JP6743328B2 - Antenna control method and antenna device - Google Patents

Description

The present invention relates to an antenna control method and an antenna device.

In recent years, smart devices such as smartphones and tablet terminals have become widespread. Many contents such as social networking services (SNS) are used in smart devices, and high-speed communication is required in an environment where wireless communication terminals are crowded such as stadium seats, station yard during rush hour commute, trains, etc. There is. However, since the base station accommodating the wireless communication terminal has only a certain frequency bandwidth, there is a problem that the bandwidth allocated to each user decreases as the number of users accommodated in the base station decreases, and the communication speed decreases. Occurs.

As a solution to this problem, a method of installing base stations at high density and reducing the number of accommodations per base station can be considered. However, when the density of base stations increases, the interference (referred to as interference) that a communication signal of a certain base station gives to a communication signal of an adjacent base station (adjacent area) becomes large, and the signal power vs. interference noise of the adjacent area. There is a problem that the power ratio (SINR) characteristic is deteriorated. The deterioration of SINR characteristics causes deterioration of transmission quality of wireless communication such as deterioration of bit error rate (BER) characteristics.

Therefore, as conventional technologies to reduce interference to adjacent areas, closed space in each area, use of directional antenna, beam forming/null forming by MIMO (Multiple-Input and Multiple-Output), etc. are considered. ..

The closed space of the area is a method of physically blocking the radio wave by installing a metal wall or the like in the area that becomes the boundary of the area. This method can prevent interference in the adjacent area, but has a problem that the landscape of the communication area is damaged and installation cost is increased.

When using a directional antenna or beamforming/null formation by MIMO, it is possible to reduce interference by directing the null of the antenna pattern toward the adjacent area.

Further, Patent Document 1 describes a wireless communication area control device using a leaky coaxial cable. The use of the leaky coaxial cable is an inexpensive method that facilitates the installation design of the base station in the construction of the wireless communication system in the building and can freely set the location and the size of the radio wave transmission area. When the leaky coaxial cable is used, it is possible to easily set and select a place where the wireless communication service can be provided and to change the system according to the change in the condition of the wireless communication service providing destination with a high degree of freedom.

Further, in Patent Document 2, an area formation information collecting unit that collects information about area formation of a peripheral base station that is a candidate for a handover destination, a "main lobe", a "side lobe" in an antenna pattern, and At least one of the "null points between the main lobe and the side lobes" is controlled by controlling the same frequency interference (between the cell formed by the base station and the cells formed by the neighboring base stations). Methods of reducing interference are described.

JP, 2005-101861, A JP, 2007-036487, A

However, the leaky coaxial cable can construct an area in consideration of interference in the axial direction of the coaxial cable, but cannot prevent interference in an adjacent area in a direction away from the axis.

In addition, the method of preventing interference by directivity of antenna beam and null formation can construct an area considering interference in the angular direction of transmitting and receiving signals from the antenna, but control in the direction away from the antenna (distance direction). Therefore, it is impossible to prevent interference with adjacent areas existing in the same angle direction.

Furthermore, as a simple method of controlling in the distance direction, a method of lowering the transmission power of the base station can be considered, but by limiting the transmission power, not only the adjacent area but also the signal power to noise power in the own station area There is a problem that the ratio (SNR) decreases and the BER deteriorates.

In view of the above problem, the present invention focuses on a physical phenomenon called a free space propagation loss (hereinafter referred to as a distance attenuation function) in which a transmission signal is attenuated according to a distance from the antenna, and an antenna arrangement using a plurality of antennas. By controlling the amplitude, phase, and transmission timing of each transmission/reception signal, the distance attenuation function is spatially differentiated and equalized, thereby making the gradient of the distance attenuation function steep and advancing to the adjacent area in the distance direction. It is an object of the present invention to provide an antenna control method and an antenna device that reduce the interference caused by the interference.

The antenna control method according to the first aspect of the invention transmits and receives when at least one of the transmitting side antenna and the receiving side antenna is N (N≧2 integer) antennas arranged at a predetermined interval. An antenna control method for controlling a signal, wherein when the N antennas are the transmitting antennas, the spatial density of radio waves transmitted from the N antennas is attenuated according to the distance from the antennas. The amplitude, the phase, and the transmission timing of the signal to be transmitted are controlled according to the arrangement of the N antennas so as to spatially differentiate the distance attenuation function to be performed. When the N antennas are the receiving antennas, A signal received according to the arrangement of the N antennas so as to spatially differentiate a distance attenuation function in which the spatial density of the radio waves received by the N antennas attenuates according to the distance from the transmission side. that controls the amplitude and phase.

Then, the when N is 2 ^M (M ≧ 1 integer), the process of configuring the 2 ^M-number of antennas by selecting two adjacent antenna 2 ^(M-1) pieces of the new antenna by repeating M times, differentiating the distance decay function spatially.

Then , of the two adjacent antennas, the amplitude A ₁ and phase θ ₁ of the transmission signal s _Tx1 of the _first antenna, the amplitude A ₂ and phase θ ₂ of the transmission signal s _Tx2 of the second antenna, and the first antenna the distance attenuation function at a point distant by a distance r ₁ from f (r _1), wherein the first antenna and Δh the distance between the second antenna, the derivative f of the distance attenuation function '(r), When the wave number is k and a signal received at a position away from the first antenna and the second antenna is s _Rx ,
S _Rx =S _Tx1 +S _Tx2
=A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )+A ₂・exp(j・(kr ₂ +θ ₂ ))・f(r ₁ +Δh)
In the above equation, the following equation holds,
A ₁・exp(j・(kr ₁ +θ ₁ ))=-A ₂・exp(j・(kr ₂ +θ ₂ ))
When the first antenna and the second antenna are transmission-side antennas, the first antenna and the second antenna control the amplitude, phase, and transmission timing of signals to be transmitted, and When the signal is received by the antenna and the second antenna, the amplitude and phase of the signal received by the first antenna and the second antenna are controlled.

