Wireless reception device and wireless reception method

Abstract

A wireless reception device according to the present invention comprises a wireless signal reception unit that receives a plurality of wireless signals from a plurality of wireless communication terminals, a plurality of frequency conversion units that perform frequency conversion on the plurality of wireless signals received by the wireless signal reception unit, a plurality of signal processing units that perform signal processing on the plurality of wireless signals on which the plurality of frequency conversion units have performed the frequency conversion, an angle-of-arrival identification unit that identifies the angles of arrival of the plurality of wireless signals received from the plurality of wireless communication terminals, and a control unit that, when the angles of arrival of the plurality of wireless signals identified by the angle-of-arrival identification unit are different, outputs the plurality of wireless signals received from the plurality of wireless communication terminals by the wireless signal reception unit to different frequency conversion units and signal processing units from among the plurality of frequency conversion units and the plurality of signal processing units.

Description

Wireless receiving apparatus and wireless receiving method

[0001] The present invention relates to a wireless receiving apparatus and a wireless receiving method.

[0002] Conventionally, wireless communication using a millimeter-wave band that uses electromagnetic waves with a frequency of approximately 30 to 300 GHz, a terahertz band that uses electromagnetic waves with a frequency of approximately 100 GHz to 10,000 GHz, and a sub-terahertz band that uses electromagnetic waves with a frequency of approximately 100 GHz to 1 THz is known. In conventional wireless communication, a plurality of wireless communication terminals may transmit wireless signals to a base station apparatus using the same wireless resource (that is, the same time and the same frequency).

[0003] Conventionally, SIM (Stacked Intelligent Metasurface) is known as an element for receiving wireless signals (Non-Patent Document 1). SIM is configured by stacking a plurality of RISs (Reconfigurable Intelligent Surfaces) capable of controlling electromagnetic waves with high precision. RIS has a planar configuration in which a plurality of elements (meta-atoms) are arranged in a grid pattern. Each RIS can adjust the phase of electromagnetic waves, and by adjusting the phase in each RIS, the reflection angle of electromagnetic waves and the like can be adjusted.

[0004] Jiancheng An, et al., "Stacked Intelligent Metasurface Performs a 2D DFT in the Wave Domain for DOA Estimation" ICC 2024-IEEE International Conference on Communications, Denver, CO, USA, 2024, pp. 3445-3451, DOI: 10.1109 / ICC51166.2024.10622963

[0005] However, in wireless communication using wide bandwidth millimeter-wave, terahertz, and subterahertz bands, interference could occur between multiple signals when multiple wireless communication terminals transmitted radio signals to base station equipment using the same radio resources (i.e., the same time and frequency). Furthermore, in conventional wireless communication, the processing load for separating multiple radio signals using the same radio resources became significant, making real-time processing of radio signals difficult. Additionally, the power consumption required for signal processing of multiple radio signals using the same radio resources increased.

[0006] Therefore, in conventional wireless communication, when multiple wireless communication terminals use the same wireless resources, it was necessary to perform complex frequency conversion and signal processing on the wireless signals transmitted from multiple wireless communication terminals.

[0007] The present invention aims to provide a technology that eliminates the need for complex frequency conversion or signal processing for wireless signals transmitted from multiple wireless communication terminals, even when multiple wireless communication terminals use the same wireless resources.

[0008] One aspect of the present invention is a wireless receiving device comprising: a wireless signal receiving unit that receives a plurality of wireless signals from a plurality of wireless communication terminals; a plurality of frequency conversion units that perform frequency conversion on the plurality of wireless signals received by the wireless signal receiving unit; a plurality of signal processing units that perform signal processing on the plurality of wireless signals whose frequency conversion has been performed by the plurality of frequency conversion units; an arrival angle determination unit that determines the arrival angle of the plurality of wireless signals received from the plurality of wireless communication terminals; and a control unit that, when the arrival angles of the plurality of wireless signals determined by the arrival angle determination unit are different, outputs the plurality of wireless signals received by the wireless signal receiving unit from the plurality of wireless communication terminals to different frequency conversion units and signal processing units among the plurality of frequency conversion units and the plurality of signal processing units.

