Relay device, communication system, and relay method

Abstract

This invention provides a relay device, a communication system, and a relay method that can significantly reduce processing delay and processing costs while utilizing VLC. [Solution] The relay device includes a wireless receiving unit having multiple receiving antennas that receive wireless communication signals by Multiple-Input Multiple-Output, MIMO; a frequency conversion unit that converts the wireless communication signals received via the multiple receiving antennas into individual signals of different frequency bands for each receiving antenna; a radio wave-to-optical conversion unit that converts each of the individual signals into a visible light communication signal using visible light; and a visible light transmission unit that transmits multiple visible light communication signals toward a wireless communication signal destination device.

Description

Technical Field

[0001] The present disclosure relates to a relay device supporting VLC, a communication system, and a relay method.

Background Art

[0002] Visible Light Communication (VLC) is a technology that transmits information using visible light. VLC is a form of wireless communication that does not use an optical fiber or the like, and data can be transmitted and received using a lighting device such as an LED light. VLC enables extremely broadband and high-speed (for example, over 100 Gbps) communication even when compared with wireless communication using radio waves (electromagnetic waves in the frequency range of 3 Hz to 3000 GHz).

[0003] It is known that there are roughly two types of relay methods for conventional wireless communication using radio waves. Specifically, there are an AF (amplified-and-forward) method that amplifies and retransmits the received signal as it is, and a DF (decoded-and-forward); method that demodulates and detects the received signal and then modulates and transmits it again. The DF method can improve the signal-to-noise ratio (SNR) but has a large processing delay. On the other hand, the AF method cannot improve the SNR but has a small processing delay.

[0004] Non-Patent Document 1 proposes applying a wireless signal conforming to the WiFi (registered trademark) specification directly to VLC. In WiFi, advanced technologies such as distributed Massive MIMO (mMIMO: Multiple-Input Multiple-Output) are used to achieve broadband and high-speed.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] In the case of mMIMO, interference rejection between multiple beams is assumed, making relay using the AF method difficult. On the other hand, in the case of DF, reception processing of MIMO signals is required, which leads to problems such as large processing delays and increased processing costs.

[0007] Therefore, the following disclosure is made in light of these circumstances and aims to provide a relay device, communication system, and relay method that can significantly reduce processing delay and processing costs while utilizing VLC. [Means for solving the problem]

[0008] One aspect of the present disclosure is a relay device (relay device 150) comprising: a wireless receiving unit (wireless receiving unit 151) having a plurality of receiving antennas and receiving wireless communication signals by Multiple-Input Multiple-Output, MIMO; a frequency conversion unit (frequency conversion unit 153) that converts the wireless communication signals received via the plurality of receiving antennas into individual signals of different frequency bands for each receiving antenna; a radio wave-to-optical conversion unit (radio wave-to-optical conversion unit 155) that converts each of the individual signals into a visible light communication signal using visible light; and a visible light transmitting unit (visible light transmitting unit 157) that transmits a plurality of the visible light communication signals toward a destination device of the wireless communication signals.

[0009] One aspect of the present disclosure is a communication system (communication system 10) including a terminal (UE 200) and a relay device, wherein the relay device has a plurality of receiving antennas and comprises a wireless receiving unit that receives wireless communication signals by Multiple-Input Multiple-Output, MIMO, a frequency conversion unit that converts the wireless communication signals received via the plurality of receiving antennas into individual signals of different frequency bands for each of the receiving antennas, a radio wave-to-optical conversion unit that converts each of the individual signals into a visible light communication signal using visible light, and a visible light transmitting unit that transmits a plurality of the visible light communication signals to a destination device of the wireless communication signals, and the terminal comprises a visible light receiving unit (visible light receiving unit 210) that receives the visible light communication signals, an optical-to-radio wave conversion unit (optical-to-radio wave conversion unit 220) that converts the visible light communication signals into a plurality of the individual signals, a frequency inverse conversion unit (frequency inverse conversion unit 230) that converts a plurality of the individual signals into the wireless communication signal, and a receiving processing unit (receiving processing unit 240) that receives and processes the wireless communication signals according to MIMO. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of the overall configuration of the communication system 10. [Figure 2] Figure 2 shows an example of a connection configuration between multiple wireless base stations 50 and a VLC-AP 100. [Figure 3]Figure 3 is a functional block diagram of the relay device 150. [Figure 4] Figure 4 is a functional block diagram of the UE 200. [Figure 5] Figure 5 shows an example of the conversion operation from wireless communication signal to visible light communication signal related to Operation Example 1. [Figure 6] Figure 6 shows an example of the conversion operation from wireless communication signal to visible light communication signal related to Operation Example 2. [Figure 7] Figure 7 shows an example of the hardware configuration of the relay device 150 and UE 200. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the drawings. Note that identical or similar reference numerals are used to denote the same functions and components, and their descriptions will be omitted as appropriate.