2nd invention is the 1st invention, The amplitude and phase of the signal transmitted by the said 1st antenna and the said 2nd antenna, or the signal received by the said 1st antenna and the said 2nd antenna. Meets the following conditions
A ₁ =A ₂
θ ₂ = θ ₁ -2πΔh/λ-(2n+1)π (n is an integer)
It is characterized by

In a third aspect based on the first aspect or the second aspect , the antennas are arranged side by side on a straight line and have characteristics of either an omnidirectional type or a directional type, and It is characterized in that it is applied to at least one antenna on the receiving side.

An antenna device according to a fourth aspect of the present invention is N (integer of N≧2) antennas arranged at a predetermined interval, and when the N antennas are transmitting antennas, the N antennas. Amplitude and phase of signals to be transmitted and received according to the arrangement of the N antennas so that the spatial density of the radio wave transmitted from the antenna is spatially differentiated with respect to the distance attenuation function that attenuates according to the distance from the antenna. When the N antennas are reception side antennas, the transmission timing is controlled, and the spatial density of the radio waves received by the N antennas is attenuated according to the distance from the transmission side. And a control unit that controls the amplitude and phase of the received signal according to the arrangement of the N antennas so that the N is 2 ^M (an integer of M≧1). In this case, two adjacent antennas of the 2 ^M antennas are selected and the process of forming 2 ^(M−1) new antennas is repeated M times to spatially differentiate the distance attenuation function. It

Then , of the two adjacent antennas, the amplitude A ₁ and phase θ ₁ of the transmission signal s _Tx1 of the _first antenna, the amplitude A ₂ and phase θ ₂ of the transmission signal s _Tx2 of the second antenna, and the first antenna the distance attenuation function at a point distant by a distance r ₁ from f (r _1), wherein the first antenna and Δh the distance between the second antenna, the derivative f of the distance attenuation function '(r), When the wave number is k and a signal received at a position away from the first antenna and the second antenna is s _Rx ,
S _Rx =S _Tx1 +S _Tx2
=A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )+A ₂・exp(j・(kr ₂ +θ ₂ ))・f(r ₁ +Δh)
In the above equation, the following equation holds,
A ₁・exp(j・(kr ₁ +θ ₁ ))=-A ₂・exp(j・(kr ₂ +θ ₂ ))
When transmitting with the first antenna and the second antenna, the amplitude, the phase, and the transmission timing of the signals transmitted with the first antenna and the second antenna are controlled, and the first antenna and the When the signal is received by the second antenna, the amplitude and phase of the signals received by the first antenna and the second antenna are controlled.

In a fifth aspect based on the fourth aspect , an amplitude and a phase of a signal transmitted by the first antenna and the second antenna or a signal received by the first antenna and the second antenna. Meets the following conditions
A ₁ =A ₂
θ ₂ = θ ₁ -2πΔh/λ-(2n+1)π (n is an integer)
It is characterized by

An antenna control method and an antenna device according to the present invention spatially differentiate a distance attenuation function in which signals transmitted and received by a plurality of antennas are attenuated according to distances from the antennas to steepen the gradient of distance attenuation, It is possible to reduce interference with adjacent areas.

It is a figure which shows the basic example of the antenna device 100 which concerns on each embodiment. It is a figure which shows an example of an omnidirectional transmitting antenna. It is a figure which shows an example of the transmission antenna which uses the electromagnetic wave absorber 150. It is a figure which shows an example of a directional transmission antenna. It is a figure which shows an example of an omnidirectional receiving antenna. It is a figure which shows an example of a directional receiving antenna. It is a figure which shows an example of the transmission antenna which performs multiple times of differentiation. It is a figure which shows the process sequence of an antenna control method. It is a figure which shows an example of a simulation result.

Embodiments of an antenna control method and an antenna device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic example of an antenna device 100 used in each embodiment described below. In FIG. 1, an antenna device 100 includes N antennas 101(1), antennas 101(2),..., Antennas 101(N), and a controller 102. Here, when a description common to the antenna 101(1), the antenna 101(2),..., And the antenna 101(N) is given, the (number) at the end of the reference numeral is omitted and the description is given as the antenna 101.

The antenna device 100 shown in FIG. 1 transmits a signal input from the transmission/reception device 103 from N antennas 101 to a communication destination device. Alternatively, the antenna device 100 receives the signal transmitted from the communication destination device by the N antennas 101, calculates the sum of the received N signals, and outputs the sum to the transmitting/receiving device 103.

In FIG. 1, N antennas 101 from antenna 101(1) to antenna 101(N) are end fire type antenna arrays that are arranged on a straight line and have a straight line direction as a transmission/reception direction.

The control unit 102, when transmitting/receiving a signal input/output to/from the transmitting/receiving apparatus 103 by the N antennas 101, the amplitude of the signal transmitted/received by each of the antennas 101(1) to 101(N). And control the phase. For example, the control unit 102 spatially differentiates the distance attenuation function in which signals transmitted and received by the N antennas 101 are attenuated according to the distance from the antenna 101 to steepen the gradient of the distance attenuation, and the adjacent area in the distance direction. The amplitude and phase of the signal transmitted/received by each antenna 101 are controlled so that the interference with the signal is reduced. The method of spatially differentiating the distance attenuation function will be described later.
(First embodiment)
1st Embodiment demonstrates the case where the antenna device 100 demonstrated in FIG. 1 is applied to a transmission side. In this embodiment, a case where two antennas 101, that is, the antenna 101(1) and the antenna 101(2) in FIG. 1 are used will be described. An example using N antennas 101 will be described in the third embodiment. Described in.
[When the transmitting side is an omnidirectional antenna]
FIG. 2 shows an example in which the antenna device 100 described in FIG. 1 is used as the transmitting side and an omnidirectional antenna is used. In FIG. 2, two antennas 101, antenna 101(1) and antenna 101(2), are used as transmitting antennas. Further, in the example of FIG. 2, a case where an omnidirectional antenna is used as the transmitting side antenna 101 will be described, but the receiving side antenna 201 may use either a directional antenna or an omnidirectional antenna. .. Note that the number at the end of the code of the antenna 101 is added to the antenna 101 closer to the antenna 201, as in (1) and (2).

