JP6814712B2 - Wireless transmission method and wireless transmission system - Google Patents

Description

The present invention relates to a wireless transmission method and a wireless transmission system.

As a method for realizing high-speed transmission in the field of wireless communication, a MIMO (Multi-Input Multi-Output) transmission technique in which a transmitter and a receiver use a plurality of antennas is known. FIG. 27 shows an example of the MIMO wireless transmission system 700. In FIG. 27, the transmitter 701 has an antenna array 703 including a plurality of antenna elements 702 and a radio signal processing unit 704. Similarly, the receiver 711 has an antenna array 713 including a plurality of antenna elements 712 and a radio signal processing unit 714 (see, for example, Non-Patent Document 1). When multi-stream transmission using a plurality of channels is performed in the wireless transmission system 700, both the transmitter 701 and the receiver 711 transmit and receive instantaneous weighting processing based on each channel information by the antenna element 702 and the antenna element 712. High-speed transmission is possible by executing the signal.

Further, when the variation of the channel response, such as when possible prospects communicate less communication environment, a method of transmitting a simple multi-stream using a fixed weighting matrix W _s shown in Figure 28 is used (e.g., See Non-Patent Document 2). Since the detailed description of FIG. 28 is described in Non-Patent Document 2, it is omitted. However, in FIG. 28, the transmitter and the receiver are two antenna elements (# 1) and antenna elements (# 2), respectively. An example of 2 × 2 MIMO having an antenna element is shown. In the same document, instead of estimating the propagation path response H ₀ between the antenna elements of the transmitter / receiver to obtain the weighting matrix _WZF as shown in FIG. 28 (a), it is fixed as shown in FIG. 28 (b). A technique is described in which the influence between the propagation paths is removed without estimating the propagation path response H ₀ by using the weighting matrix W _s of the above, and the propagation path is orthogonalized.

I.E.Telatar, “Capacity of Multi-antenna Gaussian Channels”, European Transactions on Telecommunications, vol.10, pp.585-595, 1999. R.Kataoka, et al. “Analog Decoding Method for Simplified Short-Range MIMO Transmission,” IEICE Trans.Commun., Vol.E97-B, no.3, March, 2014. I.Sarris, ARNix, “Design and Performance Assessment of High-Capacity MIMO Architectures in the Presence of a Line-of-Sight Component,” IEEE Transactions on Vehicular Technology, vol.56, no.4, pp.2194-2202 , July 2007.

Line-of-sight waves dominate the high frequency band used in wireless transmission systems, and when multiple streams are transmitted by MIMO using multiple antenna elements on the transmitter side and receiver side, between the propagation paths of each stream. Since the correlation is high, there is a problem that it becomes difficult to obtain the multiplexing gain in MIMO transmission. Therefore, a LOS (Line Of Sight) -MIMO transmission technology is known in which an antenna element is arranged at an optimum position according to a transmission distance and a transmission direction so that a multiplexing gain can be obtained even in a line-of-sight communication environment. (See, for example, Non-Patent Document 3). However, even if the antenna element is arranged at the optimum position, the optimum position changes according to the movement or misalignment of the transmitter / receiver, which causes a problem that the channel capacity is significantly deteriorated.

Further, in LOS-MIMO transmission, the method using a fixed weighting matrix can reduce the estimation time of the propagation path response, but when the position shift occurs between the transmitter and the receiver, the propagation path response between the antennas becomes There is a problem that the channel capacity deteriorates because the propagation path can not be orthogonalized by changing and using a fixed weighting matrix. As described above, it is difficult to use a fixed weighting matrix in a communication environment in which fluctuations in the propagation path response cannot be ignored, and it is necessary to perform instantaneous weighting processing based on the propagation path response of each channel. Here, in order to perform the instantaneous weighting process based on the propagation path response on both the transmitter and the receiver, it is necessary to accurately estimate the propagation path response. As the number of streams increases, there is a problem that the estimation time of the propagation path response and the calculation amount of the weighting matrix required for accurate estimation increase. Therefore, in order to realize high-speed parallel transmission in a multi-stream transmitter / receiver using MIMO, it is necessary to use a high-speed arithmetic processing unit.

In view of the above problems, in the present invention, when multi-stream transmission is performed using MIMO, even if a positional shift occurs between the antenna array on the transmitter side and the antenna array on the receiver side. An object of the present invention is to provide a wireless transmission method and a wireless transmission system capable of realizing multi-stream transmission in which deterioration of communication path capacity is suppressed without using a high-speed arithmetic processing device.

The first invention, LOS-MIMO transmit signal K (K is an integer of 2 or more) streams between a transmitter and a receiver with on A Ntenaare surface a plurality of antenna elements arranged antenna array respectively In the wireless transmission method, at least one of the transmitter and the receiver measures the propagation path information between the transmitters and receivers and the position information including the transmission distance and the transmission direction between the transmitters and receivers, and the propagation. perform the calculation of the weighting matrix to be applied to the signals transmitted and received by a plurality of antenna elements that are selected on the basis of the road information and the position information, the transmitter is measured by the own apparatus, or received from the receiver, the Propagation path information and the position information are acquired, and based on the transmission distance and the transmission direction included in the position information, the plurality of antenna elements of the own machine are perpendicular to the transmission direction on the antenna array surface. Calculate the position where the path difference between the antenna elements arranged at equal distances from the position in contact with the plane is orthogonal to the wavelength used , and M pieces (M is K or more) arranged at the position . selects an antenna element of an integer) is calculated by the own apparatus, or received from the receiver, the M of the weighting matrix calculated on the basis of the channel information selected by applying to the transmission signal of the K streams sending from pieces of antenna elements, said receiver is measured by the own apparatus, or received from the transmit unit acquires the channel information and the positional information, the transmission distance and the included in the position information based on the transmission direction, the path difference between the antenna elements arranged equidistantly from one position in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own use the position where the orthogonality is obtained for the wavelength calculated, N pieces disposed in the position (N is K or higher integer) selects an antenna element, calculating by the own apparatus, or received from the transmit unit , that generates a signal of the K streams is applied to signals received by the N antenna elements to the selected conjugate transposed matrix of the calculated the weighting matrix based on the channel information.

The M antenna elements of the transmitter and the N antenna elements of the receiver are on a spherical surface, on a cylindrical surface, on a circumference, on an elliptical rotating body surface, on an elliptical cylinder surface, or on an elliptical circumference. It is characterized in that it is selected from the antenna elements arranged in any of the above.

The second invention is Oite the first inventions, the transmission distance is the transmitting closest antenna element between the transmitter and the receiver between the plurality of antenna elements of the receiver and the plurality of antenna elements of the transmitter determined in each of the machine and the receiver, and shadow morphism onto a plane perpendicular to the position on the transmission direction spherical surface of said determined antenna elements, pre-determined around the position obtained by projecting on the plane It is characterized in that the M antenna elements on the transmitter side and the N antenna elements on the receiver side, which are located at equal intervals on the circumference of the radius, are selected.

A third invention is Oite the first inventions, the transmission distance is the transmitting closest antenna element between the transmitter and the receiver between the plurality of antenna elements of the receiver and the plurality of antenna elements of the transmitter It is determined as a reference antenna element on the machine side and the receiver side, respectively, and is arranged on at least one of the transmitter side and the receiver side in a first direction on the antenna array surface with respect to the reference antenna element. the first antenna element and the first line connecting the center of the antenna array plane that the angular difference between the first direction of the reference line connecting the said central and said reference antenna element is ?? p (p = 1 , ..., P (an integer of P: 1 or more)), and a second antenna element arranged in a second direction different from the first direction on the antenna array surface with respect to the reference antenna element. a second line connecting said center and the angular difference between the second direction and a reference line connecting the reference antenna element and the center Δφq (q = 1, ..., Q (Q: 1 or more It is characterized in that (P × Q) antenna elements ((P × Q) is an integer of K or more) that are closest to the positions of)) and are selected.

The fourth invention is, first in the second invention or the third invention, the antenna plurality of antennas in orthogonal projection position on the second surface that is determined in advance from the position of the multiple antenna elements on the array surface The elements are arranged, and normal projection is performed on the second surface from the positions of the M antenna elements on the transmitter side and the N antenna elements on the receiver side to be selected on the antenna array surface. It is characterized in that the M antenna elements on the transmitter side and the N antenna elements on the receiver side are selected at the arranged positions.

A fifth invention is the invention of any one of the first to fourth inventions, wherein each of the weighted matrices used in the transmitter and the receiver is the propagation path with respect to a predetermined reference point. A fixed weighting matrix calculated based on the information or the position information, and the propagation path information or the position with respect to each of the M antenna elements on the transmitter side and the N antenna elements on the receiver side. Regardless of the information, the fixed weighting matrix is applied to signals transmitted and received by the plurality of antenna elements.

A sixth invention, in any of the inventions of the first to fifth inventions, corresponds to the plurality of propagation path information or the position information of the transmitter and the receiver before the start of communication. The weighting matrix is calculated in advance, and the transmitter and the receiver use the M pieces of the propagation path information or the position information, or the propagation path information or an identifier indicating the position information, based on the propagation path information or the position information. It is characterized in that communication is started by selecting the antenna element on the transmitter side, the N antenna elements on the receiver side, and the weighted matrix calculated in advance .

The seventh invention is the M pieces of the invention in any one of the first to sixth inventions, wherein the determinant of the correlation matrix of the propagation path matrix between the transmitters and receivers satisfies at least one of the maximum and the threshold value or more. It is characterized in that each combination of the antenna element on the transmitter side and the N antenna elements on the receiver side is searched for and selected.

In the eighth invention, in any of the first to sixth inventions, the matrix equation of the correlation matrix of the propagation path matrix between the transmitters and receivers is the maximum and the threshold value with respect to the antenna element of the predetermined reference. and wherein the transmitting and receiving over at least one condition is satisfied antenna elements one by 1 element of K antenna elements search and select and at each transmitter and the receiver of the K stream signal To do.

According to the ninth aspect of the present invention, in any of the first to seventh aspects, a part of the antenna array surface is set as a search range, and the M antenna elements on the transmitter side are set. And when the N antenna elements on the receiver side are selected, the angle of the center of the antenna array surface is θa in the vertical direction with respect to each of the vertical direction and the horizontal direction with the antenna array surface as the coordinate. It is characterized in that the antenna element is searched and selected with the search range from to θb and from φa to φb in the horizontal direction as the search range.

The tenth invention, in any of the first to ninth inventions, includes a plurality of types of combinations of the M antenna elements on the transmitter side and N receivers. A plurality of types of combinations of antenna elements and a plurality of types of antenna elements are set in advance as selection candidates, and the matrix expression of the correlation matrix of the propagation path matrix is at least one of the maximum and the threshold value or more according to the propagation path information or the position information. The present invention is characterized in that each combination of the M transmitter-side antenna elements and the N receiver-side antenna elements satisfying the above conditions is searched for and selected.

First aspect of the invention, in any one of the first 0 of the invention from the first aspect, in at least one of said transmitter and said receiver, said K streams of the signal on the antenna array surfaces A plurality of antenna elements adjacent to the optimum position for transmission / reception are selected, and on the transmitter side, transmission power is distributed to each antenna element according to the distance between the optimum position and each of the selected antenna elements. The signal of the K stream is transmitted, and on the receiver side, the power received by each of the selected antenna elements is synthesized according to the distance between the optimum position and each of the selected antenna elements, and the K. It is characterized by receiving a signal of a stream.

First and second invention, while at K (K is an integer of 2 or more) the stream of signal LOS-MIMO transmitter and receiver each having an antenna array which is arranged a plurality of antenna elements on the A Ntenaare surface in the radio transmission system for transmitting, the transmitter, the channel information between the own apparatus and the receiver, and a transmission-side estimator for identifying including position information transmission distance and the transmission direction, the transmission on the basis of the transmission distance and the transmission direction included in the position information specified by the side estimator, located in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at the same distance from the antenna is orthogonal to the used wavelength, and M antennas (M is an integer of K or more) arranged at the position. A weighting matrix obtained from the transmission side antenna selection unit that selects an element and the propagation path information specified by the transmission side estimation unit is generated, and the transmission signal of the K stream is weighted by the generated weighting matrix. It has a transmission side weighting processing unit that transmits from the selected M antenna elements, and the receiver obtains propagation path information between its own unit and the transmitter, and transmission distance and transmission direction. a reception side estimating unit that identifies a including position information, on the basis of the transmission distance and the transmission direction included in the position information identified by the reception side estimating section, among the plurality of antenna elements of its own The position where the path difference between the antenna elements arranged at equal distances from the position in contact with the plane perpendicular to the transmission direction on the antenna array surface is orthogonal to the wavelength used is calculated, and the position is calculated. A weighted matrix obtained from the receiving side antenna selection unit that selects N antenna elements (N is an integer of K or more) arranged in the above and the propagation path information specified by the receiving side estimation unit is generated and selected. relative received signal of said N antenna elements, generated by weighting using a conjugate transpose matrix of the weighting matrix have a, a reception-side weighting processing unit for demodulating the signal of the K streams, The M antenna elements of the transmitter and the N antenna elements of the receiver are on a spherical surface, a cylindrical surface, a circumference, an elliptical rotating body surface, an elliptical cylinder surface, or an elliptical circumference. It is characterized in that it is selected from the antenna elements arranged in the sill .

Invention of the first 3, while at K (K is an integer of 2 or more) the stream of signal LOS-MIMO transmitter and receiver each having an antenna array which is arranged a plurality of antenna elements on the A Ntenaare surface in the radio transmission system for transmitting, the transmitter, the channel information between the own apparatus and the receiver, and the transmission distance and the transmission direction estimating unit that identifies a including position information, by the estimation unit on the basis of the transmission distance and the transmission direction included in the position information identified from a position in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own equidistant Calculate the position where the path difference between the antenna elements arranged at the position is orthogonal to the used wavelength, and select M antenna elements (M is an integer of K or more) arranged at the position. and transmitting-side antenna selector, with the estimator by generating a weighting matrix obtained by the channel information is identified, and the generated information of the weighting matrix and the prior SL location information transmitted to the receiver, generating It has a transmission side weighting processing unit that weights the transmission signal of the K stream and transmits from the M antenna elements selected by the weighting matrix, and the receiver receives from the transmitter. on the basis of the transmission distance and the transmission direction included before Symbol location information that the location equidistant from the position in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged in is obtained orthogonality to the used wavelength, and select N antenna elements (N is an integer of K or more) arranged at the position. and side antenna selector, the reception signal of the N antenna elements are selected, the signal of the K streams perform weighting with using a conjugate transposed matrix of the weighting matrix received from the transmitter have a, a reception-side weighting processing unit for demodulating said N antenna elements of said M antenna elements and the receiver of the transmitter, on a spherical surface, a cylindrical surface, on the circumference, the rotation of the ellipse It is characterized in that it is selected from antenna elements arranged on the body surface, the elliptical cylinder surface, or the elliptical circumference .

Invention of the first 4, while at K (K is an integer of 2 or more) the stream of signal LOS-MIMO transmitter and receiver each having an antenna array which is arranged a plurality of antenna elements on the A Ntenaare surface in the radio transmission system for transmitting, the receiver, the channel information between the own device and the transmitter, and the transmission distance and the transmission direction estimating unit that identifies a including position information, by the estimation unit on the basis of the transmission distance and the transmission direction included in the position information identified from a position in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own equidistant Calculate the position where the path difference between the antenna elements arranged at the position is orthogonal to the wavelength used, and select N antenna elements (N is an integer of K or more) arranged at the position. a receiving antenna selection unit, together with the estimation unit by generating a weighting matrix obtained by the channel information is identified, and the generated information of the weighting matrix and the prior SL location information transmitted to the transmitter, selected relative received signal of said N antenna elements, has a receiving-side weighting processing unit for demodulating the signal of the K streams perform weighting with using a conjugate transposed matrix of said weighting matrix, the transmitter on the basis of the transmission distance and the transmission direction included before Symbol location that will receive from the receiver, to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at equal distances from the position in contact with the vertical plane is orthogonal to the wavelength used , and M pieces (M is K) arranged at the position. The transmission side antenna selection unit that selects the antenna elements (the above integers) and the M antenna elements selected by weighting the transmission signal of the K stream by the weighting matrix received from the receiver are transmitted. possess a transmitting-side weighting processing unit, wherein the N antenna elements of said M antenna elements and the receiver of the transmitter, on a spherical surface, on a cylindrical surface, on the circumference, ellipse rotation body surface on , It is characterized in that it is selected from the antenna elements arranged on either the elliptical cylinder surface or the elliptical circumference .

In the wireless transmission method and wireless transmission system according to the present invention, there is a case where a positional shift occurs between the antenna array on the transmitter side and the antenna array on the receiver side, which perform multi-stream transmission using MIMO. However, it is possible to realize multi-stream transmission in which deterioration of communication path capacity is suppressed without using a high-speed arithmetic processing device.

