COMMUNICATION DEVICE, COMMUNICATION METHOD, AND COMMUNICATION PROGRAM

Abstract

To provide a communication device, a communication method, and a communication program that can achieve spatial optical communication with high communication performance.SOLUTION: A communication device includes: an interleave unit that determines interleave length of transmission data on the basis of transmitted information regarding a transmission line of spatial optical communication and interleaves the transmission data on the basis of the determined interleave length; and a shaping unit that shapes the interleaved transmission data so that a receiving side of the spatial optical communication can detect the interleave length thereof. The information regarding the transmission line includes information at least indicating whether the spatial optical communication is communication performed between a ground station and a satellite station, between a satellite station and a satellite station, or between a ground station and a ground station.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a communication device, a communication method, and a communication program. [Background technology]

[0002] Wireless communication, which uses radio waves as a transmission medium, has been well known for some time. However, in recent years, free-space optical communication, which uses light as a transmission medium (also called optical wireless communication), has also begun to attract attention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 11-98086 Summary of the Invention [Problem to be solved by the invention]

[0004] A well-known form of optical communication is communication using optical fiber as a transmission path. It is assumed that the technology used in optical fiber can also be applied to free-space optical communication. However, since the transmission path characteristics of optical fiber and space are significantly different, simply applying the technology used in optical fiber to free-space optical communication does not necessarily result in high communication performance (e.g., high quality, low latency, etc.).

[0005] Therefore, the present disclosure proposes a communication device, a communication method, and a communication program that can realize free-space optical communication with high communication performance. [Means for solving the problem]

[0006] In order to solve the above problems, a communication device according to one embodiment of the present disclosure includes an interleaving unit that determines an interleaving length of transmission data transmitted by spatial optical communication and interleaves the transmission data based on the determined interleaving length, and a shaping unit that shapes the interleaved transmission data so that the interleaving length can be detected at a receiving side of the spatial optical communication. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating a specific configuration example of a communication system. [Diagram 3] FIG. 2 is a diagram illustrating a configuration example of a terminal device according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram illustrating a configuration example of a server device according to an embodiment of the present disclosure. [Diagram 5] FIG. 1 is a diagram illustrating a configuration example of a communication device according to an embodiment of the present disclosure. [Figure 6] FIG. 1 is a diagram illustrating a configuration example of a communication device according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a diagram showing the relationship between the OSI reference model and the physical layer configuration of a spatial optical modem. [Figure 8] FIG. 2 is a diagram illustrating an example of a block format of a basic block. [Figure 9] FIG. 2 is a diagram illustrating an example of a block format of a basic block. [Figure 10] FIG. 13 is a diagram showing an error correction block format when the interleave length is extended. [Figure 11] FIG. 13 is a diagram showing an error correction block format when the interleave length is extended. [Figure 12] FIG. 2 is a diagram for explaining a basic operation of the communication system. [Figure 13] FIG. 2 is a diagram for explaining transmission data processing according to the present embodiment. [Figure 14] FIG. 4 is a diagram for explaining received data processing according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0009] The present disclosure will be described in the following order. 1. Introduction 2.Communication System Configuration 2-1. Overall configuration of the communication system 2-2. Specific configuration examples of communication systems 2-3. Terminal device configuration 2-4. Server device configuration 2-5. Configuration of communication equipment (ground station) 2-6.Communication Equipment (Satellite Station) Configuration 2-7. Relationship between the OSI reference model and the physical layer configuration of communication devices 3. Error correction block format 3-1.Basic configuration 3-2.Extended configuration 4. Operation of the communication system 4-1.Basic operation 4-2. Transmission data processing 4-3. Received data processing 5. Variations 5-1. Modifications to Processing 5-2. Modifications to equipment configuration 5-3.Other modifications 6. Conclusion

[0010] <<1. Introduction>> In recent years, free-space optical communication (also called wireless optical communication), which uses light as a transmission medium, has begun to attract attention. A well-known example of optical communication is communication using optical fiber as a transmission path, and it is assumed that the technology used in optical fiber can also be applied to free-space optical communication. However, because the transmission path characteristics of optical fiber and space are significantly different, simply applying the technology used in optical fiber to free-space optical communication does not necessarily result in high communication performance (e.g., high quality, low latency, etc.).

[0011] For example, in optical communication systems that use optical fiber as a transmission path, the data error rate increases as the transmission speed increases. For this reason, forward error correction (FEC) is introduced in optical communication systems that use optical fiber as a transmission path to ensure sufficient communication quality. It is assumed that this error correction mechanism can also be applied to free-space optical communication. However, the error correction method used in optical communication systems that use optical fiber as a transmission path is an error correction method that assumes that the data error distribution is a random error caused by a deterioration in the signal-to-noise ratio (S / N) of the received signal. For this reason, it is assumed that there will be many cases where burst errors caused by atmospheric turbulence, which are likely to occur in free-space optical communication, will be impossible to correct.

[0012] Furthermore, when optimizing the communication method according to the transmission path characteristics of free-space optical communication, there is a concern that there will be poor compatibility between communication methods, which could increase development costs and implementation risks for the entire communication system.

[0013] In this embodiment, this problem is solved by the following means.

[0014] The communication system of this embodiment is a free-space optical communication system including a communication device capable of free-space optical communication. The communication device is, for example, an optical transceiver having a forward error correction function.

[0015] The communication device on the transmitting side includes an interleave unit (e.g., an interleaver) configured to be able to change the interleave length, and a frame synchronization signal generating circuit. The communication device on the transmitting side determines the interleave length of the transmission data to be transmitted by the spatial optical communication. The interleave unit then interleaves the transmission data based on the determined interleave length. The communication device on the transmitting side shapes the interleaved transmission data so that the interleave length can be detected on the receiving side of the spatial optical communication. For example, a frame synchronization signal generating circuit included in the communication device adds a frame synchronization signal that allows the interleave length to be determined on the receiving side.

[0016] The communication device on the receiving side includes a deinterleave unit (e.g., a deinterleaver) configured to be able to change the interleave length, and a frame synchronization signal receiving circuit. The communication device on the receiving side automatically adjusts the interleave length based on the received frame synchronization signal.

[0017] The communication device of the communication system may have a dedicated data communication function between devices in addition to the payload data. The communication system may be configured to perform transmission and reception with an optimal interleave length for a transmission path by performing negotiation between the communication devices.

[0018] As a result, the communication system can realize free-space optical communication with high communication performance. For example, the communication system of the present embodiment can change the interleave length as desired, and can realize stable communication by changing the interleave length according to the characteristics of the transmission space.

[0019] The outline of this embodiment has been described above, and the communication system 1 of this embodiment will be described in detail below.

[0020] <<2. Communication System Configuration>> The communication system 1 is a system for transmitting various data such as packet data. The data transmitted by the communication system 1 may be stream data such as video data and audio data (for example, stream data for broadcasting). Broadcasting can also be considered as a type of communication.

[0021] The communication system 1 includes a plurality of communication devices capable of spatial optical communication, and performs spatial optical communication between the communication devices. Here, spatial optical communication refers to wireless communication performed using light such as infrared light or visible light (for example, electromagnetic waves with wavelengths between infrared and visible light). Spatial optical communication can be called "spatial optical communication" or "wireless optical communication". Here, the light used in spatial optical communication may be laser light or synchrotron radiation. Note that when the light used in spatial optical communication is infrared light, the light used in spatial optical communication may be light with a wavelength in the 1500 nm band, which is longer than the 790 nm band light used in CDs (Compact Discs).

[0022] The configuration of the communication system 1 will now be described in detail.