In FIG. 2, the distance between the antenna 101(1) and the antenna 201 is r ₁ , and the distance between the antenna 101(2) and the antenna 201 is r ₂ . If the distance (interval) between the antenna 101(1) and the antenna 101(2) is Δh, the distance r ₂ between the antenna 101(2) and the antenna 201 is r ₂ =r ₁ +Δh.

In FIG. 2, the signal transmitted from the transmitting-side antenna 101(1) is received by the receiving-side antenna 201 located at a distance r _{1 and the} amount of attenuation of the signal amplitude per unit area due to this propagation. Depends on the propagation distance r ₁ . Therefore, the function f of the propagation distance r ₁ is expressed as the distance attenuation function f(r ₁ ). Similarly, the signal transmitted from the transmitting side antenna 101(2) is received by the receiving side antenna 201, and the distance attenuation function representing the amplitude attenuation amount of this signal can be represented by f(r ₂ ). Let s _{Tx1 be} the complex amplitude of the transmission signal at the position of distance r ₁ from the transmission-side antenna 101(1), and s _{Tx2 be} the complex amplitude of the transmission signal at the position of the distance r ₂ from the transmission-side antenna 101(2). It can be expressed as in equations (1) and (2), respectively.

s _Tx1 =A ₁・f(r ₁ )・exp(j・(kr ₁ +θ ₁ )) …(1)
s _Tx2 =A ₂ ·f(r ₂ )·exp(j·(kr ₂ +θ ₂ )) …(2)
Here, k is the wave number (k=2π/λ(λ: wavelength)), A(A ₁ , A ₂ ) is the initial amplitude, and θ(θ ₁ , θ ₂ ) is the initial phase.

At this time, assuming that the complex amplitude of the reception signal of the antenna 201 is s _Rx , the signal received by the reception antenna becomes the expression (3).

s _Rx =s _Tx1 +s _Tx2
=A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )+A ₂・exp(j・(kr ₂ +θ ₂ ))・f(r ₁ +Δh) …(3)
Here, the differential f′(r) with respect to the argument r of the function f(r) can be expressed as the equation (4) from the definition equation of the differential.

さらに、式（４）を変形すると、式（５）及び式（６）のように変形できる。

Furthermore, if the equation (4) is transformed, it can be transformed into the equations (5) and (6).

一方、式（３）において、次の式（７）の条件を満たすとき、
A₁・exp(j・(kr₁+θ₁))=-A₂・exp(j・(kr₂+θ₂)) …（７）
式（３）は、以下のように、式（８）を経て式（９）のように変形することができ、式（９）の右辺は、式（６）の右辺と同じ形になる。

On the other hand, when the condition of the following formula (7) is satisfied in the formula (3),
A ₁・exp(j・(kr ₁ +θ ₁ ))=-A ₂・exp(j・(kr ₂ +θ ₂ )) …(7)
The formula (3) can be transformed into the formula (9) through the formula (8) as follows, and the right side of the formula (9) has the same shape as the right side of the formula (6).

s _Rx =A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )-A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ +Δh) …( 8)
s _Rx /(A ₁ ·exp(j ·(kr ₁ +θ ₁ )))=f(r ₁ )-f(r ₁ +Δh) …(9)
Then, by substituting the equation (9) into the equation (6), the equations (10) and (11) can be obtained.

s _Rx /(A ₁ ·exp(j ·(kr ₁ + θ ₁ )))=-Δh·f'(r) …(10)
s _Rx =-A ₁ · exp(j · (kr ₁ + θ ₁ )) · Δh · f'(r) …(11)
Here, f'(r) corresponds to the differentiation of the distance attenuation function f(r), and by differentiating the distance attenuation function f(r), the attenuation characteristic of the distance attenuation function f(r) becomes steep, A distance attenuation effect is obtained.

Further, in order for the condition of the above-mentioned expression (7) to be satisfied, it is necessary to satisfy the following expressions (11) and (12) (expression (13)).

A ₁ =A ₂ …(11)
kr ₁ +θ ₁ =kr ₂ +θ ₂ +(2n+1)π (12)
θ ₂ = θ ₁ -2πΔh/λ-(2n+1)π (n is an integer) (13)
That is, for two transmission signals having the same initial amplitude, the initial phase or the transmission timing is controlled so that the signal transmitted from the transmission antenna 101(2) undergoes anti-phase synthesis at the transmission antenna 101(1). It means that you can send it. Although the signals are weakened by anti-phase synthesis, the positions of the transmitting antennas differ by Δh, so perfect cancellation (cancellation in which the amplitude is always 0) does not occur, and as a result of weakening, spatial differentiation and equalization do not occur. It becomes a transmission signal.

As an example of satisfying the above formulas (11) and (13), in FIG. 2, the distance Δh between the antenna 101(1) and the antenna 101(2) is λ/2 (Δh=λ/2), A method of transmitting signals of the same phase from the antenna 101(1) and the antenna 101(2) can be considered. Alternatively, as another example, when the distance Δh between the antenna 101(1) and the antenna 101(2) is λ (Δh=λ), signals of opposite phases are output from the antenna 101(1) and the antenna 101(2). A method of sending can be considered. By transmitting such a signal from the antenna 101(1) and the antenna 101(2), the condition of the expression (7) can be satisfied, so that the distance attenuation function is differentiated to make the slope of the distance attenuation steep, It is possible to reduce interference with adjacent areas in the distance direction.

Note that, in directions other than the line segment that connects the antenna 101(1) and the antenna 101(2), the strengthening of the transmission signals may occur. This case can be dealt with by preventing unnecessary radio waves from traveling in directions other than the antenna 201, as described in the next figure. As a method of preventing unnecessary radio waves from traveling in a direction other than the antenna 201, for example, a method of using a directional antenna described later or a method of disposing a radio wave absorber described below can be considered.

FIG. 3 shows an example in which a radio wave absorber is arranged. Here, in FIG. 3, the antenna 101(1), the antenna 101(2), and the antenna 201 are the same as the antennas described in FIG. Further, the antenna 101(1) and the antenna 101(2) transmit signals that satisfy the equations (11) and (13), as in the case of FIG.