[0009] Another aspect of the present invention is a wireless reception method comprising: a wireless signal reception process for receiving multiple wireless signals from multiple wireless communication terminals; a frequency conversion process for performing frequency conversion on the multiple wireless signals received in the wireless signal reception process; a signal processing process for performing signal processing on the multiple wireless signals whose frequency conversion has been performed in the frequency conversion process; an arrival angle identification process for identifying the arrival angles of the multiple wireless signals received from the multiple wireless communication terminals; and a control process for outputting the multiple wireless signals received from the multiple wireless communication terminals in the wireless signal reception process to different frequency conversion units and signal processing units among the multiple frequency conversion units and multiple signal processing units, if the arrival angles of the multiple wireless signals identified in the arrival angle identification process are different.

[0010] The present invention eliminates the need for complex frequency conversion and signal processing for wireless signals transmitted from multiple wireless communication terminals, even when multiple wireless communication terminals use the same wireless resources.

[0011] This is a schematic diagram of the wireless receiver according to the first embodiment of the present invention. This is a schematic diagram of the RIS according to the first embodiment of the present invention. This is a schematic diagram showing the configuration of a wireless communication system according to the first embodiment of the present invention. This is a flowchart showing the processing of the wireless receiver according to the first embodiment of the present invention. This is a diagram showing a first example of detection of a wireless signal by the wireless signal receiving unit according to the first embodiment of the present invention. This is a diagram showing a second example of detection of a wireless signal by the wireless signal receiving unit according to the first embodiment of the present invention. This is a diagram showing a third example of detection of a wireless signal by the wireless signal receiving unit according to the first embodiment of the present invention. This is a schematic diagram showing the configuration of a wireless communication system according to the second embodiment of the present invention. This is a flowchart showing the processing of the wireless receiver according to the second embodiment of the present invention. This is a diagram showing a first example of detection of a wireless signal by the wireless signal receiving unit according to the second embodiment. This is a diagram showing a second example of detection of a wireless signal by the wireless signal receiving unit according to the second embodiment. This is a diagram showing a third example of detection of a wireless signal by the wireless signal receiving unit according to the second embodiment. This is a diagram showing a fourth example of detection of a wireless signal by the wireless signal receiving unit according to the second embodiment.

[0012] The first and second embodiments of the present invention will be described below with reference to the drawings.

[0013] [First Embodiment] First, a first embodiment of the present invention will be described. Figure 1 is a schematic diagram of the wireless receiving device 20a according to the first embodiment of the present invention. Note that Figure 1 shows only a part of the configuration of the wireless receiving device 20a, but the details will be explained in Figure 2, which will be described later.

[0014] The wireless receiver 20a is a base station device and communicates with multiple wireless communication terminals using wireless signals. The wireless receiver 20a is equipped with a SIM (Stacked Intelligent Metasurface) 2. The SIM 2 is composed of multiple RIS 1-1, 1-2, 1-3, 1-4, ..., 1-A (where A is an integer of 2 or more) stacked on top of each other.

[0015] The wireless receiver 20a includes processing units 3-1, 3-2, 3-3, 3-4, ..., 3-(M-3), 3-(M-2), 3-(M-1), and 3-M (where M is an integer of 2 or more). The wireless signal transmitted from the wireless communication terminal is received by RIS1-1, passes through RIS1-2, 1-3, 1-4, ..., and is output from RIS1-A. The signal output from RIS1-A is output to one of the processing units 3-1, 3-2, 3-3, 3-4, ..., 3-(M-3), 3-(M-2), 3-(M-1), or 3-M, where frequency conversion processing and signal processing are performed.

[0016] Figure 2 is a schematic diagram of RIS1-1 (Figure 1) according to the first embodiment of the present invention. Note that RIS1-2, 1-3, 1-4, ..., 1-A shown in Figure 1 have the same configuration as RIS1-1 shown in Figure 2.

[0017] RIS1-1 is constructed by arranging subwavelength unit cells 1-1-1, 1-1-2, ..., 1-1-C, 1-2-1, 1-2-2, ..., 1-2-C, ..., 1-B-1, 1-B-2, ..., 1-B-C in a B x C matrix. The subwavelength unit cells 1-1-1, 1-1-2, ..., 1-1-C, 1-2-1, 1-2-2, ..., 1-2-C, ..., 1-B-1, 1-B-2, ..., 1-B-C are fine structures of subwavelength size and have a single shape, size, and material. The subwavelength unit cells 1-1-1, 1-1-2, ..., 1-1-C, 1-2-1, 1-2-2, ..., 1-2-C, ..., 1-B-1, 1-B-2, ..., 1-B-C induce specific changes in phase, amplitude, and polarization with respect to the incident electromagnetic wave.