[0023] <2-1. Overall configuration of the communication system> 1 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present disclosure. The communication system 1 includes a terminal device 10, a server device 20, a communication device 30, and a communication device 40. Note that, although only one each of the terminal device 10, the server device 20, the communication device 30, and the communication device 40 are shown in the example of FIG. 1, the communication system 1 may include multiple each of the terminal device 10, the server device 20, the communication device 30, and the communication device 40.

[0024] The devices in the figure may be considered as devices in a logical sense, that is, some of the devices in the figure may be realized by a virtual machine (VM), a container, a Docker, etc., and these may be implemented on the same physical hardware.

[0025] In this embodiment, the concept of a communication device includes not only portable mobile devices (terminal devices) such as mobile terminals, but also devices installed in structures and mobile bodies. The structures and mobile bodies themselves may be considered as communication devices. The concept of a communication device also includes not only terminal devices, but also base station devices and relay devices. A communication device is a type of processing device and information processing device. A communication device can also be referred to as a transmitting device or a receiving device.

[0026] [Terminal Device] The terminal device 10 is an information processing device capable of exchanging data with a communication device having a spatial optical communication function such as the communication device 30. The terminal device 10 may be a communication device itself having a spatial optical communication function. The terminal device 10 is, for example, a mobile phone, a smart device (smartphone or tablet), a PDA (Personal Digital Assistant), or a personal computer. The terminal device 10 may also be a device such as a commercial camera equipped with a communication function, or a motorcycle or a mobile broadcasting vehicle equipped with a communication device such as an FPU (Field Pickup Unit). The terminal device 10 may also be an M2M (Machine to Machine) device or an IoT (Internet of Things) device. The terminal device 10 can be regarded as a type of communication device. The connection between the terminal device 10 and another device (for example, the communication device 30) may be a wired connection or a wireless connection.

[0027] The terminal device 10 may also be a mobile device. Here, the mobile device is a mobile information processing device. In this case, the terminal device 10 may be an information processing device installed in the mobile device, or may be the mobile device itself. For example, the terminal device 10 may be a vehicle that moves on a road, such as an automobile, a bus, a truck, or a motorcycle, or a wireless communication device mounted on the vehicle. The mobile device may be a mobile terminal, or may be a mobile device that moves on land (on land in the narrow sense), underground, on water, or underwater. The mobile device may be a mobile device that moves within the atmosphere, such as a drone or a helicopter, or may be a mobile device that moves outside the atmosphere, such as an artificial satellite.

[0028] The terminal device 10 does not necessarily have to be a device that is directly used by a person. The terminal device 10 may be a sensor installed on a factory machine or the like, such as a so-called MTC (Machine Type Communication). The terminal device 10 may be an M2M (Machine to Machine) device or an IoT (Internet of Things) device. The terminal device 10 may be a device equipped with a relay communication function, such as D2D (Device to Device) or V2X (Vehicle to everything). The terminal device 10 may be a device called CPE (Client Premises Equipment) used in wireless backhaul or the like.

[0029] The terminal device 10 may also be an optical communication device equipped with a spatial optical communication function. In this case, the terminal device 10 may be equipped with the optical communication function of the communication device 30 or the communication device 40 described later, and function as the communication device 30 or the communication device 40. In this case, the terminal device 10 can be regarded as the communication device 30 or the communication device 40 itself.

[0030] [Server device] The server device 20 is an information processing device capable of exchanging data with a communication device having a spatial optical communication function such as the communication device 40. The server device 20 may be a communication device itself having a spatial optical communication function. For example, the server device 20 is a server host computer that processes requests from a client computer (e.g., the terminal device 10). The server device 20 may be a PC server, a mid-range server, or a mainframe server. The server device 20 may be regarded as a type of communication device. The connection between the server device 20 and another device (e.g., the communication device 40) may be a wired connection or a wireless connection. The server device 20 may be referred to as a cloud server device, a local server device, a management device, a processing device, or the like.

[0031] The server device 20 may be an optical communication device equipped with a spatial optical communication function. In this case, the terminal device 10 may be equipped with the optical communication function of the communication device 30 or the communication device 40 described later, and function as the communication device 30 or the communication device 40. In this case, the server device 20 can be regarded as the communication device 30 or the communication device 40 itself.

[0032] The server device 20 can be used, operated, and / or managed by various entities (subjects). For example, the entities can be a mobile network operator (MNO), a mobile virtual network operator (MVNO), a mobile virtual network enabler (MVNE), a neutral host network (NHN) operator, an enterprise, an educational institution (a school corporation, a board of education of each local government, etc.), a real estate (building, condominium, etc.) manager, an individual, etc.

[0033] Of course, the entity that uses, operates, and / or manages the server device 20 is not limited to these. The server device 20 may be installed and / or operated by one business entity, or may be installed and / or operated by one individual. Of course, the entity that installs and operates the server device 20 is not limited to these. For example, the server device 20 may be installed and operated jointly by multiple business entities or multiple individuals. Furthermore, the server device 20 may be a shared facility used by multiple business entities or multiple individuals. In this case, the installation and / or operation of the facility may be performed by a third party different from the user.

[0034] The server device 20 provides a predetermined communication service to the terminal device 10 via an optical communication device such as the communication device 40. For example, the server device 20 provides, via wireless communication, to the terminal device 10 in which a predetermined application program is installed, an execution service of information processing (hereinafter referred to as application processing) required by the application program.

[0035] Here, the application processing performed by the server device 20 refers to, for example, recognition processing of an object in an image, which is performed based on a request from a program (e.g., an application) included in the mobile device, or is information processing at the application layer level performed in cooperation with the program. For example, the application processing performed by the server device 20 may be edge processing as referred to in edge computing. Note that the application processing is different from the processing at the physical layer, data link layer, network layer, transport layer, session layer, and presentation layer levels as referred to in the OSI reference model. However, if the application processing includes processing at the application layer level, such as image recognition processing, the application processing may include processing at the physical layer to presentation layer levels as an auxiliary.

[0036] [Communication equipment (ground station)] The communication device 30 is an optical wireless communication device that performs wireless communication using light with the communication device 40 or another communication device 30. For example, the communication device 30 is an optical communication modem. Note that the communication device 30 is not limited to an optical communication modem. For example, the communication device 30 may be a device equivalent to a wireless base station or a wireless access point. The communication device 30 may be a wireless relay station or a road base station device such as an RSU (Road Side Unit).

[0037] Unlike the communication device 40, the communication device 30 is located on the ground. The communication device 30 can be called a ground station device. The communication device 30 may be a device located on the ground itself, or a device mounted on an object (structure, device, etc.) located on the ground. For example, the communication device 30 may be a communication device disposed on a structure on the ground, or a communication device installed on a mobile body moving on the ground. More specifically, the communication device 30 may be an antenna installed on a structure such as a building and a signal processing device connected to the antenna. Of course, the communication device 30 may be a structure or a mobile body itself. The term "ground" refers not only to land (ground in the narrow sense) but also to ground, on water, and underwater in a broad sense.

[0038] The communication device 30 does not necessarily have to be fixed. The communication device 30 may be installed on a moving object such as an automobile. Furthermore, the communication device 30 does not necessarily have to be on land (on land in the narrow sense), but may be an object in the air such as an aircraft, drone, helicopter, etc., or an object on or under the sea such as a ship, submarine, etc. In this case, the communication device 30 may perform wireless communication with another communication device that is fixedly installed.

[0039] The communication device 30 may be a structure itself, or may be a device installed in a structure. The structure is, for example, a building such as an office building, a house, a steel tower, a station facility, an airport facility, a port facility, a stadium, etc. The concept of a structure includes not only buildings, but also non-building structures such as tunnels, bridges, dams, fences, and steel pillars, and equipment such as cranes, gates, and windmills. The concept of a structure includes not only land (ground in the narrow sense) or underground structures, but also water-based structures such as piers and megafloats, and underwater structures such as oceanographic observation facilities.