In the example of FIG. 3, the radio wave absorber 150 is arranged in a direction other than the receiving side antenna 201 on the line segment connecting the antenna 101(1) and the antenna 101(2), and unnecessary radio waves are directed in a direction other than the antenna 201. I try not to fly. As a result, when the directional directions of the antenna 101(1) and the antenna 101(2) are not aligned, or when the antenna 101(2) is not on the straight line connecting the antenna 201 and the antenna 101(1). Also, the effect of steepening the distance attenuation gradient in the direction of the antenna 201 can be obtained, and interference with adjacent areas can be prevented. In the example of FIG. 3, the electromagnetic wave absorber 150 seems to be vacant in the direction other than the antenna 201 also in the paper surface direction, but FIG. 3 is a cross-sectional view for making the inside easy to understand, and actually The antenna 101(1) and the antenna 101(2) have an opening only in the direction of the antenna 201, and are surrounded by the radio wave absorber 150.

As described above, in the case of an omnidirectional antenna, signals other than the straight line connecting the transmitting antennas are transmitted by transmitting the signals satisfying the equations (11) and (13) from the antennas 101(1) and 101(2). It is possible to reduce the interference with the adjacent area by making the gradient of the distance attenuation steep in the direction of the straight line without radiating to the adjacent area.

Here, in the present embodiment, in the antenna device 100 described with reference to FIG. 1, since the two antennas 101, that is, the antenna 101(1) and the antenna 101(2) are used as the transmitting side, the number of differentiation is once. Become. The gradient of the distance attenuation function can be made steeper by differentiating the distance attenuation function f(r) a plurality of times. The case of performing the differentiation a plurality of times will be described in the third embodiment.
[When the transmitting side is a directional antenna]
In FIG. 2, the case where the omnidirectional antenna is used has been described, but the same can be applied to the directional antenna.

FIG. 4 shows an example of using a directional antenna on the transmitting side. In FIG. 4, for example, two directional antennas 101a (antennas 101a(1) and 101a(2)) are used to align the directional directions, and signals that satisfy equations (11) and (13) are transmitted. As a result, similar to the two omnidirectional antennas 101 (antenna 101(1) and antenna 101(2)) described with reference to FIG. 2, the effect of steepening the gradient of distance attenuation can be obtained.

Note that when the directional directions of the antenna 101a(1) and the antenna 101a(2) are not aligned, or when the antenna 101a(2) is not on the straight line connecting the antenna 201 and the antenna 101a(1), By arranging the antenna 101a(1) and the antenna 101a(2) that satisfy (11) and the equation (13) and selecting the pointing direction, the effect of steepening the gradient of distance attenuation can be obtained.

Thus, even in the case of a directional antenna, signals other than the straight line connecting the transmitting antennas can be obtained by transmitting the signals satisfying the equations (11) and (13) from the antennas 101a(1) and 101a(2). It is possible to reduce the interference with the adjacent area by making the gradient of the distance attenuation steep in the direction of the straight line without radiating to the adjacent area.
(Second embodiment)
In the second embodiment, a case where the antenna device 100 described in FIG. 1 is applied to the receiving side will be described. In the present embodiment, a case where two antennas 101 (1) and 101 (2) in FIG. 1 are used on the receiving side will be described, and an example using N antennas 101 will be described in a third example. The embodiment will be described.
[When the receiving side is an omnidirectional antenna]
FIG. 5 shows an example in which the antenna device 100 described in FIG. 1 is used as a receiving side and an omnidirectional antenna is used for the receiving side. Note that, in FIG. 5, two antennas 201, that is, the antenna 201(1) and the antenna 201(2) are used as receiving antennas, and the antenna 201(1) and the antenna 201(2) are the antenna 101( shown in FIG. This corresponds to the case where 1) and the antenna 101(2) operate as receiving antennas. Further, in the example of FIG. 5, a case where an omnidirectional antenna is used as the receiving side antenna 201 will be described, but the transmitting side antenna 201 may use either a directional antenna or an omnidirectional antenna. .. The number at the end of the code of the antenna 201 is added and described from the antenna 201 closer to the transmitting side antenna 101 to (1) and (2).

In FIG. 5, the distance between the antenna 101 and the antenna 201(1) is r ₁ , and the distance between the antenna 101 and the antenna 201(2) is r ₂ . Further, when the distance (interval) between the antenna 201(1) and the antenna 201(2) is Δh, the distance r ₂ between the antenna 201(2) and the antenna 101 is r ₂ =r ₁ +Δh.

In FIG. 5, the signal transmitted from the transmitting-side antenna 101 is received by the receiving-side antenna 201(1) located at a distance r _{1 and the} amount of attenuation of the signal amplitude per unit area due to this propagation. Depends on the propagation distance r ₁ . Therefore, as in the case of FIG. 2, the function f of the propagation distance r ₁ is expressed as the distance attenuation function f(r ₁ ). Similarly, the antenna 201(2) on the receiving side can be represented by the distance attenuation function f(r ₂ ). The transmission signal of the complex amplitude of the antenna 101 of the transmitting side is _{s Tx,} from the antenna 101 reception-side antenna 201 of the position of the distance _{r 1} the complex amplitude of the received signal (1) _{r Rx1,} from the antenna 101 a distance _{r 2} When the complex amplitude of the reception signal of the antenna 201(2) on the receiving side at the position is r _Rx2 , it can be expressed as in Expression (14) and Expression (15), respectively. In addition,
r _Rx1 =A ₁・f(r ₁ )・exp(j・(kr ₁ +θ ₁ )) …(14)
r _Rx2 =A ₂ ·f(r ₂ )·exp(j·(kr ₂ +θ ₂ )) …(15)
Here, k is the wave number (k=2π/λ(λ: wavelength)), A(A ₁ , A ₂ ) is the initial amplitude, and θ(θ ₁ , θ ₂ ) is the initial phase.