[0018] Figure 3 is a schematic diagram showing the configuration of a wireless communication system 100a according to a first embodiment of the present invention. The wireless communication system 100a comprises wireless communication terminals 10a-1, 10a-2, 10a-3 and a wireless receiving device 20a. The wireless communication terminals 10a-1, 10a-2, and 10a-3 are mobile terminals such as smartphones, and transmit and receive signals with the wireless receiving device 20a using wireless communication. Although Figure 2 shows the case where there are three wireless communication terminals 10a-1, 10a-2, and 10a-3, the number of wireless communication terminals is not limited to three and can be any number.

[0019] The wireless receiving device 20a includes a wireless signal receiving unit 21a, an arrival angle determination unit 22a, a storage unit 23a, a control unit 24a, frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M, signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M, and an output unit 27a.

[0020] The wireless signal receiving unit 21a is equipped with a SIM card and corresponds to SIM 2 in Figure 1. The wireless signal receiving unit 21a receives wireless signals transmitted from wireless communication terminals 10a-1, 10a-2, and 10a-3 and outputs them to the angle of arrival determination unit 22a and the control unit 24a.

[0021] The arrival angle identification unit 22a identifies the arrival angle, which indicates the direction from which the received radio signal originated, based on the radio signal received by the radio signal receiving unit 21a, and outputs it to the control unit 24a.

[0022] The storage unit 23a is equipped with a memory or other storage device. The storage unit 23a stores programs necessary to drive the wireless receiver 20a, and information that the wireless receiver 20a transmits and receives between itself and wireless communication terminals 10a-1, 10a-2, and 10a-3. Based on instructions from the control unit 24a, the storage unit 23a outputs information it has stored to the control unit 24a, and stores information output from the control unit 24a in the storage unit 23a.

[0023] The control unit 24a includes a processing unit such as a CPU (Central Processing Unit). The control unit 24a controls each part of the wireless receiver 20a. The wireless receiver 20a also controls which of the frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M the wireless signal received by the wireless signal receiving unit 21a is output to, based on the arrival angle output by the arrival angle determination unit 22a.

[0024] Each frequency conversion unit 25a-1, 25a-2, 25a-3, ..., 25a-M is assigned an arrival angle. When a radio signal with an assigned arrival angle is received by the radio signal receiving unit 21a, the frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M perform processing such as frequency conversion on the radio signal output from the control unit 24a and output it to the subsequent signal processing unit. More specifically, the frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M amplify the signal level of the radio signal received by the radio signal receiving unit 21a, perform filtering to remove signals such as noise outside the desired frequency band, frequency convert high-frequency signals to lower-frequency signals, and perform automatic gain control processing to stabilize the signal level when the signal strength changes.

[0025] The signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M perform predetermined signal processing on the signals output from the corresponding frequency conversion units and output them to the output unit 27a. Specifically, the signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M convert analog signals output from frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M into digital signals, perform demodulation processing based on the modulation scheme used on the wireless communication terminals 10a-1, 10a-2, 10a-3, correct errors that occurred during the transmission of wireless signals using error correction codes, and decode the signals so that they can be used by higher-level devices.

[0026] The frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M and the signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M correspond to the processing units 3-1, 3-2, 3-3, 3-4, ..., 3-(M-3), 3-(M-2), 3-(M-1), 3-M in Figure 1. The output unit 27a outputs the signals output from the signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M to the higher-level device of the wireless receiver 20a.

[0027] Figure 4 is a flowchart showing the processing of the wireless receiver 20a according to the first embodiment of the present invention. First, the control unit 24a acquires the location information of the wireless communication terminals 10a-1, 10a-2, and 10a-3 (step S11). The location information of the wireless communication terminals 10a-1, 10a-2, and 10a-3 is acquired, for example, by the wireless receiver 20a receiving the location information of each wireless communication terminal measured by the wireless communication terminals 10a-1, 10a-2, and 10a-3 using GPS (Global Positioning System). The control unit 24a stores the acquired location information of the wireless communication terminals 10a-1, 10a-2, and 10a-3 in the storage unit 23a. The control unit 24a also acquires the location information of the wireless receiver 20a using GPS or the like, and stores it in the storage unit 23a in advance. Furthermore, the storage unit 23a also stores information about the direction in which the SIM card equipped in the wireless signal receiving unit 21a of the wireless receiving device 20a is facing, in advance by the administrator of the wireless communication system 100 or the like.

