitted through the antenna elements 11a-1 and 11a-2 can be adjusted.

  The beam control unit 16 instructs the phase shift adjustment unit 14 on the phase control amount θ (t). The phase shift adjustment unit 14 gives the phase control amount θ (t) to the signal transmitted via the antenna element 11a-2. Thereby, the phase difference between the signals transmitted by the antenna elements 11a-1 and 11a-2 is controlled to θ (t).

  In addition, the beam control unit 16 instructs the level adjustment unit 15 about the level control amount A (t). The level adjustment unit 15 gives the level control amount A (t) to the signal transmitted through the antenna element 11a-2. Thereby, the level difference between the signals transmitted by the antenna elements 11a-1 and 11a-2 is controlled to A (t).

FIG. 2 is a block diagram showing a configuration of the beam control unit 16 shown in FIG. In FIG. 2, the beam control unit 16 includes a beam control phase unit 21 and a beam control level unit 22.
The beam control phase unit 21 generates a phase control amount θ (t). The phase control amount θ (t) may be a phase shift amount that varies with time at a fixed angular velocity, or a phase shift amount that varies with time according to an angular velocity fluctuation function with reference to the fixed angular velocity. Also good. The angular velocity fluctuation function is a random function whose average between angular velocity fluctuation periods is zero.

  The beam control level unit 22 generates a level control amount A (t). The level control amount A (t) will be described in detail below.

As the level control amount A (t), a random function in which the average between the level fluctuation periods T [s] becomes the average level A _Const [dBm] is used. The level change amount of the level control amount A (t) per time slot is assumed to be sufficiently small. A specific example of the level fluctuation function A (t) that gives the level control amount A (t) is shown below.

(Example 1)
A (t) = A _Const + α × sin ((2 × π × t / T) + φ _Initial ) (1)
Where α is the coefficient of variation [dBm] and φ _Initial is the initial constant [rad].

(Example 2)
A (t) = A _Const + α × PN (t, T) (2)
Where α is the coefficient of variation [dBm]. Further, PN (t, T) is a pseudo-random sequence having a length of T / Δt and elements of {−1, 1}, and its cycle is a level fluctuation cycle T.

Next, the level control processing procedure according to the present embodiment will be described with reference to FIG. FIG. 3 is a control flowchart of the beam control level unit 22 shown in FIG.
In FIG. 3, first, the beam control level unit 22 performs initial setting (S1). Specifically, the initial setting of the average level A _Const [dBm] and the initial setting of each parameter of the level fluctuation function A (t) are performed. Next, the time t = t + Δt is set (S2), and the value of the level fluctuation function A (t) is calculated (S3). Next, the calculation result of the level fluctuation function A (t) is output to the level adjustment unit 15 as a level control amount A (t) (S4). Thereafter, the above steps S2 to S4 are repeated.

  As described above, according to the present embodiment, a level difference is given by the level control amount A (t) to the signal transmitted by each antenna element. Therefore, even if there is a fixed output level difference between the antenna elements due to a characteristic difference between the antenna circuit elements, the level difference between signals transmitted by each antenna element varies. As a result, when the time variation of the average SINR on the receiving side is caused by controlling the phase amount of the signal radiated from each antenna element, the influence of the fixed output level difference between the antenna elements can be almost ignored. Thus, the control result of the phase amount is sufficiently reflected in the combined beam. As a result, the gain of the combined beam for each receiving station can be sufficiently varied in time. Therefore, it is possible to prevent the time variation of the average SINR on the receiving side from being reduced.

  The number of antenna elements of the array antenna may be three or more. In this case, the phase control amount θ (t) can be obtained as “N−1” relative phase vectors with respect to N antenna elements with reference to one antenna element. Each relative phase vector is calculated from an independent fixed angular velocity or angular velocity fluctuation function. Similarly, the level control amount A (t) can be obtained as “N−1” relative level vectors with respect to N antenna elements with reference to one antenna element. Each relative level vector is calculated from an independent level fluctuation function.

