Communication equipment and communication methods

Abstract

The present invention provides a communication device and communication method that can significantly suppress data retransmission delays even when frame-by-frame automatic retransmission control is applied. [Solution] The communication device comprises a visible light communication unit that performs visible light communication using visible light, and a wireless communication unit that performs wireless communication using radio waves in a first direction and a second direction opposite to the first direction. The visible light communication unit performs visible light communication to which a first frame length applied in the time direction is applied, and the wireless communication unit performs wireless communication to which a second frame length longer than the first frame length is applied, and in the second direction, a subframe having a frame length shorter than the second frame length is applied.

Description

Technical Field

[0001] The present disclosure relates to a communication device and a communication method that support VLC.

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, exceeding 100 Gbps) communication compared to wireless communication using radio waves (electromagnetic waves in the frequency range of 3 Hz to 3000 GHz).

[0003] Therefore, there has been a search for applying VLC to a mobile communication network, which is a wireless network for performing voice calls and data communication using a mobile device such as a mobile phone or a smartphone (Non-Patent Documents 1 to 3). For example, a configuration is known in which broadband and high-speed VLC is applied to the downlink (DL), and wireless communication or infrared communication (IR) is applied to the uplink (UL).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

[0005] As mentioned above, when VLC is combined with wireless communication, the frame length in the direction using wireless communication (e.g., UL) becomes extremely long compared to the frame length in the direction using high-speed VLC (e.g., DL). For example, the frame length of UL is expected to be several tens of times longer than the frame length of DL.

[0006] Therefore, when Time Division Duplex (TDD) is applied to a communication system combining VLC and wireless communication, it relies on frame-by-frame retransmission via Automatic Repeat Request (ARQ). As a result, a long time is required between the transmission of a Negative Acknowledgement (NACK) via UL and the actual retransmission of the data. This raises concerns that the wideband and high-speed characteristics of VLC may not be fully utilized.

[0007] Therefore, the following disclosure is made in light of these circumstances and aims to provide a communication device and communication method that can significantly suppress data retransmission delays even when frame-by-frame automatic retransmission control is applied. [Means for solving the problem]

[0008] One aspect of the present disclosure is a communication device (e.g., UE 200) comprising: a visible light communication unit (visible light receiving unit 210) that performs visible light communication using visible light in a first direction which is either a downlink or an uplink; and a wireless communication unit (wireless communication unit 220) that performs wireless communication using radio waves in the first direction and a second direction opposite to the first direction, wherein the visible light communication unit performs the visible light communication using a first frame length applied in the time direction, the wireless communication unit performs the wireless communication using a second frame length longer than the first frame length, and in the second direction, a subframe having a frame length shorter than the second frame length is applied. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of the overall configuration of the communication system 10. [Figure 2] Figure 2 is a functional block diagram of the UE 200. [Figure 3] Figure 3 shows an example of conventional automatic retransmission control when VLC is applied in the DL direction and radio-based wireless communication is applied in the UL and DL directions. [Figure 4] Figure 4 shows an example of automatic retransmission control related to the operation example. [Figure 5] Figure 5 shows an example of automatic retransmission control related to the operation example (when the delay until retransmission is minimized). [Figure 6] Figure 6 shows an example of automatic retransmission control related to the operation example (when the delay until retransmission is at its maximum). [Figure 7] Figure 7 shows an example of the hardware configuration of the wireless base station 50, VLC-AP 100, and UE 200. [Modes for carrying out the invention]

[0010] 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.

[0011] (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).

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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 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 a radio access network (RAN) or core network (CN).

[0017] 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 called a gNodeB (gNB), an access point (AP), etc. Note that the radio base station 50 may be called a radio access point from the perspective of distinguishing it from the VLC-AP 100.

[0018] The radio base station 50 may support Massive MIMO (Multiple-Input Multiple-Output) that generates a more directional beam by controlling radio signals transmitted from a plurality of antenna elements, carrier aggregation (CA) that bundles and uses a plurality of component carriers (CC), etc.

[0019] The communication system 10 may include a router 60 and a VLC-AP 100 as VLC-side entities. The router 60 can perform routing, priority control, etc. of packets transmitted and received by the VLC-AP 100. Note that depending on the network configuration, the router 60 may not necessarily be provided.