[0028] Next, the arrival angle determination unit 22a determines the arrival angle based on the position information acquired in step S11 (step S12). Specifically, the arrival angle determination unit 22a determines the arrival angle, which indicates the angle at which the wireless signal arrives at the wireless receiver 20a from the wireless communication terminals 10a-1, 10a-2, and 10a-3, based on the position information of the wireless communication terminals 10a-1, 10a-2, and 10a-3 acquired in step S11, the position information of the wireless receiver 20a stored in the storage unit 23a, and the information of the direction that the SIM equipped in the wireless signal receiving unit 21a is facing.

[0029] Next, the control unit 24a determines whether or not a wireless signal has been received by the wireless signal receiving unit 21a (step S13). Specifically, the control unit 24a monitors the RIS 1-1, 1-2, 1-3, 1-4, ..., 1-A that constitute the SIM provided by the wireless signal receiving unit 21a. The control unit 24a then determines that a wireless signal has been received by a subwavelength unit cell if the signal level detected by a predetermined subwavelength unit cell 1-1-1, 1-1-2, ..., 1-1-C, 1-2-1, 1-2-2, ..., 1-2-C, ..., 1-B-1, 1-B-2, ..., 1-B-C (Figure 2) that constitutes the RIS becomes greater than a predetermined value.

[0030] Figures 5A, 5B, and 5C show examples of wireless signal detection by the wireless signal receiving unit 21a according to the first embodiment of the present invention. In Figures 5A, 5B, and 5C, the vertical direction of the paper refers to the vertical direction of the paper in Figure 2. In Figures 5A, 5B, and 5C, the horizontal direction of the paper refers to the vertical direction of the horizontal plane in Figure 2.

[0031] Figure 5A shows the case where a wireless signal transmitted from the wireless communication terminal 10a-1 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21a. In Figure 5A, the wireless signal transmitted from the wireless communication terminal 10a-1 is detected in the subwavelength unit cell located in the upper left part of RIS1-1.

[0032] Figure 5B shows the case where a wireless signal transmitted from the wireless communication terminal 10a-2 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21a. In Figure 5B, the wireless signal transmitted from the wireless communication terminal 10a-2 is detected in the subwavelength unit cell located in the upper left part of RIS1-1.

[0033] Figure 5C shows the case where a wireless signal transmitted from the wireless communication terminal 10a-3 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21a. In Figure 5C, the wireless signal transmitted from the wireless communication terminal 10a-3 is detected in the subwavelength unit cell located in the lower left part of RIS1-1.

[0034] Returning to the explanation of Figure 4, if in step S13 the control unit 24a determines that the wireless signal receiving unit 21a has not received a wireless signal (NO in step S13), the control unit 24a performs the process of step S13 again after a predetermined time (for example, 0.1 seconds) has elapsed.

[0035] On the other hand, if in step S13 the control unit 24a determines that the wireless signal receiving unit 21a has received a wireless signal (YES in step S13), the arrival angle determination unit 22a determines the arrival angle of the wireless signal received in step S13 (step S14). Specifically, the arrival angle of the wireless signal received in step S13 is determined based on which subwavelength unit cell in the multiple RISs constituting the wireless signal receiving unit 21a detected the wireless signal. Note that the method for determining the arrival angle using a SIM composed of multiple RISs is publicly known as described in Non-Patent Document 1, so that explanation will be omitted.

[0036] Next, the control unit 24a outputs the radio signal received in step S13 to the frequency conversion unit among the multiple frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M that corresponds to the radio signal whose angle of arrival was determined in step S14 (step S15). The frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M perform signal level amplification processing, filtering processing, frequency conversion processing, automatic gain control processing, etc.

[0037] For example, the memory unit 23a stores in advance information (such as a list) that determines which of the multiple frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M should output the radio signal received by the radio signal receiving unit 21a, depending on the angle of arrival. This allows the system to identify the angle of arrival of the radio signal received in step S13 in step S14, and then determine which wireless communication terminal transmitted the radio signal received in step S13.

[0038] For example, if the angle of arrival is D1 degree, information is pre-stored in the storage unit 23a that the radio signal received by the radio signal receiving unit 21a will be output to the frequency conversion unit 25a-1. Also, for example, if the angle of arrival is D2 degree, information is pre-stored in the storage unit 23a that the radio signal received by the radio signal receiving unit 21a will be output to the frequency conversion unit 25a-2. Furthermore, for example, if the angle of arrival is D3 degree, information is pre-stored in the storage unit 23a that the radio signal received by the radio signal receiving unit 21a will be output to the frequency conversion unit 25a-3.

