JP2014027367A - Radio communication system and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make channel phase difference θbe close to a desired value without changing an interval between antenna elements.SOLUTION: A radio communication system (1) comprises: a phase difference estimation unit (760) for estimating phase difference between channels formed between a transmission sub array antenna included in a transmission array antenna and a reception sub array antenna included in a reception array antenna; and a control device (150) for functioning as a phase difference adjustment unit for adjusting the phase difference between channels formed between the transmission sub array antenna and reception sub array antenna by controlling a power ratio of a signal transmitted from a transmission antenna element composing the transmission sub array antenna included in the transmission array antenna and a power ratio of a signal received by a reception antenna element composing the reception sub array antenna included in the reception array antenna on the basis of the phase difference.

Description

  The present invention relates to a wireless communication system and a wireless communication method provided with an array antenna including a plurality of antenna elements.

  In recent years, it has been required to realize gigabit-class high-speed wireless communication in a limited frequency band. One of the implementation methods is a MIMO (Multiple-Input Multiple-Output) transmission technology. In MIMO transmission, different signals are transmitted from multiple transmitting antennas at the same time and at the same frequency, and each signal is separated by signal processing on the receiver side by using a multipath environment between the transmitter and the receiver. And decrypt. Thereby, it is possible to improve the communication speed according to the number of transmitting / receiving antenna elements without expanding the use frequency band.

  Normally, MIMO transmission assumes a multipath environment. When the environment between the transmitter and the receiver is not a multipath environment, the propagation paths of a plurality of signals transmitted and received are substantially equal, and the spatial correlation increases. For this reason, signal separation becomes difficult and the channel capacity decreases. However, in recent years, for example, as shown in Non-Patent Document 1, the MIMO transmission technology is also used in short-range communication in which the transmission antenna and the reception antenna are close to each other and the environment between the transmitter and the receiver is not a multipath environment. It has been noted that it can be applied. Hereinafter, MIMO transmission in near field communication is referred to as near field MIMO transmission.

  According to the technique of Non-Patent Document 1, in short-range MIMO transmission, the antenna spacing is appropriately set according to the distance between the transmitter and the receiver, so that the antenna can be used even in a multipath environment. The spatial correlation between them becomes low, and a high channel capacity can be achieved. Non-Patent Document 2 proposes a short-range ultrahigh-speed wireless relay system that uses the inside of an obstacle such as a concrete wall as a propagation path. According to this short-range ultrahigh-speed wireless relay system, high-speed communication by short-range MIMO transmission is possible even in an environment where a line-of-sight antenna cannot be obtained due to a wall, etc.

  Further, in Non-Patent Document 2, studies for increasing the channel capacity in short-distance MIMO transmission are performed. However, in order to realize actual MIMO transmission, in addition to a technique for increasing the channel capacity, a signal processing technique in the transceiver is required. Regarding this signal processing technique, Non-Patent Document 1 is known as the characteristic of eigenmode transmission (hereinafter referred to as EM-BF), which is known as an optimal transmission / reception method for MIMO transmission, and a method for performing signal processing only on the receiving side. The characteristics of zero forcing (hereinafter referred to as ZF) are compared. Non-Patent Document 2 shows that the characteristics of the EM-BF and the characteristics of the ZF substantially coincide with each other due to the optimum element spacing of the array antenna.

FIG. 14 is an explanatory diagram showing an arrangement example of antenna elements in short-range MIMO transmission. In FIG. 14, the number of antenna elements Tx _j on the transmission side (j is a positive integer satisfying 1 ≦ j ≦ M, and M is a positive integer satisfying M ≧ 2) and the antenna element Rx _i (reception side). i is a positive integer satisfying 1 ≦ i ≦ M. The antenna element Tx _j on the transmission side is arranged on the plane PT, and the antenna element Rx _i on the reception side is in the propagation space FS with the antenna element Tx _j on the transmission side on the plane PR parallel to the plane PT. It is arrange | positioned so that it may oppose on both sides. The distance between the plane PT and the plane PR is D. Hereinafter, the distance D between the plane PT and the plane PR is referred to as “transmission / reception interval D”. In addition, on both the transmitter side and the receiver side, the distance between any two adjacent antenna elements is d. In the following, for simplification of description, the case of M = 2, that is, the case of 2 × 2 (two inputs and two outputs) near field MIMO transmission will be described.

  FIG. 15 is a model diagram of 2 × 2 short-range MIMO transmission. In the 2 × 2 short-range MIMO transmission shown in FIG. 15, when the channel matrix H is expressed by Expression (1), the received signal is expressed by Expression (2).

Here, in the expressions (1) and (2), the element h _ij (i and j are positive integers of 2 or less) is a signal propagated through the channel from the transmitting antenna element Tx _j to the receiving antenna element Rx _i . Is a matrix element that indicates the change rate of the phase and amplitude of, for example, by complex number expression. Further, s _j is a signal transmitted from the transmitting antenna element Tx _j, r _i is a matrix element representing the signal received by the receiving antenna element Rx _i, n _i is a matrix representing the noise added to the received signal Is an element.

  In addition, when a reception weight matrix W for signal separation in 2 × 2 MIMO transmission is expressed as in Expression (3), a signal output to each receiving circuit after reception weight calculation is expressed in Expression (4).

In Expressions (3) and (4), matrix elements w _ij (i and j are each a positive integer equal to or less than 2) are data series corresponding to the data series s ′ transmitted by the transmitting antenna element Tx _i . In order to extract s ′ _i , the weight multiplied by the signal received by the receiving antenna element Rx _j is shown.

In 2 × 2 short-range MIMO transmission, the antenna element spacing d is such that the phase difference θ _H = tan ⁻¹ (h ₂₁ / h ₁₁ ) = tan ⁻¹ (h ₁₂ / h ₂₂ ) of each channel is 90 degrees. The channel capacity is maximized when is set. Hereinafter, the antenna element interval d that maximizes the channel capacity is referred to as “optimal element interval d _opt ”.

When the antenna element interval d is set to the optimum element interval d _opt , the channel matrix H of 2 × 2 short-distance MIMO transmission is approximated by Equation (5). Here, in Expression (5), a propagates the amplitude of the signal propagated through the channel from the transmission antenna element Tx ₁ to the reception antenna element Rx ₁ and the channel from the transmission antenna element Tx ₁ to the reception antenna element Rx ₂ . Represents the ratio to the amplitude of the measured signal.

At this time, the reception weight matrix W _{ZF in ZF} is approximated by Equation (6).

  From Equation (5) and Equation (6), the product of the channel matrix and the reception weight matrix is represented by a diagonal matrix as shown in Equation (7). That is, the signals transmitted from the respective transmission antennas are separated by multiplying the reception weight in the receiver, and are received without causing interference.

Honma, Nishimori, Seki, Mizoguchi, “Evaluation of Transmission Capacity in Near-field MIMO Communication” IEICE Technical Report, AP2008-125, Nov. 2008 Seki, Nishimori, Honma, Nishikawa, “Short-range Ultra-high-speed Relay System” IEICE Technical Report, AP2008-124, Nov. 2008

As described above, in 2 × 2 short-distance MIMO transmission, the phase difference θ _H = tan ⁻¹ (h ₂₁ / h ₁₁ ) = tan ⁻¹ (h ₁₂ / h ₂₂ ) of each channel is 90 degrees. The channel capacity is maximized when the distance d between the antenna elements is set.
However, usually, at the design stage of a planar array antenna as shown in FIG. 14, a specific transmission / reception interval D is assumed, and the interval d of antenna elements is set to a specific value according to the transmission / reception interval D. In this antenna manufacturing process, antenna elements are arranged on one substrate at a specific interval d set in the above-described design stage. Therefore, not only the phase difference theta _H of each channel 90 degrees and the transmission and reception intervals other than transmission and reception interval D assumed in the design stage, there is a problem that the characteristics of short-range MIMO transmission is deteriorated.

