COMMUNICATION CONTROL DEVICE, COMMUNICATION SYSTEM, AND METHOD

Abstract

The purpose of the present disclosure is to provide a communication control device, a communication system, a method, and a non-transitory computer-readable medium with which it is possible to spatially multiplex data signals to a user device, increase overall communication volume, and improve communication quality, A communication control device (11) according to the present disclosure includes a control means (113) for: selecting a prescribed wireless communication device (12p) that is closest to a terminal (13), from among a plurality of wireless communication devices (12), on the basis of the position of the terminal (13) and the positions of the plurality of wireless communication devices (12); identifying an estimated position of the terminal (13) at the time when a data signal from the prescribed wireless communication device (12p) is transmitted, on the basis of the position and speed vector of the terminal (13) at the time when a reference signal (RS) directed to the prescribed wireless communication device (12p) is received; and controlling the prescribed wireless communication device (12p) so as to transmit a data signal such that antenna directivity is oriented in a direction extending from the prescribed wireless communication device (12p) toward the estimated position of the terminal (13).

Description

[Technical Field]

[0001] The present disclosure relates to a communication control device, a communication system, a method, and a non-transitory computer-readable medium, and in particular to a communication control device, a communication system, a method, and a non-transitory computer-readable medium that are capable of spatially multiplexing data signals to user devices, thereby increasing overall communication volume and improving communication quality. [Background technology]

[0002] The use of millimeter-wave and sub-THz (terahertz) frequency bands is being considered for use in fifth-generation (5G) and sixth-generation (6G) mobile communications. Because millimeter-wave and sub-THz frequency bands have a high degree of signal directionality and significant attenuation over propagation distance, antenna beamforming technology is sometimes used to improve antenna gain for communications. To perform beamforming, it is necessary to actually transmit radio waves to determine the direction and propagation channel to the user equipment (UE), the communication target.

[0003] Paragraph 0047 of Patent Document 1 states, "The reflected waveforms will be time delayed and Doppler frequency shifted relative to the direct radio OTFS waveform burst. Thus, these time delayed and Doppler frequency shifted waveforms will be referred to as 'time delayed and Doppler frequency shifted reflected radio OTFS waveform bursts' when received at a radio receiver. Furthermore, even the direct waveforms may be time delayed and frequency shifted depending on the relative locations and velocities of the transmitter and receiver."

[0004] Paragraph 0060 of Patent Document 2 states, "In step 1102, the UE determines a first set of beamforming directions for communicating with a BS in the first network. In one aspect, the first network may be an LTE network using a carrier having a frequency below 6.0 GHz." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-002846 [Patent Document 2] Japanese Patent Application Publication No. 2018-107810 [Non-patent literature]

[0006] [Non-Patent Document 1] R. Hadani et al., "Orthogonal Time Frequency Space Modulation," 2017 IEEE Wireless Communications and Networking Conference (WCNC), 2017, pp. 1-6. Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, beamforming requires that the direction and propagation channel to the UE, the communication target, be determined by actually transmitting radio waves.However, since radio waves have difficulty reaching the millimeter wave and sub-THz frequency bands, determining the beam direction is difficult.

[0008] Furthermore, in 5G and 6G, access points (APs) are sometimes installed with overlapping communication ranges (cells) to increase communication capacity and eliminate radio wave dead zones. These APs operate independently, and signals may be transmitted simultaneously from multiple APs to a single UE. If the phase of signals from multiple APs can be controlled and coherently combined at the UE's position, degradation of communication quality due to interference can be prevented. However, millimeter wave and sub-THz frequency bands have short wavelengths, and even slight variations in the UE's position can cause phase changes, making it difficult to coherently combine signals. This has led to the issue of signals from multiple APs interfering with each other and degrading communication quality.

[0009] Therefore, in order to search for the direction of the communication target, a pencil beam is formed and the beam direction is swept in all directions to search for the communication target. This is called beam search. Because propagation attenuation is large in the millimeter wave and sub-THz frequency bands, antenna gain may be increased by increasing the number of antenna elements. However, when antenna gain is increased, the directionality of the radio waves becomes stronger and the angular range in which the radio waves can be detected becomes narrower. For this reason, in beam search, it is necessary to finely adjust the beam angle, which poses the issue of increasing the time required to search for the communication target.

[0010] In some cases, both the AP and the UE use beamforming technology. The AP determines the direction of the UE, and the UE determines the direction of the AP through beam search. However, due to the directivity of radio waves, communication is only possible when the AP's beam direction and the UE's beam direction are aligned, and they cannot detect each other's direction. To detect each other's direction, for example, the UE must repeatedly perform a beam search in all directions each time the AP's beam direction changes, thereby determining the direction of the AP from the UE and the direction of the UE from the AP. This method increases the number of attempts required to detect each other's direction, and requires a long beam search time. Beam searches are generally performed by oscillating beams at maximum power in all directions, consuming a lot of time and power. Furthermore, frequent beam searches are required to accommodate UE movement, which, combined with the aforementioned long beam search times, increases power consumption. Additionally, data communication is not possible during beam search, resulting in a decrease in overall communication traffic.

