JP2014192865A - Method for arranging antenna of short-range mimo, program and transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an antenna arrangement for preventing performance of MIMO from being deteriorated in a propagation environment where direct wave is dominant.SOLUTION: An antenna arrangement is provided which is for a short-range MIMO where direct wave is dominant. At this antenna arrangement, a distance (r) between a transmitter and a receiver, propagation coefficients (α, β, γ ) between the transmitter and the receiver, an offset (δ) between the transmitter and the receiver, and a distance (d) between antennas on the transmitter side or a distance (d) between antennas on the receiver side are included in parameters. Then, at least two parameters are assigned from these parameters. As a result, the antenna arrangement is determined which increases or decreases channel capacity (c).

Description

The technology of the present disclosure relates to, for example, short-range MIMO (Multiple Input Multiple Output) antenna technology used in a propagation environment where a direct wave is dominant.

  In a wireless communication system such as a mobile phone and a wireless local area network (LAN), MIMO transmission is known as one of transmission techniques. MIMO transmission has an advantage that both a transmitter and a receiver are provided with a plurality of antennas, the transmission speed is increased without increasing the frequency bandwidth, and highly reliable communication is possible.

For this MIMO transmission, the path phase difference between the receiving antennas close to the plurality of transmitting antennas and the intersecting receiving antennas is made close to (n / 2 + 1/4) λ, the desired wave of the propagation coefficient is set as a real term, and the unnecessary wave is set as an imaginary term, It is known to reduce the amount of MIMO processing (for example, Patent Document 1). It is known to increase the transmission capacity by signal transmission using the MIMO system and both polarized waves and polarized waves orthogonal to each other (for example, Patent Document 2). It is known that a power difference between propagation coefficients is increased by providing an antenna that communicates with horizontal polarization and an antenna that communicates with vertical polarization (for example, Patent Document 3). It is known that an antenna beam is directed to an opposing antenna, directivity nulls are directed to other antenna directions, and an amplitude difference using orthogonal polarization is used (for example, Patent Document 4).

JP 2011-077756 A International Publication No. 2009/069798 Special table 2010-516170 gazette JP 2005-236686 A

  FIG. 1A shows a MIMO transmission system 2. This MIMO transmission system 2 is in a propagation environment in which direct waves are dominant. The transmitter T is provided with a pair of antennas Tx1 and Tx2, and the receiver R is provided with a pair of antennas Rx1 and Rx2.

  Here, the distance between the transmitter T and the receiver R (the distance between the transmitter and the receiver) is r, and the distance between the antenna y1 and the antenna y2 (the distance between the antennas) is d.

  The relationship between the transmitter / receiver distance r and the antenna distance d is r >> d. That is, when the distance r between the transmitter and the receiver is sufficiently large compared to the inter-antenna distance d, if the propagation path from the antenna Tx1 to the antenna Rx1 is r1, and the propagation path from the antenna Tx2 to the antenna Rx2 is r2, these are The propagation paths r1 and r2 are parallel transmission paths. In this case, when the transmission signal x1 of the antenna Tx1 and the transmission signal x2 of the antenna Tx2 are received by either the antenna Rx1 or Rx2, the radio wave passes through the parallel propagation path.

  FIG. 1B shows the arrival angle θ (or radiation angle) of the radio wave in each of the propagation paths r1 and r2. The phase φ of the received signals y1 and y2 is determined by the arrival angle θ. The transmission signals x1, x2 and the reception signals y1, y2 are

となる。但し、位相φは、図１のＢから

It becomes. However, the phase φ is from B in FIG.

となる。

It becomes.

  As described above, the phase φ of the reception signals y1 and y2 is determined by the arrival angle θ of the radio wave. In this case, in the reception, when the antenna Rx2 is used, the phase φ is advanced from the antenna Rx1, and in the transmission, when the antenna Tx2 is used, the phase rotation becomes small.