  In addition, the above-described problem is caused by setting the transmission / reception interval D as shown in Non-Patent Document 2, as in a system that performs short-distance MIMO transmission by installing transmitters / receivers on both sides of a wall between rooms or indoors / outdoors. It becomes even more noticeable when it cannot be adjusted to an arbitrary interval.

The present invention has been made in order to solve the above-described problems, and an object of the present invention is to make the actual transmission / reception interval deviate from the transmission / reception interval assumed in the design stage of the planar array antenna, and the channel phase difference θ _H is a desired value. To provide a wireless communication system and a wireless communication method capable of bringing the phase difference θ _{H of the} channel close to a desired value without changing the interval between the antenna elements even when it deviates from (for example, 90 degrees). is there.

  The present invention has been made to solve the above-described problems, and a wireless communication system according to an aspect of the present invention includes a transmission array antenna including a plurality of transmission subarray antennas each including a plurality of transmission antenna elements, and the plurality of the transmission array antennas. A reception sub-array antenna comprising a plurality of reception sub-array antennas each composed of a plurality of reception antenna elements facing each of the transmission antenna elements, the transmission sub-array antenna provided in the transmission array antenna, A phase difference estimation unit for estimating a phase difference of a channel formed between the reception array antenna and the reception subarray antenna; and the transmission array antenna based on the phase difference estimated by the phase difference estimation unit. Transmitting antenna elements constituting the transmitting subarray antenna By controlling the power ratio of the transmitted signals and the power ratio of the signals received by the receiving antenna elements constituting the receiving sub-array antenna of the receiving array antenna, the desired channel capacity can be obtained. A first phase difference adjustment unit that adjusts a phase difference of a channel formed between the transmission subarray antenna and the reception subarray antenna (element corresponding to the “first phase difference adjustment unit” of claim 1); It is characterized by comprising.

  A wireless communication system according to an aspect of the present invention includes a transmission array antenna including a plurality of transmission subarray antennas configured from a plurality of transmission antenna elements, and a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A wireless communication system comprising a receiving array antenna having a plurality of configured receiving subarray antennas, wherein the transmitting subarray antenna is provided between the transmitting subarray antenna and the receiving subarray antenna provided in the receiving array antenna. A phase difference estimator that estimates the phase difference of the channel to be formed, and a transmission antenna element that constitutes a transmission subarray antenna included in the transmission array antenna, based on the phase difference estimated by the phase difference estimator Power ratio and phase relationship of the received signal and the receiving The transmission subarray antenna and the reception subarray antenna are configured so as to obtain a desired channel capacity by controlling the power ratio and phase relationship of signals received by the reception antenna elements constituting the reception subarray antenna included in the array antenna. And a second phase difference adjusting unit (an element corresponding to the “first phase difference adjusting unit” in claim 2) that adjusts the phase difference of the channel formed between the first and second channels. .

  In the wireless communication system according to an aspect of the present invention, when the first phase difference adjustment unit cannot adjust the phase difference of each channel so as to obtain a desired channel capacity only by controlling the power ratio, the reception is performed. The phase difference is further adjusted by controlling the phase relationship of the signals to be transmitted.

  A wireless communication system according to an aspect of the present invention includes a transmission array antenna configured by a plurality of transmission antenna elements, and a reception array antenna configured by a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A plurality of transmission antenna elements constituting the transmission array antenna and a plurality of transmission units are connected to each other via a switch unit, and a plurality of reception antenna elements constituting the reception array antenna and a weight calculation circuit are respectively provided. A wireless communication system connected via a switch unit, wherein a phase difference estimation unit that estimates a phase difference of a channel formed between the transmission array antenna and the reception array antenna, and the phase difference estimation unit Transmission used for communication by switching the switch unit based on the estimated phase difference A third phase difference that adjusts a phase difference of a channel formed between the transmission antenna element and the reception antenna element so that a desired channel capacity can be obtained by selecting the antenna element and the reception antenna element. And an adjustment unit (element corresponding to the “second phase difference adjustment unit” in claim 3).

  A wireless communication system according to an aspect of the present invention includes either the first phase difference adjustment unit or the second phase difference adjustment unit and the third phase difference adjustment unit. And

  In addition, a wireless communication method according to an aspect of the present invention includes a transmission array antenna including a plurality of transmission subarray antennas configured from a plurality of transmission antenna elements, and a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A wireless communication method using a wireless communication system including a reception array antenna including a plurality of reception subarray antennas, wherein the transmission subarray antenna includes the transmission array antenna, and the reception subarray antenna includes the reception array antenna. A phase difference estimation procedure for estimating the phase difference of the channel formed between the transmission sub-array antenna and the transmission constituting the transmission sub-array antenna included in the transmission array antenna based on the phase difference estimated by the phase difference estimation procedure The power ratio of the signal transmitted from the antenna element and the previous By controlling the power ratio of the signals received by the receiving antenna elements constituting the receiving sub-array antenna included in the receiving array antenna, the transmission sub-array antenna and the receiving sub-array antenna are arranged so as to obtain a desired channel capacity. And a first phase difference adjustment procedure for adjusting a phase difference between channels formed therebetween.

  In addition, a wireless communication method according to an aspect of the present invention includes a transmission array antenna including a plurality of transmission subarray antennas configured from a plurality of transmission antenna elements, and a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A wireless communication method using a wireless communication system including a reception array antenna including a plurality of reception subarray antennas, wherein the transmission subarray antenna includes the transmission array antenna, and the reception subarray antenna includes the reception array antenna. A phase difference estimation procedure for estimating the phase difference of the channel formed between the transmission sub-array antenna and the transmission constituting the transmission sub-array antenna included in the transmission array antenna based on the phase difference estimated by the phase difference estimation procedure Power ratio of signals transmitted from antenna elements and By controlling the phase relationship and the power ratio and phase relationship of the signals received by the receiving antenna elements constituting the receiving subarray antenna included in the receiving array antenna, the transmission subarray is obtained so that a desired channel capacity can be obtained. And a first phase difference adjustment procedure for adjusting a phase difference of a channel formed between an antenna and the reception subarray antenna.

  In the wireless communication method according to one aspect of the present invention, in the second phase difference adjustment procedure, when the phase difference of each channel cannot be adjusted so as to obtain a desired channel capacity only by controlling the power ratio, the reception is performed. The phase difference is further adjusted by controlling the phase relationship of the signals to be transmitted.

  In addition, a wireless communication method according to an aspect of the present invention includes a transmission array antenna configured from a plurality of transmission antenna elements, and a reception array antenna configured from a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A plurality of transmission antenna elements constituting the transmission array antenna and a plurality of transmission units are connected to each other via a switch unit, and a plurality of reception antenna elements constituting the reception array antenna and a weight calculation circuit are respectively provided. A wireless communication method using a wireless communication system connected via a switch unit, the phase difference estimation procedure for estimating a phase difference of a channel formed between the transmission array antenna and the reception array antenna, Communication is performed by switching the switch unit based on the phase difference estimated in the phase difference estimation procedure. Secondly, the phase difference of the channel formed between the transmission antenna element and the reception antenna element is adjusted so that a desired channel capacity can be obtained by selecting the transmission antenna element and the reception antenna element to be used. And a phase difference adjustment procedure.

  In addition, a wireless communication method according to an aspect of the present invention includes either the first phase difference adjustment procedure or the second phase difference adjustment procedure, and the third phase difference adjustment procedure. .

  According to the present invention, when the transmission / reception interval deviates from the transmission / reception interval assumed at the time of designing the planar array antenna and the phase difference of each channel deviates from the phase difference when the channel capacity of short-distance MIMO transmission is maximized. However, the phase difference of each channel can be brought close to a desired phase difference when the channel capacity is maximized without changing the spacing of the antenna elements. Therefore, it is possible to suppress a decrease in channel capacity and to suppress deterioration in characteristics of short-distance MIMO transmission.