[0011] An object of the present disclosure is to provide a communication control device, a communication system, a method, and a non-transitory computer-readable medium that solves any of the above-mentioned problems. [Means for solving the problem]

[0012] The communication control device according to the present disclosure includes: a first estimation means for estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; a second estimation means for estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; a control means for selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the position of the terminal and the positions of the plurality of wireless communication devices, specifying an estimated position of the terminal at the time of transmission of a data signal from the predetermined wireless communication device based on the position of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector, and controlling the predetermined wireless communication device to transmit the data signal by directing the directivity of the antenna in a direction from the predetermined wireless communication device to the estimated position of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for signals from the wireless communication device to the terminal.

[0013] The communication system according to the present disclosure includes: A communication control device that controls a plurality of wireless communication devices that communicate with a terminal, Each of the plurality of wireless communication devices a receiving means for receiving, via an antenna, an orthogonal time-frequency-space modulated reference signal transmitted by the terminal; a transmitting means for transmitting a data signal by directing the directivity of the antenna based on control from the communication control device, The communication control device a first estimation means for estimating, for each of the plurality of wireless communication devices, a signal delay amount from the terminal to the antenna and a relative speed between the terminal and the wireless communication device, based on the reference signal received by each of the plurality of wireless communication devices from the terminal; a second estimation means for estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; a control means for selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the position of the terminal and the positions of the plurality of wireless communication devices, specifying an estimated position of the terminal at the time of transmission of a data signal from the predetermined wireless communication device based on the position of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector, and controlling the predetermined wireless communication device to transmit the data signal by directing the directivity of the antenna in a direction from the predetermined wireless communication device to the estimated position of the terminal, a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for signals from the wireless communication device to the terminal.

[0014] The method according to the present disclosure comprises: Estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the location of the terminal and the locations of the plurality of wireless communication devices; determining an estimated location of the terminal at the time of transmission of the data signal from the predetermined wireless communication device based on the location of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector; controlling the predetermined wireless communication device to transmit the data signal with the directivity of the antenna directed in a direction from the predetermined wireless communication device toward the estimated location of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for signals from the wireless communication device to the terminal.

[0015] The present disclosure provides a non-transitory computer-readable medium, comprising: Estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the location of the terminal and the locations of the plurality of wireless communication devices; determining an estimated location of the terminal at the time of transmission of the data signal from the predetermined wireless communication device based on the location of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector; controlling the predetermined wireless communication device to transmit the data signal with the directivity of the antenna directed in a direction from the predetermined wireless communication device toward the estimated location of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal. A program that causes a computer to execute the above is stored. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to provide a communication control device, a communication system, a method, and a non-transitory computer-readable medium that can spatially multiplex data signals to user devices, thereby increasing overall communication volume and improving communication quality. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a block diagram illustrating a communication system including a communication control device according to a first embodiment. [Figure 2] FIG. 10 is a block diagram illustrating a communication system according to a second embodiment. [Figure 3] FIG. 10 is a block diagram illustrating a communication system according to a second embodiment. [Figure 4] 10 is a flowchart illustrating an operation of a communication system according to a second embodiment. [Figure 5] FIG. 10 is a schematic diagram illustrating an RS in a DD space of an OTFS signal transmitted from a UE. [Figure 6] 10 is a schematic diagram illustrating an example of an RS in a DD space of an OTFS signal received by an AP. [Figure 7] 1 is a schematic diagram illustrating a plurality of APs and the distance from each AP to a UE. [Figure 8] 1 is a schematic diagram illustrating multiple APs and velocity vectors of UEs corresponding to each AP. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0019] [Embodiment 1] <Minimum configuration> FIG. 1 is a block diagram illustrating a communication system including a communication control device according to the first embodiment. FIG. 1 shows the minimum configuration of a communication control device according to the first embodiment.

[0020] In recent years, an Orthogonal Time Frequency Space (OTFS) modulation method has been proposed. Details are described in Non-Patent Document 1. While Orthogonal Frequency Division Multiplexing (OFDM) arranges data in time-frequency space, OTFS arranges data in delay-Doppler space. Therefore, the position of the transmission source of an OTFS signal can be estimated based on the signal delay and Doppler shift. The signal delay can be used to estimate the distance from the signal transmission source to the signal reception source. Furthermore, the Doppler shift can be used to estimate the velocity in the vector direction connecting the signal transmission source and the signal reception source. The technology disclosed herein utilizes the characteristics of OTFS signals.

