Wireless communication system, transmitting device, and receiving device

Abstract

Provided is a radio communication system including a transmission device and a reception device. This transmission device includes multiple UCAs including a first UCA and a second UCA, this reception device includes a third UCA, the transmission axis of the first UCA and the transmission axis of the second UCA are oriented in different directions, and the first UCA faces the third UCA.

Description

[Technical field]

[0001] The present invention relates to a technique for spatially multiplexing and transmitting wireless signals using the orbital angular momentum (OAM) of electromagnetic waves. [Background technology]

[0002] In recent years, in order to improve transmission capacity, spatial multiplexing transmission technology of radio signals using OAM has been studied (for example, Non-Patent Document 1). In electromagnetic waves with OAM, equiphase surfaces are distributed in a spiral shape along the propagation direction centered on the propagation axis. Since electromagnetic waves with different OAM modes propagating in the same direction have orthogonal spatial phase distributions in the direction of the rotation axis, it is possible to multiplex and transmit signals by separating the signals of each OAM mode modulated with different signal sequences at the receiving device.

[0003] In a wireless communication system using this OAM multiplexing technology, a uniform circular array antenna (hereinafter referred to as UCA (Uniform Circular Array)) in which multiple antenna elements are arranged at equal intervals in a circle is used to generate, combine and transmit multiple OAM modes, thereby realizing spatial multiplexing transmission of different signal sequences (for example, Non-Patent Document 2). For example, a Butler circuit (Butler matrix circuit) is used to generate and separate signals for the multiple OAM modes. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] J. Wang et al., "Terabit free-space data transmission employing orbital angular momentum multiplexing," Nature Photonics, Vol.6, pp.488-496, July 2012. [Non-Patent Document 2] Y. Yan et al., "High-capacity millimeter-wave communications with orbital angular momentum multiplexing," Nature Commun., vol.5, p.4876, Sep. 2014. Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, a transmitter and receiver using UCA enables large-capacity communications, but in the future, it is hoped that it will be compatible with cellular systems, particularly for access lines.

[0006] However, in conventional wireless transmission technology using UCA, in order to separate signals of multiple OAM modes without interference between the modes, the transmitting antenna and the receiving antenna must be installed in positions facing each other, and axis alignment is required. This makes it difficult to support multi-directional operation. In addition, accurate axis alignment is difficult, and axis misalignment between the transmitting antenna and the receiving antenna can cause inter-mode interference, which can lead to a decrease in transmission capacity.

[0007] The present invention has been made in view of the above-mentioned points, and has an object to provide a technique that enables multi-directional support and reduction of inter-mode interference in a wireless transmission technique using UCA. [Means for solving the problem]

[0008] According to the disclosed technology, there is provided a wireless communication system including a transmitting device and a receiving device, the sending device comprises a plurality of UCAs including a first UCA and a second UCA, the receiving device comprises a third UCA, a transmission axis of the first UCA and a transmission axis of the second UCA are oriented in different directions, the first UCA faces the third UCA, The transmitting device transmits a signal to a terminal located in any direction using the second UCA. A wireless communication system is provided. Effect of the Invention

[0009] According to the disclosed technology, a technology is provided that enables multi-directional support and reduction of inter-mode interference in a wireless transmission technology using UCA. [Brief description of the drawings]