[0012] (1) Overall outline of the communication system Figure 1 is a schematic diagram of the overall configuration of the communication system 10 according to this embodiment. The communication system 10 uses a combination of Visible Light Communication (VLC) and radio wave wireless communication technologies. VLC is a form of wireless communication that does not use optical fibers or the like, and can send and receive data using lighting devices such as LED lights. In particular, the VLC according to this embodiment can achieve a high transmission speed (data rate), and enables extremely wideband and high-speed communication (for example, over 100 Gbps) compared to wireless communication using radio waves (electromagnetic waves with frequencies in the range of 3 Hz to 3000 GHz).

[0013] The visible light used in VLCs generally refers to light with wavelengths ranging from approximately 380 nanometers (nm) to 750 nanometers (nm), which corresponds to the range of light visible to the human eye. Visible light does not need to include ultraviolet or infrared light.

[0014] Wireless communication using radio waves can typically be interpreted as wireless communication using a mobile communication network, which is a wireless network used for voice calls and data communication using mobile devices such as mobile phones and smartphones. A mobile communication network may also be called a Public Land Mobile Network (PLMN). The frequency bands used by mobile communication networks include the low frequency band: 600 MHz to 1 GHz, the medium frequency band: 3.5 GHz to 4.7 GHz, and the high frequency band (millimeter wave): 24 GHz to 40 GHz. Mobile communication networks may comply with the technical specifications of the 3rd Generation Partnership Project (3GPP: registered trademark), such as 4G (LTE), 5G, or 6G.

[0015] Furthermore, the wireless network using radio waves does not necessarily have to be a mobile communication network; for example, a network conforming to the technical specifications of other wireless communication technologies, such as wireless LAN (Wi-Fi®), may also be used.

[0016] As shown in Figure 1, the communication system 10 includes a communication network 20. The communication network 20 may include a part of the mobile communication network described above, and may also include other wireless networks and wired networks.

[0017] The communication system 10 may include a CCU 30 and a radio base station 50 as entities (which may also be called nodes) on the mobile communication network side. The CCU 30 (Central Control Unit) is one of the control elements of the mobile communication network and may also be called a communication control device. The CCU 30 has the function of controlling the mobile communication network and may be implemented by entities (which may also be called Functions) that constitute the radio access network (RAN) or core network (CN).

[0018] The radio base station 50 performs wireless communication using radio waves with the terminal 200 (User Equipment 200, hereinafter referred to as UE 200). The radio base station 50 may be referred to as a gNodeB (gNB), an access point (AP), etc. Note that the radio base station 50 may be referred to as a radio access point.

[0019] The radio base station 50 may support Massive MIMO (Multiple-Input Multiple-Output) that generates a more directional beam by controlling wireless signals transmitted from a plurality of antenna elements, carrier aggregation (CA) that bundles and uses a plurality of component carriers (CC), etc.

[0020] Also, the radio base station 50 can be connected to the relay device 150 by wireless communication using radio waves. The wireless communication using radio waves may be wireless communication according to a mobile communication network or may be a wireless LAN or the like. Massive MIMO may be applied to the wireless communication.

[0021] The relay device 150 relays the downlink (DL) data for the UE 200 received from the radio base station 50. The relay device 150 converts the wireless communication signal received from the radio base station 50 into a visible light communication signal and transmits the converted visible light communication signal toward the UE 200.

[0022] [[ID=1,6]]UE 200 may be referred to as a user device, a user apparatus, etc., and is a mobile device that can move. UE 200 may be a portable terminal or may be for IoT (Internet of Things) devices such as in-vehicle terminals.

[0023] The UE 200 has wireless communication capabilities via a mobile communication network, as well as visible light communication capabilities using VLC. Specifically, the UE 200 can send and receive radio signals using radio waves via the radio base station 50. In other words, the UE 200 may support communication in both the downlink (DL) and uplink (UL) directions via a mobile communication network.