It is a figure which shows the basic principle of the wireless transmission system 100 which concerns on each embodiment. It is a figure which shows the configuration example of the wireless transmission system 100 (1) which concerns on 1st Embodiment. It is a figure which shows the processing example of the wireless transmission system 100 (1) which concerns on 1st Embodiment. It is a figure which shows the structural example of the wireless transmission system 100 (2) a which concerns on 2nd Embodiment. It is a figure which shows the structural example of the wireless transmission system 100 (2) b which concerns on 2nd Embodiment. It is a figure which shows the processing example of the wireless transmission system 100 (2) a which concerns on 2nd Embodiment. It is a figure which shows the processing example of the wireless transmission system 100 (2) b which concerns on 2nd Embodiment. It is a figure which shows the calculation example of the 3rd Embodiment (in the case of K = 4). It is a figure which shows the calculation example of the 4th Embodiment (in the case of K = 3). It is a figure which shows the calculation example of the 5th Embodiment (in the case of K = 2). It is a figure which shows the arrangement example of the antenna element of 6th Embodiment. It is a figure which shows the simulation result of a misalignment and a channel capacity. It is a figure which shows an example of the deterioration amount of a channel capacity. It is a figure which shows an example of the linear array / square array of 8th Embodiment. It is a figure which shows the processing example of the wireless transmission system 100 (1) which concerns on 8th Embodiment. It is a figure which shows the processing example of the wireless transmission system 100 (2) a which concerns on 8th Embodiment. It is a figure which shows the processing example of the wireless transmission system 100 (2) b which concerns on 8th Embodiment. In the ninth embodiment, it is a figure which shows an example of the process of searching for the antenna element which maximizes a determinant. In the ninth embodiment, it is a figure which shows an example of the process of searching for the antenna element whose determinant is equal to or more than a threshold value. In the ninth embodiment, it is a figure which shows an example of the process which searches for the antenna element which the determinant becomes the maximum or the threshold value or more. It is a figure which shows another processing example of the 9th Embodiment. In the tenth embodiment, it is a figure which shows an example of the process of searching for the antenna element which maximizes the determinant. In the tenth embodiment, it is a figure which shows an example of the process of searching for an antenna element whose determinant is equal to or more than a threshold value. In the tenth embodiment, it is a figure which shows an example of the process of searching the antenna element which the determinant becomes the maximum or the threshold value or more. It is a figure which shows an example of the selection method of the antenna element which concerns on eleventh embodiment. It is a figure which shows an example of the selection method of the antenna element which concerns on 14th Embodiment. It is a figure which shows the configuration example of the conventional wireless transmission system 700. It is a figure which shows the processing example of the conventional wireless transmission system 700.

Hereinafter, embodiments of a wireless transmission method and a wireless transmission system according to the present invention will be described with reference to the drawings.

FIG. 1 shows the basic principle of the wireless transmission system 100 according to each embodiment. In FIG. 1, the wireless transmission system 100 is a system that transmits multiple streams using MIMO, and the transmitter 201 side in which a plurality of antenna elements 111T are arranged at discrete points on a spherical surface (antenna arrangement surface 220T). The antenna array 202 and the antenna array 212 on the receiver 211 side in which a plurality of antenna elements 111R are arranged at discrete points on a spherical surface (antenna arrangement surface 220R). Here, the antenna arrangement surface 220T and the antenna arrangement surface 220R correspond to the antenna array surfaces on which the plurality of antenna elements 111T and the plurality of antenna elements 111R are arranged. The antenna array surface is a curved surface or a flat surface, and the transmitter 201 side and the receiver 211 side do not have to have the same shape. For example, the antenna array surface on the transmitter 201 side may be curved and the antenna array surface on the receiver 211 side may be flat, or conversely, the antenna array surface on the transmitter 201 side may be flat and on the receiver 211 side. The antenna array surface may be curved. Of course, the transmitter 201 side and the receiver 211 side may have antenna array surfaces having the same shape.

The wireless transmission system 100 according to the present embodiment is displaced between the antenna array 202 on the transmitter 201 side and the antenna array 212 on the receiver 211 side facing the transmitter 201 in a communication environment such as line-of-sight communication where the fluctuation of the propagation path response is small. Even when the above occurs, the deterioration of the communication path capacity can be reduced as compared with the conventional technique, and multi-stream transmission using a fixed weighting matrix becomes possible.

The example of FIG. 1 shows a method of selecting the antenna element 111R on the receiver 211 side when transmitting and receiving a signal of a K (K is an integer of 2 or more) stream. First, the antenna array 202 on the transmitter 201 side is shown. And the antenna array 212 on the receiver 211 side determine the antenna element 111R (# 0) at the position closest to the opposite surface in the z-axis direction (the surface of the antenna array 202 and the antenna array 212 in contact with the spherical surface). Next, N antenna elements (N is an integer of K or more) arranged at a predetermined distance (on the circumference 151 of the radius L in the example of FIG. 1) from the antenna element 111R (# 0) ((#). Select 1) to (#N)). Here, FIG. 1 shows a case where N = K, but when the number N of the antenna elements 111R to be selected is N> K, the signals obtained by the N antenna elements 111R are received and combined, and K streams. May be obtained. In this case, the number of elements of the plurality of antenna elements 111R is increased, and the array directivity gain is improved, so that the reception gain is improved. Similarly, on the transmitter 201 side as well as on the receiver 211 side, M antenna elements 111T (M is an integer of K or more) are selected. Each of the K streams may be distributed to the M antenna elements 111T and transmitted. In this case, the number of elements of the plurality of antenna elements 111T is increased, and the array directivity gain is improved, so that the transmission gain is improved.

Although FIG. 1 describes a case where the antenna element 111R arranged on the circumference 151 having a radius L is selected (referred to as a circular array), the antenna element 111R may be selected in a linear shape or a rectangular shape. (Called a straight array or a square array).

In FIG. 1, the transmission distance (D ₀ ) and the transmission direction (elevation angle (θ), azimuth angle (φ)) between the antenna array 202 and the antenna array 212 are used as position information. Further, the radius L is calculated based on, for example, position information (a calculation example will be described later). Then, in the example of FIG. 1, four antenna elements 111R from the antenna element 111R (# 1) to the antenna element 111R (# 4) arranged on the circumference of the radius L are selected, and K = 4. Stream transmission is performed.

In this way, the wireless transmission system 100 according to the present embodiment can perform K stream transmissions (hereinafter referred to as K stream transmissions) by K antenna elements 111R selected according to the position information. Since the optimum antenna element 111R is selected even when the position shift occurs, the deterioration of the communication path capacitance can be reduced as compared with the conventional technique. Then, in the wireless transmission system 100 according to the present embodiment, K stream transmission can be performed by executing a signal processing operation using a fixed weighting matrix. The arithmetic circuit in K-stream transmission according to the transmission direction and K-stream transmission using a fixed weighting matrix can be configured by, for example, an analog power supply circuit in which a digital signal processing circuit, a 90 ° phase shifter, a switch, etc. are combined. Is. Further, in FIG. 1, the plurality of antenna elements 111R may be arranged not only on a spherical surface but also on a cylindrical surface or a circumference depending on the direction in which the positional deviation occurs. Although the antenna array 212 on the receiver 211 side has been described in FIG. 1, the same applies to the antenna array 202 on the transmitter 201 side.

Here, in the description of the present specification, when the description common to the antenna element 111R and the antenna element 111T is given, the trailing R or T is omitted and referred to as the antenna element 111. Further, when describing a specific antenna element 111 among the plurality of antenna elements 111 of the antenna array 202 and the antenna array 212, the antenna elements 111 are designated by the reference numerals (# 1) to (#M (or # N)). It is expressed as (#M (or #N)), antenna element 111T (#M (or #N)), and antenna element 111R (#M (or #N)).

As described above, in the wireless transmission system 100 according to the present embodiment, by arranging the antenna element 111 on the spherical surface, the transmitter 201 and the receiver 211 are arranged at an arbitrary position where the position shift occurs between the transmitters and receivers. It can be considered that the antenna elements 111 on the spherical surface close to the facing surfaces (the antenna element 111T on the transmitting side and the antenna element 111R on the receiving side) are always facing each other. As a result, in the wireless transmission system 100 according to the present embodiment, the phase change of the propagation path matrix component due to the path difference between the antenna elements 111 (between the antenna elements 111T on the transmitting side or between the antenna elements 111R on the receiving side) is reduced. .. That is, the deviation between the fixed weighting matrix and the propagation path matrix component caused by the positional deviation is reduced, and the deterioration of the channel capacity is suppressed.

Conventionally, when a fixed weighting matrix is used, there is a problem that the communication path capacity is deteriorated due to a positional shift between transmitters and receivers. However, in the wireless transmission system 100 according to the present embodiment, there is a spherical surface (or a cylindrical surface or a circle). By arranging a plurality of antenna elements 111 on the circumference) and selecting the antenna element 111 to be used from among them, the optimum antenna element 111 according to the transmission direction can always be selected even if the position shift occurs, so that communication is possible. It is possible to reduce the deterioration of the road capacity.

In this way, in the wireless transmission system 100 according to the present embodiment, it is possible to realize multi-stream transmission using a fixed weighting matrix even when the antenna array of the transmitter / receiver is at an arbitrary position.
(First Embodiment)
FIG. 2 shows a configuration example of the wireless transmission system 100 (1) according to the first embodiment. In FIG. 2, the transmitter 201 (1) has an antenna array 202, an antenna selection / weighting processing unit 203, and an estimation unit 204. Further, the receiver 211 (1) has an antenna array 212, an antenna selection / weighting processing unit 213, and an estimation unit 214. Here, the operation of each part of the transmitter 201 (1) and the receiver 211 (1) shown in FIG. 2 will be described in FIG. 3 below.

FIG. 3 shows a processing example of the wireless transmission system 100 (1) according to the first embodiment. The processing from step S101 to step S106 is executed on the transmitter 201 (1) side, and the processing from step S111 to step S116 is executed on the receiver 211 (1) side.

First, the process executed on the transmitter 201 (1) side will be described.

In step S101, the estimation unit 204 measures the propagation path information or the position information (transmission distance (D ₀ ) or transmission direction (θ, φ)). For the propagation path information, the transfer function of the propagation path can be measured by transmitting and receiving a well-known training signal. Further, the measurement of the position information between the transmitter 201 (1) and the receiver 211 (1) that communicate in the line-of-sight environment uses information such as images and moving images taken by a three-dimensional camera or a plurality of cameras. This is possible with well-known techniques such as methods and methods for measuring position by beam scanning.

In step S102, the antenna selection / weighting processing unit 203 determines the antenna element 111T (# 0) closest to the transmission direction among the plurality of antenna elements 111T on the spherical surface based on the measurement result in step S101. Here, the antenna selection / weighting processing unit 203 may be divided into an antenna selection unit and a weighting processing unit.

In step S103, the antenna selection / weighting processing unit 203 calculates the radius L centered on the antenna element 111T (# 0) according to the position information. The calculation method of the radius L will be described later.

In step S104, the antenna selection / weighting processing unit 203 selects M antenna elements 111T (# 1) to (# M) on the circumference of the radius L from the antenna element 111T (# 0).

In step S105, the antenna selection / weighting processing unit 203 calculates the propagation path matrix and the weighting matrix based on the respective positions of the M antenna elements 111T. For example, the propagation path matrix is generated based on, for example, the phase difference of each antenna element 111T with respect to the reference antenna element 111T (# 0). The calculation method of the weighting matrix will be described later.

In step S106, the antenna selection / weighting processing unit 203 transmits the K stream signal by applying the weighting matrix calculated in step S105 to the signal transmitted from the M antenna elements 111T selected in step S104.

In this way, the transmitter 201 (1) can reselect the M antenna elements 111T according to the misalignment even if the misalignment occurs with the receiver 211 (1). , It is possible to suppress a decrease in the communication path capacity due to misalignment.

Next, the process executed on the receiver 211 (1) side will be described.

In step S111, the estimation unit 214 measures the propagation path information or the position information (transmission distance (D ₀ ) or transmission direction (θ, φ)). The measuring method is the same as in step S101 of the transmitter 201 (1).

In step S112, the antenna selection / weighting processing unit 213 determines the antenna element 111R (# 0) closest to the transmission direction among the plurality of antenna elements 111R on the spherical surface based on the measurement result in step S111. Here, similarly to the transmitter 201 (1), the antenna selection / weighting processing unit 203 may be divided into an antenna selection unit and a weighting processing unit.

In step S113, the antenna selection / weighting processing unit 213 calculates the radius L centered on the antenna element 111R (# 0) according to the position information. The calculation method of the radius L will be described later.

In step S114, the antenna selection / weighting processing unit 213 selects N antenna elements 111R (# 1) to (# N) on the circumference of the radius L from the antenna element 111R (# 0).

In step S115, the antenna selection / weighting processing unit 213 calculates the propagation path matrix and the weighting matrix based on the respective positions of the N antenna elements 111R. For example, the propagation path matrix is generated based on the phase difference of each antenna element 111R with respect to the reference antenna element 111R (# 0). The calculation method of the weighting matrix will be described later.

In step S116, the antenna selection / weighting processing unit 213 applies the conjugate transpose matrix of the weighting matrix calculated in step S115 to the signals received by the N antenna elements 111R to generate a K-stream signal (also referred to as demodulation). ).

In this way, the receiver 211 (1) can reselect the N antenna elements 111R according to the misalignment even when the misalignment occurs with the transmitter 201 (1). , It is possible to suppress a decrease in the communication path capacity due to misalignment.

Here, as an example of the weighting matrix, when the propagation path matrix H is decomposed into singular values such as H = USV ^H , the unitary matrix decomposed by singular values is used, and the weighting matrix V _K on the transmitting side is V _K =. V, the weighting matrix U _K on the receiving side is U _K = U ^H. Alternatively, using the array directivity forming matrix W _{M × K} , W _{N × K,} and the unitary matrix, the weighting matrix U _K = W _{N × K} ^H U ^H on the receiving side, and the weighting matrix V _K = W _{M ×} on the transmitting side. _It may be KV. The array directivity formation matrices W _{M × K} and W _{N × K} are matrices of M rows and K columns and N rows and K columns, respectively, and an example is a discrete Fourier transform matrix. Alternatively, when N = M = K, the inverse matrix is used, and the weighting matrix _UK = (H ^H H) ^-1 H ^H on the receiving side, the weighting matrix V _K = I _K on the transmitting side, or the weighting matrix V _K = I _K on the receiving side. It can be calculated as the weighting matrix U _K = I _K and the transmitting side weighting matrix V _K = H ^H (HH ^H ) ^-1 (where each symbol indicates a vector notation). Note that I _K indicates an identity matrix of K rows and K columns, and indicates that nothing is performed as signal processing. Further, S indicates a diagonal matrix having an eigenvalue of the propagation path matrix as a diagonal component. Here, (H ^H H) ^-1 H ^H and H ^H (H ^{H H} ) ^-1 are for making it difficult to diverge in the calculation process, and may simply be the inverse matrix H ^-1 of the propagation path matrix H. .. Alternatively, when N> K or M> K, the array directivity formation matrix W _{M × K} , W _{N × K,} and the inverse matrix are used, and the weighting matrix _UK = W _{N × K} ^H (H ^H H) on the receiving side. ) ^-1 H ^H , the weighting matrix V _K = WM _{× K} on the transmitting side, or the weighting matrix _UK = W _{N × K} ^H on the receiving side, the weighting matrix V _K = H ^H (HH ^H ) on the transmitting side ^{− It} can be calculated as ¹ WM _{× K.}

The antenna element 111 may be arranged not only on the spherical surface but also on a cylindrical surface or a circumference depending on the direction in which the positional deviation occurs. Further, the antenna element 111 may be arranged on a part of a spherical surface, a cylindrical surface, a circumference, or the like according to the mounting volume of the antenna element 111.

(Second embodiment)
In the second embodiment, the position information (transmission distance (D ₀ ), transmission direction (θ, φ)) is measured and the weighting matrix is calculated on either the transmitting side or the receiving side, and the measured position information or The calculated weighted matrix information (each matrix component) is transmitted to the side that did not measure the position information or calculate the weighted matrix for use.

FIG. 4 shows a configuration example of the wireless transmission system 100 (2) a according to the second embodiment. In the wireless transmission system 100 (2) a, the position information and the information of the weighting matrix are transmitted from the transmitter 201 (2) a to the receiver 211 (2) a. In FIG. 4, the transmitter 201 (2) a has an antenna array 202, an antenna selection / weighting processing unit 203 (2) a, and an estimation unit 204. The receiver 211 (2) a has an antenna array 212 and an antenna selection / weighting processing unit 213 (2) a. Here, the difference from the first embodiment is that the receiver 211 (2) a does not have the estimation unit 214, and the antenna selection / weighting processing unit 203 (2) a of the transmitter 201 (2) a is the transmitter. Not only the calculation of the weighting matrix used in 201 (2) a, but also the calculation of the weighting matrix used in the receiver 211 (2) a is performed. Further, transmitting the position information measured by the estimation unit 204 of the transmitter 201 (2) a and the information of the weighting matrix used by the receiver 211 (2) a to the receiver 211 (2) a, the receiver 211 ( 2) The antenna element 111R of the antenna array 212 is selected and received by the antenna selection / weighting processing unit 213 (2) a of a based on the position information received from the transmitter 201 (2) a and the information of the weighting matrix. Is different from the first embodiment. The blocks having the same reference numerals as those in FIG. 2 of the first embodiment operate in the same manner as or in the same manner as in FIG. Here, in the following description, the block in which (2) a is added to the end of the code has the same basic operation as the block of the first embodiment having the same code number (203, 213, etc.). However, the operation peculiar to this embodiment is also performed (the same applies to other blocks and other embodiments).