[0010] [Figure 1] FIG. 13 is a diagram illustrating an example of phase setting of a UCA for generating an OAM mode signal. [Diagram 2] 1A to 1C are diagrams illustrating examples of phase distribution and signal intensity distribution of an OAM multiplexed signal. [Diagram 3] 1 is a schematic configuration diagram of a communication system according to an embodiment of the present invention. [Figure 4] FIG. 13 is a diagram for explaining an outline of the operation. [Diagram 5] FIG. 13 is a diagram for explaining an outline of the operation. [Figure 6] FIG. 11 is a sequence diagram showing a processing flow. [Figure 7] FIG. 11 is a sequence diagram showing a processing flow. [Figure 8] FIG. 11 is a sequence diagram showing a processing flow. [Figure 9] FIG. 11 is a diagram for explaining an operation example. [Figure 10] FIG. 11 is a diagram for explaining an operation example. [Figure 11] FIG. 2 is a diagram illustrating a configuration example of a transmitting device according to an embodiment of the present invention. [Figure 12] FIG. 2 is a diagram illustrating a configuration example of a receiving device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0012] (Basic operation example) First, a basic setting and operation example relating to UCA used in the transmitting device and the receiving device in this embodiment will be described.

[0013] Figure 1 shows an example of phase setting of a UCA for generating an OAM mode signal. The UCA shown in Figure 1 is a UCA consisting of eight antenna elements.

[0014] In Fig. 1, signals of OAM modes 0, 1, 2, 3, ... on the transmitting side are generated by the phase difference of the signals supplied to each antenna element (indicated by ●) of the UCA. In other words, a signal of OAM mode n is generated by setting the phase of the signal supplied to each antenna element so that the phase rotates n times (n x 360 degrees). For example, when the UCA is composed of m = 8 antenna elements as shown in Fig. 1 and a signal of OAM mode n = 2 is generated, a phase difference of 360n / m = 90 degrees (0 degrees, 90 degrees, 180 degrees, 270 degrees, 0 degrees, 90 degrees, 180 degrees, 270 degrees) is set counterclockwise for each antenna element so that the phase rotates two times as shown in Fig. 1 (3).

[0015] Note that a signal with the phase rotation direction reversed to that of an OAM mode n signal is called OAM mode -n. For example, the phase rotation direction of a positive OAM mode signal is counterclockwise, and the phase rotation direction of a negative OAM mode signal is clockwise.

[0016] By generating different signal sequences as signals in different OAM modes and transmitting the generated signals simultaneously, wireless communication using spatial multiplexing can be performed. On the transmitting side, signals to be transmitted in each OAM mode may be generated and combined in advance and a combined signal for each OAM mode may be transmitted using a single UCA, or multiple UCAs may be used to transmit signals for each OAM mode using different UCAs for each OAM mode. It is also possible to perform OAM-MIMO multiplexing transmission using multiple UCAs.

[0017] To separate the OAM multiplexed signals on the receiving side, the phase of each antenna element of the UCA on the receiving side is set to be opposite to the phase of the antenna element on the transmitting side. In addition, to separate the signals of OAM-MIMO multiplexed transmission, MIMO technology such as MIMO equalization is used.

[0018] Figure 2 shows examples of phase distribution and signal intensity distribution of OAM multiplexed signals. In Figures 2(1) and (2), the arrows represent the phase distribution of OAM mode 1 and OAM mode 2 signals as viewed from the end face (orthogonal propagation plane) perpendicular to the propagation direction from the transmitting side. The arrows start at 0 degrees, the phase changes linearly, and end at 360 degrees. In other words, an OAM mode n signal propagates while its phase rotates n times (n x 360 degrees) on the orthogonal propagation plane. Note that the arrows of the phase distribution of OAM mode -1 and -2 signals point in opposite directions.

[0019] The signal intensity distribution and the position where the signal intensity is maximum differ for each OAM mode. However, the intensity distribution is the same for the same OAM mode with different signs. Specifically, the higher the order of the OAM mode, the farther the position where the signal intensity is maximum is from the propagation axis (Non-Patent Document 2). Here, the OAM mode with a larger value is called a higher order mode. For example, a signal of OAM mode 3 is a higher order mode than signals of OAM mode 0, OAM mode 1, and OAM mode 2.

[0020] Figure 2 (3) shows the position where the signal strength is maximum for each OAM mode as a circle. The higher the OAM mode, the farther the position where the signal strength is maximum is from the central axis. Also, the beam diameter of the OAM mode multiplexed signal expands depending on the propagation distance, so the circle showing the position where the signal strength is maximum for each OAM mode becomes larger.