[0040] Furthermore, the communication device 30 may be a donor station or a relay station (relay station). When the communication device 30 is a relay station, the device in which the communication device 30 is mounted is not limited as long as the relay function is satisfied. For example, the communication device 30 may be mounted on a terminal device such as a smartphone, a car or a rickshaw, a balloon, an airplane, or a drone, or may be mounted on home appliances such as a television, a game machine, an air conditioner, a refrigerator, or a lighting fixture. Of course, these devices themselves may be regarded as the communication device 30.

[0041] Furthermore, the communication device 30 may be a fixed station or a mobile station. A mobile station is a wireless communication device configured to be movable. In this case, the communication device 30 may be a device installed in a mobile body, or may be the mobile body itself. For example, a relay station device having mobility can be regarded as the communication device 30 as a mobile station. Furthermore, devices that are inherently mobile and equipped with a communication function (at least an optical wireless communication function), such as vehicles, drones, and smartphones, also fall under the category of the communication device 30 as a mobile station.

[0042] Here, the moving body may be a mobile terminal such as a smartphone, a mobile phone, etc. Also, the moving body may be a moving body that moves on land (ground in the narrow sense) (for example, a car, a bicycle, a bus, a truck, a motorcycle, a train, a linear motor car, etc.) or a moving body that moves underground (for example, in a tunnel) (for example, a subway).

[0043] Furthermore, the moving body may be a moving body that moves on the water (e.g., a ship such as a passenger ship, a cargo ship, or a hovercraft) or a moving body that moves underwater (e.g., a submersible vessel such as a submarine, a submarine, or an unmanned underwater vehicle).

[0044] The moving body may also be a moving body that moves within the atmosphere (for example, an aerial vehicle such as an airplane, an airship, or a drone). can.

[0045] The communication device 30 may be a communication device capable of floating in the air. For example, the communication device 30 may be an aircraft station device. The aircraft station device is a wireless communication device capable of floating in the atmosphere (including the stratosphere), such as an aircraft. The aircraft station device may be a device mounted on the aircraft, or may be the aircraft itself. The concept of an aircraft includes not only heavier aircraft such as airplanes and gliders, but also lighter aircraft such as balloons and airships. The concept of an aircraft includes not only heavier aircraft and lighter aircraft, but also rotorcraft such as helicopters and autogyros. The aircraft station device (or an aircraft on which the aircraft station device is mounted) may be an unmanned aerial vehicle such as a drone.

[0046] The concept of unmanned aerial vehicles also includes unmanned aerial systems (UAS) and tethered UAS. The concept of unmanned aerial vehicles also includes lighter than air UAS (LTA) and heavier than air UAS (HTA). The concept of unmanned aerial vehicles also includes high altitude UAS platforms (HAPs).

[0047] As described above, the communication device 30 may be a relay station device (relay device). The relay station device is, for example, an aircraft station or an earth station. The aircraft station is a radio station installed on the ground or on a mobile object moving on the ground to communicate with an aircraft station device. The earth station is a radio station located on the earth (including in the air) to communicate with a satellite station device. The earth station may be a large earth station or a small earth station such as a VSAT (Very Small Aperture Terminal).

[0048] The earth station may be a VSAT control earth station (also called a master station or a HUB station) or a VSAT earth station (also called a slave station). The earth station may be a radio station installed on a moving object moving on the ground. For example, an earth station installed on a vessel may be an on-board earth station (ESV: Earth Stations on board Vessels). The earth station may include an aircraft earth station installed on an aircraft (including a helicopter) and communicating with a satellite station. The earth station may include an aircraft earth station installed on a moving object moving on the ground and communicating with an aircraft earth station via a satellite station. The relay station device may be a portable and mobile radio station that communicates with a satellite station or an aircraft station.

[0049] The communication device 30 may be used, operated, and / or managed by various entities. For example, the entities may be a mobile network operator (MNO), a mobile virtual network operator (MVNO), a mobile virtual network enabler (MVNE), a neutral host network (NHN) operator, an enterprise, an educational institution (a school corporation, a local government board of education, etc.), a real estate (building, condominium, etc.) manager, an individual, etc. Of course, the subject of use, operation, and / or management of the communication device 30 is not limited to these.

[0050] The communication device 30 may be installed and / or operated by a single business operator or by a single individual. Of course, the entity that installs and operates the communication device 30 is not limited to these. For example, the communication device 30 may be installed and operated jointly by multiple business operators or multiple individuals. Furthermore, the communication device 30 may be a shared facility used by multiple business operators or multiple individuals. In this case, the installation and / or operation of the facility may be performed by a third party different from the user.

[0051] [Communication equipment (satellite station)] The communication device 40 is an optical wireless communication device that performs wireless communication using light with the communication device 30 or another communication device 40. For example, the communication device 40 is an optical communication modem. Note that the communication device 40 is not limited to an optical communication modem. For example, the communication device 30 may be a device equivalent to a wireless base station or a wireless access point. The communication device 30 may be a wireless relay station.

[0052] Unlike the communication device 30, the communication device 40 is located outside the atmosphere (in space). For example, the communication device 40 is a device (satellite station device) installed on a moving body (hereinafter referred to as a space moving body) that moves outside the atmosphere. For example, the communication device 40 is a communication device mounted on an artificial satellite. Examples of the space moving body include artificial celestial bodies such as artificial satellites, spacecraft, space stations, and probes. The communication device 30 may be the space moving body itself. For example, the communication device 40 may be the artificial satellite itself. In this case, the communication device 40 can also be considered as a satellite station device.

[0053] Here, the satellite station device refers to a wireless communication device capable of floating outside the atmosphere. The satellite station device may be a device mounted on a space vehicle such as an artificial satellite, or may be the space vehicle itself. The satellite that becomes the satellite station device may be any of a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, and a highly elliptical orbit (HEO) satellite. Of course, the satellite station device may be a device mounted on a low earth orbit satellite, a medium earth orbit satellite, a geostationary satellite, or a highly elliptical orbit satellite.

[0054] The communication device 40 may be used, operated, and / or managed by various entities, similar to the communication device 30. Furthermore, the communication device 40 may be installed and / or operated by a single business entity, or may be installed and / or operated by a single individual, similar to the communication device 30.

[0055] <2-2. Specific configuration examples of communication systems> FIG. 2 is a diagram showing an example of a specific configuration of the communication system 1. As shown in FIG.

[0056] The terminal device 10 is, for example, a client PC, and the server device 20 is, for example, a server in an artificial satellite. The communication device 30 is, for example, an optical communication modem serving as a ground station, and the communication device 40 is, for example, an optical communication modem serving as a satellite station. Note that the configuration shown in FIG. 2 is merely an example. The configuration of the communication system 1 is not limited to the configuration shown in FIG. 2.

[0057] 2, the terminal device 10, the server device 20, the communication device 30, and the communication device 40 are each configured to be connectable with a connector such as an RJ45. The terminal device 10 and the communication device 30 can be connected with a communication cable such as an Ethernet cable. Similarly, the server device 20 and the communication device 40 can be connected with a communication cable such as a LAN cable.

[0058] Each of the communication devices 30 and 40 has a functional block that functions as a wired LAN physical layer and a functional block that functions as an optical FEC physical layer. These functional blocks are connected via a standard interface such as a Media-Independent Interface (MII).

[0059] A specific configuration example of the communication system 1 has been described above, but the configuration of each device constituting the communication system 1 according to the embodiment will be specifically described below. Note that the configuration of each device shown below is merely an example. The configuration of each device may be different from the following configuration.