In the above description, the weighting matrix used by the antenna selection / weighting processing unit 203 (2) a on the receiver 211 (2) a side is also calculated, and the calculated weighting matrix information is sent to the receiver 211 (2) a. Although an example of transmission is shown, only the position information is transmitted to the receiver 211 (2) a without calculating the weighting matrix used on the receiver 211 (2) a side on the transmitter 201 (2) a side. You may do so. In this case, the antenna selection / weighting processing unit 213 (2) a of the receiver 211 (2) a calculates a weighting matrix based on the position information received from the transmitter 201 (2) a and uses it for reception.

FIG. 5 shows a configuration example of the wireless transmission system 100 (2) b according to the second embodiment. In the wireless transmission system 100 (2) b, the position information and the information of the weighting matrix are transmitted from the receiver 211 (2) b to the transmitter 201 (2) b. In FIG. 5, the transmitter 201 (2) b has an antenna array 202 and an antenna selection / weighting processing unit 203 (2) b. The receiver 211 (2) b has an antenna array 212, an antenna selection / weighting processing unit 213 (2) b, and an estimation unit 214. Here, the difference from the first embodiment is that the transmitter 201 (2) b does not have the estimation unit 204, and the antenna selection / weighting processing unit 213 (2) b of the receiver 211 (2) b is the receiver. Not only the calculation of the weighting matrix used in 211 (2) b, but also the calculation of the weighting matrix used in the transmitter 201 (2) b is performed. Further, transmitting the position information measured by the estimation unit 214 of the receiver 211 (2) b and the information of the weighting matrix used in the transmitter 201 (2) b to the transmitter 201 (2) b, the transmitter 201 ( 2) The antenna element 111T of the antenna array 202 is selected and transmitted based on the position information and the weighting matrix information received from the receiver 211 (2) b by the antenna selection / weighting processing unit 203 (2) b of b. Is. The blocks having the same reference numerals as those in FIG. 2 of the first embodiment operate in the same manner as or in the same manner as in FIG.

Further, in the above description, the antenna selection / weighting processing unit 213 (2) a also calculates the weighting matrix used on the transmitter 201 (2) a side and transmits the information of the weighting matrix to the transmitter 201 (2) a. Although an example is shown, only the position information is transmitted to the transmitter 201 (2) a without calculating the weighting matrix used on the transmitter 201 (2) a side on the receiver 211 (2) a side. You may. In this case, the antenna selection / weighting processing unit 203 (2) a of the transmitter 201 (2) a calculates a weighting matrix based on the position information received from the receiver 211 (2) a and uses it for transmission.

FIG. 6 shows a processing example of the wireless transmission system 100 (2) a according to the second embodiment. Since the processes from step S101 to step S104, the process of step S106, and the process of step S116 are executed in the same manner as in the case of the wireless transmission system 100 according to the first embodiment described with reference to FIG. 3, they overlap. The description to be made is omitted.

In step S200, the antenna selection / weighting processing unit 203 (2) a of the transmitter 201 (2) a executes the same processing as in step S105 shown in FIG. 3 on the transmitter 201 (2) a side. Along with calculating the weighting matrix to be used, the weighting matrix used on the receiver 211 (2) a side is also calculated. As will be described later, there is also a form in which the weighting matrix used on the receiver 211 (2) a side is not calculated.

In step S201, the transmitter 201 (2) a transmits information necessary for selecting the N antenna elements 111R and determining the weighting matrix on the receiver 211 (2) a side.

Here, two forms are conceivable: a mode in which the transmitter 201 (2) a transmits the position information and the information of the weighting matrix to the receiver 211 (2) a, and a form in which only the position information is transmitted. In the first embodiment, the weighting matrix used on the receiver 211 (2) a side in step S200 is also calculated. In this case, in step S201, the receiver 211 (2) a side calculated in step S200 also calculates. The information of the weighting matrix to be used and the position information are transmitted to the receiver 211 (2) a. The conjugate transpose matrix may be calculated on the transmitter 201 (2) a side and transmitted to the receiver 211 (2) a side. In the second form, the transmitter 201 (2) a transmits only the position information to the receiver 211 (2) a.

The antenna selection / weighting processing unit 203 (2) a may transmit the position information and the weighting matrix information, or the control unit (not shown) that controls the operation of the entire transmitter 201 (2) a. May go. Further, these pieces of information may be transmitted and received from the antenna array 202 using a control channel, or another communication channel may be provided between the transmitter 201 (2) a and the receiver 211 (2) a. You may send and receive.

On the other hand, the receiver 211 (2) a performs the process as follows.

In step S211 the receiver 211 (2) a selects the antenna element 111R of the antenna array 212 based on the position information received from the transmitter 201 (2) a, and the weighting received from the transmitter 201 (2) a. The conjugate transposition matrix calculated based on the matrix information (or the conjugate transposition matrix received from the transmitter 201 (2) a) is applied to the signal received by the selected N antenna elements 111R, and the K stream signal is applied. Generate. Alternatively, the receiver 211 (2) a selects the antenna element 111R of the antenna array 212 based on the position information received from the transmitter 201 (2) a, and further creates a weighting matrix and a conjugate transposition matrix based on the position information. It is calculated and applied to the signals received from the selected N antenna elements 111R to generate a K-stream signal.

In this way, the receiver 211 (2) b of the wireless transmission system 100 (2) b according to the second embodiment is a transmitter without performing position estimation processing or calculation of a weighting matrix. The K stream signal transmitted from the transmitter 201 (2) a can be received by using the position information and the weighting matrix information received from the 201 (2) a.

FIG. 7 shows a processing example of the wireless transmission system 100 (2) b according to the second embodiment. Since the processes from step S111 to step S114, the process of step S106, and the process of step S116 are executed in the same manner as in the case of the wireless transmission system 100 according to the first embodiment described with reference to FIG. 3, they overlap. The description to be made is omitted.

In step S310, the antenna selection / weighting processing unit 213 (2) b of the receiver 211 (2) b executes the same processing as in step S105 shown in FIG. 3 on the receiver 211 (2) b side. Along with calculating the weighting matrix to be used, the weighting matrix used on the transmitter 201 (2) b side is also calculated. As will be described later, there is also a form in which the weighting matrix used on the transmitter 201 (2) b side is not calculated.

In step S311 the receiver 211 (2) b transmits information necessary for selecting the M antenna elements 111T and determining the weighting matrix on the transmitter 201 (2) b side.

Here, as in the case of FIG. 6, the receiver 211 (2) a transmits the position information and the weighting matrix information to the transmitter 201 (2) a, and the receiver 211 (2) a transmits only the position information. There are two possible forms. In the first embodiment, the weighting matrix used on the transmitter 201 (2) b side is also calculated in step S310. In this case, in step S311 on the transmitter 201 (2) b side calculated in step S310. The information of the weighting matrix to be used and the position information are transmitted to the transmitter 201 (2) b. In the second form, the receiver 211 (2) b transmits only the position information to the transmitter 201 (2) b.

As in the case of FIG. 6, the antenna selection / weighting processing unit 213 (2) b may transmit the position information and the weighting matrix information, or the entire receiver 211 (2) b may be operated. A control unit (not shown) that controls the control may perform the operation. Further, these pieces of information may be transmitted and received from the antenna array 212 using a control channel, or another communication channel may be provided between the receiver 211 (2) b and the transmitter 201 (2) b. You may send and receive.

On the other hand, the transmitter 201 (2) b performs the process as follows.

In step S301, the transmitter 201 (2) b selects the antenna element 111T of the antenna array 202 based on the position information received from the receiver 211 (2) b, and the weighting received from the receiver 211 (2) b. The weighting matrix is determined based on the matrix information, applied to the signal of the K stream, and transmitted from the selected M antenna elements 111T.

In this way, the transmitter 201 (2) b of the wireless transmission system 100 (2) b according to the second embodiment is a receiver without performing position estimation processing or calculation of a weighting matrix. The K stream signal can be transmitted to the receiver 211 (2) b by using the position information received from 211 (2) b and the information of the weighting matrix.

(Third embodiment)
FIG. 8 shows a calculation example of the third embodiment (in the case of K = 4). In FIG. 8, the number of streams K and the number N of the antenna elements 111R on the receiver 211 side are both 4 (K = N = 4). The same applies to the transmitter 201 side (K = M = 4). In the third embodiment, in the wireless transmission system 100 shown in FIG. 1, the antenna element 111R selected in the case of K = N = M = 4 (number of streams K and receiver 211 side (or transmitter 201 side)). To select the antenna element 111 and the calculation example of the propagation path matrix and the weighting matrix when the number N (or M) of (or the antenna element 111T) is 4 (N (or M) is an integer of K or more)). An example of calculating the radius L of is shown. The calculation example described in this embodiment can be applied to each of the above-described embodiments. Here, FIG. 8A is a diagram corresponding to FIG. 1, and is selected on the circumference 151 of the radius L of the antenna array 202 on the transmitter 201 side and the antenna array 212 on the receiver 211 side. The four antenna elements 111R (# 1- # 4) and the antenna element 111R (# 0) (corresponding to the reference point) closest to the facing surface (antenna element 111T (# 0) of the transmitter 201) are shown. There is.

Further, in FIG. 8B, the antenna arrangement surface 220T (spherical surface with the center Ra) on which the antenna array 202 on the transmitter 201 side of FIG. 8A is arranged and the antenna array 212 on the receiver 211 side are arranged. A cross-sectional view of the antenna arranging surface 220R (spherical surface as the center Rb) when cut by a plane perpendicular to each antenna arranging surface including a line connecting the center Ra and the center Rb is shown. In FIG. 8B, the antenna element 111T (# 1), the antenna element 111T (# 3), and the receiver 211 are on the surface 221T (direction perpendicular to the paper surface) including the selected antenna element on the transmitter 201 side. The surface 221R (direction perpendicular to the paper surface) including the selected antenna element on the side includes the antenna element 111R (# 1) and the antenna element 111R (# 3), respectively. Note that FIG. 8 shows a state in which the antenna element 111T (# 1), the antenna element 111T (# 3), the antenna element 111R (# 1), and the antenna element 111R (# 3) are cut so as to be included in the cross-sectional view. ing. In particular, in the present embodiment, since the number of antenna elements N selected is an even number (4), two antenna elements are included on the transmitter 201 side and the receiver 211 side of the cross-sectional view, respectively. When the antenna element 111 of the above is selected on the circumference of the radius L, the cross-sectional view does not include the two antenna elements 111.

Further, the surface 221T containing the selected antenna element and the surface 221R containing the selected antenna element connect the center Ra of the antenna arrangement surface 220T and the center Rb of the antenna arrangement surface 220R of the antenna array 212 on the receiver 211 side. The surface is perpendicular to the straight line (in FIG. 8B, the surface is perpendicular to the paper surface).

Here, in FIG. 8B, the transmission distance between the antenna element 111T (# 1) on the transmitter 201 side and the antenna element 111R (# 1) on the receiver 211 side is D ₀ , and the antenna element 111T (# 1). The transmission distance between 1) and the antenna element 111R (# 3) is D ₀ + (1/2 + m) λ ₀ (m is an integer). Further, in FIG. 8A, four pieces arranged in a square on a circumference 151 having a radius L centered on the antenna element 111R (# 0) of the antenna array 212 of the wireless transmission system 100 described with reference to FIG. Antenna element 111R (# 1), antenna element 111R (# 2), antenna element 111R (# 3), and antenna element 111R (# 4) are selected. Similarly, four antenna elements 111T (# 1), antenna elements 111T (# 2), arranged in a square on the circumference of a radius L centered on the antenna element 111T (# 0) of the antenna array 202, The antenna element 111T (# 3) and the antenna element 111T (# 4) are selected.

When K = 4, the propagation paths of the antenna elements 111T (# 1) to 111T (# 4) arranged in a square and the antenna elements 111R (# 1) to 111R (# 4) arranged in a square are The matrix H is as shown in Eq. (1) due to the symmetry of the arrangement of the antenna element 111T (# 1) to the antenna element 111T (# 4) and the antenna element 111R (# 1) to the antenna element 111R (# 4). The matrix is proportional to the circulant matrix. In Eq. (1), the off-diagonal component is a complex number having a magnitude of 1.

Here, when a3 = exp (jπ) = -1, diagonalization is performed by the product of the propagation path matrix H and its conjugate transpose matrix H ^H , as shown in Eq. (2).

In FIG. 8, the path difference from the antenna element 111R (# 1) to the two adjacent antenna elements 111R (# 3) in the circumferential direction is multiplied by (1/2 + m) the wavelength λ ₀ (m is a positive integer). By setting), the phase difference of the propagation path response becomes π, and the propagation path matrix component a3 = exp (jπ) = -1.

Therefore, the radius L for giving the above-mentioned path difference can be obtained, for example, in the right triangle shown by the dotted line in FIG. 8 by the three-square theorem as in Eqs. (3) and (4).

In equation (4), when K = 4, the radius L can be obtained by equation (5).

The antenna element 111R located on the circumference of the radius L thus obtained is selected. In the example of FIG. 8, the antenna element 111R (# 4) is selected from the antenna element 111R (# 1). Here, in the case of FIG. 8, the distance between the antenna element 111R (# 1) and the antenna element 111R (# 3) is 2L. The same applies to the transmitter 201 side.

Here, the weighting matrix, for example, a weighting matrix V ₄ of the transmitter 201 side and the conjugate transpose matrix of the channel matrix H, and the receiver 211 side of the weight matrix U ₄ identity matrix (no weighting operation). Alternatively, conversely, the transmitter 201 side of the weighting matrix V ₄ identity matrix and (unweighted calculation), the weighting matrix U ₄ of the receiver 211 side with the conjugate transpose matrix of the channel matrix H. By obtaining the weighting matrices on the transmitter 201 side and the receiver 211 side in this way, it is possible to make the propagation paths orthogonal to each other when K = 4.

As other combinations of matrix used in the weighting matrix V ₄ and U _4, a combination of the discrete Fourier transform matrix and its conjugate transpose matrix, a combination of zero-forcing matrix or MMSE (Minimum Mean Square Error) matrix and the unit matrix is used May be done.

Further, when K ≧ 5, the antenna element 111 has a circular array arrangement, and the propagation path matrix H has the equations (6) and (7) due to the symmetry of the arrangement of the antenna elements 111 as in the case of the square. The matrix is proportional to the circulant matrix as shown.

(When K = 2n−1 (odd number))

(When K = 2n (even number))

Here, n is an integer of 3 or more.

In the case of K ≧ 5, for example, the antenna element 111 is selected by using an arbitrary value for the radius L, the propagation path matrix H in the selected antenna element 111 is obtained, and the weighting described in the first embodiment is performed. by obtaining the weighting matrix U _K weighting matrix V _K and the receiving side of the transmission side in the calculation method of the matrix (singular value decomposition of the unitary matrix and the inverse matrix, etc.) are possible channel orthogonalization.

(Fourth Embodiment)
FIG. 9 shows a calculation example of the fourth embodiment (in the case of K = 3). In FIG. 9, the number of streams K and the number N of the antenna elements 111R on the receiver 211 side are both set to 3 (K = N = 3). The same applies to the transmitter 201 side (K = M = 3). In the fourth embodiment, in the wireless transmission system 100 shown in FIG. 1, a calculation example of the propagation path matrix and the weighting matrix when K = N (or M) = 3 and a radius for selecting the antenna element 111 An example of calculation of L is shown. The calculation example described in this embodiment can be applied to the first embodiment and the second embodiment described above. Here, in FIG. 9, the transmission distance between the antenna element 111T (# 0) on the transmitter 201 side and the antenna element 111R (# 1) on the receiver 211 side is D ₀ , and the antenna element 111T (# 0). The transmission distance to and from the antenna element 111R (# 2) is D ₀ + (± 1/3 + m) λ ₀ (m is an integer). Further, in FIG. 9, the antenna element 111R (# 0) arranged in an equilateral triangle on the circumference 151 of the radius L centered on the antenna element 111R (# 0) of the antenna array 212 of the wireless transmission system 100 described with reference to FIG. # 1), antenna element 111R (# 2) and antenna element 111R (# 3) are selected. Similarly, the three antenna elements 111T (# 1), the antenna elements 111T (# 2), and the antenna elements 111T (# 2) arranged in a square on the circumference of the radius L centered on the antenna element 111T (# 0) of the antenna array 202. The antenna element 111T (# 3) is selected.

When K = 3, the antenna elements 111T (# 1) to 111T (# 3) arranged in an equilateral triangle and the antenna elements 111R (# 1) to 111R (# 3) arranged in an equilateral triangle The propagation path matrix H between them is based on the symmetry of the arrangement of the antenna element 111T (# 1) to the antenna element 111T (# 3) and the antenna element 111R (# 1) to the antenna element 111R (# 3). It becomes a cyclic matrix as shown in.

Here, when a = exp (± j (2π / 3)) =-(1/2) ± j (√3) / 2), the propagation path matrix H and its conjugate transpose are shown in Eq. (9). diagonalized by the product of the matrix H ^H. That is, by selecting the antenna elements 111R arranged on the circumference of the radius L at intervals where the path difference is {± (1/3) + m} times the wavelength λ ₀ (m is an integer), the equation (9) ) Can be satisfied.

Here, Re (a) represents the real part of the complex number a.