At this time, when the signals received by the antennas 201(1) and 201(2) are combined and the complex amplitude of the signal output to the receiving apparatus is r _Rx , equation (16) is obtained.

r _Rx =r _Rx1 +r _Rx2
=A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )+A ₂・exp(j・(kr ₂ +θ ₂ ))・f(r ₁ +Δh) …(16)
Here, the differential f′(r) with respect to the argument r of the function f(r) should be expressed in the same manner as the equations (4), (5) and (6) described in FIG. You can

On the other hand, similarly to the equation (3) described in FIG. 2, when the condition of the above equation (7) is satisfied in the equation (16), the equation (16) passes through the equation (17) as follows. It can be transformed as in Expression (18), and the right side of Expression (18) has the same shape as the right side of Expression (6).

r _Rx =A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )-A ₁・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ +Δh) …( 17)
r _Rx /(A ₁ ·exp(j ·(kr ₁ +θ ₁ )))=f(r ₁ )-f(r ₁ +Δh) …(18)
Then, by substituting the equation (18) into the equation (6) described in the first embodiment, the equations (19) and (20) can be obtained.

r _Rx /(A ₁・exp(j・(kr ₁ + θ ₁ )))=-Δh・f'(r) …(19)
r _Rx =-A ₁ · exp(j · (kr ₁ + θ ₁ )) · Δh · f'(r) …(20)
Thus, even when the antenna device 100 described in FIG. 1 is used on the receiving side as shown in FIG. 5, f′(r) is the distance attenuation function f(r when the condition of Expression (7) is satisfied. ), and the distance attenuation effect is obtained. In order for the condition of Expression (7) to hold, it is necessary to satisfy Expression (11) and Expression (13) described in FIG.

That is, for example, in FIG. 5, the distance Δh between the antenna 201(1) and the antenna 201(2) is λ/2 (Δh=λ/2), and the antenna 201(1) and the antenna 201(2) are the same. For example, the control unit 102 shown in FIG. 1 controls the amplitude and phase of each reception signal so as to receive the phase signal. Alternatively, as another example, the distance Δh between the antenna 201(1) and the antenna 201(2) is λ (Δh=λ), and signals received from the antenna 201(1) and the antenna 201(2) are For example, the control unit 102 shown in FIG. 1 controls the amplitude and phase of each reception signal so that the signals have opposite phases. As a result, the signals received from the antennas 201(1) and 201(2) can satisfy the condition of the equation (7), and the distance attenuation function is approximately differentiated to steeply increase the distance attenuation gradient. Interference from adjacent areas in the same direction can be reduced. Here, in the example of FIG. 2, since the antenna device 100 of FIG. 1 is applied to the transmitting side, the interference of the signal transmitted from the transmitting side antenna 101 to the adjacent area can be reduced, but in the example of FIG. The antenna device 100 of FIG. 1 is applied to the receiving side to reduce the interference given to the signals received by the receiving-side antennas 201(1) and 201(2) from adjacent areas.
[When the receiving side is a directional antenna]
In FIG. 5, the case of using the omnidirectional antenna has been described, but the same can be applied to the directional antenna.

FIG. 6 shows an example of using a directional antenna on the receiving side. In FIG. 6, for example, two directional antennas 201a (antennas 201a(1) and 201a(2)) are used to align the directional directions, and the antennas 201 of each antenna 201 are filled so as to satisfy equations (11) and (13). Control the amplitude and phase of the received signal. As a result, similar to the two omnidirectional antennas 201 (antenna 201(1) and antenna 201(2)) described in FIG. 5, the effect of steepening the gradient of distance attenuation can be obtained.

Note that, as in the case of FIG. 4, the antenna 201a(1) and the antenna 201a(2) are not aligned in the directivity direction, or the antenna 201a(2) is connected to the straight line connecting the antenna 101 and the antenna 201a(1). ) Does not exist, the effect of making the gradient of distance attenuation steep by arranging the antennas 201a(1) and 201a(2) satisfying the equations (11) and (13) and selecting the pointing direction. Is obtained.

As described above, even when the receiving side antennas 201a(1) and 201a(2) are directional antennas, the antennas 201a(1) and 201a(2) satisfy the formulas (11) and (13). By controlling the amplitude and phase of the signal received from (1), the gradient of the distance attenuation can be made steeper and the interference given from the adjacent area can be reduced.
(Third Embodiment)
In the third embodiment, a case will be described in which the number of the two antennas 101(1) and 101(2) on the transmission side described in the first embodiment is N. Here, N is an arbitrary integer of 2 or more. Note that, for example, when N=2 ^M (M is an integer of 1 or more), differentiation can be performed M times, and the gradient of distance attenuation can be made steeper than in the case of the first embodiment.
[When the transmitting side has N antennas]
FIG. 7 shows an example of the case where the antenna device 100 described in FIG. 1 is used as the transmission side and N omnidirectional antennas are used on the transmission side. In FIG. 7, N omnidirectional antennas 101 including the antenna 101(1), the antenna 101(2), the antenna 101(3), the antenna 101(4), and the antenna 101(N) and the receiving-side antenna 201. Are arranged on a straight line. Note that the receiving antenna 201 may use either a directional antenna or an omnidirectional antenna. Further, the number at the end of the code of the antenna 101 is added and described as (1), (2), (3), (4),... (N) from the antenna 101 closer to the antenna 201.

In FIG. 7, the distance between the antenna 101(1) and the antenna 201 is r ₁ , and the distance between the antenna 101(2) and the antenna 201 is r ₂ . Further, the distance (spacing) between the antenna 101(1) and the antenna 101(2) is Δh _1, and the distance r ₂ between the antenna 101(2) and the antenna 201 is r ₂ =r ₁ +Δh ₁ . .. Similarly, the distance (interval) between the antenna 101(2) and the antenna 101(3) is Δh ₂ , the distance (interval) between the antenna 101(3) and the antenna 101(4) is Δh ₃ , and the antenna 101( The sum of the distances from 1) to the antenna 101(N) is given by equation (21).

ここで、各アンテナ１０１間の距離は同じであってもよいし、異なっていてもよい。

Here, the distances between the antennas 101 may be the same or different.