[0060] <2-3. Terminal device configuration> First, the configuration of the terminal device 10 will be described. The terminal device 10 is an information processing device capable of exchanging data with a communication device having a spatial optical communication function, such as the communication device 30. The terminal device 10 may have a spatial optical communication function, similar to the communication device 30 and the communication device 40. In this case, the terminal device 10 can be regarded as a communication device.

[0061] Fig. 3 is a diagram showing a configuration example of a terminal device 10 according to an embodiment of the present disclosure. The terminal device 10 includes a communication interface 11, a storage unit 12, and a control unit 13. Note that the configuration shown in Fig. 3 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the terminal device 10 may be distributed and implemented in multiple physically separated configurations.

[0062] The communication interface 11 is an interface for communicating with other devices (e.g., the communication device 30). The communication interface 11 may be a network interface or a device connection interface. For example, the communication interface 11 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a Universal Serial Bus (USB) interface configured with a USB host controller, a USB port, etc. The communication interface 11 may be a wired interface or a wireless interface. The communication interface 11 functions as a communication means of the terminal device 10.

[0063] The storage unit 12 is a data readable / writable storage device such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, a hard disk, etc. The storage unit 12 functions as a storage unit of the terminal device 10.

[0064] The control unit 13 is a controller that controls each unit of the terminal device 10. The control unit 13 is realized by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 13 is realized by the processor executing various programs stored in a storage device inside the terminal device 10 using a RAM (Random Access Memory) or the like as a working area. The control unit 13 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0065] The control unit 13 may have the same functions as the control units of the communication device 30 and / or the communication device 40 described below. For example, the control unit 13 may have functional blocks that perform the same operations as the functional blocks (acquisition unit to reception control unit) that configure the control unit of the communication device 30.

[0066] <2-4. Server device configuration> Next, the configuration of the server device 20 will be described. The server device 20 is an information processing device capable of exchanging data with a communication device having a spatial optical communication function, such as the communication device 40. The server device 20 may have a spatial optical communication function, similar to the communication device 30 and the communication device 40. In this case, the server device 20 can be regarded as a communication device.

[0067] Fig. 4 is a diagram showing a configuration example of the server device 20 according to the embodiment of the present disclosure. The server device 20 includes a communication interface 21, a storage unit 22, and a control unit 23. Note that the configuration shown in Fig. 4 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the server device 20 may be distributed and implemented in multiple physically separated configurations.

[0068] The communication interface 21 is an interface for communicating with other devices (for example, the communication device 40). The communication interface 21 may be a network interface or a device connection interface. For example, the communication interface 21 may be a LAN interface such as a NIC, or a USB interface configured by a USB host controller, a USB port, etc. The communication interface 21 may be a wired interface or a wireless interface. The communication interface 21 functions as a communication means of the server device 20.

[0069] The storage unit 22 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 22 functions as a storage means of the server device 20.

[0070] The control unit 23 is a controller that controls each unit of the server device 20. The control unit 23 is realized by a processor such as a CPU or an MPU. For example, the control unit 23 is realized by the processor executing various programs stored in a storage device inside the server device 20 using a RAM or the like as a working area. The control unit 23 may be realized by an integrated circuit such as an ASIC or an FPGA. The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0071] The control unit 23 may have the same functions as the control units of the communication device 30 and / or the communication device 40 described below. For example, the control unit 23 may have functional blocks that perform the same operations as the functional blocks (from the acquisition unit to the reception control unit) that configure the control unit of the communication device 40.

[0072] <2-5. Configuration of communication equipment (ground station)> Next, a description will be given of the configuration of the communication device 30. The communication device 30 is an optical wireless communication device that wirelessly communicates with the communication device 40 or another communication device 30 using light.

[0073] Fig. 5 is a diagram showing a configuration example of a communication device 30 according to an embodiment of the present disclosure. The communication device 30 includes an optical space communication unit 31, a communication interface 32, a storage unit 33, and a control unit 34. Note that the configuration shown in Fig. 5 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the communication device 30 may be distributed and implemented in multiple physically separated devices.

[0074] The optical space communication unit 31 is a communication interface for performing spatial optical communication with other communication devices (e.g., communication device 40 or other communication devices 30) equipped with a spatial optical communication function. The transmission medium used by the optical space communication unit 31 in spatial optical communication is not limited to visible light, and may be infrared light. The light used as a transmission medium by the optical space communication unit 31 may be highly directional light such as laser light. Of course, the light used as a transmission medium by the optical space communication unit 31 may also be less directional light such as radiant light.

[0075] The optical space communication unit 31 includes a reception processing unit 311 and a transmission processing unit 312. The reception processing unit 311 performs signal processing of an optical signal received via, for example, an optical sensor, and the transmission processing unit 312 performs signal processing of, for example, converting transmission data into an optical signal. The optical space communication unit 31 may include a plurality of reception processing units 311 and transmission processing units 312. When the optical space communication unit 31 supports a plurality of wireless access methods, each unit of the optical space communication unit 31 may be configured individually for each wireless access method. For example, if the communication device 30 supports a plurality of wireless access methods with different error correction methods, the reception processing unit 311 and the transmission processing unit 312 may be configured individually for each of the plurality of wireless access methods.

[0076] The communication interface 32 is an interface for communicating with other devices (for example, the terminal device 10). The communication interface 32 may be a network interface or a device connection interface. For example, the communication interface 32 may be a LAN interface such as a NIC, or a USB interface configured with a USB host controller, a USB port, etc. The communication interface 21 may be a wired interface or a wireless interface. The communication interface 32 functions as a communication means of the communication device 30.

[0077] The storage unit 33 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 33 functions as a storage means of the communication device 30. The storage unit 33 stores error correction blocks, received data, and the like.

[0078] The control unit 34 is a controller that controls each unit of the communication device 30. The control unit 34 is realized by a processor such as a CPU or an MPU. For example, the control unit 34 is realized by the processor executing various programs stored in a storage device inside the communication device 30 using a RAM or the like as a working area. The control unit 34 may be realized by an integrated circuit such as an ASIC or an FPGA. The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0079] As shown in FIG. 5, the control unit 34 includes an acquisition unit 341, a shaping unit 342, an error correction unit 343, an interleave unit 344, a transmission control unit 345, a detection unit 346, a deinterleave unit 347, and a reception control unit 348. Each block (acquisition unit 341 to reception control unit 348) constituting the control unit 34 is a functional block indicating a function of the control unit 34. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a software module realized by software (including a microprogram), or may be a circuit block on a semiconductor chip (die). Of course, each functional block may be a processor or an integrated circuit. The functional blocks may be configured in any manner. The control unit 44 may be configured in a functional unit different from the above-mentioned functional blocks.

[0080] As described above, the control unit 13 of the terminal device 10 and the control unit 23 of the server device 20 may have each functional block of the control unit 34 of the communication device 30. In this case, the description of "communication device 30" appearing in the following description can be replaced with "terminal device 10" or "server device 20" as appropriate. Furthermore, the descriptions of "control unit 34" and "acquisition unit 341" to "reception control unit 348" appearing in the following description can be replaced with "control unit 13" or "control unit 23" as appropriate.

[0081] Furthermore, the control unit 34 may have the same functions as the control unit of the communication device 40 described below. For example, the operation of each functional block (acquisition unit 341 to reception control unit 348) of the control unit 34 may be the same as the operation of each functional block (acquisition unit to reception control unit) constituting the control unit of the communication device 40. In this case, descriptions indicating each functional block of the control unit 34 appearing in the following description ("acquisition unit 341" to "reception control unit 348") can be appropriately replaced with descriptions indicating each functional block of the control unit of the communication device 40.