  When Expressions (1) and (2) are expressed using a propagation matrix,

となる。式(5)において、αは伝搬路の係数（伝搬係数）である。

It becomes. In Expression (5), α is a propagation path coefficient (propagation coefficient).

  In this case, the propagation matrix is det (H) = 0. For this reason, simultaneous equations of equations (1) and (2) cannot be solved.

  In this way, when r >> d, a parallel transmission path is formed, the phase φ of the reception signals y1 and y2 is determined by the radiation angle or arrival angle θ of the radio wave, and the transmission signals x1 and x2 transmitted simultaneously are received. It cannot be separated from the signals y1 and y2. That is, decoding cannot be performed. For this reason, the performance of MIMO transmission deteriorates. Here, the performance degradation of the MIMO transmission means that a necessary channel capacity cannot be obtained. In this case, the channel represents a propagation path, and the channel capacity represents the maximum amount of information (that is, the achievable transmission rate) that can be transmitted per unit time on the propagation path.

  In this MIMO transmission, FIG. 2 shows a case where the distance r between the transceivers is short. Even if r> d, if r >> d as described above, the propagation paths r1, r2 from the antenna Tx1 to the antennas Rx1, Rx2 are not parallel transmission paths. That is, when the transmitter-receiver distance r is short and the transmitter-receiver distance r approaches the inter-antenna distance d, the distances of the propagation paths r1, r2 between the antenna Tx1 and the antennas Rx1, Rx2 are different. In such a case, it cannot be said that the MIMO performance is degraded, and there may be an antenna arrangement that does not degrade the MIMO transmission performance in a propagation environment in which a short-distance direct wave is dominant.

Accordingly, in view of the above problems, an object of the present disclosure is to realize an antenna arrangement that does not cause MIMO performance degradation in a propagation environment in which direct waves are dominant.

In order to achieve the above object, according to one aspect of the technology of the present disclosure, a short-range MIMO antenna arrangement in which a direct wave is dominant is provided. In this antenna arrangement, the distance between the transmitter / receiver, the propagation coefficient between the transmitter / receiver, the offset between the transmitter / receiver, the distance between the antennas on the transmitter side or the distance between the antennas on the receiver side are included in the parameters. Therefore, at least two parameters are designated from these parameters. This determines the antenna arrangement that increases or decreases the channel capacity.

  According to the technique of the present disclosure, any of the following effects can be obtained.

  (1) With respect to the antenna arrangement necessary for short-range MIMO transmission in which direct waves are dominant, arrangement information for increasing the channel capacity or reducing the channel capacity when determining the antenna arrangement of the short-range MIMO can be provided.

  (2) An antenna arrangement suitable for short-range MIMO in which direct waves are dominant can be realized, or an antenna arrangement not suitable for short-range MIMO in which direct waves are dominant can be avoided.

Other objects, features, and advantages of the present invention will become clearer with reference to the accompanying drawings and each embodiment.

It is a figure which shows the relationship between the transmission system of near field MIMO, and the arrival angle of a transmission radio wave. It is a figure which shows the transmission system of short-distance MIMO with the short distance between transmitter / receivers. It is a figure which shows the transmission system of the short-distance MIMO which concerns on 1st Embodiment. It is a figure which shows an antenna radiation pattern. It is a figure which shows the coordinate of antenna arrangement | positioning. It is a figure which shows an antenna radiation pattern table. It is a figure which shows the arithmetic processing element of antenna arrangement | positioning. It is a figure which shows an example of the hardware of the computer which performs an antenna arrangement | positioning program. It is a flowchart which shows an example of the process sequence when not considering an antenna radiation pattern. It is a flowchart which shows an example of the process sequence when an antenna radiation pattern is considered. It is a figure which shows the propagation coefficient condition table of near field MIMO. It is a figure which shows the antenna arrangement | positioning of near field MIMO. It is a figure which shows the calculation result of the channel capacity | capacitance and eigenvalue in the antenna arrangement | positioning of short-distance MIMO. It is a figure which shows the calculation result of the channel capacity | capacitance and eigenvalue in the antenna arrangement | positioning of short-distance MIMO. It is a figure which shows the antenna arrangement | positioning which concerns on 2nd Embodiment. It is a figure which shows the antenna arrangement | positioning and antenna radiation pattern which concern on 3rd Embodiment.