It is a block diagram which shows schematic structure of the radio | wireless communications system in the 1st Embodiment of this invention. It is a flowchart which shows the communication procedure of the 1st Embodiment of this invention. It is explanatory drawing which shows the directivity pattern example of the subarray antenna using the variable power divider | distributor of the 1st Embodiment of this invention. It is explanatory drawing which shows the principle of the phase difference adjustment in the 1st Embodiment of this invention. It is explanatory drawing which shows the principle of the phase difference adjustment in the 1st Embodiment of this invention. It is explanatory drawing of the model used for the effectiveness verification of the 1st Embodiment of this invention. FIG. 6 is an explanatory diagram showing the relationship between the power distribution ratio (α) of the subarray antenna 1 and the channel phase difference (θ _H ) in the model shown in FIG. 5 of the first embodiment of the present invention. It is a block diagram which shows schematic structure of the radio | wireless communications system in the 2nd Embodiment of this invention. It is a flowchart which shows the communication procedure of the 2nd Embodiment of this invention. It is explanatory drawing of the model used for the effectiveness verification of the 2nd Embodiment of this invention. It is explanatory drawing which shows the relationship between the power distribution ratio ((alpha)) and channel phase difference ((theta) _H ) of the subarray antenna 1 in the model shown in FIG. 10 of the 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the radio | wireless communications system in the 3rd Embodiment of this invention. It is a flowchart which shows the communication procedure of the 3rd Embodiment of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the antenna element in short distance MIMO transmission. It is a model figure of 2x2 short distance MIMO transmission.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, the same code | symbol represents the same element over all embodiment and all drawings demonstrated below.

<First Embodiment>
[Description of configuration]
A configuration of the wireless communication system 1 according to the first embodiment of the present invention will be described.
FIG. 1 is a configuration diagram showing a schematic configuration of a wireless communication system 1 according to the first embodiment of the present invention. The wireless communication system 1 includes a communication device 100 that functions as a transmitter and a communication device 700 that functions as a receiver. In 2 × 2 MIMO (two-input two-output MIMO) transmission, the communication device 100 communicates with the communication device 700. Data communication of two series (data series S1 and data series S2) is performed. Here, the communication device 100 transmits the data series S1, S2, and includes transmission units 112, 112, variable power distributors 131, 132, a plurality of transmission antenna elements 141, 142, 143, 144, And a control device 150.

Among these, the transmission part 111 produces | generates the transmission signal of data series S1, and the transmission part 112 produces | generates the transmission signal of data series S2. The variable power distributors 131 and 132 distribute transmission signals to a plurality of transmission antenna elements 141, 142, 143, and 144 at a power ratio designated by the control device 150 under the control of the control device 150. The transmission antenna elements 141, 142, 143, and 144 transmit transmission signals as radio signals (radio waves). The control device 150 sets the power ratio and designates it to the variable power distributors 131 and 132 based on channel phase difference information described later, and controls the power ratio to control the position of the channel described later. functions as a first phase difference adjusting section for adjusting a phase difference theta _H.

  On the other hand, the communication device 700 is for receiving the sequence data S1 and S2 transmitted from the communication device 100. The receiving units 711 and 712, the weight calculation circuit 720, the combiners 731 and 732, and the receiving antenna Elements 741, 742, 743, and 744, a control device 750, and a phase difference estimation unit 760 are provided. Among these, the receiving antenna elements 741, 742, 743, and 744 are for receiving radio signals. The combiners 731 and 732 combine received signals received by the respective reception antenna elements at a combination ratio designated by the control device 750 under the control of the control device 750.

The weight calculation circuit 720 performs signal separation by multiplying the combined reception signal by a reception weight. The receiving units 711 and 712 perform processing such as demodulation and decoding on the received signals after signal separation. The control device 750 designates a combination ratio corresponding to the above-described power ratio to the combiners 731 and 732, and functions as a first phase difference adjustment unit together with the above-described control device 150. The phase difference estimator 760 estimates the phase difference θ _H of each channel of the received signal and feeds back information on the phase difference θ _H to the communication apparatus 100.

  However, the present invention is not limited to this example, and the control device 150 and the variable power distribution units 131 and 132 may be handled as the first phase difference adjustment unit, and the control device 750 and the combiners 731 and 732 are the first. The control devices 150 and 750, the variable power distribution units 131 and 132, and the combiners 731 and 732 may be handled as the first phase difference adjustment unit. .

Next, the configuration of the transmitting antenna elements 141 to 144 and the receiving antenna elements 741 to 744 will be described in detail.
In the present embodiment, the transmission antenna elements 141 to 144 constituting the communication device 100 are arranged on the same plane with a distance d. Similarly, the receiving antenna elements 741 to 744 constituting the communication device 700 are also arranged on the same plane with a distance d. The plane on which the transmission antenna elements 141 to 144 are arranged and the plane on which the reception antenna elements 741 to 744 are arranged are parallel to each other. The distance between the plane on which the transmitting antenna elements 141 to 144 are arranged and the plane on which the receiving antenna elements 741 to 744 are arranged, that is, the transmission / reception interval is D.

  Hereinafter, an antenna including a plurality of antenna elements arranged on the same plane is referred to as an array antenna, and a set of antenna elements that handle the same data series is referred to as a subarray antenna. In the present embodiment, the transmission antenna elements 141 to 144 constitute the transmission array antenna 140, and the reception antenna elements 741 to 744 constitute the reception array antenna 740. Among these, the transmission antenna element 141 and the transmission antenna element 142 constitute a transmission subarray antenna 1412, and the transmission antenna element 143 and the transmission antenna element 144 constitute a transmission subarray antenna 1434. The reception antenna element 741 and the reception antenna element 742 constitute a reception subarray antenna 7412, and the reception antenna element 743 and the reception antenna element 744 constitute a reception subarray antenna 7434.

  In the present embodiment, the receiving antenna elements 741 to 744 are arranged at positions facing the transmitting antenna elements 141 to 144, respectively. Specifically, the reception antenna element 741 is disposed at a position facing the transmission antenna element 141, the reception antenna element 742 is disposed at a position facing the transmission antenna element 142, and the reception antenna element 743 is composed of the transmission antenna element 743. The reception antenna element 744 is disposed at a position facing the transmission antenna element 144.

  As described above, the wireless communication system 1 according to the present embodiment includes a transmission array antenna 140 including a plurality of transmission subarray antennas configured of a plurality of transmission antenna elements, and a plurality of reception antennas respectively facing the plurality of transmission antenna elements. A receiving array antenna 740 including a plurality of receiving sub-array antennas 740 each including an element.

  Further, in the present embodiment, the center position (radiation point) of the transmission antenna element 141 and the center position of the transmission antenna element 142 are arranged at positions separated by a distance d ′ in the same plane. Similarly, the center position of the transmission antenna element 143 and the center position of the transmission antenna element 144 are arranged at a position separated by a distance d ′ in the same plane. Further, the center position of the transmission subarray antenna 1412 composed of the transmission antenna elements 141 and 142 and the center position of the transmission subarray antenna 1434 composed of the transmission antenna elements 143 and 144 are separated by a distance d in the same plane. Placed in position. The same applies to the receiving antenna elements 741 to 744 with respect to the arrangement interval of such antenna elements.

As described above, in this embodiment, each of the communication device 100 and the communication device 700 included in the wireless communication system 1 includes four antenna elements. However, as will be described later, the wireless communication system 1 includes 2 × In 2MIMO (2-input 2-output MIMO) transmission, the communication device 100 functions as a device that performs two-sequence (data sequence S1 and data sequence S2) data communication from the communication device 700 to the communication device 700.
In addition, it is not limited to the above-mentioned example, The number of transmitting antenna elements and the number of receiving antenna elements corresponding to this are arbitrary.

[Description of operation]
Next, the operation of the wireless communication system 1 according to the present embodiment will be described.
In communication apparatus 100 functioning as a transmitter, transmission section 111 acquires data sequence S1, performs processing such as encoding and modulation, generates a transmission signal of data sequence S1, and outputs it to variable power distributor 131. To do. Similarly, the transmission unit 112 acquires the data sequence S2, performs processing such as encoding and modulation, generates a transmission signal of the data sequence S2, and outputs the transmission signal to the variable power distributor 132. Here, the data series S1 and the data series S2 may be independent from each other or may be series having correlation.