[0082] <2-6. Configuration of communication equipment (satellite station)> Next, a description will be given of the configuration of the communication device 40. This is an optical wireless communication device that wirelessly communicates with the communication device 30 or another communication device 40 using light.

[0083] Fig. 6 is a diagram showing a configuration example of a communication device 40 according to an embodiment of the present disclosure. The communication device 40 includes an optical space communication unit 41, a communication interface 42, a storage unit 43, and a control unit 44. Note that the configuration shown in Fig. 6 is a functional configuration, and the hardware configuration may be different from this. In addition, the functions of the communication device 40 may be distributed and implemented in multiple physically separated devices.

[0084] The optical space communication unit 41 is a communication interface for performing spatial optical communication with other communication devices (e.g., communication device 30 or another communication device 40) equipped with a spatial optical communication function. The transmission medium used by the optical space communication unit 41 in spatial optical communication is not limited to visible light, but may be infrared light. The light used as a transmission medium by the optical space communication unit 41 may be highly directional light such as laser light. Of course, the light used as a transmission medium by the optical space communication unit 41 may be highly directional light such as synchrotron radiation.

[0085] The optical space communication unit 41 includes a reception processing unit 411 and a transmission processing unit 412. The reception processing unit 411 performs signal processing of an optical signal received via, for example, an optical sensor, and the transmission processing unit 412 performs signal processing of, for example, converting transmission data into an optical signal. The optical space communication unit 41 may include a plurality of reception processing units 411 and transmission processing units 412. When the optical space communication unit 41 supports a plurality of wireless access methods, each unit of the optical space communication unit 41 may be configured individually for each wireless access method. For example, if the communication device 40 supports a plurality of wireless access methods with different error correction methods, the reception processing unit 411 and the transmission processing unit 412 may be configured individually for each of the plurality of wireless access methods.

[0086] The communication interface 42 is an interface for communicating with other devices (for example, the server device 20). The communication interface 42 may be a network interface or a device connection interface. For example, the communication interface 42 may be a LAN interface such as a NIC, or a USB interface configured with a USB host controller, a USB port, etc. The communication interface 21 may be a wired interface or a wireless interface. The communication interface 42 functions as a communication means of the communication device 40.

[0087] The storage unit 43 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 43 functions as a storage means of the communication device 40. The storage unit 43 stores error correction blocks, received data, and the like.

[0088] The control unit 44 is a controller that controls each part of the communication device 40. The control unit 44 is realized by a processor such as a CPU or an MPU. For example, the control unit 44 is realized by the processor executing various programs stored in a storage device inside the communication device 40 using a RAM or the like as a working area. The control unit 44 may be realized by an integrated circuit such as an ASIC or an FPGA. The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0089] As shown in FIG. 6, the control unit 44 includes an acquisition unit 441, a shaping unit 442, an error correction unit 443, an interleave unit 444, a transmission control unit 445, a detection unit 446, a deinterleave unit 447, and a reception control unit 448. Each block (acquisition unit 441 to reception control unit 448) constituting the control unit 44 is a functional block indicating a function of the control unit 44. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be one software module realized by software (including a microprogram), or may be one circuit block on a semiconductor chip (die). Of course, each functional block may be one processor or one integrated circuit. The functional blocks may be configured in any manner. The control unit 44 may be configured in a functional unit different from the above-mentioned functional blocks.

[0090] As described above, the control unit 13 of the terminal device 10 and the control unit 23 of the server device 20 may have each functional block that the control unit 44 of the communication device 40 has. In this case, the description of "communication device 40" that appears in the following description can be replaced with "terminal device 10" or "server device 20" as appropriate. In addition, the descriptions of "control unit 44" and "acquisition unit 441" to "reception control unit 448" that appear in the following description can also be replaced with "control unit 13" or "control unit 23" as appropriate.

[0091] Furthermore, the control unit 44 may have the same functions as the control unit 34 of the communication device 30 described above. For example, the operation of each functional block (acquisition unit 441 to reception control unit 448) of the control unit 44 may be the same as the operation of each functional block (acquisition unit 341 to reception control unit 348) constituting the control unit 34 of the communication device 30. In this case, the description indicating each functional block of the control unit 44 appearing in the following description ("acquisition unit 441" to "reception control unit 448") can be replaced with the description indicating each functional block of the control unit 34 of the communication device 30 ("acquisition unit 341" to "reception control unit 348") as appropriate. Of course, the description indicating each functional block of the control unit 34 appearing in the following description ("acquisition unit 341" to "reception control unit 348") may be replaced with the description indicating each functional block of the control unit 44 of the communication device 40 ("acquisition unit 441" to "reception control unit 448").

[0092] <2-7. Relationship between the OSI reference model and the physical layer configuration of communication devices> In the example of Fig. 2, the communication device 30 and the communication device 40 are, for example, spatial optical modems, each having a wired LAN physical layer and an optical FEC layer. The relationship between the OSI reference model and the physical layer configuration of the communication device (communication device 30 and / or communication device 40) is shown below. In this section (<2-7>), both the communication device 30 and the communication device 40 are spatial optical modems, but of course the communication device 30 and the communication device 40 are not limited to spatial optical modems.

[0093] In the following description, Ethernet refers to Ethernet in a broad sense, including not only Ethernet (registered trademark) as a registered trademark, but also Ethernet as a standard specification such as IEEE 802.3. Of course, the description of "Ethernet" that appears in the following description can be replaced with, for example, "IEEE 802.3," "IEEE 802.3 ETHERNET," "standard network interface," "wired LAN," or "Ethernet as a standard specification."

[0094] 7 is a diagram showing the relationship between the OSI reference model and the physical layer configuration of the spatial optical modem. The spatial optical modem (communication devices 30, 40) of this embodiment corresponds to the physical layer in the OSI reference model. In the Ethernet standard IEEE 802.3, MII (Media-Independent Interface), GMII (Gigabit Media-Independent Interface), XGMII (10 Gigabit Media-Independent Interface), XAUI (10 Gigabit Attachment Unit Interface), etc. are defined as media-independent interface standards connecting the MAC layer and the physical layer. By connecting the optical FEC physical layer with this interface and using the upper layer of the existing Ethernet as it is, the spatial optical modem can function as an Ethernet media converter.

[0095] The optical FEC physical layer of the spatial optical modem of this embodiment corresponds to, for example, a PCS (Physical Coding Sub-layer) and a PMA (Physical Medium Attachment). The PMD (Physical Medium Dependent) shown in Fig. 7 corresponds to, for example, a laser, an optical modulator, a transmission / reception optical system, and a photodetector.

[0096] In the following embodiment, a 100 Mbps network (100BASE-TX, etc.) is targeted as an example. However, the application of the present embodiment is not limited to a 100 Mbps network, and may be, for example, a 1 Gbps network (1000BASE-T, etc.). When the spatial optical modem of the present embodiment is compatible with 1 Gbps (1000BASE-T, etc.), the optical FEC physical layer may be connected to the upper layer by GMII as shown on the right side of FIG. 7. In addition, in order to improve error correction capability and redundancy, the parity length and symbol length of the Reed-Solomon code may be extended, and the data modulation method may be replaced with 64B / 66B, etc. Even if the spatial optical modem of the present embodiment needs to be compatible with a higher speed network such as 10 Gbps, as long as the medium independent interface complies with the Ethernet standard, the spatial optical modem of the present embodiment can function as an Ethernet media converter even if the error correction method and block structure are significantly changed.

[0097] <<3. Error correction block format>> The communication devices 30 and 40 of this embodiment are configured to be able to change the interleave length. The communication device 30 or 40 changes the interleave length according to the characteristics of the transmission space, thereby realizing stable spatial optical communication. In this embodiment, the data format is a format that allows the interleave length to be detected, so that the interleave length used by the transmitting side of the spatial optical communication (e.g., the communication device 30) can be detected by the receiving side of the spatial optical communication (e.g., the communication device 40).