[0024] Furthermore, UE 200 can receive visible light communication signals from the relay device 150. In other words, UE 200 can support DL direction communication using VLC. Note that UE 200 may also support UL direction VLC communication, but in this embodiment, it may be assumed that UL direction communication will utilize a mobile communication network.

[0025] Figure 2 shows an example of a connection configuration between multiple radio base stations 50 and a VLC-AP 100. As shown in Figure 2, the VLC-AP 100 may be connected to multiple upstream radio base stations 50 (#1 to #3). The VLC-AP 100 is a visible light communication access point (AP). The VLC-AP 100 can perform visible light communication using visible light communication signals directed toward the UE 200. In this way, the VLC-AP 100 supports visible light communication in the DL direction. On the other hand, the mobile communication network (CCU 30 and radio base stations 50) may support wireless communication using radio waves in the UL and DL directions. The VLC-AP 100 may also implement the functions of the relay device 150 described above.

[0026] (2) Functional block configuration of the communication system 10 Next, the functional block configuration of the communication system 10 will be described. Specifically, the functional block configurations of the relay device 150 and the UE 200 will be described. Figure 3 is a functional block configuration diagram of the relay device 150. Figure 4 is a functional block configuration diagram of the UE 200. Note that Figures 3 and 4 only show the main functional blocks relevant to the description of the embodiment, and the relay device 150 and UE 200 have other functional blocks (for example, a power supply unit).

[0027] (2.1) Relay device 150 As shown in Figure 3, the relay device 150 includes a wireless receiving unit 151, a frequency conversion unit 153, a radio wave-to-optical conversion unit 155, a visible light transmission unit 157, and a multiplexing unit 159.

[0028] The wireless receiver 151 has multiple receiving antennas and receives wireless communication signals using Multiple-Input Multiple-Output (MIMO). These receiving antennas may also be called antenna arrays or array antennas, and by controlling their directional characteristics, they can receive wireless communication signals (which may be interpreted as radio waves, beams, etc.) arriving from different directions.

[0029] It is desirable that the multiple receiving antennas be installed at different locations. These different locations refer to geographical locations, and only differ in longitude, latitude, or altitude. Furthermore, the multiple receiving antennas may be pointed in different directions. Specifically, this can be done by having different azimuths or elevations.

[0030] There are no specific restrictions on the number of receiving antennas, but for MIMO, 2 to 8 antennas are acceptable, and for mMIMO, 64 or 128 antennas are acceptable.

[0031] The frequency conversion unit 153 converts the wireless communication signals received by the wireless receiver unit 151 via multiple receiving antennas into individual signals in different frequency bands for each receiving antenna. Specifically, the frequency conversion unit 153 converts the received signals output from each receiving antenna into signals in different (non-overlapping) frequency bands. Such a conversion may also be called frequency conversion and may be interpreted as converting to signals having different wavelengths.

[0032] For example, if you have four receiving antennas, the received signals output from each receiving antenna (which at this point include interference from MIMO (multiple transmitting antennas)) are converted into signals of different frequency bands (wavelengths) (individual signals). Specific examples of this conversion will be discussed further later.

[0033] The frequency conversion unit 153 may determine the number of individual signals to be multiplexed as a visible light communication signal based on the number of individual signals that the UE 200 can process in parallel. Specifically, the frequency conversion unit 153 may determine the number of individual signals to be multiplexed at or below the number of processing capabilities provided by the multiplexing number acquisition unit 159.

[0034] The radio wave-to-optical conversion unit 155 converts each of the individual signals whose frequency has been converted by the frequency conversion unit 153 into a visible light communication signal using visible light. The radio wave-to-optical conversion unit 155 converts the frequency-converted individual signals (which can be interpreted as wireless communication signals using radio waves) into a visible light communication signal using visible light (i.e., conversion from radio waves to visible light). Note that the visible light communication signal may also contain MIMO interference, similar to the individual signals.

[0035] The visible light transmitting unit 157 transmits a plurality of visible light communication signals converted by the radio wave-to-optical conversion unit 155 toward the UE 200. Specifically, the visible light transmitting unit 157 may transmit the plurality of visible light communication signals toward the UE 200, which is the destination device (destination) of the wireless communication signal received by the wireless receiving unit 151.