  Subsequently, the variable power distributor 131 controls the transmission signal output from the transmission unit 111 under the control of the control device 150, which is performed based on phase difference information described later fed back from the phase difference estimation unit 760. It is distributed to the transmitting antenna element 141 and the transmitting antenna element 142 at a power ratio specified by the device 150, and is output to the antenna element 141 and the antenna element 142 in the same phase. Similarly, the variable power distributor 132 controls the transmission signal output from the transmission unit 112 under the control of the control device 150 implemented based on phase difference information described later fed back from the phase difference estimation unit 760. It is distributed to the transmission antenna element 143 and the transmission antenna element 144 at a power ratio specified by the device 150, and is output to the antenna element 143 and the antenna element 144 in the same phase.

Here, the control device 150 controls the power ratio of the transmission signals distributed to the respective transmission antenna elements by the variable power distributors 131 and 132 based on phase difference information to be described later fed back from the phase difference estimation unit 760. . That is, the control device 150 controls the power ratio of signals transmitted from the transmission antenna elements constituting the transmission subarray antennas 1412 and 1434 included in the transmission array antenna 140. As a result, the control device 150 allows the transmission subarray antennas 1412 and 1434 and the reception subarray so that the phase difference θ _{H of the} channel approaches a desired value (for example, 90 degrees), that is, a desired channel capacity is obtained. The phase difference θ _{H of the} channel formed between the antennas 7412 and 7434 is adjusted.

In the present embodiment, control device 150 includes phase difference θ _H between the channel (h ₁₁ ) from transmission subarray antenna 1412 to reception subarray antenna 7412 and the channel (h ₂₁ ) from transmission subarray antenna 1412 to reception subarray antenna 7434. = Tan ⁻¹ (h ₂₁ / h ₁₁ ) Based on the information, the power ratio of the transmission signals distributed to the transmission antenna elements 141 and 142 by the variable power distributor 131 is controlled. Similarly, control device 150 has a phase difference θ _H = tan between a channel (h ₂₂ ) from transmission subarray antenna 1434 to reception subarray antenna 7434 and a channel (h ₁₂ ) from transmission subarray antenna 1434 to reception subarray antenna 7412. Based on the information of ⁻¹ (h ₁₂ / h ₂₂ ), the power ratio of the transmission signals distributed to the transmission antenna elements 143 and 144 by the variable power distributor 132 is controlled.
As described above, the control device 150 adjusts the channel phase difference θ _H so as to obtain a desired channel capacity based on phase difference information described later fed back from the phase difference estimation unit 760. The feedback and the principle of phase difference adjustment will be described later.

  Under the control of the control device 150 described above, the transmission subarray antenna 1412 including the transmission antenna elements 141 and 142 transmits the transmission signal output from the variable power distributor 131 with the power ratio specified by the control device 150 as a radio signal. Transmit as (radio wave). Similarly, a transmission subarray antenna 1434 including transmission antenna elements 143 and 144 transmits a transmission signal output from the variable power distributor 132 at a power ratio specified by the control device 150 as a radio signal (radio wave). These radio signals are radiated into the propagation space.

Subsequently, the communication apparatus 700 extracts each series of data from the radio signal received from the communication apparatus 100 as described below.
The reception antenna element 731 and the reception antenna element 732 receive the radio signal transmitted from the transmission subarray antenna 1412 and the radio signal transmitted from the transmission subarray antenna element 1434 as a radio signal in which both radio signals are combined, This is output to the combiner 731 as a received signal. The combiner 731 combines the received signals with the power ratio specified by the control device 750 and outputs the combined signal to the weight calculation circuit 720. Similarly, the combiner 731 combines the reception signals received by the reception antenna element 743 and the reception antenna element 744 with the power ratio specified by the control device 750 and outputs the combined signal to the weight calculation circuit 720.

Here, similarly to the control device 150 described above, the control device 750 controls the combination ratio of the received signals in the combiners 731 and 732 based on phase difference information described later fed back from the phase difference estimation unit 760. That is, the control device 750 controls the synthesis ratio of signals received by the transmission antenna elements constituting the reception subarray antennas 7412 and 7434 provided in the reception array antenna 740. Thus, the control device 750 causes the transmission subarray antennas 1412 and 1434 and the reception subarray so that the phase difference θ _{H of the} channel approaches a desired value (for example, 90 degrees), that is, a desired channel capacity is obtained. The phase difference θ _{H of the} channel formed between the antennas 7412 and 7434 is adjusted.

  The weight calculation circuit 720 performs signal separation by multiplying the signal output from the combiner 731 and the signal output from the combiner 732 by the reception weight. Then, the weight calculation circuit 720 acquires a signal of the sequence S1 ′ corresponding to the signal of the sequence S1 transmitted by the transmission subarray antenna 1412 by the above signal separation, and outputs the signal of the sequence S1 ′ to the reception unit 711. . Further, the weight calculation circuit 720 obtains a signal of the sequence S2 ′ corresponding to the signal of the data sequence S2 transmitted by the transmission subarray antenna 1434 by the above signal separation, and outputs the signal of the sequence S2 ′ to the reception unit 712. To do.

  The receiving unit 711 performs a process such as demodulation and decoding on the signal of the sequence S1 'output from the weight calculation circuit 720, and generates a data sequence S1'. The receiving unit 712 performs a process such as demodulation and decoding on the signal of the sequence S2 'output from the weight calculation circuit 720 to generate a data sequence S2'. As a result, the data sequences S1 and S2 transmitted from the communication device 100 on the transmission side are restored as data sequences S1 'and S2' in the communication device 700 on the reception side.

Next, a description will be given feedback of the phase difference information to be used for adjusting the phase difference theta _H of the aforementioned channel.
Here, the channel matrix element h _ij between the transmitting antenna elements TXA1 and TXA2 and the receiving antenna elements RXA1 and RXA2 shown in FIG. The matrix element is h ₁₁ , the matrix element of the channel from the transmission subarray antenna 1412 to the reception subarray antenna 7434 is h ₂₁ , the matrix element of the channel from the transmission subarray antenna 1434 to the reception antenna element 7412 is h ₁₂ , and reception from the transmission subarray antenna 1434 is performed. A matrix element of a channel to the subarray antenna 7434 is represented as h ₂₂ .

The phase difference estimation unit 760 of the communication apparatus 700 estimates the phase difference θ _H of each channel formed between each transmission subarray antenna included in the transmission array antenna 140 and each reception subarray antenna included in the reception array antenna 740. To do. In the present embodiment, the phase difference estimation unit 760 estimates the phase difference θ _H from the relational expression θ _H = tan ⁻¹ (h ₂₁ / h ₁₁ ) = tan ⁻¹ (h ₁₂ / h ₂₂ ). Then, the phase difference estimation unit 760 feeds back the estimated phase difference θ _H to the control device 150 and the control device 750 as phase difference information. The control device 150 and the control device 750 control the power ratio and the synthesis ratio so that the phase difference θ _H approaches 90 degrees based on the information on the phase difference θ _H fed back from the phase difference estimation unit 760.

In the present embodiment, the communication device 100, before transmitting the data sequence S1 and data sequence S2, and transmits a training signal for estimating a phase difference theta _H channel. Then, the phase difference estimation unit 760 of the communication device 700 uses the phase difference θ _H estimated using the training signal transmitted from the communication device 100 as phase difference information, and the control device 150 of the communication device 100 and the control device of the communication device 700. 750 is fed back.

Controller 150, among the phase difference information fed back from the phase difference estimation unit 760, a channel _{h 21} from transmit subarray antenna 1412 to the receiving sub-array antenna 7434, the channel _{h 11} from transmit subarray antenna 1412 to the receiving sub-array antenna 7412 Based on the information of the phase difference θ _H = tan ⁻¹ (h ₁₂₁ / h ₁₁ ), the power ratio of the variable power distributor 131 is controlled so that the phase difference θ _H approaches 90 degrees (desired value). Do. In addition, the control device 150 determines the phase difference θ _H = tan ⁻¹ (h ₁₂₎ between the channel h ₁₂ from the transmission subarray antenna 1434 to the reception subarray antenna 1412 and the channel h ₂₂ from the transmission subarray antenna 1434 to the reception subarray antenna 7434. / H ₂₂ ), the power ratio of the variable power distributor 132 is controlled so that the phase difference θ _H approaches 90 degrees (desired value).