[0098] In this embodiment, the data format is, as an example, an error correction block format. The error correction block format of this embodiment will be described below. First, the basic error correction block format will be described. After that, the extended format in this embodiment will be described.

[0099] <3-1. Basic configuration> First, a basic error correction block format will be described. In the following description, the basic error correction block may be referred to as a basic block. The block format of the basic block is composed of an error correction block encoded by a product code. Figs. 8 and 9 are diagrams showing an example of the block format of the basic block. The block format shown in Figs. 8 and 9 is a forward error correction format for free-space optical communication using a Reed-Solomon product code. In the following description, the vertical direction in the drawing is referred to as the vertical direction, and the horizontal direction in the drawing is referred to as the horizontal direction.

[0100] As shown in Fig. 8 and Fig. 9, the basic block has a size of 240 bytes (2+230+8 bytes) in the horizontal direction and 253 bytes in the vertical direction. A synchronization code (hereinafter referred to as SYNC code) is attached to the basic block at the beginning in the horizontal direction (i.e., the block boundary). In the example of Fig. 8, 2 bytes in the horizontal direction are the SYNC code. The basic block has an inner code (PI (Parity Inner)) of 8 bytes in the horizontal direction and an outer code (PO (Parity Outer)) of 32 bytes in the vertical direction. The 230 B sandwiched between the SYNC code and the PO parity is the interleave block. The interleave block contains 1 byte of sub-data in the vertical direction. 50.6 KB of the interleave block excluding the sub-data and PO is user data (payload data).

[0101] The sub-data is data used for exchanging control information between communication devices such as spatial optical modems. In the communication system of this embodiment, various control signals can be communicated between optical modems using sub-data superimposed separately from payload data. For example, the receiver notifies the transmitter of the reception status such as an error rate, so that the transmitter can change the transmission interleave length and select the optimal interleave length for the transmission space. In addition, the transmitter can monitor the amount of received light, so that control such as automatic adjustment of the transmission optical output and correction of the transmission optical axis can be realized. In this way, by utilizing sub-data communication, it is possible to perform system operations such as negotiation between devices, control optimization, and various monitors.

[0102] In the error correction block of this embodiment, when transmitting data, data is input vertically and transmitted data is output horizontally as shown in Fig. 8. On the other hand, when receiving data, received data is input horizontally and PO decoding is performed vertically as shown in Fig. 9. Therefore, the longer the horizontal dimension of the interleave block, the longer the interleave length (230 bytes in the examples of Figs. 8 and 9).

[0103] Reed-Solomon product codes with PO parity and PI parity have excellent burst error correction capabilities, and it is possible to further improve the correction capabilities by performing erasure correction and repeated correction. Therefore, they are also effective against burst errors caused by atmospheric turbulence, which are likely to occur in free-space optical communications.

[0104] It should be noted that the block formats shown in Figures 8 and 9 are merely examples. The error correction block format is not limited to the formats shown in Figures 8 and 9. Furthermore, the specific numerical values ​​appearing in Figures 8 and 9 can be changed as appropriate.

[0105] <3-2. Extended configuration> The extended format in this embodiment will be described. The extended format described below is an error correction block format in which the interleave length is extended. Figures 10 and 11 are diagrams showing the error correction block format in the case where the interleave length is extended.

[0106] The extended format is a format with a structure in which the basic blocks shown in Figures 8 and 9 are arranged horizontally. In the example of Figures 10 and 11, the basic block is extended to four blocks. In the example of Figures 10 and 11, the interleave length is four times the basic block, so as shown in Figure 11, burst errors (marked with x) are distributed among four blocks by deinterleaving. Therefore, it is possible to extend the burst error length correctable by PO parity by four times. If it is desired to further increase the interleave length, this can be achieved by increasing the number of linked blocks.

[0107] On the other hand, while increasing the interleave length improves burst error tolerance, it also increases the memory capacity required for interleaving, which in turn increases the latency of transmission and reception. Therefore, a mechanism is needed to select the optimal interleave length according to the characteristics of the space (transmission path) in which communication is actually performed.

[0108] As in the structures shown in Figures 10 and 11, if a mechanism is used in which any number of basic blocks are arranged horizontally to extend the blocks, the transmitting communication device can easily change the interleave length.

[0109] In addition, in order to enable the receiving side to detect the interleaving length, the transmitting communication device assigns a special SYNC code (first synchronization code) to the SYNC code of the first block, and assigns a SYNC code (second synchronization code) different from that of the first block to the other blocks. Here, the first synchronization code is a code that indicates the start or end point of interleaving, and is a code that indicates the continuation point of interleaving.

[0110] This allows the receiving communication device to detect the interleave length used by the transmitting side from the reception interval of the first SYNC (first synchronization code). This allows the receiving communication device to automatically match the deinterleave length to the interleave length of the transmitting side. As another implementation example, it is also possible to detect the interleave length by embedding a block number in the SYNC code. In this case, too, the SYNC code in which the number that is the first SYNC is embedded may be regarded as the first code, and the SYNC code in which another number is embedded may be regarded as the second code.

[0111] Even if the error correction block format is a convolutional code different from the block format such as a Reed-Solomon product code, it is possible to detect the interleave length from the received SYNC code and automatically adjust the deinterleave length.

[0112] It should be noted that the formats shown in Figures 10 and 11 are merely examples. The error correction block format is not limited to the formats shown in Figures 10 and 11. Furthermore, the specific numerical values ​​appearing in Figures 10 and 11 can be changed as appropriate. Of course, the number of basic blocks to be arranged is not limited to four and can be changed as appropriate.

[0113] <<4. Operation of the communication system>> Next, the operation of the communication system 1 will be described.

[0114] <4-1.Basic operation> First, a description will be given of a basic operation of the communication system 1. FIG 12 is a diagram for explaining the basic operation of the communication system 1.

[0115] In the following description, it is assumed that the terminal device 10 is located on the ground, and the server device 20 is located inside an artificial satellite. The terminal device 10 is connected to the communication device 30 via a communication cable, and the server device 20 is connected to the communication device 40 via a communication cable. The communication devices 30 and 40 are, for example, free-space optical communication modems. Below, a case will be described where the terminal device 10 requests data from the server device 20 using the TCP-IP protocol.

[0116] When the terminal device 10 transmits a TCP packet (GET request) to a communication cable such as an Ethernet cable, the wired LAN physical layer in the communication device 30 receives the packet (step S11). The wired LAN physical layer transmits the packet to the optical FEC physical layer in the communication device 30 via a media independent interface (MII, GMII, XGMII, XAUI, etc.) (step S12). The optical FEC physical layer adds error correction parity to the received data and modulates the serial signal to be output after performing interleaving processing, etc. (step S13). The optical FEC physical layer transmits the emitted light generated by the modulation toward a distant satellite station (step S14).

[0117] Meanwhile, the communication device 40 in the satellite detects the modulated light emitted from the communication device 30 on the ground with a receiving detector in the optical FEC physical layer. Then, the optical FEC physical layer in the communication device 40 converts the detected data into parallel data, and then performs deinterleaving and error correction processing (step S15). The optical FEC physical layer transmits the error-corrected data (TCP packets) to the wired LAN physical layer in the communication device 40 via a media independent interface (step S16). Then, the wired LAN physical layer delivers the TCP packets to the server device 20 connected by a communication cable (step S17).