[0036] The visible light communication signal is not particularly limited as long as it uses the wavelengths described above, but in this embodiment, it is desirable that the VLC can achieve wireless communication with extremely wide bandwidth and high speed (e.g., over 100 Gbps) compared to the transmission speed achievable by mobile communication networks.

[0037] As mentioned above, the coverage of visible light communication signals is generally much narrower than the coverage of the cell (beam) formed by the radio base station 50. The visible light transmission unit 157 often transmits visible light communication signals using a single visible light communication element, but it may also transmit visible light communication signals using multiple visible light communication elements.

[0038] The visible light transmission unit 157 may transmit a visible light communication signal in which a reference signal (RS) used for processing visible light communication is multiplexed (frequency multiplexed). The reference signal may be interpreted as a pilot signal that serves as a reference for identifying the position (wavelength) of each of multiple visible light communication signals with different wavelengths. The reference signal may be provided in association with the visible light communication signal for each wavelength used. An example of multiplexing of the reference signal will be described later.

[0039] Furthermore, the visible light transmitter 157 may transmit a visible light communication signal in which control signals used for controlling visible light communication are multiplexed, in the same manner as the reference signal. The purpose of the control signals is not particularly limited, but for example, they may be used for the control and reception processing of visible light communication signals and wireless communication signals in the UE 200.

[0040] The multiplexing unit 159 acquires the number of individual signals that the UE 200, which is the destination device (destination) for the wireless communication signals received by the wireless receiver unit 151, can process in parallel. Specifically, the multiplexing unit 159 can provide the frequency conversion unit 153 with the number of processing capabilities that has been fed back (reported) from the UE 200.

[0041] The UE 200 may report the number of items that can be processed via UL to the radio base station 50. The number of items that can be processed may be notified from the radio base station 50 to the relay device 150. Alternatively, if VLC in the UL direction is supported, the number of items that can be processed may be fed back directly from the UE 200 to the relay device 150.

[0042] (2.2)UE 200 As shown in Figure 4, the UE 200 includes a visible light receiving unit 210, a wireless communication unit 215, an optical-to-radio wave conversion unit 220, a frequency inverse conversion unit 230, and a reception processing unit 240.

[0043] The visible light receiver 210 receives visible light communication signals from the relay device 150. Specifically, the visible light receiver 210 supports VLC and receives visible light communication signals in the DL direction. Because visible light communication signals have strong directivity, their coverage is usually narrower than that of the radio signals (beams) transmitted by the radio base station 50.

[0044] Furthermore, as described above, the visible light communication signal transmitted from the relay device 150 can be interpreted as a multiplexing of multiple visible light communication signals using different wavelengths corresponding to multiple individual signals.

[0045] The wireless communication unit 215 transmits and receives wireless communication signals in accordance with the specifications of the mobile communication network. Specifically, the wireless communication unit 215 can transmit wireless communication signals using radio waves toward the radio base station 50. In addition, the wireless communication unit 215 can receive wireless communication signals using radio waves from the radio base station 50. In other words, the wireless communication unit 215 can transmit wireless communication signals in the UL direction to the mobile communication network and receive wireless communication signals in the DL direction from the mobile communication network.

[0046] The optical-to-radio wave conversion unit 220 converts the visible light communication signal received by the visible light receiving unit 210 into multiple individual signals. Specifically, the optical-to-radio wave conversion unit 220 performs the reverse processing of the radio wave-to-optical conversion unit 155 of the relay device 150. More specifically, the optical-to-radio wave conversion unit 220 converts each of the multiple visible light communication signals with different wavelengths into multiple individual signals in frequency bands associated with each of the receiving antennas of the relay device 150.

[0047] The frequency inverse converter 230 converts the multiple individual signals output from the optical-to-radio wave converter 220 into wireless communication signals in the frequency band used by wireless communication using radio waves. Specifically, the frequency inverse converter 230 performs the reverse processing of the frequency converter 153 of the relay device 150. More specifically, the frequency inverse converter 230 converts the individual signals in different frequency bands for each receiving antenna into wireless communication signals in the frequency band received via the receiving antenna.