[0021] As shown in Fig. 1, a communication system 10 according to the first embodiment includes a terminal 13, a plurality of wireless communication devices 12 that communicate with the terminal 13, and a communication control device 11 that controls the plurality of wireless communication devices 12. The terminals may also be referred to as user equipment (UE). Although only one UE is shown in Fig. 1, the present invention is not limited to this. Although only four wireless communication devices are shown in Fig. 1, the present invention is not limited to this.

[0022] Each of the multiple wireless communication devices 12 has receiving means 122 and transmitting means 121. The receiving means 122 receives an OTFS-modulated reference signal (RS) transmitted by the UE 13 via an antenna. The transmitting means 121 transmits a data signal by directing the antenna directionally from the wireless communication device 12 to the UE 13 based on control from the communication control device 11. The orthogonal time-frequency spaced reference signal is sometimes referred to as an OTFS-RS.

[0023] An impulse signal or a signal similar to it may be used as the reference signal, which makes it possible to obtain a channel impulse response (CIR) that includes information about the radio wave propagation path.

[0024] The communication control device 11 includes a first estimation means 111 , a second estimation means 112 , and a control means 113 .

[0025] The first estimation means 111 estimates, for each of the plurality of wireless communication devices 12, the amount of signal delay from UE 13 to the antenna of wireless communication device 12 and the amount of Doppler shift between UE 13 and wireless communication device 12, based on the reference signal that each of the plurality of wireless communication devices 12 receives from UE 13. From the amount of signal delay, it is possible to estimate the distance from UE 13 to wireless communication device 12. Furthermore, from the amount of Doppler shift, it is possible to estimate the speed in the direction of the vector connecting UE 13 and wireless communication device 12. The amount of Doppler shift is referred to as relative speed.

[0026] The second estimation means 112 estimates the position and velocity vector of UE 13 based on the positions of the multiple wireless communication devices 12, the amount of signal delay estimated for each of the multiple wireless communication devices 12, and the relative velocity. Specifically, the second estimation means 112 estimates the position of UE 13 based on the positions of the multiple wireless communication devices 12 and the distance to UE 13 for each of the multiple wireless communication devices 12. Furthermore, the second estimation means 112 estimates the velocity vector of UE 13 by combining the velocities in the vector direction connecting UE 13 and wireless communication device 12 related to all of the wireless communication devices 12.

[0027] The control means 113 selects a predetermined wireless communication device 12p that is closest to the UE 13 from among the plurality of wireless communication devices 12, based on the position of the UE 13 and the positions of the plurality of wireless communication devices 12. The control means 113 identifies an estimated position of the UE 13 at the time of transmission of a data signal from the predetermined wireless communication device 12p, based on the position and velocity vector of the UE 13 at the time of reception of a reference signal to the predetermined wireless communication device 12p. The control means 113 controls the predetermined wireless communication device 12p to transmit the data signal with the directivity of the antenna directed in a direction from the predetermined wireless communication device 12p toward the estimated position of the UE 13.

[0028] A first frequency f1 is used for signals transmitted from UE 13 to wireless communication device 12. A second frequency f2, which is higher than the first frequency f1, is used for signals transmitted from wireless communication device 12 to UE 13. A signal transmitted from UE 13 to wireless communication device 12 is sometimes referred to as an uplink (UL) signal, and a signal transmitted from wireless communication device 12 to UE 13 is sometimes referred to as a downlink (DL) signal.

[0029] <Effects> In the communication system 10 according to the embodiment, a data signal is transmitted by directing the antenna direction of the predetermined wireless communication device 12p in a direction from the predetermined wireless communication device 12p that is closest to the target UE 13 toward the estimated location of the UE 13. This allows the antenna direction of the predetermined wireless communication device 12p to be narrowed to only the target UE, reducing interference with other UEs, and thus enabling spatial multiplexing of data signals. Furthermore, since interference with other UEs is reduced, the amount of communication traffic can be increased and communication quality can be improved.

[0030] As a result, according to embodiment 1, it is possible to provide a communication control device, a communication system, a method, and a non-transitory computer-readable medium that can spatially multiplex data signals to user devices, thereby increasing overall communication volume and improving communication quality.

[0031] According to the first embodiment, the wireless communication device 12 that transmits the DL signal can be limited to only the optimum predetermined wireless communication device 12p, so that unnecessary transmission of the DL signal can be avoided and power efficiency per communication volume can be improved.

[0032] In addition, instead of selecting a predetermined wireless communication device 12p that is closest to the UE 13 based on the location of the UE 13 and the locations of the multiple wireless communication devices 12, the control means 113 may select the wireless communication device that received the reference signal with the highest received power as the predetermined wireless communication device 12p.

[0033] [Embodiment 2] <Summary> FIG. 2 is a block diagram illustrating a communication system according to the second embodiment. FIG. 2 is a diagram showing a plurality of access points (APs) that are distributed and a plurality of UEs that exist within the access ranges of these APs. 2 shows only three UEs 13 within the communication range of multiple APs 12, but is not limited to this. Also, while FIG. 2 shows only four APs, is not limited to this.