[0039] Therefore, if a wireless signal transmitted from the wireless communication terminal 10a-1 is received in step S13 and the angle of arrival of the wireless signal is determined to be D1 degrees in step S14, the control unit 24a can determine that the wireless signal received in step S13 was transmitted from the wireless communication terminal 10a-1, based on the angle of arrival D1 determined in step S14 and the information stored in the storage unit 23a.

[0040] Furthermore, if a wireless signal transmitted from the wireless communication terminal 10a-2 is received in step S13 and the angle of arrival of that wireless signal is determined to be D2 degrees in step S14, the control unit 24a can determine that the wireless signal received in step S13 was transmitted from the wireless communication terminal 10a-2, based on the angle of arrival D2 determined in step S14 and the information stored in the storage unit 23a.

[0041] Further, when the radio signal transmitted from the radio communication terminal 10a-3 is received in step S13, and the angle of arrival of the radio signal is specified to be D3 degrees in step S14, the control unit 24a can specify, based on the angle of arrival D3 specified in step S14 and the information stored in the storage unit 23a, that the radio signal received in step S13 is the one transmitted from the radio communication terminal 10a-3.

[0042] Next, the frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M output signals output from the frequency conversion units to the corresponding signal processing unit among the plurality of signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M (step S16). The signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M perform processing such as analog-to-digital conversion processing, demodulation processing, error correction processing, and decoding processing.

[0043] For example, when the frequency conversion unit that has performed processing such as frequency conversion in step S15 is the frequency conversion unit 25a-1, a signal is output to the signal processing unit 26a-1 connected to the subsequent stage of the frequency conversion unit 25a-1. Further, when the frequency conversion unit that has performed processing such as frequency conversion in step S15 is the frequency conversion unit 25a-2, a signal is output to the signal processing unit 26a-2 connected to the subsequent stage of the frequency conversion unit 25a-2. Further, when the frequency conversion unit that has performed processing such as frequency conversion in step S15 is the frequency conversion unit 25a-3, a signal is output to the signal processing unit 26a-3 connected to the subsequent stage of the frequency conversion unit 25a-2.

[0044] Next, the output unit 27a outputs signals output from the signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M to a host device (step S17). The host device is a device that supervises the radio reception device 20a which is a base station device and other base station devices, and manages, controls, and operates the radio access network of the entire radio communication system.

[0045] According to the first embodiment described above, in a wireless communication system using high frequency bands such as millimeter wave bands, terahertz bands, and sub-terahertz bands, even if a plurality of wireless communication terminals transmit wireless signals to a wireless reception device 20a which is a base station device using the same wireless resource (that is, the same time and the same frequency), the wireless reception device 20a can separate each wireless signal without performing complex digital signal processing, thereby reducing the amount of signal processing and achieving power saving associated therewith. In addition, along with this, radio wave utilization efficiency can also be improved. Further, according to the first embodiment, without processing digital signals, a wireless signal receiving unit 21a provided with an SIM separates a plurality of wireless signals having different arrival angles and the same wireless resource using radio wave waveforms themselves, therefore, it is not necessary to separately provide a signal processing device for separating a plurality of wireless signals having the same wireless resource in the wireless reception device 20a.

[0046] That is, according to the first embodiment, even when a plurality of wireless communication terminals use the same wireless resource, it is possible to eliminate the need for performing complex frequency conversion processing and signal processing on wireless signals transmitted from the plurality of wireless communication terminals.

[0047] [Second Embodiment] Next, a second embodiment of the present invention will be described. Descriptions of points where the second embodiment is the same as the first embodiment will be omitted.

[0048] FIG. 6 is a schematic diagram showing the configuration of a wireless communication system 100b according to the second embodiment of the present invention. The wireless communication system 100b includes wireless communication terminals 10b-1, 10b-2, 10b-3, 10b-4, and a wireless reception device 20b. The wireless communication terminals 10b-1, 10b-2, 10b-3, 10b-4 are mobile terminals such as smartphones, and transmit and receive signals to and from the wireless reception device 20b using wireless communication. Although FIG. 6 shows a case where there are four wireless communication terminals 10b-1, 10b-2, 10b-3, 10b-4, the number of wireless communication terminals is not limited to four, and may be any number.