[0021] (Summary of the embodiment of the present invention) As mentioned above, a transmitter and receiver using UCA enables large-capacity communication, but it is difficult to support multi-directional communication because the transmitter antenna and the receiver antenna must be installed facing each other directly in front of each other. Even if they are installed facing each other, inter-mode interference is likely to occur due to the axial misalignment between the transmitter and receiver antennas.

[0022] In this embodiment, a technique is described that enables multi-directional support, reduces inter-mode interference, and enables large-capacity transmission between devices. The system configuration and an example of the operation in this embodiment are described in detail below.

[0023] (System Configuration) A schematic configuration example of a wireless communication system according to the present embodiment is shown in Fig. 3. As shown in Fig. 3, the wireless communication system according to the present embodiment includes a transmitting device 100 and a receiving device 200. Also, a UE 300, which is a terminal, exists at an arbitrary location. Note that the UE 300 does not necessarily have to exist.

[0024] The transmitting device 100 and the receiving device 200 each include a UCA. In transmitting and receiving desired data, the transmitting device 100 multiplexes and transmits signals of one or more OAM modes, and the receiving device 200 receives the signal transmitted from the transmitting device 100 in which one or more OAM modes are multiplexed, and separates the signals of each OAM mode. In addition, both the transmitting device 100 and the receiving device 200 can also perform MIMO multiplexing transmission. Note that OAM multiplexing transmission and MIMO multiplexing transmission may also be called OAM transmission and MIMO transmission.

[0025] UE300 may support MIMO multiplexing transmission and not support OAM multiplexing transmission, or may support OAM multiplexing transmission and not support MIMO multiplexing transmission, or UE300 may support both MIMO multiplexing transmission and OAM multiplexing transmission.

[0026] In this embodiment, it is assumed that both the transmitting device 100 and the receiving device 200 are stationary devices (for example, base stations), however, this is merely an example.

[0027] (Operation overview) An overview of the operation of the wireless communication system in this embodiment will be described with reference to Fig. 4. The transmitting device 100 has two UCAs (called transmitting UCA1 and transmitting UCA2), and the receiving device 200 has one UCA (called receiving UCA). The transmitting device 100 may have three or more UCAs, one of which faces the receiving UCA. The receiving device 200 may also have two or more UCAs.

[0028] In the transmitting device 100, the transmission axis of the transmitting UCA1 and the transmission axis of the transmitting UCA2 are oriented in different directions. The transmitting UCA1 and the receiving UCA are arranged to face each other. Although the transmitting UCA1 and the receiving UCA face each other, precise axis alignment is not required.

[0029] 4, the transmitting device 100 transmits a signal to the receiving UCA by OAM transmission using the transmitting UCA1, and performs MIMO transmission using precoding using the transmitting UCA2. Note that it is also possible to perform OAM transmission using the transmitting UCA2.

[0030] As for the transmission UCA2, the transmission device 100 adaptively switches between the following two uses (1) and (2).

[0031] (1) The transmitting UCA 2 is used to communicate with the UE 300 located at a position different from the receiving UCA by MIMO transmission (or OAM transmission).

[0032] (2) A signal arriving at the receiving UCA from the transmitting UCA 2 as a reflected wave or the like is used to reduce inter-mode interference caused by axial misalignment between the transmitting UCA 1 and the receiving UCA.

[0033] Note that (1) and (2) may be performed simultaneously. In addition, in Fig. 4, an image is depicted in which the radio wave from the transmitting UCA 2 is reflected by the ground and the reflected wave reaches the receiving UCA, but using the reflected wave from the ground is just one example. The reflected wave may be a wave reflected from a building or the like.