[0034] In the second embodiment, the wireless communication device according to the first embodiment is shown as an AP, and the communication control device is shown as a DU (Distributed Unit). That is, the AP in Fig. 2 corresponds to the wireless communication device in Fig. 1, and the DU (Distributed Unit) in Fig. 2 corresponds to the communication control device in Fig. 1.

[0035] Each of the multiple APs 12 is connected to one DU 11, and these multiple APs 12 operate in cooperation with the DU 11.

[0036] It is assumed that both the AP 12 and the UE 13 support both a first frequency f1 and a second frequency f2. The first frequency f1 is lower than the second frequency f2. In the UL, the first frequency f1 is used, and the UL signal is modulated with OTFS. In the DL, the second frequency f2 is used, and the DL signal is modulated with single carrier modulation.

[0037] The AP 12 and the UE 13 switch between DL / UL communication using time division duplex (TDD). That is, the UL time period in which UL signals are communicated and the DL time period in which DL signals are communicated are alternately switched. However, the second embodiment is not limited to TDD. The second embodiment can also be applied to frequency division duplex (FDD).

[0038] When both AP 12 and UE 13 use the first frequency f1, they use an omni-directional antenna or an equivalent antenna with low directivity. When both AP 12 and UE 13 use the second frequency f2, they perform beamforming using an antenna with multiple antenna elements. That is, each of the antennas of AP 12 and UE 13 is composed of multiple antenna elements, and weighting is applied to each of the multiple antenna elements to perform beamforming (forming directivity). This makes it possible to increase the antenna gain in the direction where UE 13 is located, thereby improving the quality of communication with UE 13. Note that antenna elements may also be referred to as antenna elements.

[0039] The second embodiment is particularly effective in a communication system in which stable communication is possible by using a first frequency f1 in UL communication, while a second frequency f2 is used in DL communication, and communication is not possible unless the antenna directivity (beam) is directed toward UE13.

[0040] The first frequency f1 may be, for example, a frequency within a frequency band called FR1 (450 MHz (megahertz) to 6 GHz (gigahertz)) in 3GPP (Third Generation Partnership Project). The second frequency f2 may be, for example, FR2 (24.25 GHz to 52.6 GHz) in 3GPP or a frequency within a higher frequency band called sub-THz. However, the embodiment is not limited to these frequency bands.

[0041] <Detailed configuration> FIG. 3 is a block diagram illustrating a communication system according to the second embodiment.

[0042] <ap> As shown in Fig. 3, a DU 11 and multiple APs 12 are connected by optical cables. AP 12 has a digital front end (DFE), an f1 modulator / demodulator, an f2 modulator / demodulator, a distributor, a phase shifter, an f1 antenna, and an f2 antenna. The f1 modulator / demodulator and the receiving section of the DFE shown in Fig. 3 correspond to the receiving means 122 shown in Fig. 1. Furthermore, the transmitting section of the DFE, the f2 modulator / demodulator, the distributor / combiner, and the phase shifter shown in Fig. 3 correspond to the transmitting means 121 shown in Fig. 1.

[0043] The f1 antenna receives an RF signal of the first frequency f1. The f1 modem converts between baseband signals and RF signals of the first frequency f1. The DFE performs digital-to-analog signal conversion. The f2 modem converts between baseband signals and RF signals of the second frequency f2. The distributor-combiner distributes the RF signal of the second frequency f2. The phase shifter adjusts the phase of each distributed RF signal. The f2 antenna radiates an RF signal of the second frequency f2.

[0044] The antenna for f2 has the same number of antenna elements as the number of RF distributions in order to radiate each of the multiple distributed RF signals. The multiple APs 12 are controlled by the DU 11 and operate in coordination.

[0045] <ue> Like the AP 12, the UE 13 has a DFE, an f1 modem, an f2 modem, a distributor / combiner, a phase shifter, an f1 antenna, and an f2 antenna.

[0046] The DFE performs digital-to-analog signal conversion. The f1 modulator-demodulator converts between baseband signals and RF signals of the first frequency f1. The f1 antenna emits RF signals of the first frequency f1. The f2 antenna receives RF signals of the second frequency f2. The phase shifter adjusts the phase of the received RF signals. The distributor-combiner combines RF signals of the second frequency f2. The f2 modulator-demodulator converts between baseband signals and RF signals of the second frequency f2.

[0047] <Operation> FIG. 4 is a flowchart illustrating the operation of the communication system according to the second embodiment. FIG. 5 is a schematic diagram illustrating an RS in the DD space of an OTFS signal transmitted from a UE. The horizontal axis of FIG. 5 is the Doppler index, and the vertical axis is the delay index. 5 indicate the element positions of the RS at the time of transmission from the UE 13. Furthermore, elements shown in white indicate empty elements.