[0020] The CCU 30 and the router 60 (or the VLC-AP 100) may be directly connected by the optical fiber 40. Of course, the CCU 30 and the router 60 can also communicate via the communication network 20.

[0021] The VLC-AP 100 is an access point (AP) for visible light communication. The VLC-AP 100 can transmit a visible light communication signal using visible light toward the UE 200. Thus, the VLC-AP 100 supports visible light communication in the downlink (DL) direction. On the other hand, the mobile communication network (the CCU 30 and the radio base station 50) may support wireless communication using radio waves in the uplink (UL) and DL directions.

[0022] The UE 200, also known as user equipment or user device, is a mobile device that can be moved. The UE 200 may be a portable terminal or an IoT (Internet of Things) device such as an in-vehicle terminal.

[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 transmit and receive radio signals using radio waves via the radio base station 50. In other words, the UE 200 may support DL and UL communication via a mobile communication network.

[0024] Furthermore, the UE 200 can receive visible light communication signals via the VLC-AP 100. In other words, the UE 200 can support DL-direction communication via VLC. Note that the UE 200 (and VLC-AP 100) may also support UL-direction VLC communication, but in this embodiment, it is assumed that UL-direction communication will utilize a mobile communication network.

[0025] However, VLC may be applied in the UL direction and radio-based wireless communication may be applied in the DL direction. In this case, the radio base station 50 and / or VLC-AP 100 may have functions similar to those of the UE 200 described later. From this perspective, the radio base station 50, VLC-AP 100 and UE 200 may function as communication devices to which the subframes described later can be applied.

[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 configuration of the UE 200 will be described. Figure 2 is a functional block configuration diagram of the UE 200. Note that Figure 2 shows only the main functional blocks related to the description of the embodiment, and the UE 200 has other functional blocks (for example, a power supply unit).

[0027] As shown in Figure 2, the UE 200 includes a visible light receiving unit 210, a wireless communication unit 220, and a control unit 230.

[0028] The visible light receiving unit 210 receives a visible light communication signal in the DL direction transmitted from the VLC-AP 100, which is a visible light communication access point. The visible light receiving unit 210 may perform visible light communication using visible light in the DL direction (first direction). In this embodiment, the visible light receiving unit 210 may constitute a visible light communication unit that performs visible light communication using visible light in the first direction, which is either a downlink or an uplink. In this embodiment, the first direction may be the DL direction, and the second direction may be the UL direction.

[0029] The visible light receiving unit 210 may perform visible light communication to which a frame, which is a predetermined time frame in the direction of time, is applied. Specifically, the visible light receiving unit 210 may receive a visible light communication signal to which a predetermined frame length (referred to as the first frame length) applied in the direction of time is applied. Since DL by VLC is extremely fast, the predetermined frame length (first frame length) may be extremely short. For example, the wireless frame length of a mobile communication network (e.g., 5G) is about 10 milliseconds, and the subframe length is about 1 millisecond, but the predetermined frame length may be significantly shorter than this (e.g., half).

[0030] The wireless communication unit 220 transmits wireless communication signals in accordance with the specifications of the mobile communication network. Specifically, the wireless communication unit 220 can transmit wireless communication signals using radio waves toward the radio base station 50. In other words, the wireless communication unit 220 may transmit wireless communication signals in the UL direction toward the mobile communication network. The wireless communication unit 220 may also receive wireless communication signals in the DL direction transmitted from the radio base station 50.

[0031] Thus, the wireless communication unit 220 may perform wireless communication in accordance with the specifications of the mobile communication network in the DL and UL directions. That is, the wireless communication unit 220 can perform wireless communication using radio waves in the first direction (DL) and the second direction (UL) opposite to the first direction. Time division duplexing (TDD) may be applied to UL and DL.

[0032] The wireless communication unit 220 may perform wireless communication by applying a frame length (second frame length) that is longer than the first frame length applied to the visible light communication signal. As mentioned above, the wireless frame length of 5G is about 10 milliseconds, and the subframe length is about 1 millisecond.