[0048] The receiving processing unit 240 receives and processes the wireless communication signal output from the frequency inverse conversion unit 230 according to MIMO. Specifically, the receiving processing unit 240 uses the multiple wireless communication signals received by each receiving antenna to perform MIMO interference removal, demodulates the wireless communication signal, and obtains DL data.

[0049] (3) Operation of the communication system 10 Next, the operation of the communication system 10 will be described. Specifically, the operation of the relay device 150 converting wireless communication signals to visible light communication signals and relaying the converted visible light communication signals to the UE 200 will be described.

[0050] (3.1) Operation overview The relay device 150 bundles wireless communication signals transmitted from multiple mMIMO APs (radio base stations 50, Radio APs), relays them using visible light communication, and achieves ultra-high-speed data communication.

[0051] Specifically, the relay device 150 (which may also be called a VLC relay) receives wireless communication signals (radio signals) from each mMIMO AP using different antenna arrays (which may be interpreted as multiple receiving antennas). However, multiple different wireless communication signals may interfere with each other in the receiving antenna arrays.

[0052] The received signals output from each receiving antenna are frequency-converted into visible light communication signals in different visible light bands (i.e., different wavelengths). The relay device 150 may simply frequency-convert the received wireless communication signal and convert it into a visible light communication signal in the visible light band.

[0053] The signal that corresponds to the receiving antenna and has been frequency-converted may be called an individual signal, as described above. Furthermore, a reference signal (and / or control signal) may be multiplexed into multiple visible light communication signals corresponding to such individual signals. Specifically, the reference signal may be inserted into the visible light communication signal by frequency multiplexing.

[0054] The UE 200 supports visible light communication and receives visible light communication signals. The UE 200 receives the visible light communication signal and can separate the signals (remove interference) by applying MIMO signal processing to the converted individual signals. The UE 200 can also feed back to the relay device 150 the number of individual signals that can be multiplexed into the visible light communication signal that can be processed. As described above, this number of processing capabilities may be determined based on the number of individual signals that the UE 200 can process in parallel.

[0055] The relay device 150 can convert the mMIMO wireless communication signal into a visible light communication signal and relay it to the UE 200. This enables ultra-high-speed, high-capacity wireless communication using a low-latency, low-cost relay method utilizing VLC.

[0056] (3.2) Example of operation (3.2.1) Example of operation 1 Figure 5 shows an example of the conversion operation from wireless communication signals to visible light communication signals related to Operation Example 1. As shown in Figure 5, wireless communication signals transmitted from multiple mMIMO APs (wireless base station 50, Radio AP, APs 1 to 4 in the figure) may be received by multiple receiving antennas (Rx E1 to Rx E4) of the relay device 150.

[0057] The signals (individual signals) output from the multiple receiving antennas (subarrays) may be directly frequency-converted to different frequency bands (wavelengths) and transmitted to the UE 200 as visible light communication signals. This frequency conversion may be interpreted as conversion to the visible light band. It is desirable that each individual signal be frequency-converted to frequency bands (wavelengths) where the operating bands (wavelengths) do not overlap, taking bandwidth into consideration.

[0058] UE 200 may receive a visible light communication signal from the relay device 150, perform MIMO processing (assuming the UE has MIMO processing capability), and acquire DL data.

[0059] Furthermore, since the spatial multiplexing number for radio wave communication, or the frequency multiplexing number for visible light communication signals (multiplexing number of individual signals) is determined by the processing capacity of UE 200, UE 200 may feed back the number of individual signals (processable number) to the relay device 150, and the multiplexing number may be determined according to the processing capacity of UE 200 (adaptive multiplexing).

[0060] With the operation of the relay device 150 and UE 200, wireless communication signals received from multiple mMIMO APs are directly converted into visible light communication signals, enabling low-latency and low-cost relaying. Furthermore, interference between APs can be eliminated by the MIMO reception processing in the UE 200, so it can directly support MIMO as used in mobile communication networks and other applications.

[0061] (3.2.2) Example of operation 2 Figure 6 shows an example of the conversion operation from wireless communication signal to visible light communication signal related to Operation Example 2. The following mainly explains the differences from Operation Example 1.

[0062] In this example, a reference signal (which may also be a control signal) is multiplexed in the visible light band used by the visible light communication signal. As shown in Figure 6, it is desirable that the wavelength (frequency) of the reference signal be close to the wavelength of the individual signal corresponding to each receiving antenna, through frequency multiplexing (which may also be called wavelength multiplexing).