[0048] As shown in Fig. 4, each UE 13 transmits an OTFS-modulated reference signal (RS) converted into an RF signal of a first frequency f1 (step S101). The OTFS-modulated RS signal may also be referred to as an OTFS signal or an OTFS-RS. OTFS modulation is a modulation method in which a data signal is allocated to a DD space and modulated. Details of OTFS modulation are described in Non-Patent Document 1, and a detailed description thereof will be omitted here.

[0049] In the second embodiment, a case will be described in which OTFS signals are transmitted simultaneously from three UEs 13 (UE 13a, UE 13b, and UE 13c shown in FIG. 2) as an example.

[0050] After step S101, each AP 12 receives an OTFS signal transmitted from the UE 13, and the DU 11 calculates the signal delay amount and Doppler shift amount (relative velocity) of each UE 13 (step S102). The signal delay amount and Doppler shift amount of each UE 13 are transmitted to the DU 11.

[0051] 5, the position of the element of the RS transmitted from each UE 13 is arranged at a different element position for each UE 13 so that the AP 12 can determine which UE 13 transmitted the RS. For example, for UE 13a, the RS is arranged at the position of an element with a Doppler index of 2 and a delay index of 4.

[0052] FIG. 6 is a schematic diagram illustrating an example of RS in the DD space of the OTFS signal received by the AP 12a. The horizontal axis of FIG. 6 is the Doppler index, and the vertical axis is the delay index. FIG. 6 shows an example in which OTFS signals transmitted from three UEs 13 are received and demodulated by the AP. 6, the elements shown in black indicate the element positions of the RS at the time of detection (reception) by the AP 12a, and the elements shown in diagonal lines indicate the element positions of the RS at the time of transmission by the UE 13.

[0053] In Figure 6, the greater the distance between AP 12a and UE 13, the greater the measured position of the element of the received RS (shown in black) is shifted in the vertical direction (delay direction) from the element position transmitted by UE 13 (shown in diagonal lines). This shift in the delay direction is referred to as the signal delay amount. Furthermore, the greater the speed of UE 13 relative to AP 12a, the greater the measured position of the element of the received RS (shown in black) is shifted in the horizontal direction (Doppler direction) from the element position transmitted by UE 13 (shown in diagonal lines). The relative speed can be calculated from this shift in the Doppler direction, i.e., the Doppler shift amount of the OTFS-modulated RS.

[0054] Therefore, based on the displacement of the element position, that is, the element position in the DD space during transmission from the UE13 of the RS (indicated by the diagonal lines in FIG. 6) and the element position of the RS in the DD space during reception at the AP12a of the RS (indicated by the black color in FIG. 6), the signal delay amount and the relative speed can be obtained.

[0055] Returning to FIG. 4, after step S102, the DU11 obtains the distance from the AP12 to the UE13 and the speed in the direction connecting the AP12 and the UE13 based on the signal delay amount and the Doppler shift amount (relative speed) respectively measured and obtained by the plurality of AP12s. By knowing the positions of each of the plurality of AP12s, the DU11 estimates the position and velocity vector of the UE13 based on the distance and speed to the UE13. That is, the DU11 obtains the position and velocity vector of each UE13 based on the measured signal delay amount and Doppler shift amount (step S103).

[0056] <Method for estimating the position and velocity vector of the UE> A specific estimation method will be described below. FIG. 7 is a schematic diagram illustrating the distances from a plurality of APs to the UE for each AP. FIG. 7 is a diagram for explaining the method of estimating the position of the UE. The circles indicated by the dotted lines in FIG. 7 represent the distances from each AP12 to the UE13 measured by each AP12 using OTFS.

[0057] As shown in FIG. 7, in three or more AP12s, the position of the UE13 can be uniquely estimated by obtaining the distances from each AP12 to the UE13.

[0058] FIG. 8 is a schematic diagram illustrating the velocity vectors of the UE corresponding to a plurality of APs. FIG. 8 is a diagram for explaining the method of estimating the velocity vector of the UE. The arrows indicated by the dotted lines in FIG. 8 represent the velocity vectors of the UE with respect to each AP measured using OTFS.

[0059] As shown in Fig. 8, the velocity vector of the UE 13 can be uniquely estimated by calculating the velocity in the direction connecting each of the APs 12 and the UE 13 at three or more APs 12. In Fig. 8, the velocity vector measured at each AP is E The actual velocity vector of UE 13 is projected from UE 13 in the direction of AP 12. The intersection of the actual velocity vector of UE 13 with a perpendicular line drawn to the line connecting UE 13 and each AP 12 represents the magnitude of the velocity measured at AP 12. In this way, the position of UE 13 and the velocity vector of UE 13 are estimated.

[0060] Also, returning to FIG. 6, by finding the amplitude of the element that detected the OTFS-RS from each UE 13 and the surrounding elements, the received power of the OTFS-RS transmitted from each UE 13 can be found.