[0049] The wireless receiving device 20b comprises a wireless signal receiving unit 21b, an arrival angle determination unit 22b, a storage unit 23b, a control unit 24b, frequency conversion units 25b-1, 25b-2, 25b-3, ..., 25b-M, signal processing units 26b-1, 26b-2, 26b-3, ..., 26b-M, and an output unit 27b. Furthermore, the wireless signal receiving unit 21b, angle of arrival identification unit 22b, storage unit 23b, control unit 24b, frequency conversion units 25b-1, 25b-2, 25b-3, ..., 25b-M, signal processing units 26b-1, 26b-2, 26b-3, ..., 26b-M, and output unit 27b of the wireless receiving device 20b of the second embodiment perform the same processing as the wireless signal receiving unit 21a, angle of arrival identification unit 22a, storage unit 23a, control unit 24a, frequency conversion units 25a-1, 25a-2, 25a-3, ..., 25a-M, signal processing units 26a-1, 26a-2, 26a-3, ..., 26a-M, and output unit 27a of the wireless receiving device 20a of the first embodiment, so the explanation of their processing will be omitted.

[0050] Unlike the wireless receiver 20a of the first embodiment, the wireless receiver 20b of the second embodiment further includes a wireless resource allocation unit 28b and a notification unit 29b. The wireless resource allocation unit 28b allocates wireless resources to be used by wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 when they perform wireless communication with the wireless receiver 20b, based on the arrival angle information of the wireless signal received by the wireless signal receiving unit 21b. The method by which the wireless resource allocation unit 28b allocates wireless resources to wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 will be described later using the flowchart in Figure 7.

[0051] The notification unit 29b notifies the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 of the wireless resources allocated to them by the wireless resource allocation unit 28b. As a result, the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 can communicate with the wireless receiving device 20a using the wireless resources allocated by the wireless resource allocation unit 28b.

[0052] Figure 7 is a flowchart showing the processing of the wireless receiver 20b according to the second embodiment of the present invention. In addition to the processing shown in the flowchart of Figure 4 performed by the wireless receiver 20a according to the first embodiment, the wireless receiver 20b according to the second embodiment also performs the processing shown in the flowchart of Figure 7.

[0053] First, the control unit 24b determines whether or not a wireless signal has been received by the wireless signal receiving unit 21b (step S21). Specifically, the control unit 24b monitors the RIS 1-1, 1-2, 1-3, 1-4, ..., 1-A (Figure 1) that constitute the SIM provided by the wireless signal receiving unit 21b. Then, the control unit 24b determines that a wireless signal has been received by a subwavelength unit cell if the signal level detected by a predetermined subwavelength unit cell 1-1-1, 1-1-2, ..., 1-1-C, 1-2-1, 1-2-2, ..., 1-2-C, ..., 1-B-1, 1-B-2, ..., 1-B-C (Figure 2) that constitutes the RIS becomes greater than a predetermined value.

[0054] Figures 8A, 8B, 8C, and 8D show examples of wireless signal detection by the wireless signal receiving unit 21b according to the second embodiment. In Figures 8A, 8B, 8C, and 8D, the vertical direction of the paper refers to the vertical direction of the paper in Figure 2. In Figures 8A, 8B, 8C, and 8D, the horizontal direction of the paper refers to the vertical direction of the horizontal plane in Figure 2.

[0055] Figure 8A shows the case where a wireless signal transmitted from the wireless communication terminal 10b-1 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21b. In Figure 8A, the wireless signal transmitted from the wireless communication terminal 10b-1 is detected in the subwavelength unit cell located in the upper left part of RIS1-1.

[0056] Figure 8B shows the case where a wireless signal transmitted from the wireless communication terminal 10b-2 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21b. In Figure 8B, the wireless signal transmitted from the wireless communication terminal 10b-2 is detected in the subwavelength unit cell located in the upper left part of RIS1-1.

[0057] Figure 8C shows the case where a wireless signal transmitted from the wireless communication terminal 10b-3 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21a. In Figure 8C, the wireless signal transmitted from the wireless communication terminal 10b-3 is detected in the subwavelength unit cell located in the upper left part of RIS1-1.

[0058] Figure 8D shows the case where a wireless signal transmitted from the wireless communication terminal 10b-4 is detected in RIS1-1, which constitutes the SIM in the wireless signal receiving unit 21b. In Figure 8D, the wireless signal transmitted from the wireless communication terminal 10b-4 is detected in the subwavelength unit cell located in the lower left part of RIS1-1.