[0034] Also, in FIG. 4 (and the examples described hereinafter with reference to FIG. 6 and later), the case where the transmission UCA1 of the transmission device 100 and the reception UCA are each one UCA is shown, but this is just an example. As shown in FIG. 5, the transmission device 100 and the reception device 200 may each perform OAM-MIMO multiplex transmission using two or more pairs of opposing UCAs. In the example of FIG. 5, the transmission device 100 includes three UCAs: transmission UCA1, transmission UCA2, and transmission UCA3. The reception device 200 includes two UCAs: reception UCA1 and reception UCA2. Even when the transmission device 100 and the reception device 200 each perform OAM-MIMO multiplex transmission using two or more pairs of opposing UCAs, the basic operations are the same as those in the above (1), (2), and the operations described hereinafter.

[0035] (Detailed operation example) With reference to FIGS. 6 to 8, a more detailed operation example based on the configuration of FIG. 4 will be described. Hereinafter, the cases where the UE300 exists and where the UE300 does not exist will be described respectively.

[0036] <When the UE300 exists> An operation example when the UE300 exists will be described according to the sequence shown in FIG. 6. Note that "the UE300 exists" means, for example, that the UE300 exists at a position where it can receive and appropriately demodulate the signal transmitted from the transmission UCA2.

[0037] In S101 (step 101), the UE300 makes a connection request to the transmission device 100. By this connection request, the UE300 notifies the transmission device 100 which of the OAM multiplex transmission or MIMO multiplex transmission methods to use in receiving the signal from the transmission device 100.

[0038] In S102, the transmitting device 100 transmits a signal by OAM multiplexing transmission to the receiving UCA of the receiving device 200 using the transmitting UCA1, and simultaneously transmits a signal to the UE 300 by OAM multiplexing transmission or MIMO multiplexing transmission in response to a request from the UE 300 using the transmitting UCA2. In this example, it is assumed that the signal transmitted from the transmitting UCA2 reaches the UE 300 and also reaches the receiving device 200 due to reflection from the ground or the like.

[0039] The transmitting device 100 adds a preamble to the signal transmitted from the transmitting UCAs 1 and 2 and transmits the signal. The preamble is a signal of a fixed pattern added to the beginning of a transmission signal (transmission packet), and the receiving side can perform channel estimation and the like using the preamble. The preamble may be called a known signal. In this embodiment, a plurality of orthogonal preambles (orthogonal sequences) are used. The orthogonal preambles are transmitted, for example, for each UCA and for each mode.

[0040] In S103, UE 300 receives and demodulates a signal from transmitting device 100. In S104, receiving device 200 performs channel estimation using the orthogonal preambles added to the transmission signal from transmitting UCA1 and the transmission signal from transmitting UCA2.

[0041] In S105, the receiving device 200 uses the channel estimated in S104 to remove (reduce) interference from the transmitting UCA 2 and demodulate the signal from the transmitting UCA 1. The interference removal can be performed using digital signal processing such as MIMO equalization processing, channel equalization processing, and successive interference removal processing.

[0042] The sequence shown in Fig. 6 is an example, and other sequences can be implemented. For example, the operation of the sequence shown in Fig. 7 may be performed.

[0043] S111 and S112 in Fig. 7 are the same as S101 and S102 in Fig. 6. In S113 in Fig. 7, UE300 performs channel estimation using a preamble received from the transmitting UCA2, and in S115, feeds back the channel estimation result to the transmitting device 100. The transmitting device 100 precodes a signal for UE300 using the received feedback and transmits it from UCA2. In S118, US300 demodulates the signal.

[0044] Alternatively, UE 300 may add a preamble to an uplink signal and transmit it, and transmitting device 100 that receives the uplink signal may perform channel estimation based on the preamble, and the channel estimation result may be used for precoding.

[0045] On the other hand, in S114, the receiving device 200 performs channel estimation using the preambles added to the transmission signal from the transmitting UCA1 and the transmission signal from the transmitting UCA2, and feeds back the channel estimation result to the transmitting device 100. The transmitting device 100 uses the feedback for precoding the signal of UCA1.