In FIG. 7, as in the case of FIG. 2, the signals transmitted by the N antennas 101 from the transmitting side antenna 101(1) to the antenna 101(N) are the receiving side antennas 201 separated by a distance r. Since the signal is received by, the amount of attenuation of the signal amplitude per unit area due to the propagation depends on the propagation distance r. Therefore, as in the case of FIG. 2, the distance attenuation function f(r) is represented by the function f of the propagation distance r. Further, the signal transmitted from the transmitting side antenna 101(2) is received by the receiving side antenna 201, and the distance attenuation function indicating the amplitude attenuation amount of this signal can be expressed by f(r ₂ ). Similarly, the distance attenuation function of the signal transmitted from the transmitting-side antenna 101(3) is f(r ₃ ), and the distance attenuation function of the signal transmitted from the transmitting-side antenna 101(4) is f(r ₄ ). The distance attenuation function of the signal transmitted from the transmitting antenna 101(N) is f(r _N ).

In the distance from each antenna 101 of the transmitting side antenna 101(1), the antenna 101(2), the antenna 101(3), the antenna 101(4),..., The antenna 101(N) to the receiving side antenna 201. When the complex amplitude of the transmission signal is s _Tx1 , s _Tx2 , s _Tx3 , s _Tx4 ,..., S _TxN , equations (22), (23), (24), (25) and (25) and (25), respectively. 26). In addition,
s _Tx1 =A ₁・f(r ₁ )・exp(j・(kr ₁ +θ ₁ )) …(22)
s _Tx2 =A ₂ ·f(r ₂ )·exp(j·(kr ₂ +θ ₂ )) …(23)
s _Tx3 =A ₃・f(r ₃ )・exp(j・(kr ₃ +θ ₃ )) …(24)
s _Tx4 =A ₄・f(r ₄ )・exp(j・(kr ₄ +θ ₄ )) …(25)
・
s _TxN =A _N・f(r _N )・exp(j・(kr _N +θ _N )) …(24)
Here, k is the wave number (k=2π/λ(λ: wavelength)), A(A ₁ , A ₂ , A ₃ , A ₄ ,..., A _N ) is the initial amplitude, and θ(θ ₁ , θ ₂ , θ ₃ , θ ₄ ,..., θ _N ) are initial phases.

In the present embodiment, as described with reference to FIG. 2, first, in an antenna in which two adjacent antennas 101 are paired, the two antennas 101 transmit so as to satisfy the expressions (11) and (13). Control the amplitude and phase of the signal. For example, in FIG. 7, antenna 101(1) and antenna 101(2) are paired to form antenna 301(1), and the sum (s _Tx1 +s _Tx2 ) of equation (22) and equation (23) is given by equation ( 11) and the equation (13) are satisfied so that the amplitude and phase of the signals transmitted from the antenna 101(1) and the antenna 101(2) are controlled. As a result, the antenna 301(1) acts as an antenna obtained by differentiating the distance attenuation function once, steepens the gradient of the distance attenuation, and can reduce interference to adjacent areas.

Similarly, in FIG. 7, the antenna 301(2) is configured by pairing the antenna 101(3) and the antenna 101(4), and the sum (s _Tx3 +s _Tx4 ) of the equation (24) and the equation (25) is obtained. The amplitude and phase of signals transmitted from the antenna 101(3) and the antenna 101(4) are controlled so as to satisfy the expressions (11) and (13). As a result, the antenna 301(2) acts as an antenna obtained by differentiating the distance attenuation function once, similarly to the antenna 301(1), steepens the gradient of the distance attenuation, and reduces interference to adjacent areas. be able to.

The same process is performed for each antenna 101 from the antenna 101(5) to the antenna 101(N). As a result, N/2 virtual antennas from the antenna 301(1) to the antenna 301(N/2) obtained by differentiating the distance attenuation function once are configured.

Furthermore, in FIG. 7, the antenna 301(1) and the antenna 301(2) are paired to form the antenna 401(1), and the antenna 301(1) and the antenna 301(1) are configured to satisfy the equations (11) and (13). The amplitude and phase of the signal transmitted from 301(2) are controlled. As a result, the antenna 401(1) acts as an antenna obtained by differentiating the distance attenuation function only twice, and the gradient of the distance attenuation is made steeper than that in the case of the antenna 301 to reduce interference to adjacent areas. can do. Note that the same processing is performed for each of the antennas 301(3) to 301(N/2). As a result, N/4 virtual antennas from the antenna 401(1) to the antenna 401(N/4) obtained by differentiating the distance attenuation function twice are configured.

Similarly, a virtual antenna that forms a pair of N/4 antennas 401 from the antennas 401(1) to 401(N/4) is formed in the same manner, and the antennas for each pair are expressed as The amplitude and phase of the signal to be transmitted are controlled so as to satisfy (11) and equation (13).

Such a process is repeatedly executed M times (an integer of M≧1) and the distance attenuation function f(r) is differentiated approximately M times, whereby the gradient of the distance attenuation is steeply increased stepwise according to the number of differentiations. Can be converted.

Here, in the present embodiment, N=2 ^M has been described, but the number N of the antennas 101 included in the antenna device 100 may not be a power of 2. In this case, transmission/reception is performed using the number of antennas 101 that is a power of 2, and transmission/reception of signals is not performed with the fractional antennas 101. For example, when the number of antennas 101 included in the antenna device 100 is N=17, signals are transmitted/received using 2 ^M =16 antennas 101 with M=4, and the remaining one antenna 101 transmits/receives signals. Does not. It should be noted that the 16 antennas 101 to be used are controlled by controlling the amplitudes and phases of the signals to be transmitted and received so as to satisfy the equations (11) and (13), thereby determining which position of the 17 antennas 101 the antenna device 100 has. The antenna 101 may be selected.