Therefore, the radius L for giving the above-mentioned path difference can be obtained, for example, in the right triangle shown by the dotted line in FIG. 9 by the three-square theorem as in Eqs. (10) and (11).

The antenna element 111R located on the circumference of the radius L thus obtained is selected. In the example of FIG. 8, the antenna element 111R (# 3) is selected from the antenna element 111R (# 1). The same applies to the transmitter 201 side.

Here, the weighting matrix, for example, a weighting matrix V ₃ of the transmitter 201 side and the conjugate transpose matrix of the channel matrix H, the weight matrix U ₃ of the receiver 211 side matrix (no weighting operation). Alternatively, conversely, the transmitter 201 side of the weighting matrix V ₃ identity matrix and (unweighted calculation), the weighting matrix U ₃ of the receiver 211 side with the conjugate transpose matrix of the channel matrix H. By obtaining the weighting matrices on the transmitter 201 side and the receiver 211 side in this way, it is possible to make the propagation paths orthogonal to each other when K = 3.

As other combinations of matrix used in the weighting matrix V ₃ and U _3, the combination of the discrete Fourier transform matrix and its conjugate transpose matrix, may be a combination of zero-forcing matrix or MMSE matrix and the identity matrix are used.

(Fifth Embodiment)
In the fifth embodiment, in the wireless transmission system 100 shown in FIG. 1, a calculation example of the propagation path matrix and the weighting matrix when K = 2 and a calculation example of the radius L of the circle for selecting the antenna element 111. And will be explained. The calculation examples described in this embodiment include the wireless transmission system 100 (1) of FIG. 2, the wireless transmission system 100 (2) a of FIG. 4, and the wireless transmission system 100 of FIG. 5 described in the previous embodiment. 2) Applicable to any configuration of b.

FIG. 10 shows a calculation example of the fifth embodiment (in the case of K = 2). In FIG. 10, the number of streams K and the number N of the antenna elements 111R on the receiver 211 side are both 2 (K = N = 2). The same applies to the transmitter 201 side (K = M = 2). Here, FIG. 10A is a diagram corresponding to FIG. 1, and is a circumference 151 having a radius L among the antenna array 202 on the transmitter 201 side and the antenna array 212 on the receiver 211 side shown in FIG. The two selected antenna elements 111R (# 1, # 2) above are shown. The antenna element 111R (# 0) is the antenna element 111R (corresponding to the reference point) closest to the facing surface (antenna element 111T (# 0) of the transmitter 201).

Further, in FIG. 10B, similarly to FIG. 8B, the surface (here, the spherical surface) on which the antenna array 202 on the transmitter 201 side of FIG. 10A is arranged and the antenna on the receiver 211 side are shown. A cross-sectional view of the surface on which the array 212 is arranged (here, a spherical surface) when cut by a surface perpendicular to the antenna arrangement surface is shown. In FIG. 10B, the antenna element 111T (# 1), the antenna element 111T (# 2), and the selected antenna element on the receiver 211 side are mounted on the surface 221T including the selected antenna element on the transmitter 201 side. The antenna element 111R (# 1) and the antenna element 111R (# 2) are selected for the surface 221R including the antenna element 111R (# 1). The surface 221T containing the selected antenna element and the surface 221R containing the selected antenna element are the same as in FIG. 8B.

Here, in FIG. 10B, the transmission distance between the antenna element 111T (# 1) on the transmitter 201 side and the antenna element 111R (# 1) on the receiver 211 side is D ₀ , and the antenna element 111T (# 1). The transmission distance between 1) and the antenna element 111R (# 2) is D ₀ + (± 1/4 + m) λ ₀ (m is an integer).

The wireless transmission system according to the present embodiment is the same as the wireless transmission system 100 (1), the wireless transmission system 100 (2) a or the wireless transmission system 100 (2) b described with reference to FIGS. 3, 6 or 7. It is composed of.

When K = 2, in the transmitter (201 (1), 201 (2) a and 201 (2) b) or the receiver (211 (1), 211 (2) a and 211 (2) b) The calculated propagation path matrix between the antenna arrays is a matrix proportional to the circulant matrix as shown in Eq. (12). The matrix of Eq. (12) is a complex number having a magnitude of one off-diagonal component.

Here, when a ₂ = exp (± j (π / 2)) = ± j, it is diagonalized by the product of the propagation path matrix H and its conjugate transpose matrix H ^H as shown in Eq. (13). ..

Further, by setting the wavelength λ ₀ (± 1/4 + m) (m is an integer) of the radio wave for transmitting and receiving the path difference between the two antenna elements, the phase difference of the propagation path response becomes ± π / 2, and the propagation path becomes ± π / 2. The matrix component is a ₂ = exp (± j (π / 2)) = ± j.

Therefore, the radius L for giving the above-mentioned path difference can be obtained, for example, in the right triangle shown by the dotted line in FIG. 10 (b) by the three-square theorem as in Eq. (14).

In this way, the antenna element to be used is selected based on the circle having the radius L obtained by the equation (14).

Here, the weighting matrix is 8 and similar to the embodiments, such as FIG. 9, for example, a weighting matrix V ₂ of the transmitter 201 side and the conjugate transpose matrix of the channel matrix H, the weighting matrix of the receiver 211 side U ₂ Is a unit matrix (no weighting operation). Alternatively, conversely, the transmitter 201 side of the weighting matrix V ₃ identity matrix and (unweighted calculation), the weighting matrix U ₃ of the receiver 211 side with the conjugate transpose matrix of the channel matrix H. By obtaining the weighting matrices on the transmitter 201 side and the receiver 211 side in this way, it is possible to make the propagation paths orthogonal to each other when K = 2.

As other combinations of the matrices used for the weighted matrices V ₂ and U ₂ , a combination of a discrete Fourier transform matrix and its conjugate transposed matrix, a zero forcing matrix, a combination of an MMSE matrix and an identity matrix, or the like may be used.
(Sixth Embodiment)
FIG. 11 shows an arrangement example of the antenna element of the sixth embodiment. In the sixth embodiment, unlike the first embodiment or the second embodiment in which the plurality of antenna elements 111 are arranged on a spherical surface, the plurality of antenna elements 111 are arranged on a plane. In the plane antenna array 250 shown in FIG. 11, a plurality of antenna elements 111 are arranged on a plane. Here, the position of the antenna element 111 on the planar antenna array 250 is such that the position of the antenna element 111 arranged on the spherical surface described with reference to FIG. 1 or the like is positive on the second surface (xz plane in the example of FIG. 11). This is the projected position. FIG. 11A shows a view of the plane antenna array 250 on the xz plane from the y-axis direction, and FIG. 11B shows the position on the plane antenna array 250 from the position of the antenna element 111 on the spherical surface. An example of direct projection to is shown.

For example, in FIG. 11B, assuming that the radius of the sphere is r ₀ and the position of the antenna element 111 on the sphere is the elevation angle θ _a and the azimuth angle φ _a , the planar antenna array corresponding to the position of the antenna element 111 on the sphere. The position (x, z) of the antenna element 111 on the 250 is obtained by the equations (15) and (16).

x = r ₀ sin (θ _a ) cos (φ _a )… (15)
z = r ₀ cos (θ _a )… (16)
That is, since the position of the antenna element 111 on the spherical surface is normally projected onto the flat antenna array 250, the flat antenna array 250 at the position where the position of the antenna element 111 on the spherical surface selected in the previous embodiment is normally projected. By selecting the above antenna element 111, the same effect as that of the previous embodiment can be obtained.

As described above, by using the planar antenna array 250 according to the sixth embodiment, it is possible to obtain an effect that the manufacturing becomes easier as compared with the case where the antenna element 111 is arranged on the spherical surface.
(Use of fixed weighting matrix)
Here, an example in which a fixed weighting matrix obtained at a reference point is used in the first to sixth embodiments will be described. The configuration of the wireless transmission system is the same as that of the system described in other embodiments. For example, in the case of the first embodiment, the wireless transmission system 100 (1) includes a transmitter 201 (1) having an antenna array 202, an antenna selection / weighting processing unit 203, and an estimation unit 204, an antenna array 212, and an antenna selection. / A receiver 211 (1) having a weighting processing unit 213 and an estimation unit 214 is provided.

Then, for example, the antenna selection / weighting processing unit 203 on the transmitter 201 (1) side and the antenna selection / weighting processing unit 213 on the receiver 211 (1) side are weighted with the central position of the range in which the misalignment occurs as a reference point. Using a fixed weighting matrix for which the matrix has been calculated, M or N antenna elements 111 are selected according to the transmission direction, and K-stream signals are transmitted and received. As a method of obtaining the reference point, for example, the position obtained by averaging the position of the receiver 211 (1) when the receiver 211 (1) is displaced with respect to the transmitter 201 (1) by a probability distribution is used as a reference. There is a way to make a point.

As described above, by using the fixed weighting matrix obtained at the reference point, the processing amount on the transmitter 201 side and the receiver 211 side is significantly reduced.
(7th Embodiment)
In the seventh embodiment, assuming a plurality of position information (transmission distance and transmission direction) of the transmitter / receiver, each weighting matrix corresponding to each position information is calculated in advance. Then, the weighted matrix calculated in advance is associated with an identifier such as a transmission direction or a number and stored in the transmitter / receiver before the start of communication.

For example, a weighting matrix calculated by calculating a weighting matrix for each position information of a plurality of position information within a range in which there is a possibility of misalignment (if the transmitting side and the receiving side are different, each weighting matrix) is calculated. Is numbered. Then, the learning information in which the number, the position information, and the weighting matrix are associated with each other is created. The learning information may be created by either the transmitter or the receiver, or the learning information may be created by a computer different from the transmitter / receiver. Then, the created learning information is shared between the transmitter side and the receiver side before the start of communication, and is stored in their respective memories. The method of sharing the learning information may be, for example, transmission / reception via a control channel or the like, transmission / reception via another line, or offline storage in a transmitter / receiver.

For example, when the wireless transmission system according to the present embodiment is applied to the flowchart of FIG. 6 of the second embodiment, the transmitter 201 (2) a (or an external computer or the like) is used to transmit a plurality of position information before the start of communication. The weighting matrix corresponding to each is calculated and an identifier such as a number is given, and learning information in which the identifier, the position information, and the weighting matrix are associated with each other is created. Then, the learning information is stored in the memories of the transmitter 201 (2) a and the receiver 211 (2) a.

In this state, when the transmitter 201 (2) a executes step S101 to measure the position information, the weighting matrix associated with the measured position information can be read out from the learning information stored in advance. As a result, the transmitter 201 (2) a does not need to calculate the weighting matrix in step S200. Further, in step S201, the transmitter 201 (2) a reads out the position information measured in step S101 and the identifier associated with the weighting matrix, and transmits only the identifier to the receiver 211 (2) a.

On the other hand, in step S211 the receiver 211 (2) a reads the position information and the weighting matrix corresponding to the identifier received from the transmitter 201 (2) a from the learning information stored in advance in the memory. Then, the receiver 211 (2) a selects N antenna elements 111R corresponding to the position information read from the learning information, and similarly uses the weighting matrix read from the learning information to transmit the transmitter 201 (2) a. Can receive the K-stream signal transmitted by.

Similarly, when the wireless transmission system according to the present embodiment is applied to the flowchart of FIG. 7 of the second embodiment, a plurality of position information is provided by the receiver 211 (2) b (or an external computer or the like) before the start of communication. The weighting matrix corresponding to each of the above is calculated and an identifier such as a number is given, and learning information in which the identifier, the position information, and the weighting matrix are associated with each other is created. Then, the learning information is stored in the memories of the transmitter 201 (2) b and the receiver 211 (2) b.

In this state, when the receiver 211 (2) b executes step S111 to measure the position information, the weighting matrix associated with the measured position information can be read out from the learning information stored in advance. This eliminates the need for the receiver 211 (2) b to calculate the weighting matrix in step S310. Further, in step S311 the receiver 211 (2) b reads out the position information measured in step S111 and the identifier associated with the weighting matrix, and transmits only the identifier to the receiver 211 (2) b.

On the other hand, in step S301, the transmitter 201 (2) b reads out the position information and the weighting matrix corresponding to the identifier received from the receiver 211 (2) b from the learning information stored in advance in the memory. Then, the transmitter 201 (2) b selects M antenna elements 111T corresponding to the position information read from the learning information, and similarly uses the weighting matrix read from the learning information to receive the receiver 211 (2) b. A K-stream signal can be transmitted to.

Here, in the above description, the learning information is shared between the transmitter 201 (2) and the receiver 211 (2), and the position information and the identifier associated with the weighting matrix are transmitted and received. For example, when applied to the flowchart of FIG. 3 of the first embodiment, it is not necessary to send and receive an identifier. For example, in the flowchart of FIG. 3, a weighting matrix corresponding to each of a plurality of position information is calculated by the transmitter 201 (1) and the receiver 211 (1) (or an external computer, etc.) before the start of communication, and the positions are determined. Create learning information that associates information with a weighting matrix. Then, the learning information is stored in the memories of the transmitter 201 (1) and the receiver 211 (1), respectively.

In this state, when the transmitter 201 (1) executes step S101 and measures the position information, the weighting matrix associated with the measured position information can be read out from the learning information stored in advance. Further, when the receiver 211 (1) executes step S111 to measure the position information, the receiver 211 (1) can read out the weighting matrix associated with the measured position information from the learning information stored in advance. Then, the transmitter 201 (1) does not need to calculate the weighting matrix in step S105. Further, when the receiver 211 (1) executes step S111 to measure the position information, the receiver 211 (1) can read out the weighting matrix associated with the measured position information from the learning information stored in advance. Then, the receiver 211 (1) does not need to calculate the weighting matrix in step S115.

As described above, the wireless transmission system according to the present embodiment calculates the weighting matrix for each position information of the plurality of position information within the range where there is a possibility of misalignment before the start of communication, and the calculated weighting matrix. By storing the learning information in which the position information and the identifier are associated with each other in advance, the amount of processing during communication can be reduced.
(simulation result)
FIG. 12 shows the simulation results of the misalignment and the channel capacity. The simulation result shown in FIG. 12 corresponds to the wireless transmission system 100 described in the first to seventh embodiments. In this simulation, the antenna element 111 is placed on a spherical surface with a radius of 22 λ ₀ (λ ₀ is the free space wavelength of the carrier) in the range of elevation angle φ = 0 degrees to 180 degrees and azimuth angle θ = 60 degrees to 120 degrees. , Use antenna arrays arranged on a spherical surface at 0.5 degree intervals in the φ direction and 60 degree intervals in the θ direction. Then, in the simulation, the characteristics of the channel capacity when four elements were selected according to the positional deviation (K = 4) were obtained. Specifically, in the coordinate system of the wireless transmitter system 100 described with reference to FIG. 1, the center position of the antenna array 212 on the receiver 211 side is fixed at (x, y, z) = (0,1000λ ₀ , 0). , changing the center position of the transmitter 201 side of the antenna array 202 (x, y, z) = from (0,0,0) to (100λ _0, 0,0).

In FIG. 12, the horizontal axis represents the positional deviation λ ₀ , and the vertical axis represents the channel capacity (bits / s / Hz) per unit frequency. In FIG. 12, when a weighting matrix according to the position is used (ideal), when a fixed weighting matrix is used in which the antenna elements are arranged on a spherical surface and set as a reference point (x = 4.5λ ₀ , y = 1000λ ₀ ) ( (Corresponding to the seventh embodiment), when a fixed weighting matrix is used in which the antenna elements are arranged on a plane and at equal intervals to set a reference point (x = 4.5λ ₀ , y = 1000λ ₀ ) (conventional), a single antenna. A comparative example is shown when communicating with each other. In FIG. 12, the horizontal axis shows the positional deviation λ ₀ , and the vertical axis shows the channel capacity (bits / s / Hz) per unit frequency. Here, in FIG. 12, the alternate long and short dash line: ideal, solid line (thick line). ): Corresponds to the seventh embodiment, broken line (thick line): conventional, dotted line (thin line): single antenna (SISO: Single Input Single Output). The solid line (thin line): the average communication capacity of the solid line (thick line), and the broken line (thin line): the average communication capacity of the broken line (thick line) are shown.

From the simulation results of FIG. 12, it can be seen that the wireless transmission system 100 according to the present embodiment can obtain a channel capacity closer to the ideal as compared with the conventional method.

FIG. 13 shows an example of the amount of deterioration of the channel capacity. The amount of deterioration shown in FIG. 13 is the amount of deterioration with respect to the ideal channel capacity of the prior art and the present embodiment shown in FIG. In FIG. 13, the horizontal axis shows the positional deviation λ ₀ , the vertical axis shows the channel capacity per unit frequency (bits / s / Hz), and the solid line shows the ideal channel capacity according to the method of the seventh embodiment. The value obtained by subtracting the channel capacity and the broken line indicate the value obtained by subtracting the channel capacity of the conventional method from the ideal channel capacity.

From the results of FIGS. 12 and 13, it can be seen that by arranging the antenna element 111 on the spherical surface, the deterioration of the channel capacity can be reduced and the average value of the channel capacity can be improved even when the position shift occurs.