Note that means and a method for feeding back phase difference information related to the phase difference θ _H estimated by the phase difference estimation unit 760 of the communication device 700 to the control device 150 of the communication device 100 are TDD (Time Division Duplex) or Arbitrary means and methods, such as FDD (Frequency Division Duplex), can be used, and it is not limited to a specific means.

Next, the procedure of the above-described operation will be generally described with reference to the flowchart of FIG.
First, in step S101, the communication apparatus 100 transmits a training signal before transmitting radio signals of the data series S1 and the data series S2. Subsequently, in step S102, the communication apparatus 700 receives the training signal transmitted from the communication apparatus 100, estimates the phase difference θ _H of each channel by the phase difference estimation unit 760, and then uses the information of the phase difference θ _{H as} the information. The phase difference information is fed back to the control devices 150 and 750. Subsequently, in step S103, the control devices 150 and 750 control the power distribution ratios of the variable power distributors 131 and 132 and the combining ratios of the combiners 731 and 732 based on the fed back phase difference information, and the subarray antenna. The phase difference θ _H between the channels is adjusted to approach 90 degrees. Subsequently, in step S104, after the adjustment of the phase difference theta _H above, the communication apparatus 100 starts transmission of a radio signal data series S1 and data sequence S2.

Next, the principle of phase difference adjustment according to the present embodiment will be described with reference to FIGS.
FIG. 3 is an explanatory diagram showing an example of the directivity pattern of the subarray antenna 1412 using the variable power distributor 131. 4 and 5 are explanatory views showing the principle of phase difference adjustment according to the present embodiment. In the following, for simplification of description, the description will be given focusing on the transmission subarray antenna 1412. However, the directivity pattern of the transmission subarray antenna 1434 is also described in the same manner as the transmission subarray antenna 1412. Also, with respect to reception subarray antenna 7412 and reception subarray antenna 7434, the directivity similar to that on the transmission side is set by setting the combination ratio of combiners 731 and 732 to the same value as the power ratio of variable power distributors 131 and 132. It becomes a pattern.

  When the ratio of the power of the input signal of the transmission antenna element 141 to the power of the transmission signal input to the variable power distributor 131 is expressed as α (0 ≦ α ≦ 1), the power P1 of the signal input to the transmission antenna element 141 And the power distribution ratio of the signal input to the transmission antenna element 142, that is, the power distribution ratio is represented by P1: P2 = α: 1−α.

  FIG. 3A illustrates the directivity pattern of the sub-array antenna at the power distribution ratio when α = 1, and FIG. 3B illustrates the directivity of the sub-array antenna at the power distribution ratio when α = 0.5. FIG. 3C illustrates the directivity pattern of the subarray antenna in the power distribution ratio when α = 0. Here, it is assumed that signals transmitted from the transmission antenna element 141 and the transmission antenna element 142 are transmitted in the same phase.

  As illustrated in FIG. 3A, when α = 1, that is, when all the signals input to the variable power distributor 131 are distributed to the transmission antenna element 141, the transmission signal is a directivity pattern of the transmission antenna element 141. Is radiated to the propagation space based on In this case, the radiation point of the signal radiated from the transmission subarray antenna 1412 coincides with the radiation point of the transmission antenna element 141.

  3B, when α = 0.5, the power of the transmission signal is equally distributed to the transmission antenna element 141 and the transmission antenna element 142, and the transmission antenna element 141 and the transmission antenna element 142 A signal is radiated with equal power. In this case, the radiation point of the signal radiated from the transmission subarray antenna 1412 exists on the vertical bisector of the line connecting the radiation point of the transmission antenna element 141 and the radiation point of the transmission antenna element 142, and this vertical bisector. A directivity peak of the transmission subarray antenna 1412 is formed in front of the line.

  Further, as illustrated in FIG. 3C, when α = 0, that is, when all signals input to the variable power distributor 131 are distributed to the transmission antenna element 142, the transmission signal is directed to the transmission antenna element 142. Radiated into the propagation space based on the sex pattern. In this case, the radiation point of the signal radiated from the transmission subarray antenna 1412 coincides with the radiation point of the transmission antenna element 142.

As described above, the radiation point of the signal transmitted from the transmission subarray antenna 1412 changes according to the power distribution ratio (α) of the variable power distributor 131. Thus, as shown in FIGS. 4 and 5, the channel _{h 11} from transmit subarray antenna 1412 to the receiving sub-array antenna 7412, a phase difference between the channel _{h 21} from transmit subarray antenna 1412 to the receiving sub-array antenna 7434 theta _H = tan ⁻¹ (h ₂₁ / h ₁₁ ) can be adjusted.

Here, FIG. 4 shows a case where the radiation point of the transmission subarray antenna 1412 coincides with the radiation point of the transmission antenna element 141. In this case, the phase difference θ _H between the channel h ₁₁ and the channel h ₂₁ is represented by θ _H1 . Has been. FIG. 5 shows a case where the radiation point of the transmission subarray antenna 1412 coincides with the radiation point of the transmission antenna element 142. In this case, the phase difference θ _H between the channel h ₁₁ and the channel h ₂₁ is represented by θ _H2. ing. As understood from FIGS. 4 and 5, there is a magnitude relationship of θ _H1 <θ _H2 between the phase difference θ _H1 and the phase difference θ _H2, and the phase difference θ _H according to the position of the radiation point. Has changed. Therefore, it is possible to adjust the channel phase difference θ _H by moving the radiation point of the transmission subarray antenna 1412 as described above.

Similarly, by changing the power distribution ratio of the variable power distributor 132, the radiating point of the signal transmitted from the transmission subarray antenna 1434 is changed, so that the channel h from the transmission subarray antenna 1434 to the reception subarray antenna 7412 is changed. ₁₂ and the phase difference θ _H = tan ⁻¹ (h ₁₂ / h ₂₂ ) between the channel h ₂₂ from the transmission subarray antenna 1434 to the reception subarray antenna 7434 can be adjusted.

As understood from the above, the antenna element spacing of the array antenna is changed by controlling the power distribution ratio of the transmission signal in the variable power distributors 131 and 132 and the reception signal combining ratio in the combiners 731 and 732. In addition, the channel phase difference θ _H can be brought close to 90 degrees at which the channel capacity of short-distance MIMO transmission is maximized, and a desired channel capacity can be obtained.

  In the configuration of FIG. 1, the communication device 100 on the transmission side includes variable power distributors 131 and 132, the communication device 700 on the reception side includes combiners 731 and 732, and both the transmission side and the reception side are subarray antennas. However, one of the communication device 100 and the communication device 700 may be configured to control the directivity pattern of the subarray antenna. In this case, the communication device that does not control the directivity pattern does not need to subarray the antenna elements, so that the variable power distributors 131 and 132 or the combiners 731 and 732 can be omitted.

  In the above description, as means for controlling the synthesis ratio of signals transmitted from the transmission antenna elements of the transmission subarray antennas 1412 and 1434 or signals received by the reception antenna elements of the reception subarray antennas 7412 and 7434, Although a configuration using a distributor or synthesizer with a variable ratio has been described, the present invention is not limited to a configuration using a distributor or a synthesizer with such a variable ratio, and the signal power ratio is controlled. Any means or method can be used as long as it can be configured. For example, the power ratio may be controlled by giving a different attenuation amount to each signal using a variable attenuator.