[0061] 4, after step S103, the DU 11 selects the AP 12 closest to the estimated position of the UE 13 or the AP 12 with the highest received power of the OTFS signal as the predetermined AP 12p that will communicate with each UE 13 (step S104). The received power of the OTFS-RS received by the AP 12 can be found by finding the amplitude of the element that detected the OTFS-RS from each UE 13 and the surrounding elements with reference to FIG.

[0062] The DU 11 calculates the estimated location of the UE 13 at the time of transmitting the DL signal, and obtains the direction from the predetermined AP 12p to the estimated location of the target UE 13 (step S105).

[0063] The AP 12p weights the antenna elements, directs the antenna, and transmits a DL signal at the second frequency f2 from the AP 12p to the target UE 13 (step S106).

[0064] The UE 13 performs a beam search using the signal of the second frequency f2 to estimate the direction of the target AP 12p (step S107). The beam search may use a peak search method, a MUSIC (Multiple Signal Classification) method, and / or an ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) method. This causes the beam directions of the AP 12 and the UE 13 to point in each other's direction, enabling communication in a short time.

[0065] Furthermore, since the beam direction of AP 12 is directed toward the location of UE 13, UE 13 can perform a beam search efficiently, thereby shortening the time required for the beam search. This allows UE 13 to reduce the power required for the beam search. Furthermore, UE 13 can use the time required for the beam search for data communication, thereby increasing the amount of communication traffic.

[0066] If the AP 12 is found (step S108: Yes), the UE 13 directs a beam of the second frequency f2 in that direction and starts data communication (step S109).

[0067] If the AP 12 is not found (step S108: No), the UE 13 returns to step S101 and repeats the attempt to search for the beam direction of the AP 12 and the UE 13.

[0068] After starting data communication at the second frequency f2, UE13 returns to step S101 after a certain time has elapsed, or when the signal-to-noise ratio (SNR) becomes equal to or less than a predetermined threshold (step S110: Yes), and performs a beam direction search for AP12 and UE13.

[0069] <Effects> If each AP 12 does not cooperate with each other and independently transmits signals to all UEs 13 within its reach, signals from multiple APs 12 will reach a single UE 13. Since millimeter wave and sub-THz frequency bands have high frequencies and coherent phase combining is difficult, interference occurs in the received signals at the UE 13. This interference causes fluctuations and degradation in communication quality.

[0070] Therefore, in the second embodiment, interference can be reduced by transmitting a DL signal from only one appropriate AP 12, with the antenna directivity directed from the AP 12 to the direction from the AP 12 to the UE 13. This makes it possible to spatially multiplex signals from multiple UEs 13 and increase the communication volume of the entire communication system.

[0071] Furthermore, when a single AP 12 transmits DL signals for multiple UEs 13, the power per UE decreases because the power that can be transmitted from the AP 13 is constant, which reduces the received power of the UEs 13 and leads to a deterioration in communication quality.

[0072] Therefore, in the second embodiment, the transmission power per UE is increased and communication quality is improved by transmitting a DL signal only from one appropriate AP 12. Furthermore, since low-quality communication is not performed, energy efficiency per communication amount can be improved.

[0073] In addition, in the second embodiment, the location of UE 13 is estimated by using the OTFS signal of the first frequency f1. Then, by using the location information of UE 13 for the beam angle (directivity) of the second frequency f2, the time required for beam search can be reduced. This allows the time allocated to data communication to increase the communication volume and reduce power consumption.

[0074] Furthermore, the second embodiment is also applicable to a case where the UE 13 does not perform beamforming at the second frequency f2, in which case the process of step S107 shown in FIG.

[0075] Furthermore, the second embodiment is applicable even when the UE 13 does not have an OTFS modulation means (a portion implementing an ISFFT (Inverse Symplectic Finite Fourier Transform)). The OTFS signal is generated by modulating data allocated in a DD space into data in a time frequency space by performing an ISFFT, and then performing OFDM modulation. Therefore, in the second embodiment, data that has been subjected to an ISFFT in advance for a reference signal (RS) for OTFS modulation is stored in the UE 13. When the delay amount and relative speed of the UE 13 are to be calculated, this signal is OFDM modulated and transmitted, thereby making the second embodiment applicable even to a UE 13 that does not have an OTFS modulation means.

[0076] <Features> In the embodiment of the present disclosure, an OTFS modulated signal is transmitted from the UE 13 using a first frequency f1 that is lower than the second frequency f2. Since the first frequency f1 has a lower propagation loss than the second frequency f2, the UE 13 can generally communicate with the AP 12 without performing a beam search.