[0046] In S117, the receiving device 200 performs interference cancellation, and in S119, demodulates the signal from the transmitting UCA1.

[0047] Through the above operations, the channels between the receiving device 200 and the transmitting device 100 and between the receiving device 200 and the UE 300 and the transmitting device 100 can be acquired, and precoding can be performed that can simultaneously reduce interference to the receiving UCA and achieve connection to the UE 300.

[0048] The sequences in Figures 6 to 7 are based on the configuration in Figure 4, but similar sequences can be used to perform processing even when the configuration shown in Figure 5 is used. Below, we will explain the sequences in Figures 6 to 7 when the configuration shown in Figure 5 is used. Below, we will mainly explain the parts that differ from what has already been explained.

[0049] 6, in S101, the UE 300 makes a connection request to the transmitting device 100. In S102, the transmitting device 100 transmits signals by OAM-MIMO multiplexing transmission toward the receiving UCA1 and receiving UCA2 of the receiving device 200 using the transmitting UCA1 and transmitting UCA2, and simultaneously transmits a signal to the UE 300 by OAM multiplexing transmission or MIMO multiplexing transmission in response to a request from the UE 300 using the transmitting UCA3.

[0050] In S103, UE 300 receives and demodulates a signal from transmitting device 100. In S104, receiving device 200 performs channel estimation using orthogonal preambles added to the transmission signals from transmitting UCA1 and transmitting UCA2, and the transmission signal from transmitting UCA3.

[0051] In S105, the receiving device 200 removes (reduces) interference from the transmitting UCA3 using the channel estimated in S104, and demodulates the signals from the transmitting UCA1 and transmitting UCA2.

[0052] The sequence shown in Fig. 6 is an example, and other sequences can be implemented. For example, the operation of the sequence shown in Fig. 7 may be performed.

[0053] S111 and S112 in Fig. 7 are the same as S101 and S102 in Fig. 6. In S113 in Fig. 7, UE300 performs channel estimation using a preamble received from the transmitting UCA3, and in S115, feeds back the channel estimation result to the transmitting device 100. The transmitting device 100 precodes a signal for UE300 using the received feedback and transmits it from UCA3. In S118, US300 demodulates the signal.

[0054] On one hand, in S114, the receiving device 200 performs channel estimation using the preambles added to the transmission signals from the transmitting UCA1 and transmitting UCA2, and the transmission signal from the transmitting UCA3, and feeds back the channel estimation result to the transmitting device 100. The transmitting device 100 uses the feedback for the precoding of the signals of UCA1 and UCA2.

[0055] In S117, the receiving device 200 performs interference cancellation, and in S119, demodulates the signals from the transmitting UCA1 and transmitting UCA2.

[0056] <When UE300 does not exist> An operation example when UE300 does not exist will be described along the sequence shown in FIG. 8. In S201, the transmitting device 100 transmits a signal to the receiving device 200 by OAM-MIMO multiplex transmission using the transmitting UCA1 and the transmitting UCA2. Here too, the transmitting device 100 adds an orthogonal preamble to each signal transmitted from the transmitting UCA1, 2 and then transmits. The transmission signal from the transmitting UCA2 is reflected by the ground or the like and reaches the receiving UCA.

[0057] In S202, the receiving device 200 performs channel estimation using the orthogonal preambles added to the transmission signals from the transmitting UCA1, 2, and at the same time calculates the inter-mode interference. In S203, the receiving device 200 feeds back the inter-mode interference information to the transmitting device 100.

[0058] As an example, when the transmitting UCA1 performs OAM multiplex transmission by multiplexing the OAM mode 1 and the OAM mode 2, inter-mode interference occurs due to the axial misalignment between the transmitting UCA1 and the receiving UCA. Due to the inter-mode interference, for example, a part of the power of the signal transmitted in the OAM mode 1 from the transmitting device 100 is obtained as the power of the signal in the OAM mode 2 at the receiving device 200.