Next, an example of the effect according to the present embodiment will be described with reference to FIGS.
FIG. 6 is an explanatory diagram of a model used for validity verification of the present invention. In the example of FIG. 6, the frequency f ₁ = 4.85 GHz, the wavelength λ ₁ = 61.8557 mm, the transmission distance D ₁ = 1434 mm, the antenna element spacing d ₁ = 3.4139λ ₁ = 211.1691 mm, and the transmission subarray antenna and spacing of the antenna elements constituting the receiving sub-array antenna is set to 0.5 [lambda _1. Among the four channels in the millimeter wave band defined by IEEE802.11ad, when the transmission distance D ₂ = 115 mm at the center frequency f ₂ = 60.48 GHz of the channel 2, the channel phase difference θ _H = tan ⁻¹ (h _The element spacing at which ₂₁ / h ₁₁ ) = tan ⁻¹ (h ₁₂ / h ₂₂ ) is 90 degrees is d ₂ = 3.4139λ ₂ = 16.993873 mm, and the transmission distance D ₁ and the element spacing d ₁ described above are This is a value determined as a scale model of the millimeter wave band.

FIG. 7 is an explanatory diagram showing the relationship between the power distribution ratio (α) and the channel phase difference (θ _H ) of the transmission subarray antenna 1412 and the transmission subarray antenna 1434 in the model shown in FIG. As shown in FIG. 7, when the power distribution ratio (α) is changed in the range of 0 to 1, the phase difference θ _H is adjusted in the range of about 40 degrees from about −70 degrees to about −110 degrees. Is possible. Accordingly, even when the channel phase difference theta _H deviates from 90 degrees (the desired value) by the change in transmission distance, by controlling the power distribution ratio of the variable power divider 131, a phase difference theta _H 90 Close to the degree. Therefore, according to this embodiment, even when the channel phase difference θ _H deviates from 90 degrees, it is possible to suppress a decrease in channel capacity without changing the antenna element spacing.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 8 is a configuration diagram showing a schematic configuration of the wireless communication system 2 in the second embodiment of the present invention. In the first embodiment, only the power ratio of the transmission signal is changed and in-phase power is supplied to each antenna element. However, in the second embodiment, as shown in FIG. In addition to the control of the ratio, the phase shifter 171, 172, 771, 772 is also used to control the phase relationship of the signals output from the respective antenna elements, and the other configurations are the same as in the first embodiment. is there.

  The wireless communication system 2 includes a communication device 2100 that functions as a transmitter and a communication device 2700 that functions as a receiver. Here, the communication device 2100 further includes phase shifters 171 and 172 in addition to the configuration of the communication device 100 in the first embodiment. In the present embodiment, the phase shifter 171 is disposed between the variable power distributor 131 and the transmission antenna element 141, and the phase shifter 172 is disposed between the variable power distributor 132 and the transmission antenna element 144. . Similarly, the communication device 2700 further includes phase shifters 771 and 772 in addition to the configuration of the communication device 700 in the first embodiment. In the present embodiment, the phase shifter 771 is disposed between the combiner 731 and the reception antenna element 741, and the phase shifter 772 is disposed between the combiner 732 and the reception antenna element 744.

  In the present embodiment, control devices 2150 and 2750 are provided as elements corresponding to the control devices 150 and 750 of the first embodiment. Here, in the first embodiment, the control device 150 controls the power distribution ratio of the variable power distributors 131 and 132. However, the control device 2150 in this embodiment includes the variable power distributors 131 and 132. The phase shifters 171 and 172 are connected to control the distribution ratio of the variable power distributors 131 and 132 and to control the phase shift amounts of the phase shifters 171 and 172. In the first embodiment, the control device 750 controls the combining ratio of the combiners 731 and 732, but the control device 2750 in this embodiment includes the combiners 731 and 732 and the phase shifters 771 and 772. , And controls the synthesis ratio of the synthesizers 731 and 732 and controls the phase shift amounts of the phase shifters 771 and 772.

Similarly to the first embodiment, the phase difference estimation unit 760 estimates the phase difference θ _H of each channel using the training signal transmitted before the transmission of the data series S1 and the data series S2, and uses this. This is fed back to the control device 2150 and the control device 2750 as phase difference information. The control device 2150 and the control device 2750 control the distribution ratio of the variable power distributors 131 and 132 and the combination ratio of the combiners 731 and 732 based on the phase difference information fed back from the phase difference estimation unit 760. a phase difference theta _H of each channel closer to 90 degrees. In the present embodiment, even if the phase difference θ _H of each channel is estimated again using the training signal, the control device is used when the phase difference θ _H of each channel cannot be adjusted to 90 degrees only by controlling the power ratio of the transmission signal. 2150,2750, in addition to the above control of the power distribution ratio, by changing each amount of phase shift of the phase shifter 171,172,771,772, adjusts the phase difference theta _H of each channel 90 degrees.

  The phase shifters 171 and 172 add the phase rotation specified by the control device 2150 to the signals output from the variable power distributors 131 and 132 and output the resultant signals to the transmission antenna elements 141 and 144. The phase shifters 771 and 772 add the phase rotation specified by the control device 2750 to the signals received by the receiving antenna elements 741 and 744 and output the resultant signals to the combiners 731 and 732. As described above, the phase shifter changes the phase relationship of signals transmitted (or received) from each antenna element of the subarray antenna, and changes the directivity pattern of the subarray antenna, thereby changing the variable power distributors 131 and 132. The effect of the phase difference adjustment obtained by controlling the power distribution ratio and the composition ratio of the combiners 731 and 732 can be made larger than the effect obtained in the first embodiment.

As described above, in the present embodiment, the control device 2150 uses the transmission subarray antennas 1412 and 1434 included in the transmission array antenna 140 based on the phase difference θ _H estimated by the phase difference estimation unit 760. The control device 2750 controls the power ratio and phase relationship of signals transmitted from the elements, and the control device 2750 receives the power ratio and phase of the signals received by the respective receiving antenna elements constituting the receiving subarray antennas 7412 and 7434 of the receiving array antenna 740. Control relationships. Thus, the control devices 2150 and 2150 adjust the phase difference θ _{H of the} channel formed between the transmission subarray antennas 1412 and 1434 and the reception subarray antennas 7412 and 7434 so that a desired channel capacity can be obtained. 1 function as a phase difference adjustment unit.

  In the configuration illustrated in FIG. 8, the transmission-side communication device 2100 includes variable power distributors 131 and 132 and phase shifters 171 and 172, and the reception-side communication device 2700 shifts to the combiners 731 and 732. The phasers 771 and 772 are provided to control the directivity pattern of the subarray antenna on both the transmission side and the reception side. However, the present invention is not limited to this example, and either the communication device 2100 or the communication device 2700 is used. It is also possible to control the directivity pattern of the subarray antenna only at. For example, the transmission-side communication device 2100 may control the power distribution ratio and the amount of phase shift (phase rotation amount), and the reception side may not control the synthesis ratio and the amount of phase shift. The communication device 2700 on the receiving side may control the synthesis ratio and the amount of phase shift without controlling the ratio and the amount of phase shift. In that case, the communication device that does not control the directivity pattern does not need to include the variable power distributors 131 and 132 or the combiners 731 and 732 that are required for sub-arraying the antenna elements, and the phase shifter 171. 172 or phase shifters 771 and 772 are not required.

Next, with reference to the flowchart of FIG.
First, in step S201, the communication apparatus 2100 transmits a training signal before transmitting the signals of the sequences S1 and S2. Subsequently, in step S202, the communication device 2700 receives a training signal transmitted from the communication device 2100, after estimating the phase difference theta _H of each channel by the phase difference estimation unit 760, the phase difference the phase difference theta _H Information is fed back to the control devices 2100 and 2700 as information. Subsequently, in step S203, the control devices 2100 and 2700, based on the phase difference information fed back from the phase difference estimation unit 760, the power distribution ratios of the variable power distributors 131 and 132 and the combiners 731 and 732, respectively. Each synthesis ratio and each phase shift amount of the phase shifters 171, 172, 771, 772 are controlled, and the phase difference θ _H of the channel between the subarray antennas is adjusted to 90 degrees. After this phase difference adjustment, in step S204, communication apparatus 2100 starts transmission of signals of series S1 and series S2.