As described above, the wireless transmission system 100 according to the present embodiment can reduce the deterioration of the channel capacity due to the positional deviation when a fixed weighting matrix is used at an arbitrary transmitter / receiver position, and many use a fixed weighting matrix. Stream transmission is possible. Further, since the weighting matrix can be calculated and the antenna element 111 can be selected only by the fixed weighting matrix at the reference point or the information of the transmission direction, it is easy without performing propagation path estimation or searching for the antenna element 111 having good characteristics. Can perform multi-stream wireless transmission.
(8th Embodiment)
In the third embodiment described with reference to FIG. 8, the fourth embodiment described with reference to FIG. 9, and the fifth embodiment described with reference to FIG. 10, the antenna element 111 arranged on the circumference having a radius L is selected. The circular array was explained. In the eighth embodiment, a linear array or a rectangular array that selects the antenna elements 111 arranged in a linear or rectangular shape will be described.

FIG. 14 shows an example of a linear array / square array according to the eighth embodiment. In FIG. 14, in the wireless transmission system 100 shown in FIG. 1, the antenna element 111 is selected linearly or squarely from a plurality of antenna elements 111 arranged on a spherical surface. In the following description, the selected antenna element 111 is referred to as a selection element. Here, the present embodiment is similarly applicable to either the antenna array 202 on the transmitter 201 side or the antenna array 212 on the receiver 211 side.

FIG. 14A shows an example when the number of selected elements is an even number. Further, FIG. 14B shows an example in the case where the number of selected elements is odd. Note that FIGS. 14 (a) and 14 (b) show the state of a straight array in the first direction (p direction) or the second direction (q direction), but in the case of a square array, the said Similarly, the selection elements are arranged linearly in the direction orthogonal to the straight array (direction perpendicular to the paper surface). That is, a straight array or a square array is formed depending on the shape of the selected element among the plurality of antenna elements 111 arranged on the spherical antenna arrangement surface 220 when viewed from the transmission direction. For example, FIG. 14C shows an example in which the shape of the selected element when viewed from the transmission direction is a straight line. In FIG. 14C, a straight array in which P selection elements are arranged on a straight line in the p direction and a straight array in which Q selection elements are arranged on a straight line in the q direction are shown. In the case of a straight line array, the selection element may be arranged not only in the p direction or the q direction but also on a straight line in the diagonal direction. On the other hand, FIG. 14D shows an example in which the shape of the selected element when viewed from the transmission direction is square. FIG. 14D shows a square array in which P selection elements are arranged on a straight line in the p direction and Q selection elements are arranged on a straight line in the q direction orthogonal to the p direction. , (P × Q) selection elements have a rectangular shape when viewed from the transmission direction. Here, P or Q is an integer of 2 or more, and the number of selected antenna elements 111 among the plurality of antenna elements 111 arranged in the p direction is P, and they are arranged in the q direction orthogonal to the p direction. The number of selected antenna elements 111 among the plurality of antenna elements 111 is Q.

In FIG. 14A showing a case where the number (P or Q) of the selection elements (P or Q) of the linear array or the square array is even, the antenna element 111a0 located on the straight line from the center R of the antenna arrangement surface 220 in the transmission direction is set as the reference point (? As the reference antenna element), the antenna element 111a2 and the antenna element 111a3 located closest to the reference point and symmetrical to the reference point are selected elements. At this time, the angle formed by the straight line connecting the antenna element 111a2 or the antenna element 111a3 from the center R and the straight line (reference line) connecting the antenna element 111a0 from the center R is defined as Δθ1 (or Δφ1). Here, the transmission direction is the same as the reference line connecting the antenna element 111a0 at the reference point and the center R. Similarly, the next selection element is the antenna element 111a1 and the antenna element 111a4, and the angle formed by the straight line connecting the center R to the antenna element 111a1 or the antenna element 111a4 and the transmission direction is Δθ2 (or Δφ2).

In FIG. 14B showing a case where the number (P or Q) of the selection elements (P or Q) of the linear array or the square array is an odd number, the antenna element 111b2 (reference antenna element) located on a straight line in the transmission direction from the center R of the antenna arrangement surface 220. ) Is used as the selection element of the reference point, and the antenna element 111b1 and the antenna element 111b3 located at symmetrical positions on both sides thereof are used as selection elements. At this time, the angle formed by the straight line connecting the center R to the antenna element 111b1 or the antenna element 111b3 and the straight line connecting the center R to the antenna element 111b2 (reference line) is defined as Δθ2 (or Δφ2). Since the reference line connecting the antenna element 111b2 and the center R at the reference point and the transmission direction are the same, the angle Δθ1 (or Δφ1) formed by the straight line connecting the antenna element 111b2 and the center R and the transmission direction is 0 degrees.

Here, the angle formed by the straight line connecting each antenna element 111 and the center R and the transmission direction is generalized and expressed as Δθ _p (or Δφ _q (q direction)) in the p direction. In the notation of Δθ _p (or Δφ _q ), in the case of a square array, two angles of Δθ _p and Δφ _q are used in the orthogonal p direction and the q direction, respectively, but in the case of a straight array, it is one direction. Either Δθ _{p in the} p direction or Δφ _{q in} the q direction may be used. As described above, Δθ _p (or Δφ _q ) indicates the angle formed between the direction connecting the center of the sphere of the antenna arrangement surface 220 of the transmitter / receiver and the selection element and the transmission direction. Then, the antenna element 111 is selected based on the angle from the antenna element closest to the transmission direction. In the example of FIG. 14A, the antenna element 111a2 or the antenna element 111a3 having an angle of Δθ1 (or Δφ1) with respect to the transmission direction and the antenna element 111a1 or the antenna element 111a1 having an angle of Δθ2 (or Δφ2) with respect to the transmission direction. The antenna element 111a4 is selected. At this time, the distance seen from the transmission direction between the antenna element 111a1 and the antenna element 111a2, the distance seen from the transmission direction between the antenna element 111a2 and the antenna element 111a3, and the distance seen from the transmission direction between the antenna element 111a3 and the antenna element 111a4. Are the same distance (v (or w)) and are apparently evenly spaced when viewed from the transmission direction, so multi-stream transmission is possible while keeping the distance between each antenna element 111 above a certain level. It becomes. Here, in the case of a straight array, as shown in FIG. 14 (c), the p direction of Δθ _p is v, or the q direction of Δφ _q is w, and in the case of a square array, it is shown in FIG. 14 (d). As shown, the p direction of Δθ _p is v, and the q direction of Δφ _q is w.

Here, for example, it is assumed that the defined directions forming the angles of Δθ _p and Δφ _q are vertical directions orthogonal to each other. When the antenna arrangement surface 220 is spherical, the spherical surface in the specified direction of Δθ _p and Δφ _q has a radius r. For example, when the antenna arrangement surface 220 is elliptical, the specified directions of Δθ _p and Δφ _q are long axes. Corresponds to the direction or the minor axis direction.

The angle Δθ _p (or Δφ _q ) when the antenna arrangement surface 220 is spherical can be expressed by Eq. (17).

As another example, the angle (Δθ _p , Δφ _q ) may be set to a constant value. In this case, by using the antenna element 111 closest to the position of a certain angular interval among the plurality of antenna elements 111 on the antenna arrangement surface 220 as the selection element, multi-stream transmission is performed while keeping the distance between the selection elements above a certain level. Is possible. By keeping the distance between the selection elements above a certain level, the influence of adjacent selection elements can be suppressed.

Alternatively, the angle (Δθ _p , Δφ _q ) may be set to a random value. In this case, by selecting the antenna element 111 closest to the position of the random angular interval among the plurality of antenna elements 111 on the antenna arrangement surface 220 as the selection element, the propagation between the antenna elements 111 in the transmitter 201 and the receiver 211 Since the path response values vary appropriately, the rank of the propagation path matrix can be made larger than 1, and signals of a plurality of streams can be transmitted.

Next, in the linear array or the square array described with reference to FIG. 14, regarding the process of selecting the antenna element 111 and transmitting the signal of the K stream, the wireless transmission system 100 according to the first embodiment described with reference to FIG. When corresponding to 1), when corresponding to the wireless transmission system 100 (2) a according to the second embodiment described with reference to FIG. 4, the wireless transmission system 100 (2) according to the second embodiment described with reference to FIG. ) B will be described for each of the three cases.
[When compatible with wireless transmission system 100 (1)]
FIG. 15 shows a processing example of the wireless transmission system 100 (1) according to the eighth embodiment. The process shown in FIG. 15 is a process of a straight array or a square array corresponding to the process of the circular array described with reference to FIG. Note that, in FIG. 15, since the processing having the same reference numerals as that in FIG. 3 is performed in the same manner as in the case of FIG. 3, redundant description will be omitted, and a portion different from the processing in FIG. 3 will be described. Here, the wireless transmission system that performs the process described with reference to FIG. 15 is configured in the same manner as the wireless transmission system 100 (1) described with reference to FIG.

First, the process executed on the transmitter 201 (1) side will be described.

The processing of steps S101 and S102 is performed in the same manner as in FIG. 3, and the antenna selection / weighting processing unit 203 is the most in the transmission direction among the plurality of antenna elements 111T on the spherical surface based on the propagation path information or the position information. Determine the nearest antenna element 111T (# 0).

In step S103a, the antenna selection / weighting processing unit 203 calculates the angle (Δθ _p , Δφ _q ) of the antenna element 111T (# 0) with respect to the transmission direction according to the propagation path information or the position information. The calculation method of the angle (Δθ _p , Δφ _q ) is as described in Eq. (18) and the like.

In step S104a, the antenna selection / weighting processing unit 203 has M antenna elements 111T (# 1) to (# 1) located at positions corresponding to the angles (Δθ _p , Δφ _q ) of the antenna elements 111T (# 0) with respect to the transmission direction. Select #M).

The processing of steps S105 and S106 is performed in the same manner as in FIG. 3, and the antenna selection / weighting processing unit 203 calculates the propagation path matrix and the weighting matrix based on the respective positions of the M antenna elements 111T, and steps. The weighting matrix calculated in step S105 is applied to the signals transmitted from the M antenna elements 111T selected in S104a to transmit the K stream signal.

In this way, the transmitter 201 (1) can reselect the M antenna elements 111T according to the misalignment even if the misalignment occurs with the receiver 211 (1). , It is possible to suppress a decrease in the communication path capacity due to misalignment.

Next, the process executed on the receiver 211 (1) side will be described.

The processing of steps S111 and S112 is performed in the same manner as in FIG. 3, and the antenna selection / weighting processing unit 213 is the most in the transmission direction among the plurality of antenna elements 111R on the spherical surface based on the propagation path information or the position information. Determine the nearest antenna element 111R (# 0).

In step S113a, the antenna selection / weighting processing unit 213 calculates the angle (Δθ _p , Δφ _q ) of the antenna element 111R (# 0) with respect to the transmission direction according to the propagation path information or the position information. The calculation method of the angle (Δθ _p , Δφ _q ) is as described in Eq. (18) and the like.

In step S114a, the antenna selection / weighting processing unit 213 has N antenna elements 111T (# 1) to (# 1) located at positions corresponding to angles (Δθ _p , Δφ _q ) of the antenna element 111R (# 0) with respect to the transmission direction. Select #N).

The processing of steps S115 and S116 is performed in the same manner as in FIG. 3, and the antenna selection / weighting processing unit 213 applies the conjugate transpose matrix of the weighting matrix to the signal received by the N antenna elements 111R to obtain the K stream. Generate a signal.

In this way, the receiver 211 (1) can reselect the N antenna elements 111R according to the misalignment even when the misalignment occurs with the transmitter 201 (1). , It is possible to suppress a decrease in the communication path capacity due to misalignment.
[When corresponding to wireless transmission system 100 (2) a]
FIG. 16 shows a processing example of the wireless transmission system 100 (2) a according to the eighth embodiment. The process shown in FIG. 16 is a process of a straight array or a square array corresponding to the process of the circular array described with reference to FIG. Note that, in FIG. 16, since the processing having the same reference numerals as that in FIG. 6 is performed in the same manner as in the case of FIG. 6, the duplicated description will be omitted, and the parts different from the processing of FIG. 6 will be described. Here, the wireless transmission system that performs the process described with reference to FIG. 16 is configured in the same manner as the wireless transmission system 100 (2) a described with reference to FIG.

First, the process executed on the transmitter 201 (2) a side will be described.

The processing of steps S101 and S102 is performed in the same manner as in FIG. 6, and the antenna selection / weighting processing unit 203 (2) a is among the plurality of antenna elements 111T on the spherical surface based on the propagation path information or the position information. The antenna element 111T (# 0) closest to the transmission direction is determined.

The processing of steps S103a and S103b is performed in the same manner as in FIG. 15, and the antenna selection / weighting processing unit 203 (2) a determines the transmission direction of the antenna element 111R (# 0) according to the propagation path information or the position information. The angle (Δθ _p , Δφ _q ) with respect to the antenna is calculated, and M antenna elements 111T (# 1) to (#M) located at the positions corresponding to the angle (Δθ _p , Δφ _q ) are selected.

The processing of steps S200 and S201 is performed in the same manner as in FIG. 6, and the antenna selection / weighting processing unit 203 (2) a calculates the weighting matrix used on the transmitter 201 (2) a side and receives the receiver 211. (2) The weighting matrix used on the a side is also calculated, and the information necessary for selecting the N antenna elements 111R and determining the weighting matrix is transmitted on the receiver 211 (2) a side.

The processing of step S106 is performed in the same manner as in FIG. 6, and the antenna selection / weighting processing unit 203 (2) a uses the weighting matrix calculated in step S200 for the signals transmitted from the M antenna elements 111T selected in step S104a. Is applied to transmit a K-stream signal.

In this way, the transmitter 201 (2) a can reselect the M antenna elements 111T according to the misalignment even if the misalignment occurs with the receiver 211 (2) a. Therefore, it is possible to suppress a decrease in the communication path capacity due to misalignment.

Next, the process executed on the receiver 211 (2) a side will be described.

The processes of steps S211 and S212 are performed in the same manner as in FIG. 6, and the receiver 211 (2) a selects the antenna element 111R of the antenna array 212 based on the position information received from the transmitter 201 (2) a. Then, N antenna elements 111R selected from the conjugate transposition matrix calculated based on the weighted matrix information received from the transmitter 201 (2) a (or the conjugate transpose matrix received from the transmitter 201 (2) a). Generates a K-stream signal by applying it to the signal received by. Alternatively, the receiver 211 (2) a selects the antenna element 111R of the antenna array 212 based on the position information received from the transmitter 201 (2) a, and further creates a weighting matrix and a conjugate transposition matrix based on the position information. It is calculated and applied to the signals received from the selected N antenna elements 111R to generate a K-stream signal.

In this way, the receiver 211 (2) b receives the position information from the transmitter 201 (2) a without measuring or estimating the propagation path information or the position information, or performing the calculation of the weighting matrix. And the information of the weighting matrix can be used to receive the K stream signal.
[When corresponding to wireless transmission system 100 (2) b]
FIG. 17 shows a processing example of the wireless transmission system 100 (2) b according to the eighth embodiment. The process shown in FIG. 17 is a process of a straight array or a square array corresponding to the process of the circular array described with reference to FIG. 7. Note that, in FIG. 17, since the processing having the same reference numerals as that in FIG. 7 is performed in the same manner as in the case of FIG. 7, the duplicated description will be omitted, and the parts different from the processing of FIG. 7 will be described. Here, the wireless transmission system that performs the process described with reference to FIG. 17 is configured in the same manner as the wireless transmission system 100 (2) b described with reference to FIG.

First, the process executed on the transmitter 201 (2) b side will be described.

The process of step S301 is performed in the same manner as in FIG. 7, and the transmitter 201 (2) b selects M antenna elements 111T of the antenna array 202 based on the position information received from the receiver 211 (2) b. Then, the weighting matrix is determined based on the information of the weighting matrix received from the receiver 211 (2) b, and is transmitted from the M antenna elements 111T selected by applying to the K stream signal.

In this way, the transmitter 201 (2) b uses the position information and the weighting matrix information received from the receiver 211 (2) b without performing the position estimation process or the calculation of the weighting matrix. The K-stream signal can be transmitted.

Next, the process executed on the receiver 211 (2) b side will be described.

The processing of steps S111 and S112 is performed in the same manner as in FIG. 3, and the antenna selection / weighting processing unit 213 (2) b is among the plurality of antenna elements 111R on the spherical surface based on the propagation path information or the position information. The antenna element 111R (# 0) closest to the transmission direction is determined.

The processing of steps S113a and S114a is performed in the same manner as in FIG. 15, and the antenna selection / weighting processing unit 213 (2) b determines the transmission direction of the antenna element 111R (# 0) according to the propagation path information or the position information. The angle (Δθ _p , Δφ _q ) with respect to the antenna is calculated, and N antenna elements 111T (# 1) to (#N) located at the positions corresponding to the angle (Δθ _p , Δφ _q ) are selected.

The processing of steps S310 and S311 is performed in the same manner as in FIG. 7, and the antenna selection / weighting processing unit 213 (2) b calculates the weighting matrix used on the receiver 211 (2) b side and the transmitter 201. (2) The weighting matrix used on the b side is also calculated, and the information necessary for selecting the M antenna elements 111T and determining the weighting matrix is transmitted on the transmitter 201 (2) b side.

The processing of step S116 is performed in the same manner as in FIG. 7, and the antenna selection / weighting processing unit 203 (2) b selects the conjugate transpose matrix of the weighting matrix calculated in step S310 in step S114a, and N antenna elements 111R. It is applied to the signal received in to generate a K-stream signal.