[First Embodiment]

  FIG. 3 shows a short-range MIMO transmission system according to the first embodiment. In FIG. 3, the same parts as those in FIG.

  This MIMO transmission system (hereinafter simply referred to as “transmission system”) 2 includes a transmitter T and a receiver R. The transmitter T is provided with a pair of antennas Tx1 and Tx2, and the receiver R is provided with a pair of antennas Rx1 and Rx2. That is, since each of the transmitter T and the receiver R includes two antennas, a 2 × 2 MIMO configuration is provided.

  In addition, the transmission system 2 is in a propagation environment in which direct waves are dominant and a parallel transmission path is not obtained regardless of which of the antennas Tx1, Tx2, Rx1, and Rx2. That is, it cannot be said that the distance r between the transmitter and the receiver is sufficiently large compared to the distance between the antennas.

  In FIG. 3, α is a propagation coefficient between the antenna Tx1 and the antenna Rx1, or a propagation coefficient between the antenna Tx2 and the antenna Rx2. β is a propagation coefficient between the antenna Tx1 and the antenna Rx2. γ is a propagation coefficient between the antenna Tx2 and the antenna Rx1. The transmission signal from the transmission antenna Txi is assumed to be xi (in this case, x1, x2), and the reception signal of the reception antenna Rxi is assumed to be yi (in this case, y1, y2).

  With respect to such a transmission system 2, the relationship between the received signal yi and the transmitted signal xi is expressed by a mathematical expression:

となる。

It becomes.

  The information of the transmission signal xi can be decoded from the reception signal yi without error if the transmission rate is equal to or less than the channel capacity c (Shannon's second basic theorem). That is, in a propagation path with a sufficiently large signal-to-noise power ratio SNR (= S / N), the channel capacity c is substantially proportional to the logarithm of SNR. Therefore, this channel capacity c is

で表現することができる。

Can be expressed as

  In equation (7), B is the bandwidth [Hz]. This expression (7) represents that the channel capacity c is determined by a mathematical expression (matrix eigenvalue) composed of the bandwidth B, the signal-to-noise power ratio SNR, and the propagation coefficients α, β, and γ.

<Antenna radiation pattern>

  FIG. 4 shows the radiation patterns of the antennas Tx1, Tx2, Rx1, and Rx2 described above. In this case, the position of the antenna Rx1 of the receiver R is taken as reference coordinates, and the positions and radiation patterns of the antennas Tx1, Tx2, Rx1, and Rx2 are shown. δ represents an offset between the transmitter and the receiver. This transmitter-receiver offset is the amount of deviation between the opposing antennas. ζi (i = 1, 2,... 6) indicates the i direction. In this case, each antenna radiation pattern indicates the pattern level at the angle in the opposite direction by the size of the arrow.

  FIG. 5 shows the x and y coordinate positions of the antenna arrangement when the antenna radiation pattern is not considered. That is, since the position of the antenna Rx2 is separated from the coordinate (0, 0) of the antenna Rx1 at the reference position by the distance d, the coordinate is (d, 0). With respect to these antennas Rx1 and Rx2, considering the inter-transmitter / receiver distance r and the transmitter / receiver offset δ, the coordinate positions of the antennas Tx1 and Tx2 are (δ, r) for the antenna Tx1 and (δ + d, r) for the antenna Tx2. Can be represented.

<Antenna radiation pattern table>

6A shows the antenna radiation pattern table 4-1 for the antennas Tx1 and Rx1. In this antenna radiation pattern table 4-1, the angles θ1, θ2,... In terms of terms are taken for the terms 1, 2,..., And radiation patterns ζ _1.1 , ζ _1.2 .