[0059] Returning to the explanation of Figure 7, the control unit 24b determines whether or not there are multiple radio signals received in step S21 (step S22). If there are not multiple radio signals received in step S21, the determination in step S22 is NO, and the processing of the flowchart in Figure 7 is terminated. On the other hand, if there are multiple radio signals received in step S21, the determination in step S22 is YES, and the processing in step S23 is performed. In this case, the angle of arrival is determined for each of the multiple radio signals received in step S21 by the angle of arrival determination unit 22b.

[0060] If the result in step S22 is YES, the control unit 24b determines whether there are any identical arrival angles among the multiple radio signals received in step S21 (step S23). If there are no identical arrival angles among the multiple radio signals received in step S21 (NO in step S23), the radio resource allocation unit 28b allocates the same radio resource to the wireless communication terminal that transmitted the multiple radio signals received in step S21 (step S24).

[0061] For example, in step S21, if the wireless signal receiving unit 21a simultaneously receives wireless signals from wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4, and the angles of arrival of the received wireless signals from the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 are different, the wireless resource allocation unit 28b allocates the same wireless resource to the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4. As a result, when the wireless receiving device 20b performs wireless communication with the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4, it only needs to use a single wireless resource, thereby improving the efficiency of wireless resource utilization. After the processing in step S24 is performed, the processing in step S27, which will be described later, is performed.

[0062] On the other hand, if there are multiple radio signals received in step S21 that have the same angle of arrival (YES in step S23), the radio resource allocation unit 28b classifies the radio communication terminals that transmitted multiple radio signals with the same angle of arrival into different groups (step S25). Note that having the same angle of arrival includes not only cases where the angles of arrival of two radio signals are exactly the same, but also cases where the angles of arrival of two radio signals are not exactly the same, but the SIM resolution of the radio signal receiving unit 21a is insufficient to distinguish between them.

[0063] In step S25, for example, if the angle of arrival of wireless communication terminal 10b-2 and the angle of arrival of wireless communication terminal 10b-3 are the same, the wireless resource allocation unit 28b classifies wireless communication terminal 10b-2 and wireless communication terminal 10b-3 into different groups. For example, the wireless resource allocation unit 28b classifies wireless communication terminal 10b-1 and wireless communication terminal 10b-2 into a first group G1 (see Figure 6). The wireless resource allocation unit 28b also classifies wireless communication terminal 10b-3 and wireless communication terminal 10b-4 into a second group G2, which is different from the first group (see Figure 6).

[0064] After the processing in step S25 is completed, the wireless resource allocation unit 28b allocates different wireless resources to the multiple groups classified in step S25 (step S26). For example, the wireless resource allocation unit 28b allocates a wireless resource R1, which is specified by a first time and a first frequency, to wireless communication terminals 10b-1 and 10b-2, which are classified into the first group shown in Figure 6.

[0065] Furthermore, the wireless resource allocation unit 28b allocates wireless resource R2, specified by a second time and a second frequency, to wireless communication terminals 10b-3 and 10b-4, which are classified into the second group shown in Figure 6. By performing this processing, the number of wireless resources used can be reduced compared to all of the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 being allocated different wireless resources, thereby improving the efficiency of frequency utilization.

[0066] After the processing in step S24 or step S26 is completed, the notification unit 29b notifies each wireless communication terminal 10b-1, 10b-2, 10b-3, and 10b-4 of the wireless resources allocated in step S24 or step S26 (step S27). As a result, the wireless communication terminals 10b-1, 10b-2, 10b-3, and 10b-4 can use the newly allocated wireless resources in step S24 or step S26 to improve the efficiency of wireless resource utilization and communicate with the wireless receiving device 20b.

[0067] According to the second embodiment described above, the same effects as the first embodiment can be obtained. In other words, according to the second embodiment, even when multiple wireless communication terminals use the same wireless resources, it is possible to eliminate the need for complex frequency conversion processing and signal processing for wireless signals transmitted from multiple wireless communication terminals.

[0068] Furthermore, in the first embodiment, when multiple wireless communication terminals use the same wireless resource and the angles of arrival of the wireless signals transmitted by those multiple wireless communication terminals are different, those wireless signals can be separated without complex processing. On the other hand, in the first embodiment, when multiple wireless communication terminals use the same wireless resource and the angles of arrival of the wireless signals transmitted by those multiple wireless communication terminals are the same, it may not be possible to separate those wireless signals. In contrast to the first embodiment, in the second embodiment, even when multiple wireless communication terminals use the same wireless resource and the angles of arrival of the wireless signals transmitted by those multiple wireless communication terminals are the same, those wireless signals can be separated by assigning different wireless resources to wireless communication terminals with the same angle of arrival.