In this way, a new antenna in which two adjacent antennas among a plurality of antennas are paired is configured, and the same processing is cyclically performed for two new antennas, and the following equation (11) is used. By controlling the amplitude and phase of the signals transmitted and received by the pair of antennas so as to satisfy Equation (13), the distance attenuation function f(r) can be approximately differentiated a plurality of times. By repeating a plurality of times, the gradient of the distance attenuation function f(r) can be gradually increased. The third embodiment is a generalized example of the first embodiment when M=1. Further, as in the first embodiment, either a directional antenna or an omnidirectional antenna may be used. Further, the respective distances Δh (Δh ₁ , Δh ₂ , Δh ₃ ,...) Between the antennas 101 do not have to be the same distance (equal intervals), but as the simplest example, the respective antennas 101 are Equations (11) and (13) can be satisfied by arranging at half wavelength intervals or distances that are integer multiples of half wavelengths and transmitting signals of the same phase from each antenna 101.
[Flowchart example]
FIG. 8 shows an example of the processing described in each embodiment. Note that FIG. 8A shows a case where a plurality of (N) transmitting antennas are used, and FIG. 8B shows a case where a plurality (N) receiving antennas are used.

In FIG. 8A, as described with reference to FIGS. 2 and 7, etc., the number of transmission antennas 101 to be used are arranged on a straight line, and each antenna is made to satisfy Expression (11) and Expression (13). The amplitude and phase of the signal transmitted from 101 are controlled.

On the other hand, in FIG. 8B, as described with reference to FIG. 5 and the like, the number of reception antennas 201 to be used are arranged on a straight line, and each antenna 201 is provided so as to satisfy the equations (11) and (13). The amplitude and the phase of the signal received at are controlled and the sum of the signals of the respective antennas 201 is used as the received signal.

First, the flowchart on the transmission side in FIG. 8A will be described. Note that FIG. 8A corresponds to FIGS. 2 and 7.

In step S101, N transmission antennas 101 (antenna 101(1) to antenna 101(N)) are prepared.

In step S102, N transmission antennas 101 are arranged on a straight line.

In step S103, the receiving antenna 201 is arranged at an arbitrary position on a straight line connecting the N transmitting antennas 101.

In step S104, the distances, amplitudes, phases, and transmission timings of the N antennas 101 for transmission are set so as to satisfy the equations (11) and (13).

In step S105, the N transmission antennas 101 are used for transmission. Here, for example, the amplitude and phase of each signal transmitted from the antenna 101(1) to the antenna 101(N) are controlled so as to satisfy the expressions (11) and (13).

In step S106, the reception antenna 201 receives the signals transmitted from the N transmission antennas 101.

Next, the flowchart on the receiving side in FIG. 8B will be described. Note that FIG. 8B corresponds to FIG. 5 and the like.

In step S201, N antennas 201 for reception (antenna 201(1) to antenna 201(N)) are prepared.

In step S202, the N receiving antennas 201 for reception are arranged on a straight line.

In step S203, the transmitting antenna 101 is arranged at an arbitrary position on a straight line connecting the N receiving antennas 201.

In step S204, the distances between the N reception antennas 201 are set so as to satisfy the expressions (11) and (13).

In step S205, the transmission antenna 101 transmits.

In step S206, the N reception antennas 201 are used for reception. Here, for example, the amplitude and phase of each signal received by the antenna 201(1) to the antenna 201(N) are controlled so as to satisfy the expressions (11) and (13), and the sum of the respective signals after the control is calculated. The received signal.
[effect]
FIG. 9 shows a simulation result of distance attenuation by differentiation explained in each embodiment. In FIG. 9, the horizontal axis represents the propagation distance (m) between the transmitting-side antenna 101(1) and the receiving-side antenna 201, and the vertical axis represents the received power (dB) at the antenna 201. The rhombus marks represent the characteristics of free space propagation loss as the conventional method, and the triangle marks represent the characteristics when the spatial differentiation of the distance attenuation of the present invention is approximately realized by two antennas on the transmitting side. There is. The square mark represents the characteristic when the differentiation is performed analytically (numerically), and is shown as a theoretical value with respect to the approximate value indicated by the triangle mark.

In FIG. 9, the reception power decreases as the propagation distance between the transmitting-side antenna 101(1) and the receiving-side antenna 201 increases, but when the differentiation indicated by the diamond mark is not performed (conventional), The slope of distance attenuation is gentle compared to other results. On the other hand, in the differential approximation amount (proposed) of the distance attenuation indicated by the triangle mark corresponding to each of the above-described embodiments, the gradient of the distance attenuation is steeper as compared with the conventional one. In each of the above-described embodiments, two adjacent antennas are used as a pair of antennas, and the signals transmitted and received by the pair of antennas are approximate differentiations that are controlled so as to satisfy Expressions (11) and (13). However, the characteristic which is almost equal to the mathematical differential amount shown by the square mark is obtained, which shows that there is a differential effect.

Note that, in FIG. 9, in the simulation of the conventional example, the attenuation characteristic of the received power according to the propagation distance was calculated in the configuration using one transmitting antenna and one receiving antenna. Further, the differential approximation of the distance attenuation function is performed with the configuration described in FIG. 2 of the first embodiment, and there are two transmitting side antennas 101 and one receiving side antenna 201. The distance Δh between the two antennas 101 on the transmission side is 0.01 m, and the distance attenuation function f(r) is the free space propagation loss (f(r)=(λ/4πr) ² ). Here, r represents the propagation distance and λ represents the wavelength. In the simulation result shown in FIG. 9, in order to compare the gradients of the distance attenuation characteristics (effects of steepening), the received power is normalized with the propagation distance of 0.1 m, and the two antennas 101 ( The attenuation on the straight line connecting 1) and the antenna 101(2) was plotted.

From the simulation results shown in FIG. 9, it is understood that the method of the present embodiment in which the distance attenuation function is approximately differentiated with respect to a plurality of antennas can make the gradient of the distance attenuation steep as compared with the conventional example in which no differentiation is performed. For example, at the point where the propagation distance is 1 m, the received power can be reduced by about 20 dB as compared with the conventional example in which differentiation is not performed, and by applying the method of this embodiment, the interference to the adjacent area is drastically reduced. The effect of causing is recognized.