FIG. 6B shows an antenna radiation pattern table 4-2 for the antennas Tx2 and Rx2. In this antenna radiation pattern table 4-2, the terms θ1, θ2,... Are taken for the terms 1, 2,..., And radiation patterns ζ _2.1 , ζ _2.2 .

<Calculation elements of antenna placement program>

  7A and 7B show elements included in the antenna arrangement program 6.

  (1) When antenna radiation pattern is not considered

  In this case, as shown in FIG. 7A, the calculation element of the antenna arrangement program 6-1 includes, as a plurality of parameters, a transmitter-receiver distance r, a transmitter-receiver offset δ, a channel capacity c, a signal-to-noise power ratio SNR, and The inter-antenna distance d is included. In this antenna arrangement program 6-1, as an example, an optimal antenna arrangement should be avoided or avoided using the channel capacity c, the signal-to-noise power ratio SNR, and the inter-antenna distance d as parameters without considering the antenna radiation pattern in the i direction. Antenna arrangement is required. For example, assuming a transmitter-receiver distance r and a transmitter-receiver offset δ as at least two parameters, the antenna-to-antenna distance d is determined in consideration of the signal-to-noise power ratio SNR.

  (2) When considering the antenna radiation pattern

  In this case, as shown in FIG. 7B, the calculation elements of the antenna arrangement program 6-2 include, as a plurality of parameters, a transmitter / receiver distance r, a transmitter / receiver offset δ, an antenna radiation pattern ζi in the i direction, and a channel capacity c. , Signal-to-noise power ratio SNR and inter-antenna distance d. In this antenna arrangement program 6-2, an antenna radiation pattern in the i direction is taken into account as an example, and an optimum antenna arrangement or an antenna arrangement to be avoided using the channel capacity c, the signal-to-noise power ratio SNR, and the inter-antenna distance d as parameters. Is required. Assuming the transmitter-receiver distance r and the transmitter-receiver offset δ as at least two parameters, the antenna-to-antenna distance d is determined in consideration of the signal-to-noise power ratio SNR.

<Computer for executing the antenna arrangement program 6>

  FIG. 8 shows an example of computer hardware for executing the antenna arrangement program 6. The computer 8 includes a processor 10, a memory 12, a RAM (Random Access Memory) 14, an input unit 16, and a display unit 18.

  The processor 8 executes an operating system (OS) and executes the antenna arrangement program 6 described above.

  The memory 12 stores the OS, the antenna arrangement program 6 and various data. For the memory 12, for example, various storage media such as a hard disk device and a semiconductor memory can be used. The above-described antenna radiation pattern tables 4-1 and 4-2 are configured as a database constructed in the memory 12. The RAM 14 is used as a work area for arithmetic processing.

  The input unit 16 inputs the above-described parameters. The display unit 18 is an example of an output unit that outputs a calculation result. The display unit 18 may be a display element such as an LCD (Liquid Crystal Display) or a printing device that presents print information as a display output.

<Processing Procedure of Antenna Placement Program 6>

  (1) Processing procedure without considering antenna radiation pattern

  FIG. 9 shows an example of a processing procedure that does not consider the antenna radiation pattern. This processing procedure shows an example of the antenna arrangement method or the antenna arrangement program of the present disclosure. In this processing procedure, an inter-antenna distance d and a transmitter / receiver distance r are input as parameters (S101). For this input parameter, the propagation coefficient α and

  From the equations (15) and (16) of the phase difference η with respect to the transmitter / receiver where η = ± (1/4) + n (where n =... -1, 0, 1, 2,...) The offset δ is calculated (S102).

  As a result of this calculation, a plurality of transmitter / receiver offsets δ are output (S103).

  In this case, the propagation matrix H is

である。この伝搬行列Ｈにおいて、α、βおよびγは、アンテナ間距離ｄ、送受信機間距離ｒおよび波長λにより

It is. In this propagation matrix H, α, β and γ are determined by the distance d between antennas, the distance r between transmitters and receivers, and the wavelength λ.