[0077] Furthermore, in the embodiment, by receiving the OTFS-RS at multiple APs 12, it is possible to acquire a CIR (Channel Impulse Response) including information on the radio wave propagation path. Furthermore, it is possible to estimate the position and velocity vector of UE 13 from the CIR. AP 12 uses the acquired CIR to weight the signal of the second frequency f2 by antenna and transmits the DL signal. This makes it possible to increase the antenna gain in the direction where UE 13 is present, thereby improving the quality of communication with UE 13.

[0078] In the above embodiment, the present disclosure has been described as a hardware configuration, but the present disclosure is not limited to this. The present disclosure can also be realized by having a CPU (Central Processing Unit) execute a computer program to perform the processing of each component.

[0079] In the above embodiments, the program can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (specifically, flexible disks, magnetic tapes, and hard disk drives), magneto-optical recording media (specifically, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, semiconductor memories (specifically, mask ROMs, PROMs (Programmable ROMs), and EPROMs (Erasable PROMs)), flash ROMs, and RAMs (Random Access Memory). The program may also be supplied to a computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable media can supply the program to a computer via a wired communication path such as an electric wire or optical fiber, or via a wireless communication path.

[0080] Additionally, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order depicted, or that all of the depicted operations be performed, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous. Similarly, although details of several specific embodiments are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable combination.

[0081] Although the contents of the present disclosure have been described above with reference to the embodiments, the present disclosure is not limited to the above. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the disclosure.

[0082] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present disclosure.

[0083] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes. (Appendix 1) a first estimation means for estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; a second estimation means for estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; a control means for selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the position of the terminal and the positions of the plurality of wireless communication devices, specifying an estimated position of the terminal at the time of transmission of a data signal from the predetermined wireless communication device based on the position of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector, and controlling the predetermined wireless communication device to transmit the data signal by directing the directivity of the antenna in a direction from the predetermined wireless communication device to the estimated position of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal. Communications control device. (Appendix 2) The signal delay amount and the relative velocity are estimated based on a position in a delay Doppler space when the reference signal is transmitted from the terminal and a position in the delay Doppler space when the reference signal is received by the wireless communication device. 2. The communication control device of claim 1. (Appendix 3) the control means selects the wireless communication device that receives the reference signal with the highest reception power as the predetermined wireless communication device, instead of selecting a predetermined wireless communication device that is closest to the terminal based on the location of the terminal and the locations of the plurality of wireless communication devices. 3. A communication control device according to claim 1 or 2. (Appendix 4) The relative velocity is calculated from a Doppler shift amount of the orthogonal time-frequency-space modulated reference signal. 4. A communication control device according to any one of claims 1 to 3. (Appendix 5) The antenna is composed of a plurality of antenna elements, The directivity is formed by weighting each of the plurality of antenna elements. 5. A communication control device according to any one of claims 1 to 4. (Appendix 6) A downlink signal from the wireless communication device to the terminal is single-carrier modulated. 6. A communication control device according to any one of appendices 1 to 5. (Appendix 7) an uplink time period in which an uplink signal is transmitted from the terminal to the wireless communication device and a downlink time period in which the downlink signal is transmitted are alternately switched; 7. The communication control device according to claim 6. (Appendix 8) The device itself and the plurality of wireless communication devices are connected by optical cables. 8. A communication control device according to any one of claims 1 to 7. (Appendix 9) A communication control device that controls a plurality of wireless communication devices that communicate with a terminal, Each of the plurality of wireless communication devices a receiving means for receiving, via an antenna, an orthogonal time-frequency-space modulated reference signal transmitted by the terminal; a transmitting means for transmitting a data signal by directing the directivity of the antenna based on control from the communication control device, The communication control device a first estimation means for estimating, for each of the plurality of wireless communication devices, a signal delay amount from the terminal to the antenna and a relative speed between the terminal and the wireless communication device, based on the reference signal received by each of the plurality of wireless communication devices from the terminal; a second estimation means for estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; a control means for selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the position of the terminal and the positions of the plurality of wireless communication devices, specifying an estimated position of the terminal at the time of transmission of a data signal from the predetermined wireless communication device based on the position of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector, and controlling the predetermined wireless communication device to transmit the data signal by directing the directivity of the antenna in a direction from the predetermined wireless communication device to the estimated position of the terminal, a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal. Communication system. (Appendix 10) The signal delay amount and the relative velocity are estimated based on a position in a delay Doppler space when the reference signal is transmitted from the terminal and a position in the delay Doppler space when the reference signal is received by the wireless communication device. 10. The communication system of claim 9. (Appendix 11) Estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the location of the terminal and the locations of the plurality of wireless communication devices; determining an estimated location of the terminal at the time of transmission of the data signal from the predetermined wireless communication device based on the location of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector; controlling the predetermined wireless communication device to transmit the data signal with the directivity of the antenna directed in a direction from the predetermined wireless communication device toward the estimated location of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal. method. (Appendix 12) Estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the location of the terminal and the locations of the plurality of wireless communication devices; determining an estimated location of the terminal at the time of transmission of the data signal from the predetermined wireless communication device based on the location of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector; controlling the predetermined wireless communication device to transmit the data signal with the directivity of the antenna directed in a direction from the predetermined wireless communication device toward the estimated location of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; A second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal. A non-transitory computer-readable medium on which a program for causing a computer to execute the program is stored. [Explanation of symbols]