In the simulation result shown in FIG. 9, the received power is normalized to the propagation distance of 0.1 m in order to compare the gradients of the distance attenuation characteristics. Therefore, for example, the wireless device of the communication destination is located at a distance of 0.5 m. In this case, the received power of the wireless device of the communication destination is about 13 dB lower than that of the conventional one, and the SNR seems to be worse, but the received power is the same at the distance where the wireless device of the communication destination is located. By normalizing as described above, the SNR can be kept equal to that in the conventional case. For example, by increasing the transmission power of the antenna device 100 according to the present embodiment by approximately 13 dB, the reception power of the wireless device of the communication destination located at a distance of 0.5 m becomes equal to that of the related art, but the method of the present embodiment. Since the gradient of distance attenuation is steeper than that of the conventional method, interference with adjacent areas at a distance of 0.5 m or more is reduced as compared with the conventional method.

As described above, the antenna control method and the antenna device according to the present invention spatially differentiate the distance attenuation function in which the signals transmitted and received by the plurality of antennas are attenuated according to the distance from the antenna to determine the slope of the distance attenuation. It is possible to make steep and reduce interference to adjacent areas in the distance direction.

100... Antenna device; 101, 101a, 101b... Transmitting side antenna; 102... Control part; 201, 201a... Receiving side antenna; 103... Transceiver device

Claims (5)

An antenna control method for controlling a signal to be transmitted and received when at least one of a transmitting antenna and a receiving antenna is N (integer of N≧2) antennas arranged at a predetermined interval,
When the N antennas are the transmitting antennas, the spatial density of the radio waves transmitted from the N antennas is spatially differentiated according to the distance from the antennas. To control the amplitude, phase and transmission timing of the signal to be transmitted according to the arrangement of the N antennas,
When the N antennas are the reception side antennas, the spatial density of the radio waves received by the N antennas is spatially differentiated according to the distance from the transmission side. To control the amplitude and phase of the received signal according to the arrangement of the N antennas ,
Wherein when N is 2 ^M (M ≧ 1 integer), the process of configuring the 2 ^M-number of antennas by selecting two adjacent antenna 2 ^(M-1) pieces of the new antenna M times Spatially differentiating the distance decay function by repeating,
Of the two adjacent antennas, the amplitude A ₁ and phase θ ₁ of the transmission signal s _Tx1 of the _first antenna, the amplitude A ₂ and phase θ ₂ of the transmission signal s _Tx2 of the _second antenna, the distance from the first antenna The distance attenuation function at a point separated by r ₁ is f(r ₁ ), the distance between the first antenna and the second antenna is Δh, the derivative f′(r) of the distance attenuation function, and the wave number are k, where s _Rx is a signal received at a position distant from the first antenna and the second antenna ,
S _Rx =S _Tx1 +S _Tx2
=A ₁ ・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )+A ₂ ・exp(j・(kr ₂ +θ ₂ ))・f(r ₁ +Δh)
In the above equation, the following equation holds,
A ₁ ・exp(j・(kr ₁ +θ ₁ ))=-A ₂ ・exp(j・(kr ₂ +θ ₂ ))
When the first antenna and the second antenna are transmitting-side antennas, the amplitude, the phase, and the transmission timing of the signals transmitted by the first antenna and the second antenna are controlled,
An antenna control method, characterized in that, when the signals are received by the first antenna and the second antenna, the amplitude and phase of signals received by the first antenna and the second antenna are controlled . The antenna control method according to claim 1 ,
The amplitude and phase of the signal transmitted by the first antenna and the second antenna or the signal received by the first antenna and the second antenna satisfy the following conditions.
A ₁ =A ₂
θ ₂ = θ ₁ -2πΔh/λ-(2n+1)π (n is an integer)
An antenna control method characterized by the above. The antenna control method according to claim 1 or 2 , wherein
The antenna is arranged side by side on a straight line, has one of the characteristics of an omnidirectional type and a directional type, and is applied to at least one antenna of a transmitting side and a receiving side. Control method. N antennas (N is an integer of 2 or more) arranged at predetermined intervals,
When the N antennas are transmitting antennas, the spatial density of radio waves transmitted from the N antennas is spatially differentiated according to the distance from the antennas. The amplitude, phase, and transmission timing of signals to be transmitted/received are controlled according to the arrangement of the N antennas, and when the N antennas are reception-side antennas, spatial distribution of radio waves received by the N antennas is controlled. A control unit that controls the amplitude and phase of the received signal according to the arrangement of the N antennas so that the distance attenuation function that spatially attenuates the density according to the distance from the transmission side is differentiated,
Wherein, said when N is 2 ^M (M ≧ 1 integer), constituting the 2 ^M-number of antennas by selecting two adjacent antenna 2 ^(M-1) pieces of the new antenna Is repeated M times to spatially differentiate the distance attenuation function ,
Of the two adjacent antennas, the amplitude A ₁ and phase θ ₁ of the transmission signal s _Tx1 of the _first antenna, the amplitude A ₂ and phase θ ₂ of the transmission signal s _Tx2 of the _second antenna, the distance from the first antenna The distance attenuation function at a point separated by r ₁ is f(r ₁ ), the distance between the first antenna and the second antenna is Δh, the derivative f′(r) of the distance attenuation function, and the wave number are k, where s _Rx is a signal received at a position distant from the first antenna and the second antenna ,
S _Rx =S _Tx1 +S _Tx2
=A ₁ ・exp(j・(kr ₁ +θ ₁ ))・f(r ₁ )+A ₂ ・exp(j・(kr ₂ +θ ₂ ))・f(r ₁ +Δh)
In the above equation, the following equation holds,
A ₁ ・exp(j・(kr ₁ +θ ₁ ))=-A ₂ ・exp(j・(kr ₂ +θ ₂ ))
When transmitting with the first antenna and the second antenna, controlling the amplitude, phase and transmission timing of the signal transmitted with the first antenna and the second antenna,
An antenna device, wherein when receiving with the first antenna and the second antenna, an amplitude and a phase of a signal received with the first antenna and the second antenna are controlled . The antenna device according to claim 4 ,
The amplitude and phase of the signal transmitted by the first antenna and the second antenna or the signal received by the first antenna and the second antenna satisfy the following conditions.
A ₁ =A ₂
θ ₂ = θ ₁ -2πΔh/λ-(2n+1)π (n is an integer)
An antenna device characterized by the above.

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