と表すことができる。

It can be expressed as.

In addition, | H | ² of the eigenvalues μ1, is μ2,

である。

It is.

  The channel capacity c is expressed using these eigenvalues μ1 and μ2.

となる。Ｓ／Ｎは信号対雑音電力比である。

It becomes. S / N is the signal to noise power ratio.

  And α and

  The phase difference η is calculated using the offset δ between the transceivers, the distance d between the antennas, and the distance r between the transceivers,

となる。

It becomes.

  For this phase difference η, the optimum phase difference η is

である。但し、式(16)において、ｎ＝・・・−１，０，１，２・・・である。

It is. However, in equation (16), n =... -1, 0, 1, 2,.

  Moreover, the phase difference η to be avoided is

である。但し、式(17)および(18)において、ｎ＝・・・−１，０，１，２・・・である。

It is. However, in the formulas (17) and (18), n =... -1, 0, 1, 2,.

  (2) Processing procedure considering antenna radiation pattern

  FIG. 10 shows a processing procedure considering the antenna radiation pattern. This processing procedure shows an example of the antenna arrangement method or the antenna arrangement program of the present disclosure. In this processing procedure, an antenna distance d, a transmitter / receiver distance r, an antenna radiation pattern ζ, and a signal-to-noise power ratio (S / N) are input as parameters (S201). Using equation (16), the transmitter-receiver offset δ that maximizes the channel capacity c is obtained (S202). As a result of this calculation, a plurality of transmitter / receiver offsets δ are output (S203).

  In this processing procedure, the propagation matrix H is as described in Equation (8). In this propagation matrix H, α, β, and γ are the inter-antenna distance d, the transmitter-receiver distance r, the antenna radiation pattern ζ, and Depending on the wavelength λ

となる。ここで、|H|²の固有値μ１、μ２は、既述の式(12)、(13)に記載の通りである。

It becomes. Here, the eigenvalues μ1 and μ2 of | H | ² are as described in the above-described equations (12) and (13).

  And in this case α

  The phase difference η of

となる。式(22)において、ωは、

It becomes. In Equation (22), ω is

である。

It is.

  When the antenna radiation pattern is considered, the optimum phase difference η is

となる。但し、式(24)において、ｎ＝・・・−１，０，１，２・・・である。

It becomes. However, in the formula (24), n =... -1, 0, 1, 2,.

  Moreover, the phase difference η to be avoided is

である。但し、式(25)および式(26)において、ｎ＝・・・−１，０，１，２・・・である。

It is. However, in the formula (25) and the formula (26), n =... -1, 0, 1, 2,.

<Condition for propagation coefficient of short-range MIMO>

  The eigenvalues μ1 and μ2 shown in the above equations (12) and (13) indicate relative power. Here, it is assumed that μ1 + μ2 is constant, and the values of μ1 and μ2 are examined.

  If the difference between the eigenvalues μ1 and μ2 is small, the channel capacity c shown in the equation (14) is large. However, the bandwidth B and the signal-to-noise power ratio SNR are constant, that is, B = 1 and SNR = 1.

  Here, for example, if μ1 = μ2 = 3, μ1 and μ2 have the same value and the difference = 0. Therefore, when these numerical values are substituted into the equation (14), the channel capacity c1 in this case is

となる。

It becomes.

  Assuming that the difference between μ1 and μ2 is large, for example, μ1 = 6 and μ2 = 0. In this case, since the difference between μ1 and μ2 is 6, the channel capacity c2 is

となる。このような数値を想定して、チャネル容量ｃを求めると、図１１に示すように求められる。μ１＝６、５、４、３、μ２＝０、１、２、３で得られるチャネル容量ｃの値を示している。

It becomes. Assuming such a numerical value, the channel capacity c is obtained as shown in FIG. The values of channel capacity c obtained by μ1 = 6, 5, 4, 3, and μ2 = 0, 1, 2, 3 are shown.