[0069] Furthermore, at least some of the functions of each part of the wireless receiving devices 20a and 20b in the first and second embodiments of the present invention described above may be implemented by a computer. In that case, the functions may be implemented by recording a program for implementing this function on a computer-readable recording medium, and then loading and executing the program recorded on this recording medium into a computer system. Here, "computer system" includes hardware such as an OS (Operating System) and peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), CD-ROMs, and storage devices such as hard disks built into a computer system. Moreover, "computer-readable recording medium" may also include those that dynamically hold programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and those that hold programs for a certain period of time, such as volatile memory inside a computer system that acts as a server or client in such cases. Furthermore, the above program may be for the purpose of realizing some of the functions described above, or it may be able to realize the above functions in combination with a program already recorded in the computer system, or it may be realized using a programmable logic device such as an FPGA.

[0070] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of the invention.

[0071] The present invention can be applied to wireless receiving devices and wireless receiving methods that require the elimination of the need for complex frequency conversion processing and signal processing for wireless signals transmitted from multiple wireless communication terminals, even when multiple wireless communication terminals use the same wireless resources.

[0072] 10a-1, 10a-2, 10a-3, 10b-1, 10b-2, 10b-3, 10b-4... Wireless communication terminals, 20a, 20b... Wireless receiving devices, 21a, 21b... Wireless signal receiving units, 22a, 22b... Angle of arrival determination units, 23a, 23b... Storage units, 24a, 24b... Control units, 25a-1, 25a-2, 25a-3, ..., 25a-M, 25b-1, 25b-2, 25b-3, ..., 25b-M... Frequency conversion units, 26a-1, 26a-2, 26a-3, ..., 26a-M, 26b-1, 26b-2, 26b-3, ..., 26b-M... Signal processing units, 27a, 27b... Output units, 28a, 28b... Wireless resource allocation unit, 29a, 29b... Notification unit

Claims

1. A wireless receiving device comprising: a wireless signal receiving unit that receives multiple wireless signals from multiple wireless communication terminals; multiple frequency conversion units that perform frequency conversion on the multiple wireless signals received by the wireless signal receiving unit; multiple signal processing units that perform signal processing on the multiple wireless signals whose frequency conversion has been performed by the multiple frequency conversion units; an arrival angle determination unit that determines the arrival angle of the multiple wireless signals received from the multiple wireless communication terminals; and a control unit that, when the arrival angles of the multiple wireless signals determined by the arrival angle determination unit are different, outputs the multiple wireless signals received by the wireless signal receiving unit from the multiple wireless communication terminals to different frequency conversion units and signal processing units among the multiple frequency conversion units and the multiple signal processing units.

2. The wireless receiving device according to claim 1, further comprising: a wireless resource allocation unit that allocates different wireless resources to the plurality of wireless communication terminals when the angles of arrival of the plurality of wireless signals identified by the angle of arrival identification unit are the same; and a notification unit that notifies the plurality of wireless communication terminals of the wireless resources allocated by the wireless resource allocation unit.

3. A wireless reception method comprising: a wireless signal reception process for receiving multiple wireless signals from multiple wireless communication terminals; a frequency conversion process for performing frequency conversion on the multiple wireless signals received in the wireless signal reception process; a signal processing process for performing signal processing on the multiple wireless signals whose frequency conversion has been performed in the frequency conversion process; an arrival angle determination process for determining the arrival angles of the multiple wireless signals received from the multiple wireless communication terminals; and a control process for outputting the multiple wireless signals received from the multiple wireless communication terminals in the wireless signal reception process to different frequency conversion units and signal processing units among the multiple frequency conversion units and multiple signal processing units when the arrival angles of the multiple wireless signals determined in the arrival angle determination process are different.

4. The wireless reception method according to claim 3, further comprising: a wireless resource allocation process for allocating different wireless resources to the plurality of wireless communication terminals when the angles of arrival of the plurality of wireless signals identified in the angle of arrival identification process are the same; and a notification process for notifying the plurality of wireless communication terminals of the wireless resources allocated in the wireless resource allocation process.

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