[0063] Although Figure 6 shows an example where a reference signal is inserted for each individual signal, the reference signal may also be inserted for multiple individual signals (for example, for the receiving antennas corresponding to AP1 and AP2 and the corresponding individual signals).

[0064] By multiplexing such reference signals (or control signals), the UE 200 can achieve higher quality conversion from individual signals to wireless communication signals, thereby improving the reliability of DL transmission by VLC via the relay device 150.

[0065] (4) Other embodiments Although embodiments have been described above, it will be obvious to those skilled in the art that the invention is not limited to those embodiments described and that various modifications and improvements are possible.

[0066] For example, in the embodiment described above, the relay device 150 supported communication only in the DL direction, but it may also support communication in the UL direction. Specifically, the relay device 150 may support receiving visible light communication signals in the UL direction, converting visible light communication signals to wireless communication signals, and transmitting wireless communication signals to multiple mMIMO APs.

[0067] For example, in the above description, configure, activate, update, indicate, enable, specify, and select may be interpreted as interchangeable. Similarly, link, associate, correspond, and map may be interpreted as interchangeable, and allocate, assign, monitor, and map may also be interpreted as interchangeable.

[0068] Furthermore, "specific," "dedicated," "UE specific," and "UE individual" may be interpreted interchangeably. Similarly, "common," "shared," "group-common," "UE common," and "UE shared" may be interpreted interchangeably.

[0069] In this disclosure, terms such as "precoding," "precoder," "weight (precoding weight)," "quasi-co-location (QCL)," "transmission configuration indication state (TCI state)," "spatial relation," "spatial domain filter," "transmit power," "phase rotation," "antenna port," "antenna port group," "layer," "number of layers," "rank," "resource," "resource set," "resource group," "beam," "beam width," "beam angle," "antenna," "antenna element," and "panel" may be used interchangeably.

[0070] Furthermore, the block diagrams (Figures 3 and 4) used in the description of the embodiments above show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Moreover, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may also be realized by combining the above one device or the above multiple devices with software.

[0071] Functions include, but are not limited to, judgment, decision, judgment, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In any case, as mentioned above, the method of implementation is not particularly limited.

[0072] Furthermore, the relay device 150 and UE 200 (the device) described above may function as a computer that processes the wireless communication method of this disclosure. Figure 7 shows an example of the hardware configuration of the device. As shown in Figure 7, the device may be configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, and bus 1007.

[0073] In the following explanation, the term "device" can be replaced with "circuit," "device," "unit," etc. The hardware configuration of the device may include one or more of the devices shown in the diagram, or it may be configured to omit some of the devices.

[0074] Each functional block of the device (see Figures 3 and 4) is implemented by any hardware element of the computer device, or a combination of such hardware elements.

[0075] Furthermore, each function in the device is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of data reading and writing in the memory 1002 and storage 1003.

[0076] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control units, arithmetic units, registers, and so on.

[0077] Furthermore, the processor 1001 reads programs (program code), software modules, data, etc., from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. Moreover, the above-mentioned various processes may be executed by one processor 1001, or by two or more processors 1001 simultaneously or sequentially. The processor 1001 may be implemented by one or more chips. The program may be transmitted from a network via a telecommunications line.

[0078] Memory 1002 is a computer-readable recording medium and may consist of at least one of the following: Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), Random Access Memory (RAM), etc. Memory 1002 may also be called a register, cache, main memory, etc. Memory 1002 can store a program (program code), software modules, etc., that can execute a method according to one embodiment of this disclosure.

[0079] Storage 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disc, a digital multipurpose disc, a Blu-ray® disc), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. Storage 1003 may also be called an auxiliary storage device. The recording medium described above may also be, for example, a database, server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0080] The communication device 1004 is hardware (transceiver / receiver device) for communicating between computers via at least one of a wired network and a wireless network, and is also called a network device, network controller, network card, communication module, etc.

[0081] The communication device 1004 may be configured to include, for example, a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD).

[0082] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0083] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0084] Furthermore, the device may include hardware such as a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), and a field-programmable gate array (FPGA), and some or all of each functional block may be implemented by such hardware. For example, processor 1001 may be implemented using at least one of these hardware components.