[0118] The server that receives the TCP packet (get request) sends the data requested by the terminal device 10 to the communication device 40. Then, the wired LAN physical layer in the communication device 40 receives the data (step S21). The wired LAN physical layer sends the data to the optical FEC physical layer in the communication device 30 via the medium independent interface (step S22). The optical FEC physical layer adds error correction parity to the received data and modulates the serial signal that is output after performing interleaving processing and the like (step S23). The optical FEC physical layer transmits the emitted light generated by the modulation toward a distant ground station (step S24).

[0119] Meanwhile, the communication device 30 located on the ground detects the modulated light emitted from the communication device 40 in the satellite with a receiving detector in the optical FEC physical layer. Then, the optical FEC physical layer in the communication device 30 converts the detected data into parallel data, and then performs deinterleaving and error correction processing (step S25). The optical FEC physical layer transmits the error-corrected data to the wired LAN physical layer in the communication device 30 via a media independent interface (step S26). Then, the wired LAN physical layer delivers the data from the server device 20 to the terminal device 10 connected by a communication cable (step S27). This allows the terminal device 10 to receive the desired data.

[0120] By adopting this connection form of spatial optical communication, the communication devices 30 and 40 function as Ethernet media converters, and when viewed from the terminal device 10 and the server device 20, it appears as if they are connected between the ground and the satellite by wired Ethernet. This enables two-way data communication between the terminal device 10 and the server device 20.

[0121] <4-2. Transmission data processing> Next, the transmission data processing executed in the optical FEC physical layer will be described. Fig. 13 is a diagram for explaining the transmission data processing of this embodiment. The transmission data processing described below is, for example, the processing of step S13 or step S23 shown in Fig. 12.

[0122] If communication device 30 is a transmitting communication device, the transmission data processing is executed by, for example, acquisition unit 341, shaping unit 342, error correction unit 343, interleaving unit 344, transmission control unit 345, etc. If communication device 40 is a transmitting communication device, the transmission data processing is executed by, for example, acquisition unit 441, shaping unit 442, error correction unit 443, interleaving unit 444, transmission control unit 445, etc.

[0123] In the following description, it is assumed that communication device 30 is a transmitting communication device, but the transmitting communication device may be communication device 40. In this case, descriptions of acquisition unit 341, shaping unit 342, error correction unit 343, interleaving unit 344, transmission control unit 345, etc. that appear in the following description can be replaced with acquisition unit 441, shaping unit 442, error correction unit 443, interleaving unit 444, transmission control unit 445, etc.

[0124] The transmission data processing will be described below with reference to FIG.

[0125] The acquisition unit 341 acquires data output from the wired LAN physical layer via a medium independent interface and inputs it to the FIFO (step S101). The shaping unit 342 embeds an IFG (Inter-Frame Gap) signal at the frame boundary, and then adds a predetermined number of bytes (e.g., 1 byte) of sub-data used for control between communication devices (step S102). Then, the error correction unit 343 adds a predetermined number of bytes (e.g., 32 bytes) of PO parity, which is a Reed-Solomon code (step S103).

[0126] Next, the interleaving unit 344 determines an interleave length of the transmission data transmitted by the free space optical communication. The interleaving unit 344 determines the interleave length based on information about the transmission path of the free space optical communication used to transmit the transmission data. The information about the transmission path is, for example, information indicating whether the free space optical communication is communication between a ground station and a satellite station or communication between satellite stations. The information about the transmission path may include information indicating whether the free space optical communication is communication between ground stations.

[0127] When the interleave length is determined based on information about the transmission path, the interleave unit 344 determines the first interleave length (e.g., one block interleave length) if the transmission path is between satellite stations. If the transmission path is between a ground station and a satellite station, the interleave unit 344 determines the second interleave length (e.g., four block interleave length) longer than the first interleave length, since it is considered that burst errors are likely to occur. Also, if the transmission path is between ground stations, the interleave unit 344 determines the third interleave length (e.g., two block interleave length) longer than the first interleave length and shorter than the second interleave length. Of course, the interleave length is not limited to this example, and may be various values. The transmission path is also not limited to between satellite stations, between a ground station and a satellite station, and between ground stations.

[0128] Moreover, the information used by the interleaving unit 344 to determine the interleaving length is not limited to information about the transmission path. The interleaving unit 344 may determine the interleaving length based on, for example, information about an error rate in communication with the receiving side of spatial optical communication. For example, when the error rate is lower than a predetermined threshold, the interleaving unit 344 determines the fourth interleaving length (for example, an interleaving length for one block). On the other hand, when the error rate is higher than the predetermined threshold, it is considered that the optical communication is in a transmission space where errors are unlikely to occur, so the interleaving unit 344 determines the fifth interleaving length (for example, an interleaving length for four blocks) that is longer than the fourth interleaving length. Of course, the interleaving length is not limited to this example, and may be various values. A plurality of predetermined thresholds may also be provided, and a plurality of interleaving lengths may be prepared according to the error rate.

[0129] Note that information used to determine the interleave length, such as information about the transmission path and information about the error rate, may be obtained from sub-data included in the received data from another communication device. For example, the acquisition unit 341 may acquire sub-data included in the error correction block, and the interleaving unit 344 may determine the interleave length based on information (e.g., error rate) included in the sub-data acquired by the acquisition unit 341.

[0130] Next, the interleaving unit 344 interleaves the transmission data based on the determined interleave length (step S104).

[0131] After that, the shaping unit 342 shapes the interleaved transmission data so that the interleave length can be detected on the receiving side of the spatial optical communication. For example, the shaping unit 342 adds PI parity and SYNC data to the interleaved transmission data. At this time, as described in <3-2. Extended configuration> above, the shaping unit 342 places a first synchronization code at a position indicating the start point (or end point) of the interleaving and a second synchronization code at a position indicating the continuation point of the interleaving.

[0132] Thereafter, the transmission control unit 445 performs 8B / 10B modulation on the transmission data (step S107). Furthermore, the transmission control unit 445 performs parallel-to-serial conversion on the 8B / 10B modulated data. This allows a modulated signal with fewer DC components to be supplied to the optical modulation unit, enabling the transmission control unit 445 to output modulated transmission light. Note that the encoding method may be 64B / 66B or 64B / 66B other than 8B / 10B. Alternatively, a randomizer (mixer) or the like may be used.

[0133] <4-3. Received data processing> Next, the received data processing executed in the optical FEC physical layer will be described. Fig. 14 is a diagram for explaining the received data processing of this embodiment. The received data processing described below is, for example, the processing of step S15 or step S25 shown in Fig. 12.

[0134] If the communication device 40 is a receiving communication device, the received data processing is performed, for example, by the detection unit 446, the deinterleaving unit 447, the reception control unit 448, etc. If the communication device 30 is a receiving communication device, the received data processing is performed, for example, by the detection unit 346, the deinterleaving unit 347, the reception control unit 348, etc.

[0135] In the following description, it is assumed that the communication device 40 is the receiving communication device, but the receiving communication device may be the communication device 30. In this case, the descriptions of the detection unit 446, the deinterleaving unit 447, the reception control unit 448, etc. that appear in the following description can be replaced with the detection unit 346, the deinterleaving unit 347, the reception control unit 348, etc.

[0136] Hereinafter, the received data processing will be described with reference to FIG.

[0137] The reception control unit 448 extracts a synchronous clock from the serial data string received by the photodetector using a PLL circuit (step S201), and converts the serial data into parallel data (step S202). After that, the reception control unit 448 performs 8B / 10B demodulation (step S203).

[0138] The received data is shaped so that the interleave length can be detected. Specifically, a first synchronization code is placed at the location indicating the start point (or end point) of the interleave, and a second synchronization code is placed at the location indicating the continuation point of the interleave. The detector 346 detects the SYNC code to identify the interleave length (step S204).