  Thus, if the difference between μ1 and μ2 is small as the condition for the propagation coefficient of short-range MIMO, the channel capacity c increases and the received power on the receiver R side increases.

<Short range MIMO antenna layout>

  To increase the difference between μ1 and μ2 in short-range MIMO propagation, it is included in equations (12) and (13) for μ1 and μ2.

  It is sufficient that the phase difference is small and the amplitude difference is small.

  For example, if the difference between μ1 and μ2 is small,

となる。

It becomes.

  On the other hand, if the difference between μ1 and μ2 is large,

となる。つまり、振幅が同一であり、μ１、μ２の差が小であれば位相差が０となり、μ１、μ２の差が大であれば位相差が大きくなる。

It becomes. That is, if the amplitude is the same and the difference between μ1 and μ2 is small, the phase difference is 0, and if the difference between μ1 and μ2 is large, the phase difference is large.

  Then, when transmission / reception is performed with propagation coefficients β and γ different from the propagation coefficient α, the channel capacity c with respect to the value of the square root of the product β * γ of the propagation coefficients β and γ is obtained from Equation (7). In this case, the channel capacity c in which the phase difference is within ± 20 degrees or 180 ± 20 degrees and the amplitude difference is within 2 [dB] is as follows. However, it is assumed that B = 1 and SNR = 100 (= 20 [dB]).

  (1) When the amplitude difference = 0 [dB] and the phase difference = 90 degrees, the channel capacity c is

となる。

It becomes.

  (2) When the amplitude difference = 0 [dB] and the phase difference = 20 degrees, the channel capacity c is

となる。

It becomes.

  (3) When the amplitude difference = 2 [dB] and the phase difference = 0 degree, the channel capacity c is

となる。但し、ａ＝１．１１である。

It becomes. However, a = 1.11.

  (4) When the amplitude difference = 0 [dB] and the phase difference = 0 degree, the channel capacity c is

となる。

It becomes.

  As is clear from this result, the channel capacity c is the maximum when the amplitude difference = 0 [dB] and the phase difference = 90 degrees, and is the minimum when the amplitude difference = 0 [dB] and the phase difference = 0 degrees. Become. If the channel capacity c is minimum, the transmission signal cannot be separated from the reception signal, so that the communication quality deteriorates.

<Short range MIMO antenna layout>

  FIG. 12 shows a state where the transmitter T and the receiver R are facing each other. The conditions when the transmitter T and the receiver R face each other and the directivities of the antennas Tx1, Tx2, Rx1, and Rx2 are uniform are as follows. In this way, when the transmitter T and the receiver R face each other, the propagation coefficients β and γ are in a relationship of β = γ.

と、

When,

との差が大きくなる条件は、送受信機間距離ｒとアンテナ間距離ｄの関係が

The difference between the distance between the transmitter and the receiver is r and the distance between the antennas d is

でなければよい。

If not.

<Calculation result of short-range MIMO>

  FIG. 13 shows a calculation result in the case of 2 × 2, frequency 2.4 [GHz], and transmitter / receiver distance r = 0.15 [m].

  This calculation result shows changes in channel capacity c and eigenvalues μ1 and μ2 with respect to the distance d between the antennas. In FIG. 13, the antenna arrangements Q1, Q2, and Q3 that are desired to be avoided are shown.

  FIG. 14 shows a calculation result of another antenna arrangement. In this calculation result, the offset between the transmitter and the receiver is set to 0.1 m. P1, P2, P3, P4, and P5 indicate distances between a plurality of antennas having a large channel capacity c. Q4 and Q5 are arrangements in which the channel capacity c is small, and indicate the distance between antennas to be avoided.

<Effects and Modifications of First Embodiment>

  (1) When the antenna arrangement and the coordinate system shown in FIG. 3 are used, the channel capacity c, which is the MIMO performance, is set using the 2 × 2 MIMO inter-antenna distance d, the inter-transmitter / receiver distance γ, and the inter-transmitter / receiver offset δ as parameters. Can express.