[0033] Thus, the wireless communication unit 220 normally performs wireless communication by applying a frame length longer than the frame length applied to the visible light communication signal. However, in this embodiment, a shorter frame length may be applied in the UL direction (second direction). Specifically, the wireless communication unit 220 may apply a subframe having a frame length shorter than the second frame length in the UL direction. In other words, the second frame length may be applied in the DL direction and in the UL direction during periods when no visible light communication signal is received. However, when the UE 200 receives a visible light communication signal in the DL direction, a subframe shorter than the second frame length may be applied.

[0034] Alternatively, the wireless communication unit 220 may apply the subframe when automatic data retransmission control (ARQ) is performed. Specifically, the subframe may be applied when ACK / NACK feedback by Hybrid ARQ (HARQ) is performed. When HARQ is performed, if HARQ is performed on a permanent basis, the subframe may be applied continuously. If HARQ is activated by a setting from a mobile communication network or the like, the subframe may be applied only when HARQ is active.

[0035] The wireless communication unit 220 may transmit a retransmission request for the data in the subframe in the UL direction closest to the timing of the failure to receive data in the DL direction (first direction). Specifically, the wireless communication unit 220 may transmit a retransmission request (which may also be called a retransmission request) for the failed-to-receive data in the earliest subframe in the UL direction that arrives after the timing of the failure to receive DL data contained in the visible light communication signal. The position of the retransmission request within the subframe is not particularly limited.

[0036] The control unit 230 controls each functional block that constitutes the UE 200. Specifically, the control unit 230 controls the visible light receiving operation of the visible light receiving unit 210 and the transmission and reception operation of wireless communication signals using radio waves by the wireless communication unit 220.

[0037] Furthermore, the control unit 230 can control the frame length applied to the UL-direction wireless communication signal. Specifically, when HARQ is performed, the control unit 230 may control the wireless communication unit 220 to apply a subframe shorter than the second frame length.

[0038] (3) Operation of the communication system 10 Next, the operation of the communication system 10 will be described. Specifically, an example of the operation of automatic retransmission control (HARQ) when VLC is applied in the DL direction and radio communication using radio waves, such as a mobile communication network, is applied in the UL and DL directions will be described.

[0039] (3.1) Operation overview Figure 3 shows an example of conventional automatic retransmission control when VLC is applied in the DL direction and radio-based wireless communication is applied in the UL and DL directions. As shown in Figure 3, the length of the frame (rectangle in the figure) in the time domain for radio-based wireless communication (Radio UL / DL) is shorter than the frame length applied to DL using VLC. This is because VLC DL is broadband and fast compared to Radio UL / DL. Note that the frame length of Radio UL / DL may vary depending on the applied subcarrier spacing (SCS).

[0040] Since HARQ feedback (e.g., NACK) is performed on a frame-by-frame basis, the length of Radio UL / DL frames becomes an issue, and the magnitude of the delay until frame retransmission is completed in VLC DL becomes an issue. Specifically, the delay until retransmission can be at most 1 DL frame + 2 UL frames of Radio UL / DL time, and at least 1 UL frame time.

[0041] Therefore, the Radio UL frame is divided into multiple short subframes, allowing VLC DL retransmission requests such as NACK to be inserted into the UL subframe immediately preceding the VLC DL frame in which DL transmission failed. This speeds up the retransmission of frames in which DL transmission failed, significantly reducing retransmission delays.

[0042] (3.2) Example of operation Figure 4 shows an example of automatic retransmission control related to the operation example. Specifically, Figure 4 shows an example of retransmission according to HARQ when VLC is applied in the DL direction and radio communication using radio waves is applied in the UL and DL directions.

[0043] As mentioned above, in Radio UL, subframes shorter than the DL frame length may be applied. In the example shown in Figure 4, transmission of frame #2 of the VLC DL fails (frame #2 transmitted from VLC-AP 100 is not received by UE 200).

[0044] UE 200 may insert HARQ feedback (ACK / NACK) into the Radio UL subframe closest to the time it detects the failure to receive frame #2. In Figure 4, UE 200 sends a NACK and requests a retransmission of frame #2. Based on this retransmission request, CCU 30 requests VLC-AP 100 to retransmit frame #2.