[0085] Furthermore, notification of information is not limited to the embodiments / models described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), upper layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or combinations thereof. RRC signaling may also be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0086] Each aspect / embodiment described herein may be applied to at least one of systems utilizing Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (where x is, for example, an integer or decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA®, GSM®, CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G).

[0087] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0088] The specific operations described in this disclosure as being performed by a base station may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal can be performed by the base station and at least one other network node (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station, it may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0089] Information and signals (such as data) can be output from a higher layer (or lower layer) to a lower layer (or higher layer). Input and output may occur via multiple network nodes.

[0090] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be sent to other devices.

[0091] The determination may be made by a value represented by 1 bit (0 or 1), by a boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0092] Each aspect / embodiment described herein may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0093] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0094] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0095] The information, signals, etc. described in this disclosure may be represented using any of the various different technologies. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0096] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0097] The terms “system” and “network” as used in this disclosure are interchangeable.

[0098] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0099] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Since various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, the various names assigned to these various channels and information elements are not restrictive in any way.

[0100] In this disclosure, terms such as "Base Station (BS)," "wireless base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0101] A base station can house one or more (e.g., three) cells (also called sectors). If a base station houses multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0102] The terms "cell" or "sector" refer to a portion or all of the coverage area of ​​at least one of the base stations and base station subsystems that provide communication services in this coverage.

[0103] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform information-based control or operation.

[0104] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0105] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate term.

[0106] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station may include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0107] Furthermore, the term "base station" in this disclosure may be interpreted as "mobile station" (user terminal, hereinafter the same). For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.). In this case, the mobile station may have the functions that a base station has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc. may be interpreted as side channel (or side link).

[0108] Similarly, the term "mobile station" in this disclosure may be interpreted as "base station." In this case, the base station may be configured to have the functions that a mobile station has.

[0109] A wireless frame may consist of one or more frames in the time domain. Each of these one or more frames in the time domain may be called a subframe. A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0110] Numerology may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerology may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain.

[0111] A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol). A slot may also be a time unit based on neurology.

[0112] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. Minislots may also be called subslots. Minislots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called a PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called a PDSCH (or PUSCH) mapping type B.

[0113] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms.

[0114] For example, one subframe may be called a Transmit Time Interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0115] Here, TTI refers to, for example, the smallest unit of time for scheduling in wireless communication. For example, in an LTE system, the base station schedules each user terminal to allocate wireless resources (such as the frequency bandwidth and transmission power available to each user terminal) in TTI units. However, the definition of TTI is not limited to this.

[0116] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. Given a TTI, the actual time interval (e.g., number of symbols) to which the transport block, code block, code word, etc. are mapped may be shorter than the given TTI.

[0117] Furthermore, if one slot or one mini-slot is referred to as TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit of scheduling. In addition, the number of slots (number of mini-slots) that constitute this minimum time unit of scheduling may be controlled.

[0118] A TTI with a time length of 1ms may also be called a normal TTI, long TTI, normal subframe, long subframe, slot, etc. A TTI shorter than a normal TTI may also be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, mini slot, sub slot, slot, etc.

[0119] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0120] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0121] Furthermore, the time domain of the RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks.

[0122] One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc.

[0123] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0124] A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a given neurology on a given carrier. Here, the common RBs may be identified by an index of the RBs relative to the carrier's common reference point. PRBs may be defined and numbered within a BWP.

[0125] A BWP may include BWPs for UL (UL BWP) and BWPs for DL ​​(DL BWP). One or more BWPs may be set within a single carrier for a UE.

[0126] At least one of the configured BWPs may be active, and the UE does not need to assume that it will send or receive a given signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0127] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within the TTI can be varied in various ways.

[0128] The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0129] The reference signal can also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

[0130] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0131] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0132] Any reference to elements using designations such as “First,” “Second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the First and Second elements do not imply that only two elements may be employed therein, or that the First element must precede the Second element in any way.

[0133] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0134] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0135] The terms “determining” and “determining” as used in this disclosure may encompass a wide variety of actions. “Determining” and “determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” and “determining” may also include, for example, receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having "judgmented" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having "judgmented" or "decided" about some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0136] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0137] (Note) The above disclosure may also be expressed as follows: The first feature is a relay device comprising: a wireless receiving unit having a plurality of receiving antennas and receiving wireless communication signals by Multiple-Input Multiple-Output, MIMO; a frequency conversion unit converting the wireless communication signals received via the plurality of receiving antennas into individual signals of different frequency bands for each receiving antenna; a radio wave-to-optical conversion unit converting each of the individual signals into a visible light communication signal using visible light; and a visible light transmitting unit that transmits a plurality of the visible light communication signals toward a destination device of the wireless communication signals.