  (2) The antenna radiation pattern shown in FIG. 4 is additionally inputted and can be expressed by the channel capacity c.

  (3) Inputting the transmitter / receiver distance r and the transmitter / receiver offset δ, the inter-antenna distance d for increasing the channel capacity c can be obtained, and a plurality of inter-antenna distances d for increasing the channel capacity c are output. Can do.

  (4) Instead of the channel capacity c, the inter-antenna distance d where the phase difference between the components generating the eigenvalues μ1 and μ2 is 90 degrees can be used as a parameter.

  (5) In addition, it is possible to guide an antenna arrangement to be avoided where the channel capacity c is small, and it is possible to prevent deterioration of the channel capacity c by the antenna arrangement avoiding this arrangement.

  (6) Degradation of MIMO performance can be avoided by avoiding an antenna arrangement in which the phase difference between the components generating the eigenvalues μ1 and μ2 is around 0 or 180 degrees and the amplitude difference between these components is small.

[Second Embodiment]

  FIG. 15 shows an antenna arrangement according to the second embodiment. 15, the same parts as those in FIG. 3 are denoted by the same reference numerals.

  In the first embodiment, the arrangement of the antennas Tx1 and Tx2 is parallel to the arrangement of the antennas Rx1 and Rx2, whereas in this embodiment, the arrangement is not parallel. In addition, the distance between the antennas Rx1 and Rx2 on the receiver side is larger than the distance between the antennas Tx1 and Tx2 on the transmitter side.

  With respect to this antenna arrangement, the coordinates of the antenna Rx1 are (0, 0, 0), and the coordinates of the antenna Rx2 are (d1, 0, 0). In this case, assuming that the offsets of the antennas Tx1 and Rx1 are δ, the coordinates of the antenna Tx1 are (δ, γ, 0), and the coordinates of the antenna Tx2 are (δ + d2cos (θ) cos (φ), r + d2cos (θ ) sin (φ), d2sin (θ)). In this case, θ and φ are displacement angles from the reference coordinates.

  In this case, the propagation matrix H is

であり、ξはＺ軸方向の伝搬係数である。

Ξ is a propagation coefficient in the Z-axis direction.

  Therefore, the propagation coefficients α, β, γ and ξ are

である。

It is.

In this case, | H | ² of the eigenvalues μ1, is μ2,

となる。

It becomes.

  And the channel capacity c is

である。

It is.

  As described above, since the eigenvalues μ1 and μ2 and the channel capacity c are obtained, even if the antenna arrangement changes as described above, the transmitter-receiver offset δ and the antenna distance d are set as in the first embodiment. Can be sought. In other words, even when the distance between the transmitting antennas is different from the distance between the receiving antennas and the transmitting and receiving antennas are not parallel, the optimum position of the antenna arrangement or the position to be avoided can be obtained.

[Third Embodiment]

  FIG. 16 shows an antenna arrangement and an antenna radiation pattern according to the third embodiment. In FIG. 16, A shows the antenna arrangement and antenna radiation pattern, and B shows the antenna arrangement coordinates excluding the antenna radiation pattern. In FIG. 16, the same parts as those in FIG.

  In the first embodiment, the radiation angle of the antenna radiation pattern is closely assumed, but in this embodiment, the antenna radiation pattern is simplified at intervals of 45 degrees.

  (1) Considering antenna radiation pattern

  In this case, the transmission matrix H is

である。

It is.

  Propagation coefficients α and β are

となる。

It becomes.

In this case, | H | ² of the eigenvalues μ1, is μ2,

である。

It is.

  And the channel capacity c is

である。

It is.

  In this case, the phase difference η between the propagation coefficients α and β is

である。

It is.

  In this phase difference η, the optimum phase difference η is

である。

It is.

  On the other hand, the phase difference η to be avoided is

である。

It is.