In this way, the receiver 211 (2) b can reselect the N antenna elements 111R according to the misalignment even if the misalignment occurs with the transmitter 201 (2) b. Therefore, it is possible to suppress a decrease in the channel capacity due to misalignment.
(9th embodiment)
In the ninth embodiment, the correlation matrix of the propagation path matrix (with the propagation path correlation matrix) for I combinations of the identifiers i (i = 1, ..., I (I is an integer)) indicating the combination of the selected antenna elements. ) Is calculated, and an antenna element is selected when the propagation path correlation matrix satisfies a predetermined condition. In the present embodiment, as a predetermined condition, when the antenna element having the maximum propagation path correlation matrix is selected, when the antenna element having the propagation path correlation matrix equal to or higher than a preset threshold value is selected, the propagation path correlation matrix is Three cases of selecting an antenna element having a maximum value or a threshold value or more will be described. Here, the wireless transmission system according to the ninth embodiment is configured in the same manner as the wireless transmission system 100 (1) described with reference to FIG. Further, the propagation path correlation matrix for the antenna array 202 on the transmitter 201 side is expressed as T, and the determinant thereof is expressed as det (T). Similarly, the propagation path correlation matrix for the antenna array 212 on the receiver 211 side is R. The determinant is expressed as det (R). Further, the propagation path correlation matrix in the identifier i indicating the combination of the antenna elements is referred to as Ti (Ri on the receiver 211 side).
[When selecting the antenna element that maximizes the propagation path correlation matrix]
FIG. 18 shows an example of the process of searching for the antenna element having the maximum determinant in the ninth embodiment. Here, in the following description, the antenna array 212 of the receiver 211 will be described, but the antenna array 202 of the transmitter 201 is also processed in the same manner.

In step S401, the estimation unit 214 (in the case of the transmission side, the estimation unit 204 (the same applies hereinafter)) measures or estimates the position information (transmission distance (D ₀ ) or transmission direction (θ, φ)). The method for measuring or estimating the position information is the same as in step S101 (or step S111).

In step S402, the antenna selection / weighting processing unit 213 (in the case of the transmitting side, the antenna selection / weighting processing unit 203 (the same applies hereinafter)) is an identifier indicating a combination from all the antenna elements 111 based on the result of step S401. Calculate the propagation path correlation matrix R1 (T1 (same below) for the transmitting side) when N antenna elements 111 (M for the transmitting side) when i is (i = 1) are selected. ..

In step S403, the antenna selection / weighting processing unit 213 uses the determinant det (R1) (or detTmax = det (T1)) having the identifier i (i = 1) indicating the combination of the determinant detRmax having the largest propagation path correlation matrix. ).

In step S404, the antenna selection / weighting processing unit 213 increments the identifier i by one (increment).

In step S405, the antenna selection / weighting processing unit 213 calculates the propagation path correlation matrix Ri (Ti in the case of the transmitting side) when N (or M) antenna elements are selected from all the antenna elements. ..

In step S406, the antenna selection / weighting processing unit 213 determines whether or not the determinant det (Ri) is larger than the maximum determinant detRmax. If the determination result is Yes, the process proceeds to step S407, and if No, the process proceeds to step S408.

In step S407, the antenna selection / weighting processing unit 213 performs a process of updating the maximum determinant detRmax to the determinant det (Ri). At this time, the antenna selection / weighting processing unit 213 associates the position information and identifiers of the M (or N) antenna elements 111 corresponding to the identifier i indicating the combination of the determinant det (Ri) with the determinant detRmax. And keep it.

In step S408, the antenna selection / weighting processing unit 213 determines whether or not the identifier i is equal to or greater than the total number of combinations I. If the determination result is Yes, the process proceeds to step S409, and if No, the process returns to step S404 and the same process is repeated. In this way, the combination of N (or M) antenna elements that maximizes the determinant det (Ri) of the propagation path correlation matrix is searched for.

In step S409, the antenna selection / weighting processing unit 213 has M (or N) antennas corresponding to the determinant detRmax at which the determinant det (Ri) of the propagation path correlation matrix searched in the above process is maximized. Select the element. Here, the antenna selection / weighting processing unit 213 selects by an identifier indicating the position information or combination of N (or M) antenna elements 111 held in association with the determinant detRmax in step S407. The power antenna element 111 can be known.

In this way, the wireless transmission system 100 (1) according to the present embodiment searches for a combination of N (or M) antenna elements in which the determinant det (Ri) of the propagation path correlation matrix has the maximum value detRmax. Then, the optimum antenna element can be selected.

Here, in the wireless transmission system 100 (1) according to the present embodiment, M antenna elements 111 are selected from all the antenna elements 111 on the transmitter 201 side, and all the antenna elements 111 on the receiver 211 side. assuming that selects the N antenna elements from the transmission distance or the channel matrix H and the channel correlation matrix from the transmission direction information R = HH H between the transmitter and receiver ^(or T = H H ^H) To calculate. Then, the wireless transmission system 100 (1) finds a combination of antenna elements 111 having the maximum determinant of the propagation path correlation matrix R (or T), and M (or N) when the determinant is maximum. The antenna element 111 of the above is selected on the transmitter 201 side and the receiver 211 side to transmit and receive the K stream signal.

In communication under a line-of-sight environment, the received SNR (Signal to Noise Ratio) is large, and at this time, the channel capacity C can be expressed by the equation (18). Here, P _s is the transmission power per stream, P _n is the noise power, and I is the identity matrix.

In equation (18), since the logarithm (log ₂ ) is a monotonically increasing function, an increase in the channel capacity C is equivalent to an increase in the determinant det (HH ^H ) of the propagation path correlation matrix of the propagation path matrix. Therefore, by selecting the antenna element 111 that increases the determinant of the propagation path correlation matrix, a higher communication path capacitance is realized as compared with the case of selecting the antenna element 111 having a relatively small determinant of the propagation path correlation matrix. can do.
[When selecting an antenna element whose propagation path correlation matrix is equal to or greater than the threshold value]
FIG. 19 shows an example of a process of searching for an antenna element whose determinant is equal to or greater than a threshold value in the ninth embodiment. Here, in the following description, the antenna array 212 of the receiver 211 will be described, but the antenna array 202 of the transmitter 201 is also processed in the same manner.

In step S501, the estimation unit 214 (in the case of the transmitting side, the estimation unit 204 (the same applies hereinafter)) performs the same processing as in step S401 described with reference to FIG. 18, and measures or estimates the position information.

In step S502, the antenna selection / weighting processing unit 213 (in the case of the transmitting side, the antenna selection / weighting processing unit 203 (the same applies hereinafter)) is combined from all the antenna elements 111 based on the result of step S501 (i = The propagation path correlation matrix R1 (T1 in the case of the transmitting side) when N antenna elements 111 (M in the case of the transmitting side) in the case of 1) are selected is calculated. Then, the threshold value detRth is set. Here, as the initial value of the threshold value detRth, for example, the propagation path correlation matrix in the case of one stream in which the propagation path matrix can be estimated relatively easily is obtained in advance, and this is set as the threshold value detRth.

In step S503, the antenna selection / weighting processing unit 213 uses the determinant det (R1) with the identifier i (i = 1) indicating the combination of the determinant detR of the propagation path correlation matrix (det (T1) in the case of the transmitting side). ).

In step S504, the antenna selection / weighting processing unit 213 increases the identifier i by one.

In step S505, the antenna selection / weighting processing unit 213 calculates the propagation path correlation matrix Ri (Ti in the case of the transmitting side) when N (or M) antenna elements are selected from all the antenna elements. ..

In step S506, the antenna selection / weighting processing unit 213 determines whether or not the determinant det (Ri) is equal to or greater than the preset threshold value detRth. If the determination result is Yes, the process proceeds to step S507, and if No, the process proceeds to step S508.

In step S507, the antenna selection / weighting processing unit 213 performs a process of updating the determinant detR to the determinant det (Ri).

In step S508, the antenna selection / weighting processing unit 213 determines whether or not the identifier i is equal to or greater than the total number of combinations I. If the determination result is Yes, the process proceeds to step S509, and if No, the process returns to step S504 and the same process is repeated.

In step S509, the antenna selection / weighting processing unit 213 did not find a combination of N (or M) antenna elements whose determinant det (Ri) of the propagation path correlation matrix is equal to or greater than the threshold detRth in the above processing. Therefore, change the threshold detRth (for example, reduce the threshold detRth). Then, the process returns to step S504 and the same process is repeated.

In step S510, the antenna selection / weighting processing unit 213 has N (or M) determinants corresponding to the determinant detR in which the determinant det (Ri) of the propagation path correlation matrix searched in the above process is equal to or greater than the threshold value detRth. Select the antenna element of.

In this way, the wireless transmission system according to the present embodiment searches for a combination of N (or M) antenna elements in which the determinant det (Ri) of the propagation path correlation matrix is equal to or greater than the threshold detRth, and is optimal. Antenna element can be selected.
[When selecting an antenna element whose propagation path correlation matrix is greater than or equal to the threshold value or the maximum value]
FIG. 20 shows an example of the process of searching for an antenna element whose determinant is maximum or equal to or greater than the threshold value in the ninth embodiment. Here, in the following description, the antenna array 212 of the receiver 211 will be described, but the antenna array 202 of the transmitter 201 is also processed in the same manner.

In step S601, the estimation unit 214 (in the case of the transmitting side, the estimation unit 204 (the same applies hereinafter)) performs the same processing as in step S401 described with reference to FIG.

In step S602, the antenna selection / weighting processing unit 213 (in the case of the transmitting side, the antenna selection / weighting processing unit 203 (same below)) performs the same processing as in step S502 described with reference to FIG.

In step S603, the determinant selection / weighting processing unit 213 combines both the determinant detR of the propagation path correlation matrix and the maximum determinant detRmax (i = 1) to determinant det (R1) (det in the case of the transmitting side). Initialize to (T1)).

In step S604, the antenna selection / weighting processing unit 213 increases the identifier i by one.

In step S605, the antenna selection / weighting processing unit 213 calculates the propagation path correlation matrix Ri (Ti in the case of the transmitting side) when N (or M) antenna elements are selected from all the antenna elements. ..

In step S606, the antenna selection / weighting processing unit 213 determines whether or not the determinant det (Ri) is equal to or greater than the maximum determinant detRth. If the determination result is Yes, the process proceeds to step S607, and if No, the process proceeds to step S608.

In step S607, the antenna selection / weighting processing unit 213 performs a process of updating the determinant detR to the determinant det (Ri).

In step S608, the antenna selection / weighting processing unit 213 determines whether or not the determinant det (Ri) is larger than the maximum determinant detRmax, as in step S406 described with reference to FIG. If the determination result is Yes, the process proceeds to step S609, and if No, the process proceeds to step S610.

In step S609, the antenna selection / weighting processing unit 213 performs a process of updating the maximum determinant detRmax to the determinant det (Ri) in the same manner as in step S407 described with reference to FIG. Then, the process proceeds to step S610. At this time, the antenna selection / weighting processing unit 213 associates the position information and identifiers of the N (or M) antenna elements 111 corresponding to the identifier i indicating the combination of the determinant det (Ri) with the determinant detRmax. And keep it.

In step S610, the antenna selection / weighting processing unit 213 determines whether or not the identifier i is equal to or greater than the total number of combinations I. If the determination result is Yes, the process proceeds to step S611, and if No, the process returns to step S604 and the same process is repeated.

In step S611, the antenna selection / weighting processing unit 213 has N (or M) antennas corresponding to the determinant detRmax at which the determinant det (Ri) of the propagation path correlation matrix searched in the above process is maximized. Select the element. Here, the antenna selection / weighting processing unit 213 selects by an identifier indicating the position information and the combination of N (or M) antenna elements 111 held in association with the determinant detRmax in step S609. The power antenna element 111 can be known.

In step S612, the antenna selection / weighting processing unit 213 has N (or M) determinants corresponding to the determinant detR in which the determinant det (Ri) of the propagation path correlation matrix searched in the above process is equal to or greater than the threshold value detRth. Select the antenna element of.

In this way, in the wireless transmission system according to the present embodiment, the combination of N (or M) antenna elements whose determinant det (Ri) of the propagation path correlation matrix is equal to or greater than the threshold detRth, or propagation path correlation. Search for the combination of N (or M) antenna elements that maximizes the determinant det (Ri) of the matrix, calculate the determinant of the propagation path correlation matrix, and N (or M) antenna elements. Can be selected. Here, in the example of FIG. 19, when the determinant detR whose determinant det (Ri) of the propagation path correlation matrix is equal to or higher than the threshold detRth is not found, it is necessary to reset the determinant detRth. In the example, even if the determinant detR in which the determinant det (Ri) of the propagation path correlation matrix is equal to or greater than the threshold detRth is not found, it corresponds to the determinant detRmax in which the determinant det (Ri) of the propagation path correlation matrix is maximized. It is possible to select M (or N) antenna elements.
(Modified example of the ninth embodiment)
A modified example of the ninth embodiment will be described. For example, in the process of the ninth embodiment shown in FIG. 18, the estimation unit 204 (or the estimation unit 214) measures or estimates the position information in step S401, but in this modification, the transmitter 201 and the receiver 211 Measure the propagation path matrix between and. That is, in the ninth embodiment, the propagation path matrix and the propagation path correlation matrix are calculated from the position information to select M or N antenna elements 111, but in this modification, the propagation path matrix is selected. Is measured, the propagation path correlation matrix is calculated, and M or N antenna elements 111 are selected.

FIG. 21 shows another processing example of the ninth embodiment. Here, a process different from that of FIG. 18 will be described. The wireless transmission system according to the modified example of the ninth embodiment is configured in the same manner as the wireless transmission system 100 (1) described with reference to FIG.

In step S401a, the estimation unit 204 (or estimation unit 214) measures the propagation path matrix between the transmitter 201 and the receiver 211. The propagation path matrix can be measured by a well-known technique using a known signal such as a training signal.

Then, in step S402, similarly to FIG. 18, the antenna selection / weighting processing unit 203 (antenna selection / weighting processing unit 213) is combined from all the antenna elements 111 based on the result of step S401a (i = 1). ), The propagation path correlation matrix R1 (or T1) when M (or N) antenna elements 111 are selected is calculated.

Hereinafter, since the processing up to step S409 is the same as the processing of FIG. 18, duplicate description will be omitted.

Here, FIG. 21 corresponds to a processing example in which the antenna element having the maximum propagation path correlation matrix described with reference to FIG. 18 is selected, but the processing of step S401a of FIG. 21 is the processing of step S501 of FIG. When selecting an antenna element whose propagation path correlation matrix is equal to or higher than a preset threshold value by substituting each of the processes in step S601 of FIG. 20, and selecting an antenna element whose propagation path correlation matrix is maximum or equal to or higher than the threshold value. The same applies to the case of.

In this way, in the wireless transmission system 100 (1) according to the present embodiment, M antenna elements 111 are selected from all the antenna elements 111 on the transmitter 201 side, and all the antenna elements 111 on the receiver 211 side. The propagation path matrix H when N antenna elements 111 are selected from the above is measured, and the propagation path correlation matrix R = HH ^H (or T = H ^H H) is calculated.

As in the ninth embodiment, in the communication under the line-of-sight environment, the received SNR is large, and the channel capacity C can be expressed by the equation (18) described above. Since the logarithm (log ₂ ) is a monotonically increasing function in Eq. (18), an increase in the channel capacity C is equivalent to an increase in the determinant det (HH ^H ) of the propagation path correlation matrix. Therefore, by selecting the antenna element 111 that increases the determinant of the propagation path correlation matrix, a higher communication path capacitance is realized as compared with the case of selecting the antenna element 111 having a relatively small determinant of the propagation path correlation matrix. can do.
(10th Embodiment)
A tenth embodiment will be described. In the ninth embodiment, the process of searching all the antenna elements 111 on the antenna arrangement surface 220 is performed by the propagation path correlation matrix, but in the present embodiment, it serves as a reference in the preset antenna search region. The antenna element 111 is selected in order from the antenna element 111. For example, a reference antenna element 111 such as the antenna element 111 closest to the transmission direction or the antenna element 111 having the best antenna radiation efficiency is selected as the first (first) antenna element, and predetermined conditions (for example, even intervals or equal intervals) are selected. Peripheral antenna elements 111 are sequentially selected based on (equal angle, etc.). Then, among the antenna elements 111 selected in order, the first selected antenna element 111 is the first stream, the second selected antenna element 111 is the second stream, ..., The Kth selected antenna. By allocating streams in order so that the element 111 becomes the K stream, once a plurality of antenna elements 111 for the K stream are determined, the antenna to be selected when the number of streams corresponds to the stream less than K. There is an advantage that the element 111 is also determined at the same time. This eliminates the need for selection processing of the antenna element 111 when the number of streams is changed to a stream less than K. For example, even when the number of streams is changed according to the amount of data transmitted / received between the transmitter 201 and the receiver 211, it is possible to eliminate the need to redo the search for the antenna element 111.