[0138] The second feature is that, in the first feature, the system includes a multiplexing unit that acquires the number of individual signals that the destination device can process in parallel, and the frequency conversion unit determines the number of multiplexing units of the individual signals to be multiplexed as a visible light communication signal based on the number of possible processing units.

[0139] The third feature is that, in the first or second feature, the visible light transmitting unit transmits the visible light communication signal, which is multiplexed with a reference signal used for processing visible light communication.

[0140] The fourth feature is that, in the first to third features, the visible light transmitting unit transmits the visible light communication signal, which is multiplexed with control signals used for controlling visible light communication.

[0141] The fifth feature is that, in the first to fourth features, the multiple receiving antennas are each provided at different locations.

[0142] The sixth feature is that, in the first to fifth features, the multiple receiving antennas each point in a different direction. [Explanation of symbols]

[0143] 10 Communication Systems 20 Communication Networks 30 CCU 50 Wireless base stations 100 VLC-AP 150 relay devices 151 Wireless Receiver 153 Frequency conversion section 155 Radio wave-to-optical conversion unit 157 Visible light transmitter 159 Multiplex number acquisition unit 200 UE 210 Visible light receiving unit 215 Wireless Communication Section 220 Optical-to-Radio Wave Conversion Unit 230 Frequency Inverse Transformer 240 Receiving Processing Unit 1001 Processor 1002 memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus

Claims

1. A wireless receiver unit having multiple receiving antennas and receiving wireless communication signals via Multiple-Input Multiple-Output, MIMO, A frequency conversion unit that converts the wireless communication signals received via the plurality of receiving antennas into individual signals of different frequency bands for each receiving antenna, A radio wave-to-optical conversion unit converts each of the aforementioned individual signals into a visible light communication signal using visible light, A visible light transmitting unit that transmits multiple visible light communication signals toward the wireless communication signal receiving device, A relay device equipped with the following features.

2. The system includes a multiplexing unit that acquires the number of individual signals that the destination device can process in parallel, The relay device according to claim 1, wherein the frequency conversion unit determines the number of times the individual signals are multiplexed as a visible light communication signal based on the number of times that can be processed.

3. The relay device according to claim 1, wherein the visible light transmitting unit transmits the visible light communication signal, which is multiplexed with a reference signal used for processing visible light communication.

4. The relay device according to claim 1, wherein the visible light transmitting unit transmits the visible light communication signal, which is multiplexed with control signals used for controlling visible light communication.

5. The relay device according to claim 1, wherein the plurality of receiving antennas are each provided at different locations.

6. The relay device according to claim 1, wherein the plurality of receiving antennas each point in a different direction.

7. A communication system including terminals and relay devices, The relay device is, A wireless receiver unit having multiple receiving antennas and receiving wireless communication signals via Multiple-Input Multiple-Output, MIMO, A frequency conversion unit that converts the wireless communication signals received via the plurality of receiving antennas into individual signals of different frequency bands for each receiving antenna, A radio wave-to-optical conversion unit converts each of the aforementioned individual signals into a visible light communication signal using visible light, A visible light transmitting unit that transmits multiple visible light communication signals toward the wireless communication signal receiving device, Equipped with, The aforementioned terminal is A visible light receiving unit that receives the aforementioned visible light communication signal, An optical-to-radio wave conversion unit that converts the visible light communication signal into a plurality of individual signals, A frequency inverse converter that converts multiple individual signals into wireless communication signals, A receiving processing unit that receives and processes the aforementioned wireless communication signal in accordance with MIMO. A communication system equipped with [the following features].

8. The process involves having multiple receiving antennas and receiving wireless communication signals using Multiple-Input Multiple-Output, MIMO, The steps include converting the wireless communication signal received through the plurality of receiving antennas into individual signals of different frequency bands for each receiving antenna, The steps include converting each of the individual signals into a visible light communication signal using visible light, The steps include transmitting a plurality of the visible light communication signals toward the wireless communication signal receiving device, and A relay method in a relay device including a relay device.

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