  (2) When antenna radiation pattern is not considered

  In this case as well, the propagation matrix H is the same as the equation (40), but the antenna radiation pattern is not considered, so the propagation coefficients α and β are

となる。

It becomes.

In this case, | H | ² of the eigenvalues μ1, is μ2,

となり、

And

  The channel capacity c is

である。

It is.

  In this case, α and

  The phase difference η of

となる。

It becomes.

  In this phase difference η, the optimum phase difference η is

である。

It is.

  On the other hand, the phase difference η to be avoided is

である。

It is.

  Thus, since the eigenvalues μ1 and μ2 and the channel capacity c are obtained, the transmitter / receiver offset δ and the inter-antenna distance d can be obtained as in the first embodiment.

[Other Embodiments]

  (1) In the above embodiment, a case has been described where two antennas are provided on the transmitter T side and two antennas are provided on the receiver R side. However, in the present invention, the system includes three or more antennas on the transmitter side and the reception side. It can also be applied to the case where it is provided on the aircraft side.

  (2) In the above embodiment, as shown in FIG. 15, the case where the transmitter antennas Tx1 and Tx2 are displaced has been described. However, the receiver antennas Rx1 and Rx2 are displaced, so that The present invention can also be applied to the case where the R side is non-parallel.

As described above, the most preferred embodiment of the antenna arrangement has been described. The present invention is not limited to the above description. Various modifications and changes can be made by those skilled in the art based on the gist of the invention described in the claims or disclosed in the embodiments for carrying out the invention. Such modifications and changes are included in the scope of the present invention.

2 MIMO transmission system T Transmitter R Receiver Tx1, Tx2 Transmitter antenna Rx1, Rx2 Receiver antenna α Propagation coefficient between antennas Tx1 and Rx1, Propagation coefficient between antennas Tx2 and Rx2 β Propagation between antennas Tx1 and Rx2 Coefficient γ Propagation coefficient between antennas Tx2 and Rx1 xi Transmitted signal yi Received signal r Transmitter / receiver distance d Transmitter side antenna distance, Receiver side antenna distance δ Transmitter / receiver offset ζi Antenna radiation pattern in i direction c Channel capacity 4-1, 4-2 Antenna radiation pattern table 6, 6-1, 6-2 Antenna arrangement program 8 Computer 10 Processor 12 Memory 14 RAM
16 Input section 18 Display section

Claims (5)

A direct-wave dominant short-range MIMO antenna arrangement method,
The parameters include transmitter-receiver distance, transmitter-receiver propagation coefficient, transmitter-receiver offset, transmitter-side antenna distance or receiver-side antenna distance,
Specify at least two parameters from these parameters,
An antenna arrangement method for short-range MIMO, comprising: determining an antenna arrangement that increases or decreases channel capacity.   The method of claim 1, wherein the parameter includes an antenna radiation pattern.   3. The transmitter-side antenna distance and the receiver-side antenna distance are individually set, and an inclination difference between the transmitter-side antenna and the receiver-side antenna is set. The antenna arrangement | positioning method of short-distance MIMO as described in 1 above. An antenna arrangement program for obtaining a short-range MIMO antenna arrangement in which a direct wave is dominant by a computer,
The parameters include transmitter-receiver distance, transmitter-receiver propagation coefficient, transmitter-receiver offset, transmitter-side antenna distance or receiver-side antenna distance,
Specify at least two parameters from these parameters,
An antenna arrangement program for short-range MIMO for causing the computer to execute processing for determining antenna arrangement for increasing or decreasing channel capacity. A short-range MIMO transmission system used in a propagation environment in which direct waves are dominant,
Including at least two antennas at the transmitter and receiver;
Either one or both of the antennas on the transmitter side or the receiver side is a transmitter-receiver distance, a propagation coefficient between the transmitters, a transmitter-receiver offset, a transmitter-side antenna distance, or a receiver-side antenna distance. A short-range MIMO transmission system comprising: an antenna arrangement that increases or decreases a channel capacity according to designation of at least two parameters from among the parameters.

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