[0084] 10. Communication Systems 11...Communication control device, DU 111...first estimation means 112...Second estimation means 113...Control means 12, 12a, 12b, 12c, 12d, 12p...wireless communication device, access point, AP 121...Transmission method 122...Receiving means 13, 13a, 13b, 13c...Terminal, user equipment, UE f1...first frequency f2...second frequency< / ue> < / ap>

Claims

1. a first estimation means for estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; a second estimation means for estimating a position and a velocity vector of the terminal based on positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; a control means for selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the position of the terminal and the positions of the plurality of wireless communication devices, specifying an estimated position of the terminal at the time of transmission of a data signal from the predetermined wireless communication device based on the position of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector, and controlling the predetermined wireless communication device to transmit the data signal by directing the directivity of the antenna in a direction from the predetermined wireless communication device to the estimated position of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; a second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal; Communications control device.

2. The signal delay amount and the relative velocity are estimated based on a position in a delay Doppler space when the reference signal is transmitted from the terminal and a position in the delay Doppler space when the reference signal is received by the wireless communication device. The communication control device according to claim 1 .

3. the control means, instead of selecting a predetermined wireless communication device that is closest to the terminal based on the location of the terminal and the locations of the plurality of wireless communication devices, acquires received power of the reference signal received by the plurality of wireless communication devices from each of the plurality of wireless communication devices, and selects the wireless communication device that received the reference signal with the highest received power among the plurality of received powers as the predetermined wireless communication device.

3. The communication control device according to claim 1 or 2.

4. The relative velocity is calculated from a Doppler shift amount of the orthogonal time-frequency-space modulated reference signal.

4. The communication control device according to claim 1.

5. The antenna is composed of a plurality of antenna elements, The directivity is formed by weighting each of the plurality of antenna elements.

5. The communication control device according to claim 1.

6. A downlink signal from the wireless communication device to the terminal is single-carrier modulated.

6. The communication control device according to claim 1.

7. an uplink time period in which an uplink signal is transmitted from the terminal to the wireless communication device and a downlink time period in which the downlink signal is transmitted are alternately switched; The communication control device according to claim 6.

8. The device itself and the plurality of wireless communication devices are connected by optical cables.

8. The communication control device according to claim 1.

9. A communication control device that controls a plurality of wireless communication devices that communicate with a terminal, Each of the plurality of wireless communication devices a receiving means for receiving, via an antenna, an orthogonal time-frequency-space modulated reference signal transmitted by the terminal; a transmitting means for transmitting a data signal by directing the directivity of the antenna based on control from the communication control device, The communication control device a first estimation means for estimating, for each of the plurality of wireless communication devices, a signal delay amount from the terminal to the antenna and a relative speed between the terminal and the wireless communication device, based on the reference signal received by each of the plurality of wireless communication devices from the terminal; a second estimation means for estimating a position and a velocity vector of the terminal based on positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; a control means for selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the position of the terminal and the positions of the plurality of wireless communication devices, specifying an estimated position of the terminal at the time of transmission of a data signal from the predetermined wireless communication device based on the position of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector, and controlling the predetermined wireless communication device to transmit the data signal by directing the directivity of the antenna in a direction from the predetermined wireless communication device to the estimated position of the terminal, a first frequency is used for signals from the terminal to the wireless communication device; a second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal; Communication system.

10. Estimating, for each of a plurality of wireless communication devices, a signal delay amount from the terminal to an antenna of the wireless communication device and a relative speed between the terminal and the wireless communication device, based on an orthogonal time-frequency-space modulated reference signal received by each of the plurality of wireless communication devices from the terminal; estimating a position and a velocity vector of the terminal based on the positions of the plurality of wireless communication devices, the signal delay amount estimated for each of the plurality of wireless communication devices, and the relative velocity; selecting a predetermined wireless communication device that is closest to the terminal from among the plurality of wireless communication devices based on the location of the terminal and the locations of the plurality of wireless communication devices; determining an estimated location of the terminal at the time of transmission of the data signal from the predetermined wireless communication device based on the location of the terminal at the time of reception of the reference signal to the predetermined wireless communication device and the velocity vector; controlling the predetermined wireless communication device to transmit the data signal with the directivity of the antenna directed in a direction from the predetermined wireless communication device toward the estimated location of the terminal; Equipped with a first frequency is used for signals from the terminal to the wireless communication device; a second frequency higher than the first frequency is used for the signal from the wireless communication device to the terminal; method.

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