FIG. 4 shows a configuration of the array antenna system 10 having N (three or more elements) antenna elements. 4, the beam control unit 16 applies relative phase vectors θ ₁ (t) and θ ₂ (respectively) to the phase shift adjustment unit 14 provided corresponding to each of the antenna elements 11a-2, 3,. t), θ ₃ (t),..., θ _N−1 (t) are output. Further, the beam control unit 16 applies relative level vectors A ₁ (t), A ₂ (t), A to a level adjustment unit 15 provided corresponding to each of the antenna elements 11a-2, 3,. A ₃ (t),..., A _N-1 (t) are output.

  FIG. 5 is an example of a base station (wireless device) 100 according to the present embodiment. A base station 100 shown in FIG. 5 is a base station of a packet-switched mobile communication system using time division multiple access. In the downlink from the base station 100 to the mobile station 200, based on the state of the radio propagation path, Time slot scheduling and adaptive channel assignment. Also, the mobile station 200 measures SINR indicating the state of the downlink radio propagation path, and notifies the base station 100 of the SINR of the measurement result.

  In FIG. 6, a base station 100 includes an array antenna system 10 according to the present embodiment, and the array antenna system 10 transmits and receives radio sections between mobile stations 200. The basic configurations of base station 100 and mobile station 200 other than array antenna system 10 shown in FIG.

  According to this embodiment, the beam pattern radiated from the base station 100 by the array antenna system 10 changes according to the angular velocity fluctuation function with reference to the fixed angular velocity or the fixed angular velocity. Here, even if there is a fixed output level difference between the antenna elements of the array antenna system 10, the influence can be almost ignored by the level operation according to the present embodiment. Thereby, each base station 100 can artificially generate sufficient fading independently. Therefore, in each mobile station, the radiation patterns of the communication base station (desired base station) and the interference base station (undesired base station) change independently, and the received signal from each base station varies instantaneously independently. Therefore, SINR instantaneously varies independently for each mobile station. Thereby, the base station 100 can perform transmission with high transmission efficiency by performing scheduling and adaptive channel allocation according to the SINR of each mobile station.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.
For example, in the above-described embodiment, the case where the transmission beam is controlled has been described as an example, but the present invention can be similarly applied to the reception beam.

  The present invention is also applicable to mobile communication systems such as time division multiple access packet switching cellular systems and wireless LAN systems using scheduling functions and adaptive channel assignment functions. For example, it can be applied to a CDMA2000 1xEV-DO system, a W-CDMA HSDPA system, or the like.

It is a block diagram which shows the structure of the array antenna system 10 which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the beam control part 16 shown in FIG. FIG. 3 is a control flowchart of the beam control level unit 22 shown in FIG. 2. It is a block diagram which shows the structure of the array antenna system 10 which concerns on other embodiment of this invention. It is a block which shows the structure of one Example of the base station (radio | wireless apparatus) 100 which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Array antenna system, 11 ... Array antenna part, 11a ... Antenna element, 12 ... Beam formation part, 13 ... Divider, 14 ... Phase shift adjustment part, 15 ... Level adjustment part, 16 ... Beam control part, 21 ... Beam Control phase section, 22 ... Beam control level section, 100 ... Base station, 200 ... Mobile station

Claims (3)

In a beam control apparatus for controlling a radiation pattern of an array antenna having a plurality of antenna elements,
A phase control amount calculating means for calculating a phase control amount for varying the phase amount with respect to a signal of the antenna element;
Level control amount calculation means for calculating a level control amount for varying the level with respect to the signal of the antenna element over time,
The level control amount calculating means calculates a level control amount for varying a level difference between the signals of the antenna elements;
A beam control apparatus characterized by that. An array antenna having a plurality of antenna elements;
A beam control device according to claim 1;
Based on the phase control amount obtained by the beam control device, phase shift adjustment means for adjusting the phase amount of the signal of the antenna element;
Level adjusting means for adjusting the signal level of the antenna element based on the level control amount obtained by the beam control device;
An array antenna system comprising: In a radio apparatus that performs time slot scheduling and adaptive channel assignment based on the state of a radio channel,
A radio apparatus comprising the array antenna system according to claim 2.

Images