[0059] The inter-mode interference information may be any information that can be used to perform interference compensation (interference reduction). For example, information on the phase shift from the correct phase (as shown in FIG. 1) as an OAM mode signal may be calculated, and the information may be fed back to the transmitting device 100 as inter-mode interference information.

[0060] In S204, the transmitting apparatus 100 generates a compensation signal based on the inter-mode interference information fed back from the receiving apparatus 200, and transmits the compensation signal from the transmitting UCA 2 by MIMO multiplexing.

[0061] In S205, the receiving device 200 demodulates the compensation signal by MIMO equalization using the channel estimated in S202, and in S206, the receiving device 200 demodulates the signal transmitted from the transmitting UCA1 by OAM multiplexing transmission by performing cross-mode interference compensation processing between the transmitting UCA1 and the receiving UCA using the compensation signal.

[0062] Note that the above-described method of reducing inter-mode interference using "feedback+compensation signal" is just one example. The receiving device 200 may autonomously perform signal processing for reducing inter-mode interference using a signal from the transmitting UCA2 (i.e., using a signal from a direction different from that of the transmitting UCA1).

[0063] The sequence in Fig. 8 is based on the configuration in Fig. 4, but processing can be performed in a similar sequence even when the configuration shown in Fig. 5 is used as a premise. Below, the sequence in Fig. 8 when the configuration shown in Fig. 5 is used as a premise will be described. Below, the parts that differ from the contents already explained will be mainly described.

[0064] In S201, the transmitting device 100 transmits a signal to the receiving device 200 by OAM-MIMO multiplexing transmission using the transmitting UCA1, the transmitting UCA2, and the transmitting UCA3.

[0065] In S202, the receiving apparatus 200 performs channel estimation using the orthogonal preambles added to the transmission signals from the transmitting UCAs 1, 2, and 3, and simultaneously calculates the inter-modal interference. In S203, the receiving apparatus 200 feeds back the inter-modal interference information to the transmitting apparatus 100.

[0066] As an example, when OAM-MIMO multiplexed transmission is performed by transmitting UCA1 and transmitting UCA2 by multiplexing and transmitting OAM mode 1 and OAM mode 2, inter-mode interference occurs due to an axis shift between transmitting UCA1 and transmitting UCA2 and receiving UCA1 and receiving UCA2. Inter-mode interference information for compensating for such inter-mode interference is fed back.

[0067] In S204, the transmitting apparatus 100 generates a compensation signal based on the inter-mode interference information fed back from the receiving apparatus 200, and transmits the compensation signal from the transmitting UCA 3 by MIMO multiplexing.

[0068] In S205, the receiving device 200 demodulates the compensation signal by MIMO equalization using the channel estimated in S202, and in S206, uses the compensation signal to perform cross-mode interference compensation processing between the transmitting UCA1 and transmitting UCA2 and the receiving UCA1 and receiving UCA2, thereby demodulating the signals transmitted from the transmitting UCA1 and transmitting UCA2 by OAM-MIMO multiplexing transmission.

[0069] Note that the above-described method of reducing inter-mode interference using "feedback+compensation signal" is just an example. The receiving device 200 may autonomously perform signal processing for reducing inter-mode interference by using a signal from the transmitting UCA3 (i.e., by using a signal from a direction different from that of the transmitting UCA1 and transmitting UCA2).

[0070] <Summary of operation example> As shown in Fig. 9, when UE 300 is present, communication with UE 300 is possible by transmitting UCA 2, so communication with UE 300 in any direction is possible. Therefore, multi-directional support can be realized. When the receiving UCA receives a reflected wave of the radio wave from transmitting UCA 2, it can be removed by interference removal processing in receiving device 200.