Next, an example of the effect of this embodiment will be described with reference to FIGS. 10 and 11.
FIG. 10 is an explanatory diagram of a model used for validity verification of the present invention. As shown in FIG. 10, in the model used for the validity verification, a phase shifter 771 is arranged between the receiving antenna element 741 and the combiner 731 and a phase shift is performed between the receiving antenna element 744 and the combiner 732. The phase shifter (phase rotation amount) given to the signal by each phase shifter is set to 45 degrees. Further, the frequency f ₁ = 4.85 GHz, the wavelength λ ₁ = 61.8557 mm, the transmission distance D ₁ = 1434 mm, the antenna element interval d ₁ = 3.4139λ ₁ = 211.1691 mm, and each antenna element constituting the subarray antenna is the interval between 0.5λ _1.

FIG. 11 is an explanatory diagram showing the relationship between each power distribution ratio (α) and channel phase difference (θ _H ) of the transmission subarray antenna 1412 and the transmission subarray antenna 1434 in the model shown in FIG. As shown in FIG. 11, when each power distribution ratio (α) of the transmission subarray antenna 1412 and the transmission subarray antenna 1434 is changed in the range of 0 to 1, it is about 70 degrees from about −55 degrees to about −125 degrees. It is possible to adjust the phase difference θ _H within the range. The phase difference theta _H adjustment range (about 70 degrees) is greater than the adjustment range of the phase difference theta _H according to the first embodiment (approximately 50 degrees).

This is because the phase relationship of the received signals is changed using the phase shifters 771 and 772 on the receiving side, thereby controlling the power distribution ratio of the variable power distributors 131 and 132 and the combining ratio of the combiners 731 and 732. This means that the effect of phase difference adjustment obtained in this case can be increased. Therefore, according to this embodiment, as compared with the first embodiment described above, can be more effectively adjust the phase difference theta _H, it is possible to further suppress a decrease in channel capacity.

In the examples of FIGS. 10 and 11, the effectiveness is verified for the case where the phase shifters 771 and 772 are provided on the reception side. However, the phase difference is similarly applied to the case where the phase shifters 171 and 172 are provided on the transmission side. θ _H can be adjusted effectively. Further, it is understood that the phase difference θ _H can be adjusted more effectively if the phase shifters 171 and 172 are provided on the transmission side and the phase shifters 771 and 772 are provided on the reception side.

<Third Embodiment>
Next, a third embodiment of the present invention will be described.
FIG. 12 is a configuration diagram showing a schematic configuration of the wireless communication system 3 according to the third embodiment of the present invention. In order to simplify the description, the case where the transmission-side communication device 1 and the reception-side communication device 2 each have four antenna elements will be described. However, the present invention is not limited to this example. Is optional.

  As illustrated in FIG. 12, the wireless communication system 3 includes a communication device 3100 that functions as a transmitter and a communication device 3700 that functions as a receiver. Among these, the communication device 3100 includes transmission units 111 and 112, transmission antenna elements 141, 142, 143, and 144, a switch unit 180, and a control device 3150. The transmission unit 111 and the transmission unit 112 are connected to the antenna elements 141 to 144 via the switch unit 180, respectively. Here, the transmission antenna elements 111 to 114 constitute the transmission array antenna 140 and are arranged in the same plane, and two adjacent transmission antenna elements are arranged at positions separated by a distance d. In the present embodiment, lines are switched in the switch unit 180 by the control device 3150, and signals are output from the transmission units 111 and 112 to the transmission antenna element specified by the control device 3150 via the switch unit 180.

  Communication device 3700 also includes reception units 711 and 712, weight calculation circuit 720, switch unit 780, reception antenna elements 741, 742, 743, and 744, phase difference estimation unit 760, and control device 3750. To do. The receiving antenna elements 741 to 744 are connected to the weight calculation circuit 720 via the switch unit 780, respectively. Here, the receiving antenna elements 741 to 744 constitute the receiving array antenna 740, are arranged in the same plane so as to face the transmitting antenna elements 141 to 144, respectively, and two adjacent receiving antenna elements are separated by a distance d. Placed in position. In the present embodiment, the line is switched in the switch unit 780 by the control device 3750, and the signal received by the reception antenna element designated by the control device 3750 is input to the weight calculation circuit 720 via the switch unit 780.

Similarly to the first embodiment, the phase difference estimation unit 760 is formed between the transmission array antenna 140 and the reception array antenna 740 using a training signal transmitted before transmission of the data series S1 and the data series S2. is the is intended to estimate a phase difference theta _H of each channel, which is fed back to the control unit 3150 and the control device 3750 as phase difference information. Based on the phase difference information fed back from phase difference estimation section 760, control apparatus 3150 determines two transmission antenna elements for transmitting the signals of data series S1 and data series S2, respectively, and switch section 180 for that purpose. Control the switching of the tracks. Further, the control device 3750 determines two receiving antenna elements that receive the radio signal transmitted from the communication device 3100 based on the phase difference information fed back from the phase difference estimation unit 760, and the switch unit 780 of the switch unit 780 Controls line switching.

As a result, two pairs of antenna elements to be used for wireless communication are selected from the transmitting antenna elements 141 to 144 on the transmitting side and the receiving antenna elements 741 to 744 on the receiving side, and a plurality of antenna elements equal to the number of combinations of antenna elements by this selection The channel phase difference θ _H is 90 degrees at various transmission distances. For this reason, high channel capacity characteristics can be achieved by short-distance MIMO transmission, and the range of transmission distance can be expanded.

Thus, in the present embodiment, the control device 3150 selects the transmission antenna element to be used for communication by switching the switch unit 180 based on the phase difference θ _H estimated by the phase difference estimation unit 760, and performs control. The device 3750 switches the switch unit 780 based on the phase difference θ _H estimated by the phase difference estimation unit 760 to select a reception antenna element used for communication. Thus, control devices 3150 and 3750 function as a second phase difference adjustment unit that adjusts the phase difference of the channel formed between the transmission antenna element and the reception antenna element so that a desired channel capacity can be obtained. To do.

Next, the procedure of the above-described operation will be described generally with reference to the flowchart of FIG.
First, in step S301, the communication device 3100 transmits a training signal before transmitting the signals of the sequences S1 and S2. Subsequently, in step S302, the communication device 3700 receives the training signal transmitted from the communication device 3100, after the phase difference estimation unit 760 has estimated the phase difference theta _H of each channel, control it as phase difference information Feedback is provided to the devices 3150 and 3750. Subsequently, in step S303, control devices 3150 and 3750 determine antenna elements (combinations) to be used for communication based on the phase difference information fed back from phase difference estimation unit 760. Subsequently, in step S304, the control unit 3150,3750, respectively, to control the switching of the line of the switch unit 180,780, adjusts the phase difference theta _H of channels between each antenna element at 90 degrees. After this phase difference adjustment, in step S305, communication apparatus 3100 starts transmission of signals of data series S1 and series S2.

  In addition, although the structure which switches the antenna element used for communication by a switch part was demonstrated as 3rd Embodiment, it demonstrated further in 1st Embodiment to the structure of the radio | wireless communications system 3 in 3rd Embodiment. You may combine the structure which controls a distribution ratio and a synthetic | combination ratio, and / or the structure which controls the phase shift amount demonstrated in 2nd Embodiment. For example, in the first and second embodiments, one or more functions of the control devices 150, 750, 2150, and 2750 that function as the first phase difference adjustment unit are used in the control device in the third embodiment. You may combine the function as 2nd phase difference adjustment part of 1 or 2 or more of 3150 and 3750. Thereby, the range of the transmission distance which can achieve a high channel capacity characteristic by short-distance MIMO transmission can be further expanded.