[0045] Figure 5 shows an example of automatic retransmission control related to the operation example (when the delay until retransmission is minimal). Figure 6 shows an example of automatic retransmission control related to the operation example (when the delay until retransmission is maximum).

[0046] As shown in Figures 5 and 6, by applying subframes to Radio UL, the delay until DL frame retransmission is at most one frame time for Radio UL / DL, and at least one subframe time for Radio UL.

[0047] Thus, according to this example, when VLC DL and Radio UL / DL are combined, data retransmission delays can be significantly suppressed even when frame-by-frame automatic retransmission control is applied.

[0048] (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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] Furthermore, the block diagram (Figure 2) used in the description of the embodiments above shows 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.

[0054] 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.

[0055] Furthermore, the aforementioned wireless base station 50, VLC-AP 100, and UE 200 (the device) 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.

[0056] 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.

[0057] Each functional block of the device (see Figure 2) is implemented by any hardware element of the computer device, or a combination of such hardware elements.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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).

[0065] 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).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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).

[0070] 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.

[0071] 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).

[0072] 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.

[0073] 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.

[0074] 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).

[0075] 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).

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] The terms “system” and “network” as used in this disclosure are interchangeable.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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)).

[0085] 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.

[0086] 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.

[0087] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0088] 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.

[0089] 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.

[0090] 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).

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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".

[0110] 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.

[0111] 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.

[0112] The reference signal can also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

[0113] 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."

[0114] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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."

[0119] 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."

[0120] (Note) The above disclosure may also be expressed as follows: The first feature is a communication device comprising: a visible light communication unit that performs visible light communication using visible light in a first direction which is either a downlink or an uplink; and a wireless communication unit that performs wireless communication using radio waves in the first direction and a second direction which is opposite to the first direction, wherein the visible light communication unit performs the visible light communication to which a first frame length applied in the time direction is applied; the wireless communication unit performs the wireless communication to which a second frame length longer than the first frame length is applied; and in the second direction, a subframe having a frame length shorter than the second frame length is applied.

[0121] The second feature is that, in the first feature, the wireless communication unit applies the subframe when automatic data retransmission control is performed.

[0122] The third feature is that, in the first or second feature, the wireless communication unit transmits a request to retransmit the data in the subframe closest to the timing when the reception of the data in the first direction failed.

[0123] The fourth feature is that, in the first to third features, the first direction is the direction of the downward link, and the second direction is the direction of the upward link. [Explanation of symbols]

[0124] 10 Communication Systems 20 Communication Networks 30 CCU 40 Optical Fibers 50 Wireless base stations 60 routers 100 VLC-AP 200 UE 210 Visible light receiving unit 220 Wireless Communication Section 230 Control Unit 1001 Processor 1002 memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus

Claims

1. A visible light communication unit that performs visible light communication using visible light in a first direction, which is either a downlink or an uplink, A wireless communication unit that performs wireless communication using radio waves in the first direction and a second direction opposite to the first direction. Equipped with, The visible light communication unit performs the visible light communication to which a first frame length applied in the time direction is applied. The aforementioned wireless communication unit is The wireless communication is performed by applying a second frame length that is longer than the first frame length. A communication device that applies a subframe having a frame length shorter than the second frame length in the second direction.

2. The communication device according to claim 1, wherein the wireless communication unit applies the subframe when automatic data retransmission control is performed.

3. The communication device according to claim 2, wherein the wireless communication unit transmits a request for retransmission of the data in the subframe closest to the timing in which the reception of data in the first direction failed.

4. The first direction is the direction of the downlink, The communication device according to claim 1, wherein the second direction is the direction of the uplink.

5. The steps include: performing visible light communication using visible light in a first direction, which is either a downlink or an uplink; The steps include performing wireless communication using radio waves in the first direction and a second direction opposite to the first direction, and Includes, In the step of performing the visible light communication, the visible light communication is performed by applying the first frame length. In the step of performing the aforementioned wireless communication, The wireless communication is performed by applying a second frame length that is longer than the first frame length. A communication method in a communication device that applies a subframe having a frame length shorter than the second frame length in the second direction.

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