[0071] As shown in FIG. 10, when the UE 300 is not present, the signal transmitted from the transmitting UCA 2 can be used to reduce inter-mode interference caused by the axis misalignment between the transmitting UCA 1 and the receiving UCA 1 .

[0072] Note that the process of reducing inter-mode interference shown in Fig. 10 can also be applied to a case where the UE 300 shown in Fig. 9 is present. That is, the process shown in Fig. 9 and the process shown in Fig. 10 may be combined.

[0073] (Example of device configuration) Next, an example of the device configuration of the transmitting device 100 and the receiving device 200 will be described.

[0074] <Transmitting device 100> First, the transmitting device 100 will be described. Fig. 11 is a diagram showing a configuration example of the transmitting device 100 in this embodiment. As shown in Fig. 11, the transmitting device 100 has UCA 110_1, UCA 110_2, an OAM mode generating unit 120, a signal processing unit 130, and a control unit 140. UCA 110_1 and UCA 110_2 correspond to the above-mentioned transmitting UCA 1 and transmitting UCA 2.

[0075] The signal processing unit 130 generates a digital signal to be transmitted on a carrier wave from the input data, converts the digital signal to an analog signal (digital-analog conversion), and converts the frequency of the analog signal to the frequency band of the carrier wave (e.g., 28 GHz band). The signal processing unit 130 inputs the generated analog signal to the OAM mode generation unit 120.

[0076] The OAM mode generation unit 120 generates a signal of each OAM mode and supplies the generated signal to the UCA 110_1 and the UCA 110_2. Note that the OAM mode signal here may be a signal of OAM mode 0 (a general antenna transmission signal).

[0077] The OAM mode generator 120 is, for example, a Butler circuit. However, generating an OAM signal by analog processing such as a Butler circuit is just one example. The OAM mode signal may be generated by digital signal processing.

[0078] The control unit 140 receives a connection request from the UE 300, and instructs the signal processing unit 130 and the OAM mode generating unit 120 to generate a signal (OAM or MIMO) in response to the connection request. The signal processing unit 130 and the OAM mode generating unit 120 perform signal generation in accordance with the instruction.

[0079] Furthermore, the control unit 140 receives feedback (inter-mode interference information) from the receiving device 200, and instructs the signal processing unit 130 and the OAM mode generating unit 120 to generate a compensation signal based on the feedback. The signal processing unit 130 and the OAM mode generating unit 120 generate a signal according to the instruction.

[0080] <Receiving device 200> Next, a description will be given of the receiving device 200. Fig. 12 is a diagram showing an example of a configuration of the receiving device 200 in this embodiment. As shown in Fig. 12, the receiving device 200 has a UCA 210, an OAM mode separation unit 220, a signal processing unit 230, and a control unit 240.

[0081] The UCA 210 corresponds to the above-mentioned receiving UCA. The OAM mode separation unit 220 has a Butler circuit. Note that using the Butler circuit for OAM mode separation is one example. OAM mode separation may be performed by digital signal processing.

[0082] The signal processing unit 230 converts the analog signal received from the OAM mode separation unit 220 (assuming a Butler circuit) into a digital signal (analog-to-digital conversion), performs demodulation, and generates and outputs data (bit string).

[0083] Moreover, the signal processing unit 230 performs channel estimation, MIMO equalization processing, channel equalization processing, successive interference cancellation processing, calculation of inter-mode interference information, etc. Moreover, the signal processing unit 230 can perform both inter-mode interference reduction processing using a compensation signal and inter-mode interference reduction processing without using a compensation signal.

[0084] The control unit 240 has a function of issuing operational instructions to the OAM mode separation unit 220 and the signal processing unit 230, as well as a function of transmitting inter-mode interference information calculated by the signal processing unit 230 to the transmitting apparatus 100 as feedback.