  In the above first to third embodiments of the present invention, the present invention has been described as a wireless communication system, but the present invention can also be expressed as a wireless communication method. In this case, the present invention provides, for example, a transmission array antenna including a plurality of transmission subarray antennas configured from a plurality of transmission antenna elements, and a reception configured from a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A wireless communication method using a wireless communication system including a plurality of receiving array antennas, wherein the transmitting array antenna includes a transmitting subarray antenna and the receiving array antenna includes a receiving subarray antenna. Based on the phase difference estimation procedure for estimating the phase difference of the formed channel and the phase difference estimated by the phase difference estimation procedure, transmission is performed from transmission antenna elements constituting a transmission subarray antenna included in the transmission array antenna. Power ratio of the received signal and the receiving array By controlling the power ratio of the signals received by the reception antenna elements constituting the reception subarray antenna of the tenor, the desired channel capacity can be obtained between the transmission subarray antenna and the reception subarray antenna. And a first phase difference adjustment procedure for adjusting the phase difference of the formed channel. This can be expressed as a wireless communication method.

  Further, for example, in the first phase difference adjustment procedure, based on the phase difference estimated by the phase difference estimation procedure, a signal transmitted from an antenna element constituting a subarray antenna included in the transmission array antenna By controlling the power ratio and phase relationship and the power ratio and phase relationship of the signals received by the antenna elements constituting the sub-array antenna included in the receiving array antenna, the transmission is performed so that a desired channel capacity can be obtained. You may adjust the phase difference of the channel formed between a subarray antenna and the said receiving subarray antenna.

  In addition, the present invention includes, for example, a transmission array antenna configured from a plurality of transmission antenna elements, and a reception array antenna configured from a plurality of reception antenna elements respectively opposed to the plurality of transmission antenna elements. A plurality of transmitting antenna elements and a plurality of transmitting units constituting the array antenna are respectively connected via a switch unit, and a plurality of receiving antenna elements and a weight calculation circuit constituting the receiving array antenna are respectively connected via a switch unit. A wireless communication method using a connected wireless communication system, comprising: a phase difference estimation procedure for estimating a phase difference of a channel formed between the transmission array antenna and the reception array antenna; and estimation by the phase difference estimation procedure A transmission amplifier used for communication by switching the switch unit based on the phase difference A second phase difference that adjusts a phase difference of a channel formed between the transmission antenna element and the reception antenna element so that a desired channel capacity can be obtained by selecting the antenna element and the reception antenna element. It can be expressed as a wireless communication method characterized by including an adjustment procedure. In this case, for example, the first phase difference adjustment procedure may be further included.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be arbitrarily modified or modified without departing from the gist of the present invention.
For example, in the first embodiment described above, the communication device 100 is a transmitter and the communication device 700 is a receiver. However, each of the communication devices 100 and 700 is a transceiver having both a transmission function and a reception function. It may be configured. The same applies to other embodiments.

  1, 2, 3 ... wireless communication system, 100, 700, 2100, 2700, 3100, 3700 ... communication device, 111, 112 ... transmission unit, 131, 132 ... variable power distributor, 141 to 144 ... transmission antenna element, 140 ... Transmitting array antenna, 150, 750, 2150, 2750, 3150, 3750 ... Control device, 171, 172, 771, 772 ... Phaser, 711, 712 ... Receiving unit, 180, 780 ... Switch unit, 720 ... Weight calculation circuit , 731,732 ... combiner, 740 ... reception array antenna, 741-744 ... reception antenna element, 760 ... phase difference estimation unit, 1412, 1434 ... transmission subarray antenna, 7412, 7434 ... reception subarray antenna.

Claims (8)

A receiving array antenna comprising a plurality of transmitting sub-array antennas comprising a plurality of transmitting antenna elements, and a plurality of receiving sub-array antennas comprising a plurality of receiving antenna elements respectively facing the plurality of transmitting antenna elements. A wireless communication system comprising:
A phase difference estimation unit that estimates a phase difference of a channel formed between a transmission subarray antenna included in the transmission array antenna and a reception subarray antenna included in the reception array antenna;
Based on the phase difference estimated by the phase difference estimation unit, a power ratio of signals transmitted from transmission antenna elements constituting a transmission subarray antenna included in the transmission array antenna and reception included in the reception array antenna. By controlling the power ratio of the signals received by the receiving antenna elements constituting the subarray antenna, the channel formed between the transmitting subarray antenna and the receiving subarray antenna can be obtained so as to obtain a desired channel capacity. A first phase difference adjusting unit for adjusting the phase difference;
A wireless communication system comprising: The first phase difference adjusting unit is
Based on the phase difference estimated by the phase difference estimator, the power ratio and phase relationship of signals transmitted from the transmission antenna elements constituting the transmission subarray antenna of the transmission array antenna, and the reception array antenna By controlling the power ratio and phase relationship of the signals received by the receiving antenna elements constituting the receiving subarray antenna, a desired channel capacity can be obtained between the transmitting subarray antenna and the receiving subarray antenna. The radio communication system according to claim 1, wherein a phase difference between channels formed in the channel is adjusted. A plurality of transmissions comprising a transmission array antenna composed of a plurality of transmission antenna elements and a reception array antenna composed of a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. A wireless communication system in which an antenna element and a plurality of transmission units are connected via a switch unit, respectively, and a plurality of reception antenna elements constituting the reception array antenna and a weight calculation circuit are connected via a switch unit. And
A phase difference estimation unit that estimates a phase difference of a channel formed between the transmission array antenna and the reception array antenna;
By switching the switch unit based on the phase difference estimated by the phase difference estimation unit and selecting a transmission antenna element and a reception antenna element used for communication, a desired channel capacity can be obtained. A second phase difference adjustment unit for adjusting a phase difference of a channel formed between the transmission antenna element and the reception antenna element;
A wireless communication system comprising:   The radio communication system according to claim 3, further comprising the first phase difference adjustment unit according to claim 1. A receiving array antenna comprising a plurality of transmitting sub-array antennas comprising a plurality of transmitting antenna elements, and a plurality of receiving sub-array antennas comprising a plurality of receiving antenna elements respectively facing the plurality of transmitting antenna elements. A wireless communication method using a wireless communication system comprising:
A phase difference estimation procedure for estimating a phase difference of a channel formed between a transmission subarray antenna included in the transmission array antenna and a reception subarray antenna included in the reception array antenna;
Based on the phase difference estimated by the phase difference estimation procedure, a power ratio of signals transmitted from transmission antenna elements constituting a transmission subarray antenna included in the transmission array antenna, and reception included in the reception array antenna. By controlling the power ratio of the signals received by the receiving antenna elements constituting the subarray antenna, the channel formed between the transmitting subarray antenna and the receiving subarray antenna can be obtained so as to obtain a desired channel capacity. A first phase difference adjustment procedure for adjusting the phase difference;
A wireless communication method comprising: In the first phase difference adjustment procedure,
Based on the phase difference estimated by the phase difference estimation procedure, the power ratio and phase relationship of signals transmitted from the antenna elements constituting the subarray antenna included in the transmission array antenna, and the reception array antenna are included. It is formed between the transmission subarray antenna and the reception subarray antenna so that a desired channel capacity can be obtained by controlling the power ratio and phase relationship of signals received by the antenna elements constituting the subarray antenna. The wireless communication method according to claim 5, wherein the phase difference of the channel is adjusted. A plurality of transmissions comprising a transmission array antenna composed of a plurality of transmission antenna elements and a reception array antenna composed of a plurality of reception antenna elements respectively facing the plurality of transmission antenna elements. Wireless communication by a wireless communication system in which an antenna element and a plurality of transmitting units are connected via a switch unit, and a plurality of receiving antenna elements and a weight calculation circuit constituting the receiving array antenna are connected via a switch unit, respectively. A communication method,
A phase difference estimation procedure for estimating a phase difference of a channel formed between the transmitting array antenna and the receiving array antenna;
By selecting the transmission antenna element and the reception antenna element used for communication by switching the switch unit based on the phase difference estimated in the phase difference estimation procedure, so as to obtain a desired channel capacity, A second phase difference adjustment procedure for adjusting a phase difference of a channel formed between the transmission antenna element and the reception antenna element;
A wireless communication method comprising:   The wireless communication method according to claim 7, further comprising the first phase difference adjustment procedure according to claim 5.

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