Next, in the tenth embodiment, similarly to FIGS. 18, 19, and 20 described in the ninth embodiment, when the antenna element having the maximum propagation path correlation matrix is selected, the propagation path correlation matrix becomes The processing in three cases of selecting an antenna element having a preset threshold value or more and selecting an antenna element having a propagation path correlation matrix of maximum or a threshold value or more will be described.
[When selecting the antenna element that maximizes the propagation path correlation matrix]
FIG. 22 shows an example of the process of searching for the antenna element having the maximum determinant in the tenth embodiment. In the present embodiment, the antenna element having the maximum propagation path correlation matrix is selected by the method of sequentially selecting the antenna elements 111 in the preset antenna search region. Here, in the following description, the antenna array 212 of the receiver 211 will be described, but the antenna array 202 of the transmitter 201 is also processed in the same manner.

Step S701 is the same process as step S401 described with reference to FIG. 18, and the estimation unit 204 (in the case of the transmitting side, the estimation unit 214 (the same applies hereinafter)) measures or estimates the position information.

In step S702, the antenna selection / weighting processing unit 203 (in the case of the transmitting side, the antenna selection / weighting processing unit 213 (the same applies hereinafter)) determines the reference antenna element, and the first (first) antenna element of i = 1. Let it be 111 (# 1). For example, the antenna selection / weighting processing unit 203 determines the antenna element 111 closest to the transmission direction, the antenna element 111 having the best antenna radiation efficiency, and the like as the reference antenna element, and uses the antenna element 111 (# 1) as the reference antenna element.

In step S703, the antenna selection / weighting processing unit 203 sets the determinant detRmax having the largest propagation path correlation matrix as the determinant det (R1) (or detTmax = det (T1)) of the first antenna element 111 (# 1). To do.

In step S704, the antenna selection / weighting processing unit 203 selects antenna elements 111 (# (i + 1)) from the preset antenna search area, and uses (i + 1) antenna elements 111. Calculate the propagation path correlation matrix R (i + 1) (or T (i + 1)) for the case.

In step S705, the antenna selection / weighting processing unit 203 determines whether or not the determinant det (R (i + 1)) is larger than the maximum determinant detRmax, as in step S406 described with reference to FIG. If the determination result is Yes, the process proceeds to step S706, and if No, the process proceeds to step S707.

In step S706, the antenna selection / weighting processing unit 203 performs a process of updating the determinant detRmax to the determinant det (R (i + 1)).

In step S707, the antenna selection / weighting processing unit 203 determines whether or not the counter i indicating the number of antenna elements 111 to be selected is larger than (I-1) with the upper limit of the number of selected elements as I. If the determination result is Yes, the process proceeds to step S708, and if No, the process returns to step S704 and the same process is repeated. In this way, the combination of M (or N) antenna elements having the maximum determinant det (R (i + 1)) of the propagation path correlation matrix is searched for.

In step S708, the antenna selection / weighting processing unit 203 has K pieces (K) corresponding to the determinant detRmax at which the determinant det (R (i + 1)) of the propagation path correlation matrix searched in the above process is maximized. Select the antenna element of ≦ I).

In this way, the wireless transmission system according to the present embodiment has a method of sequentially selecting the antenna elements 111 within the preset antenna search region, and the determinant det (R (i + 1)) of the propagation path correlation matrix. )) Can be selected for the maximum K antenna elements.
[When selecting an antenna element whose propagation path correlation matrix is equal to or greater than the threshold value]
FIG. 23 shows an example of the process of searching for an antenna element whose determinant is equal to or greater than the threshold value in the tenth embodiment. In the present embodiment, the antenna elements whose propagation path correlation matrix is equal to or higher than a predetermined threshold value are selected by the method of sequentially selecting the antenna elements 111 in the preset antenna search region. Here, in the following description, the antenna array 212 of the receiver 211 will be described, but the antenna array 202 of the transmitter 201 is also processed in the same manner.

In step S801, the process is the same as in step S501 described with reference to FIG. 19, and the estimation unit 204 (in the case of the transmission side, the estimation unit 214 (the same applies hereinafter)) measures or estimates the position information.

In step S802, the antenna selection / weighting processing unit 203 (in the case of the transmitting side, the antenna selection / weighting processing unit 213 (the same applies hereinafter)) determines the reference antenna element in the same manner as in step S702 described with reference to FIG. It is assumed that the first (first) antenna element 111 (# 1) of = 1. Then, the threshold value detRth is set. Here, as the initial value of the threshold value detRth, for example, the propagation path correlation matrix in the case of one stream in which the propagation path matrix can be estimated relatively easily is obtained in advance, and this is set as the threshold value detRth.

In step S803, the antenna selection / weighting processing unit 203 sets the determinant detR of the propagation path correlation matrix to the determinant det (R1) (or detTmax = det (T1)) of the first antenna element 111 (# 1).

In step S804, the antenna selection / weighting processing unit 203 selects the antenna element 111 (# (i + 1)) from the preset antenna search area in the same manner as in step S704 described with reference to FIG. The propagation path correlation matrix R (i + 1) (or T (i + 1)) when +1) antenna elements 111 are used is calculated.

In step S805, the antenna selection / weighting processing unit 203 determines whether or not the determinant det (R (i + 1)) is equal to or greater than the preset threshold value detRth, as in step S506 described with reference to FIG. To do. If the determination result is Yes, the process proceeds to step S806, and if No, the process proceeds to step S807.

In step S806, the antenna selection / weighting processing unit 203 performs a process of updating the determinant detR to the determinant det (R (i + 1)).

In step S807, the antenna selection / weighting processing unit 203 determines whether or not the counter i indicating the number of antenna elements 111 is larger than (I-1) with the upper limit of the number of selected elements as I. If the determination result is Yes, the process proceeds to step S808, and if No, the process returns to step S804 and the same process is repeated.

In step S808, the antenna selection / weighting processing unit 203 did not find a combination of antenna elements in which the determinant det (R (i + 1)) of the propagation path correlation matrix was equal to or greater than the threshold detRth in the above processing. Change detRth (for example, reduce the threshold detRth). Then, the process returns to step S804 and the same process is repeated.

In step S809, the antenna selection / weighting processing unit 203 has K pieces corresponding to the determinant detR in which the determinant det (R (i + 1)) of the propagation path correlation matrix searched in the above process is equal to or greater than the threshold value detRth. The antenna element of (K ≦ I) is selected.

In this way, the wireless transmission system according to the present embodiment calculates the determinant of the propagation path correlation matrix by the method of sequentially selecting the antenna elements 111 in the preset antenna search region to obtain the antenna elements. You can choose.
[When selecting an antenna element whose propagation path correlation matrix is greater than or equal to the threshold value or the maximum value]
FIG. 24 shows an example of the process of searching for the antenna element whose determinant is the maximum or the threshold value or more in the tenth embodiment. In the present embodiment, the antenna elements whose propagation path correlation matrix is equal to or more than a predetermined threshold value or the maximum value are selected by the method of sequentially selecting the antenna elements 111 in the preset antenna search region. Here, in the following description, the antenna array 212 of the receiver 211 will be described, but the antenna array 202 of the transmitter 201 is also processed in the same manner.

In step S901, the process is the same as step S701 described with reference to FIG. 22 or step S801 described with reference to FIG. 23, and the estimation unit 204 (in the case of the transmitting side, the estimation unit 214 (the same applies hereinafter)) measures or measures the position information. presume.

In step S902, the antenna selection / weighting processing unit 203 (in the case of the transmitting side, the antenna selection / weighting processing unit 213 (the same applies hereinafter)) is similar to step S702 described with reference to FIG. 22 or step S802 described with reference to FIG. The reference antenna element is determined, and the first (first) antenna element 111 (# 1) of i = 1 is set. Then, the threshold value detRth is set. Here, as the initial value of the threshold value detRth, for example, the propagation path correlation matrix in the case of one stream in which the propagation path matrix can be estimated relatively easily is obtained in advance, and this is set as the threshold value detRth.

In step S903, the antenna selection / weighting processing unit 203 sets the determinant detR of the propagation path correlation matrix and the determinant detRmax having the maximum propagation path correlation matrix as the determinant det (R1) of the first antenna element 111 (# 1). (Or detTmax = det (T1)).

In step S904, the antenna selection / weighting processing unit 203 sets the antenna element 111 (# (i + 1)) from within the preset antenna search area in the same manner as in step S704 described with reference to FIG. 22 or step S804 described with reference to FIG. )) Is selected, and the propagation path correlation matrix R (i + 1) (or T (i + 1)) when (i + 1) antenna elements 111 are used is calculated.

In step S905, the antenna selection / weighting processing unit 203 has a threshold value detRth in which the determinant det (R (i + 1)) is preset, as in step S506 described with reference to FIG. 19 or step S606 described with reference to FIG. It is determined whether or not it is the above. If the determination result is Yes, the process proceeds to step S906, and if No, the process proceeds to step S907.

In step S906, the antenna selection / weighting processing unit 203 performs a process of updating the determinant detR to the determinant det (R (i + 1)).

In step S907, the antenna selection / weighting processing unit 203 determines whether or not the determinant det (R (i + 1)) is larger than the maximum determinant detRmax, as in step S606 described with reference to FIG. If the determination result is Yes, the process proceeds to step S908, and if No, the process proceeds to step S909.

In step S908, the antenna selection / weighting processing unit 203 performs a process of updating the maximum determinant detRmax to the determinant det (R (i + 1)) in the same manner as in step S609 described with reference to FIG.

In step S909, the antenna selection / weighting processing unit 203 determines whether or not the counter i indicating the number of all antenna elements 111 is larger than (I-1) with the upper limit of the number of selected elements as I. If the determination result is Yes, the process proceeds to step S910, and if No, the process returns to step S904 and the same process is repeated.

In step S910, the antenna selection / weighting processing unit 203 has K pieces (K) corresponding to the determinant detRmax at which the determinant det (R (i + 1)) of the propagation path correlation matrix searched in the above process is maximized. Select the antenna element of ≦ I).

In step S911, the antenna selection / weighting processing unit 203 has K pieces corresponding to the determinant detR in which the determinant det (R (i + 1)) of the propagation path correlation matrix searched in the above process is equal to or greater than the threshold value detRth. The antenna element of (K ≦ I) is selected.

In this way, the wireless transmission system according to the present embodiment calculates the determinant of the propagation path correlation matrix by the method of sequentially selecting the antenna elements 111 in the preset antenna search region to obtain the antenna elements. You can choose. Here, in the example of FIG. 24, as in the case of FIG. 20, even if the determinant detR in which the determinant det (R (i + 1)) of the propagation path correlation matrix is equal to or greater than the threshold detRth is not found, propagation is performed. It is possible to select M (or N) antenna elements corresponding to the determinant detRmax at which the determinant det (R (i + 1)) of the path correlation matrix is maximized.

Here, as an example of limiting the search area (search range) of the antenna element 111, the direction perpendicular to the antenna element 111 closest to the transmission direction is from θ _a to θ _{b on} the spherical antenna arrangement surface 220. A method is conceivable in which the angle and the angle in the horizontal direction from φ _a to φ _b are limited to the search range, and the antenna element 111 within the search range is selected. At this time, the number of antenna elements 111 within the limited search range is N _lim (however, N _lim <N _max ) or M _lim (however, M _lim <M _max ). The number of all antenna elements 111 on the transmitter 201 side and the receiver 211 side is M _max and N _max . Maximum when M antenna elements 111 on the transmitter 201 side and N antenna elements 111 on the receiver 211 side are selected from the number M _max and N _max of all antenna elements 111 on the spherical antenna arrangement surface 220. The number of searches can be calculated by Eq. (19) from the calculation of the combination of the antenna elements 111. Here, C indicates a combination operator.

On the other hand, the maximum number of searches when selecting M antenna elements 111 and N antenna elements 111 from the number of antenna elements 111 within the limited search range of M _lim and N _lim is the calculation of the combination of antenna elements 111. Therefore, it can be calculated by Eq. (20).

In this way, the search amount of the antenna element 111 is 1 / (M _max · (M _max -1) ... · (M _lim +1)) on the transmitter 201 side and 1 / (N _max ) on the receiver 211 side.・ (N _max -1) ・ ... ・ (N _lim +1)). This makes it possible to reduce the search amount of the antenna element 111 and improve the characteristics of the channel capacity.
(11th Embodiment)
In the eleventh embodiment, a method of utilizing symmetry will be described as a method of reducing the search amount of the antenna element 111.

FIG. 25 shows an example of the method of selecting the antenna element according to the eleventh embodiment. In FIG. 25, for example, when the antenna elements 111 are sequentially selected in a predetermined selection direction on the antenna arrangement surface 220, the antenna elements are located at points symmetrical with respect to the reference point or the reference antenna element 111r. 111 is also selected at the same time. In the example of FIG. 25, the first antenna element 111s located in the selection direction is selected from the reference antenna element 111r on the antenna arrangement surface 220. At the same time, the antenna element 111c1, the antenna element 111c2, and the antenna element 111c3 at positions symmetrical with respect to the antenna element 111s selected around the antenna element 111r are also selected.

Here, in the case of the antenna arrangement surface 220, the number of all antenna elements 111 is proportional to the surface area of the sphere (the order of the square of the value obtained by dividing the radius of the sphere by the interval of the antenna elements 111). On the other hand, in the method utilizing the symmetry according to the present embodiment, for example, when selecting from the antenna elements 111 on a certain cross section, the number of antenna elements 111 on the order of the value obtained by dividing the radius of the sphere by the element spacing is searched. Is the target of. As a result, in the method of the present embodiment, the search amount of the antenna element 111 is significantly reduced as compared with the method of searching all the antenna elements 111 without applying the method of the present embodiment, and the processing time and the processing load are significantly reduced. Can be reduced.
(12th Embodiment)
In the twelfth embodiment, as another method of reducing the search amount of the antenna element 111, a method of presetting candidates for the combination of the antenna elements 111 to be selected will be described.

For example, a circular array, a rectangular array, or a square array composed of a combination of antenna elements 111 on the side of M transmitters 201 having an antenna element spacing of X (X is a positive integer) type is set as a selection candidate in advance. Similarly, a circular array, a rectangular array, or a square array consisting of a combination of N antenna elements 111 on the receiver 211 side having a Y (Y is a positive integer) type antenna element spacing is set as a selection candidate in advance. .. Then, the combination of the antenna elements 111 in which the determinant of the propagation path matrix is maximized or the determinant is equal to or more than the threshold value is selected from the preset selection candidates according to the propagation path information or the position information of the transmitter / receiver. Then, the K stream signal is transmitted and received. As a result, the search can be completed with only a predetermined number of types without depending on the number of antenna elements 111, so that the search amount of the antenna elements 111 can be reduced, and the processing time and the processing load can be reduced.
(13th Embodiment)
In the thirteenth embodiment, a method of improving the resolution of the selected antenna element 111 will be described. In each of the above-described embodiments, the case where the antenna arrangement surface 220 is one spherical surface has been described, but in the present embodiment, for example, a plurality of spherical surfaces are used, and in the case of one spherical surface, the antenna element 111 that can be selected is used. It is possible to provide the antenna element 111 that can be selected even in the direction (depth direction) such as the inside or the outside of the sphere that was not present.

For example, when using a plurality of spheres in which a plurality of antenna elements 111 are arranged on a sphere, the plurality of spheres have the same center and different radii, so that another sphere having a small radius inside the reference sphere is used. There is a sphere, or another sphere with a large radius is placed outside the reference sphere. By arranging the antenna elements 111 on each spherical surface, it is possible to select the antenna elements 111 inside or outside the reference spherical surface in addition to the antenna element 111 on the reference spherical surface. As a result, the degree of freedom in the position of the antenna element 111 that can be selected according to the transmission distance and the transmission direction is increased, and the resolution of the antenna element 111 can be improved.

Alternatively, when a plurality of spheres having the same radius in which a plurality of antenna elements 111 are arranged on a sphere are used, the degree of freedom in the position of the selectable antenna element 111 is increased by arranging the plurality of spheres by moving them in parallel. , The resolution of the antenna element 111 can be improved according to the transmission distance and the transmission direction.
(14th Embodiment)
In the fourteenth embodiment, a method of combining a plurality of antenna elements 111 when the antenna elements 111 are not present at the optimum spacing or position of the antenna elements 111 to be selected will be described.

FIG. 26 shows an example of a method for selecting an antenna element according to the 14th embodiment. In FIG. 26, the variable power distribution / synthesizer 301 and the variable power distribution / synthesizer 302 are provided in the antenna array 212 on the receiver 211 side facing the antenna array 202 on the transmitter 201 side. Here, the power variable distributor / combiner 301 and the power variable distributor / combiner 302 combine two input signals into one signal at a predetermined power ratio, or combine one input signal. It operates as a distributor that distributes to two signals at a predetermined power ratio. In the example of FIG. 26, since the power variable distribution / synthesizer 301 and the power variable distribution / synthesizer 302 are arranged on the receiver 211 side, they operate as synthesizers.