[0085] (Effects of the embodiment) The technology according to the present embodiment described above enables multi-directional support and inter-mode interference reduction between opposing UCAs in a wireless transmission technology using UCAs. In addition, it is possible to adaptively switch between multi-directional support and inter-mode interference reduction between opposing UCAs. It is also possible to simultaneously perform multi-directional support and inter-mode interference reduction between opposing UCAs.

[0086] (Summary of the embodiment) This specification describes at least the wireless communication system, the transmitting device, and the receiving device described in the following sections. (Section 1) A wireless communication system including a transmitting device and a receiving device, the sending device comprises a plurality of UCAs including a first UCA and a second UCA, the receiving device comprises a third UCA, The transmission axis of the first UCA and the transmission axis of the second UCA are oriented in different directions, and the first UCA faces the third UCA. Wireless communication system. (Section 2) The transmitting device transmits a signal to a terminal located in any direction using the second UCA. 2. A wireless communication system as recited in claim 1. (Section 3) The receiving device utilizes the signal transmitted from the second UCA to reduce inter-mode interference between the first UCA and the third UCA. 3. A wireless communication system according to claim 1 or 2. (Section 4) A transmitting device used in a wireless communication system including a transmitting device and a receiving device, a plurality of UCAs including a first UCA and a second UCA; The transmission axis of the first UCA and the transmission axis of the second UCA are oriented in different directions, and the first UCA faces a third UCA provided in the receiving device. Transmitting device. (Section 5) receiving information on inter-mode interference between the first UCA and the third UCA as feedback from the receiving device, and transmitting a compensation signal for compensating for the inter-mode interference to the receiving device based on the feedback; A transmitting device as described in item 4. (Section 6) A receiving device for use in a wireless communication system, the receiving device including a transmitting device having a plurality of UCAs including a first UCA and a second UCA, The transmission axis of the first UCA and the transmission axis of the second UCA are oriented in different directions, and a third UCA is provided opposite the first UCA. Receiving device. (Section 7) A signal transmitted from the second UCA is utilized to reduce inter-mode interference between the first UCA and the third UCA. 7. A receiving device as described in item 6.

[0087] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0088] 100 Transmitting device 110 UCA 120 OAM mode generation unit 130 Signal Processing Section 140 Control section 200 Receiving device 210 UCA 220 OAM mode separation section 230 Signal Processing Unit 240 Control Unit 300UE

Claims

1. A wireless communication system including a transmitting device and a receiving device, the transmitting device includes a plurality of UCAs including a first UCA and a second UCA, the receiving device includes a third UCA, a transmission axis of the first UCA and a transmission axis of the second UCA are oriented in different directions, and the first UCA faces the third UCA; The transmitting device transmits a signal to a terminal located in any direction using the second UCA. Wireless communication system.

2. A wireless communication system including a transmitting device and a receiving device, the transmitting device includes a plurality of UCAs including a first UCA and a second UCA, the receiving device includes a third UCA, a transmission axis of the first UCA and a transmission axis of the second UCA are oriented in different directions, and the first UCA faces the third UCA; The receiving device utilizes the signal transmitted from the second UCA to reduce inter-mode interference between the first UCA and the third UCA. Wireless communication system.

3. A transmitting device used in a wireless communication system including a transmitting device and a receiving device, a plurality of UCAs including a first UCA and a second UCA; a transmission axis of the first UCA and a transmission axis of the second UCA are oriented in different directions, and the first UCA faces a third UCA provided in the receiving device; receiving information on inter-mode interference between the first UCA and the third UCA as feedback from the receiving device, and transmitting a compensation signal for compensating for the inter-mode interference to the receiving device based on the feedback; Transmitting device.

4. A receiving device for use in a wireless communication system, the receiving device including a transmitting device having a plurality of UCAs including a first UCA and a second UCA, The transmission axis of the first UCA and the transmission axis of the second UCA are oriented in different directions, and a third UCA is provided opposite the first UCA. A signal transmitted from the second UCA is utilized to reduce inter-mode interference between the first UCA and the third UCA. Receiving device.

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