In FIG. 26, the antenna array 212 shows the case of K = 2 (N = 4), and the antenna element 111R does not exist on the circumference 151 of a circle having a radius L indicating the optimum position of the antenna element. Therefore, in the present embodiment, first, the antenna element 111R (# 11) and the antenna element 111R (# 14) closest to the circumference 151 are selected, and further, the antenna element 111R (# 11) and the antenna element 111R (# 14) are selected. ), The antenna element 111R (# 12) and the antenna element 111R (# 13) that are adjacent to each other with the circumference 151 interposed therebetween are selected. Then, the outputs of the antenna element 111R (# 11) and the adjacent antenna element 111R (# 12) with the circumference 151 sandwiched between them are combined by the power variable distributor / synthesizer 301. Here, the power variable distributor / synthesizer 301 has a composite ratio of the antenna element 111R (# 11) and the antenna element 111R (# 11) according to the respective distances between the antenna element 111R (# 12) and the circumference 151. The stream 1 signal obtained by combining the output power and the output power of the antenna element 111R (# 12) is output. Similarly, the outputs of the antenna element 111R (# 14) and the adjacent antenna element 111R (# 13) with the circumference 151 sandwiched between them are combined by the power variable distributor / synthesizer 302. Here, the power variable distributor / synthesizer 302 has a composite ratio of the antenna element 111R (# 14) and the antenna element 111R (# 14) according to the respective distances between the antenna element 111R (# 13) and the circumference 151. The stream 2 signal obtained by combining the output power and the output power of the antenna element 111R (# 13) is output.

When applied to the antenna array 202 on the transmitter 201 side, the power variable distributor / synthesizer 301 and the power variable distributor / synthesizer 302 are provided on the transmitter 201 side, contrary to the example of FIG. 26. Here, the case where the antenna element 111R (# 11), the antenna element 111R (# 12), the antenna element 111R (# 13), and the antenna element 111R (# 14) of the receiver 211 of FIG. 26 are used as the transmitting antenna is the transmitting side. Will be described as an example of. In this case, the variable power distributor 301 and the variable power distributor 302 operate as a distributor, and the signal of the stream 1 is input to the variable power distributor 301 and the antenna element 111R (# 11) and It is proportionally distributed according to the distance between the antenna element 111R (# 12) and the circumference 151, and is transmitted from the antenna element 111R (# 11) and the antenna element 111R (# 12). Similarly, the signal of the stream 2 is input to the power variable distributor / synthesizer 302 and is proportionally distributed according to the distance between the antenna element 111R (# 14) and the antenna element 111R (# 13) and the circumference 151, and the antenna is It is transmitted from the element 111R (# 14) and the antenna element 111R (# 13).

In this way, even if the antenna element 111 does not exist at the optimum interval or position of the antenna element 111 to be selected, the power variable distributor / synthesizer is applied to the antenna element closest to the optimum antenna element position and the adjacent antenna element. Optimum the position of the wave source of the signal to be transmitted and received by changing the distribution ratio and composition ratio of the signal power input and output to multiple antenna elements at the same time according to the position deviation from the optimum antenna element position. It can be adjusted to the position of the antenna element, and the characteristics of the communication path capacitance can be improved.
(15th Embodiment)
In the fifteenth embodiment, the case where the shape of the antenna arrangement surface 220 differs between the transmitter 201 side and the receiver 211 side will be described.

In each of the above-described embodiments, the case where the antenna arrangement surface 220 on the transmitter 201 side and the receiver 211 side is spherical is basically described, but the shape of the antenna arrangement surface 220 on the transmitter 201 side and the receiver 211 side is described. May be different. For example, one of the transmitter 201 side and the receiver 211 side may be spherical and the other may be flat. As a result, the antenna array described in each embodiment can be arranged on the transmitter 201 side or the receiver 211 side even if the installation size and depth of the device are restricted, so that the optimum antenna element 111 can be selected and the K stream can be selected. It is possible to send and receive signals.

Here, in each of the above-described embodiments, the M antenna elements 111T of the transmitter 201 and the N antenna elements 111R of the receiver 211 are on a spherical surface, a cylindrical surface, a circumference, and an elliptical rotating body surface. It may be selected from the antenna elements 111 arranged on either the elliptical cylinder surface or the elliptical circumference. In this case, the antenna arrangement surface 220 corresponds not only to a spherical surface but also to a curved surface such as a cylindrical surface, a circumference, an elliptical rotating body surface, an ellipse cylinder surface, or an ellipse circumference depending on the direction in which the positional deviation occurs. ..

As described above in each embodiment, the wireless transmission method and the wireless transmission system according to the present invention are displaced between the antenna array on the transmitter side and the antenna array on the receiver side due to the movement of the transmitter and receiver. LOS-MIMO transmission by reselecting the antenna element on the transmitter side and the antenna element on the receiver side as appropriate antenna elements based on the information on the transmission distance and transmission direction even if It is possible to maintain the multiplexing gain in.

Further, the wireless transmission method and the wireless transmission system according to the present invention perform multi-stream transmission according to the transmission direction while suppressing deterioration of the channel capacity even if a misalignment occurs in an environment such as a line-of-sight environment where there is little variation in the propagation path. It can be performed.

Further, by applying a fixed weighting matrix calculated in advance, it is possible to realize multi-stream transmission in which deterioration of the channel capacity is suppressed without using a high-speed arithmetic processing unit.

100, 100 (1), 100 (2) a, 100 (2) b, 700 ... Wireless transmission system; 111, 111T, 111R ... Antenna element; 201, 201 (1), 201 (2) a , 201 (2) b ... Transmitter; 211,211 (1), 211 (2) a, 211 (2) b ... Receiver; 202,212 ... Antenna array; 203,213 ... -Antenna selection / weighting processing unit; 204, 214 ... estimation unit

Claims (14)

(The K 2 or more integer) K between the receiver and transmitter having on A Ntenaare surface a plurality of antenna elements arranged antenna arrays, respectively a signal stream in a wireless transmission method of LOS-MIMO transmission hand,
Based on the measurement of propagation path information between transmitters and receivers and position information including transmission distance and transmission direction between transmitters and receivers at at least one of the transmitter and the receiver, and based on the propagation path information and the position information. The weighting matrix applied to the signals transmitted and received by the multiple antenna elements selected in the above is calculated.
The transmitter
Measured by the own apparatus, or received from the receiver acquires the channel information and the positional information,
Based on the transmission distance and the transmission direction included in the position information, the antenna elements of the own machine are arranged at equal distances from the position in contact with the plane perpendicular to the transmission direction on the antenna array surface. The position where the path difference between the antenna elements is orthogonal to the wavelength used is calculated, and M antenna elements (M is an integer of K or more) arranged at the position are selected.
The weighting matrix calculated based on the propagation path information calculated by the own machine or received from the receiver is applied to the transmission signal of the K stream and transmitted from the M antenna elements selected.
The receiver
Measured by the own apparatus, or received from the transmit unit acquires the channel information and the positional information,
Based on the transmission distance and the transmission direction included in the position information, the antenna elements of the own machine are arranged at equal distances from the position in contact with the plane perpendicular to the transmission direction on the antenna array surface. The position where the path difference between the antenna elements is orthogonal to the wavelength used is calculated, and N antenna elements (N is an integer of K or more) arranged at the position are selected.
Calculating by the own apparatus, or received from the transmit unit, wherein when applied to signals received by the N antenna elements of the conjugate transposed matrix is selected of the calculated the weighting matrix based on the channel state information K Generate a stream signal ,
The M antenna elements of the transmitter and the N antenna elements of the receiver are on a spherical surface, a cylindrical surface, a circumference, an elliptical rotating body surface, an elliptical cylinder surface, or an elliptical circumference. A wireless transmission method characterized in that each antenna element is selected from the antenna elements arranged in the ellipse . In the wireless transmission method according to claim 1 ,
The antenna element in which the transmission distance between the plurality of antenna elements of the transmitter and the plurality of antenna elements of the receiver is closest between the transmitters and receivers is determined in each of the transmitter and the receiver.
The position of the determined antenna element on the spherical surface is projected on a plane perpendicular to the transmission direction, and the antenna elements are located at equal intervals on a circumference having a predetermined radius centered on the projected position on the plane. A wireless transmission method comprising selecting the M antenna elements on the transmitter side and the N antenna elements on the receiver side. In the wireless transmission method according to claim 1 ,
The antenna element whose transmission distance between the plurality of antenna elements of the transmitter and the plurality of antenna elements of the receiver is closest between the transmitters and receivers is determined as the reference antenna element on the transmitter side and the receiver side, respectively. ,
At least one of the transmitter side and the receiver side connects a first antenna element arranged in a first direction on the antenna array surface with respect to the reference antenna element and the center of the antenna array surface. The angle difference between the first line and the reference line connecting the reference antenna element and the center in the first direction is Δθp (p = 1, ..., P (an integer greater than or equal to P: 1)), and A second line connecting the center and the second antenna element arranged in a second direction different from the first direction on the antenna array surface with respect to the reference antenna element, and the reference antenna element. The closest to the position where the angle difference between the antenna and the reference line connecting the center and the center is Δφq (q = 1, ..., Q (Q: 1 or more)) (P × Q). A wireless transmission method characterized in that individual antenna elements ((P × Q) is an integer greater than or equal to K) are selected. In the wireless transmission method according to claim 2 or 3 .
A plurality of antenna elements are arranged at positions that are normally projected onto a second surface determined in advance from the positions of the plurality of antenna elements on the antenna array surface.
Arranged at positions directly projected onto the second surface from the positions of the M antenna elements on the transmitter side and the N antenna elements on the receiver side to be selected on the antenna array surface. A wireless transmission method comprising selecting the M antenna elements on the transmitter side and the N antenna elements on the receiver side. The wireless transmission method according to any one of claims 1 to 4 .
Each of the weighting matrices used in the transmitter and the receiver is a fixed weighting matrix calculated based on the propagation path information or the position information with respect to a predetermined reference point.
Regardless of the propagation path information or the position information for each of the M antenna elements on the transmitter side and the N antenna elements on the receiver side, the fixed weighting matrix is formed by the plurality of antenna elements. A wireless transmission method characterized by being applied to signals to be transmitted and received. The wireless transmission method according to any one of claims 1 to 5 .
Prior to the start of communication, each weighting matrix corresponding to the plurality of propagation path information or the position information of the transmitter and the receiver is calculated in advance.
The transmitter and the receiver have the M antenna elements on the transmitter side and the N of the transmitters based on the propagation path information or the position information, or the propagation path information or an identifier indicating the position information. A wireless transmission method characterized in that communication is started by selecting the antenna elements on the receiver side and the weighted matrix calculated in advance. The wireless transmission method according to any one of claims 1 to 6 .
Each combination of the M transmitter-side antenna elements and the N receiver-side antenna elements whose determinant of the correlation matrix of the propagation path matrix between transmitters and receivers satisfies at least one of the maximum and the threshold value or more. A wireless transmission method characterized by searching for and selecting. The wireless transmission method according to any one of claims 1 to 6 .
K antenna elements are sequentially arranged one by one with the determinant of the correlation matrix of the propagation path matrix between the transmitters and receivers satisfying at least one of the maximum and the threshold value or more with respect to the antenna element of the predetermined reference. A wireless transmission method characterized in that the transmitter side and the receiver side each search and select to transmit and receive the K stream signal. The wireless transmission method according to any one of claims 1 to 7 .
When a part of the antenna array surface is set as a search range and the M antenna elements on the transmitter side and the N antenna elements on the receiver side are selected, respectively.
The angle of the center of the antenna array surface is from θa to θb in the vertical direction and from φa to φb in the horizontal direction with respect to each of the vertical direction and the horizontal direction having the antenna array surface as coordinates. A wireless transmission method characterized in that an antenna element is searched and selected as a search range. The wireless transmission method according to any one of claims 1 to 9 .
A plurality of types of combinations of the M antenna elements on the transmitter side and a plurality of types of combinations of N antenna elements on the receiver side are set in advance as selection candidates.
The M transmitter-side antenna elements and the N receivers whose determinant of the correlation matrix of the propagation path matrix satisfies at least one of the maximum and the threshold value or more according to the propagation path information or the position information. A wireless transmission method characterized in that each combination of antenna elements on the side is searched for and selected. In the wireless transmission method according to any one of claims 1 to 10 .
A plurality of antenna elements adjacent to the optimum position for transmitting and receiving the signal of the K stream on the antenna array surface are selected on at least one of the transmitter side and the receiver side.
On the transmitter side, the transmission power is distributed to each antenna element according to the distance between the optimum position and each of the selected antenna elements, and the K stream signal is transmitted.
The receiver side is characterized in that the K stream signal is received by synthesizing the power received by each of the selected antenna elements according to the distance between the optimum position and each of the selected antenna elements. Wireless transmission method. In the radio transmission system the signal of the K (K is an integer of 2 or more) streams between the transmitter and the receiver to LOS-MIMO transmission with on A Ntenaare surface a plurality of antenna elements arranged antenna array, respectively,
The transmitter
Channel information between the receiver and its own device, and a transmission-side estimator for identifying including position information transmission distance and transmission directions,
On the basis of the transmission distance and the transmission direction included in the position information specified by said sender estimator, a plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at the same distance from the contacting position is orthogonal to the wavelength used , and M pieces (M is an integer of K or more) arranged at the position. Transmitter antenna selection unit that selects the antenna element of
A weighting matrix obtained from the propagation path information specified by the transmission side estimation unit is generated, and the transmission signal of the K stream is weighted by the generated weighting matrix to transmit from the M antenna elements selected. Sender weighting processing unit and
Have,
The receiver
Channel information between the transmitter and the own apparatus, and a receiving-side estimation unit transmission distance and the transmission direction to identify the including position information,
On the basis of the transmission distance and the transmission direction included in the position information identified by the reception side estimating section, in a plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at the same distance from the contacting position is orthogonal to the wavelength used , and N pieces (N is an integer of K or more) arranged at the position. Receiving side antenna selection part that selects the antenna element of
A weighted matrix obtained from the propagation path information specified by the receiving side estimation unit is generated, and the conjugated transposed matrix of the generated weighting matrix is used for the received signals of the selected N antenna elements. A receiving side weighting processing unit that performs weighting and demodulates the K stream signal, and
Have a,
The M antenna elements of the transmitter and the N antenna elements of the receiver are on a spherical surface, a cylindrical surface, a circumference, an elliptical rotating body surface, an elliptical cylinder surface, or an elliptical circumference. Each is selected from the antenna elements arranged in the ellipse.
A wireless transmission system characterized by that. In the radio transmission system the signal of the K (K is an integer of 2 or more) streams between the transmitter and the receiver to LOS-MIMO transmission with on A Ntenaare surface a plurality of antenna elements arranged antenna array, respectively,
The transmitter
Channel information between the receiver and the own apparatus, and an estimation unit for the transmission distance and the transmission direction to identify the including position information,
On the basis of the transmission distance and the transmission direction included in the position information specified by said estimation unit, a position in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at equal distances from the antenna is orthogonal to the wavelength used , and M antennas (M is an integer of K or more) arranged at the position. The transmitting antenna selection unit that selects the element, and
Together with the estimator by generating a weighting matrix obtained by the channel information is identified, and the generated information of the weighting matrix and the prior SL location information transmitted to the receiver, the K by generated the weighting matrix A transmission side weighting processing unit that weights the transmission signal of the stream and transmits from the M antenna elements selected by weighting the stream.
Have,
The receiver
On the basis of the transmission distance and the transmission direction included before Symbol location information you received from said transmitter in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at the same distance from the position is orthogonal to the used wavelength, and N (N is an integer of K or more) arranged at the position . The receiving side antenna selection part that selects the antenna element, and
For the selected received signal of said N antenna elements, wherein said weighting matrix recipient weighting processing for demodulating the signal of the K streams perform weighting with using a conjugate transposed matrix of receiving from a transmitter Department and
Have a,
The M antenna elements of the transmitter and the N antenna elements of the receiver are on a spherical surface, a cylindrical surface, a circumference, an elliptical rotating body surface, an elliptical cylinder surface, or an elliptical circumference. Each is selected from the antenna elements arranged in the ellipse.
A wireless transmission system characterized by that. In the radio transmission system the signal of the K (K is an integer of 2 or more) streams between the transmitter and the receiver to LOS-MIMO transmission with on A Ntenaare surface a plurality of antenna elements arranged antenna array, respectively,
The receiver
Channel information between the transmitter and the own apparatus, and an estimation unit for the transmission distance and the transmission direction to identify the including position information,
On the basis of the transmission distance and the transmission direction included in the position information specified by said estimation unit, a position in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at the same distance from the antenna is orthogonal to the wavelength used , and N antennas (N is an integer of K or more) arranged at the position. The receiving side antenna selection part that selects the element, and
Wherein generating the resulting weighting matrix by the channel information identified by the estimation unit, and a generated information of the weighting matrix and the prior SL positional information and transmits to the transmitter, the N antenna selected the received signal of the element, and the receiving-side weighting processing unit which performs weighting with demodulates the signal of the K streams using a conjugate transposed matrix of said weighting matrix,
Have,
The transmitter
On the basis of the transmission distance and the transmission direction included before Symbol location that will receive from the receiver in contact with the plane perpendicular to the transmission direction on the antenna array surface of the plurality of antenna elements of its own Calculate the position where the path difference between the antenna elements arranged at equal distances from the position is orthogonal to the wavelength used , and M (M is an integer of K or more) arranged at the position . The transmitting side antenna selection unit that selects the antenna element, and
A transmission side weighting processing unit that weights the transmission signal of the K stream according to the weighting matrix received from the receiver and transmits from the M antenna elements selected.
Have a,
The M antenna elements of the transmitter and the N antenna elements of the receiver are on a spherical surface, a cylindrical surface, a circumference, an elliptical rotating body surface, an elliptical cylinder surface, or an elliptical circumference. Each is selected from the antenna elements arranged in the ellipse.
A wireless transmission system characterized by that.