[0139] The deinterleave unit 447 performs error correction on the demodulated data using a PI correction circuit (step S205), and then performs deinterleaving processing based on the interleave length detected by the detection unit 346 (step S206). After that, the reception control unit 448 performs PO correction (step S207). By dispersing burst errors through deinterleaving, it becomes possible to improve the burst error correction capability of the PO parity.

[0140] After that, the reception control unit 448 extracts sub-data and detects a frame boundary (IFG) (step S208).Then, the reception control unit 448 removes the clock frequency error by FIFO.Then, the reception control unit 448 sends the received data to the wired LAN physical layer.

[0141] <<5. Modifications>> The above-described embodiment is merely an example, and various modifications and applications are possible.

[0142] <5-1. Modifications regarding processing> For example, in the above-described embodiment, the spatial optical communication performed by the communication device is communication between a ground station and a satellite station (e.g., communication between the communication device 30 and the communication device 40), but the spatial optical communication may be communication between satellite stations (e.g., communication between the communication device 40 and the communication device 40). Moreover, the spatial optical communication may be communication between ground stations (e.g., communication between the communication device 30 and the communication device 30).

[0143] In the above embodiment, the data format configured to be able to detect the interleave length is the error correction block format, but is not limited to the error correction block format. It may be another block format configured with one or more data blocks. In this case, the data block may be provided with a SYNC code such as a first synchronization code or a second synchronization code.

[0144] In the above embodiment, the error correction block format is an error correction block encoded by a Reed-Solomon product code, but the encoding method is not limited to the Reed-Solomon product code. The encoding method may be another product code. The encoding method is not limited to the product code, and may be another block code.

[0145] In the above embodiment, the Ethernet frame is used as the payload data, but the Ethernet frame may be replaced with, for example, a GFP frame (ITU-T Recommendation G.7041 / Y.1303). This allows various client signals, including Ethernet, to be accommodated in the GFP frame, thereby enhancing the versatility of the free-space optical communication network.

[0146] <5-2. Modifications regarding equipment configuration> In the above embodiment, the terminal device 10 and the server device 20 exchange information via spatial optical communication, but devices exchanging information via spatial optical communication are not limited to the terminal device 10 and the server device 20. Information processing devices other than the terminal device 10 and the server device 20 may exchange information. For example, sensor devices may exchange information via spatial optical communication.

[0147] Furthermore, the terminal device 10 and another terminal device 10 may exchange information via spatial optical communication. Furthermore, the server device 20 and another server device 20 may exchange information via spatial optical communication.

[0148] In the above embodiment, the terminal device 10 is located on the ground and the server device 20 is located in space, but the server device 20 may be located on the ground and the terminal device 10 may be located in space. For example, the server device 20 may be located in a base station on the ground and the terminal device 10 may be located in a space station.

[0149] <5-3. Other modifications> The terminal device 10, the server device 20, the communication device 30, or the control device that controls the communication device 40 in this embodiment may be realized by a dedicated computer system or a general-purpose computer system.

[0150] For example, a communication program for executing the above-mentioned operations (e.g., transmission and reception processing) is stored in a computer-readable recording medium such as an optical disk, a semiconductor memory, a magnetic tape, or a flexible disk and distributed. Then, for example, the program is installed in a computer and the above-mentioned processing is executed to configure a control device. In this case, the control device may be a device external to the terminal device 10, the server device 20, the communication device 30, or the communication device 40 (e.g., a personal computer). Also, the control device may be a device internal to the terminal device 10, the server device 20, the communication device 30, or the communication device 40 (e.g., the control unit 13, the control unit 23, the control unit 34, or the control unit 44).

[0151] The communication program may be stored in a disk device provided in a server device on a network such as the Internet, and may be downloaded to a computer. The above-mentioned functions may be realized by cooperation between an OS (Operating System) and application software. In this case, the parts other than the OS may be stored on a medium and distributed, or the parts other than the OS may be stored in a server device and may be downloaded to a computer.

[0152] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified. For example, the various information shown in each drawing is not limited to the illustrated information.

[0153] In addition, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads, usage conditions, etc.

[0154] The above-described embodiments can be combined as appropriate in the areas where the processing contents are not contradictory. The order of the steps shown in the flowcharts and sequence diagrams of the above-described embodiments can be changed as appropriate.

[0155] Furthermore, for example, the present embodiment can be implemented as any configuration that constitutes an apparatus or system, such as a processor as a system LSI (Large Scale Integration), a module using multiple processors, a unit using multiple modules, a set in which other functions are added to a unit, etc. (i.e., a configuration of a part of an apparatus).

[0156] In this embodiment, a system means a collection of multiple components (devices, modules (parts), etc.), regardless of whether all the components are in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device in which multiple modules are housed in a single housing, are both systems.

[0157] Also, for example, this embodiment can have a cloud computing configuration in which one function is shared and processed jointly by a plurality of devices via a network.

[0158] <6. Conclusion> As described above, according to an embodiment of the present disclosure, a communication device (e.g., communication device 30, 40) determines an interleave length of transmission data to be transmitted by spatial optical communication, and interleaves the transmission data based on the determined interleave length. Then, the communication device shapes the interleaved transmission data so that the interleave length can be detected on the receiving side of the spatial optical communication.

[0159] This allows the communication device of this embodiment to arbitrarily change the interleave length, thereby achieving stable communication by changing the interleave length according to the characteristics of the transmission space.

[0160] Furthermore, since the communication device of this embodiment uses a Reed-Solomon product code in the forward error correction system, it is possible to ensure sufficient communication stability against burst errors caused by atmospheric turbulence with relatively simple implementation.

[0161] In addition, by arranging the basic blocks, it is easy to change the interleave length, and on the receiving side, it is possible to detect and determine the interleave length by sync code discrimination and decode it, so that the interleave length can be changed arbitrarily with great ease according to the characteristics of the transmission space.

[0162] In addition, the communication device of this embodiment supports variable-length frames and ensures compatibility with the Ethernet physical layer, so it functions as an Ethernet media converter. This allows the upper layers of currently popular Ethernet to be used as is, significantly reducing the resources and risks involved in introducing a communication system.

[0163] In addition, the communication device of this embodiment can superimpose sub-data used between devices separately from the payload data, making it possible to exchange various control information between optical communication devices. As a result, it becomes possible to optimize the interleave length, transmission output, transmission optical axis, etc. in real time, making it possible to maintain stable free-space optical communication.

[0164] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments as they are, and various modifications are possible without departing from the gist of the present disclosure. In addition, components of different embodiments and modifications may be appropriately combined.

[0165] Furthermore, the effects of each embodiment described in this specification are merely examples and are not limiting, and other effects may also be provided.

[0166] The present technology can also be configured as follows. (1) an interleave unit that determines an interleave length of transmission data transmitted by free space optical communication and interleaves the transmission data based on the determined interleave length; a shaping unit that shapes the interleaved transmission data so that the interleave length can be detected at a receiving side of the spatial optical communication; A communication device comprising: (2) The shaping unit shapes the interleaved transmission data based on a data format configured to enable detection of the interleave length at a receiving side of the spatial optical communication. The communication device according to (1) above. (3) The data format includes a synchronization code in the data, The shaping unit places at least two types of synchronization codes in the transmission data so that the interleave length can be detected at a receiving side of the spatial optical communication. The communication device according to (2). (4) the shaping unit arranges, for each predetermined data length based on the determined interleave length, either a first synchronization code indicating a start point or an end point of interleaving, or a second synchronization code indicating a continuation point of interleaving; The communication device according to (3). (5) the data format is a block format consisting of one or more data blocks, The block format is composed of one or more data blocks with a synchronization code arranged at a block boundary, the shaping unit arranges either the first synchronization code or the second synchronization code at the block boundary based on the determined interleave length. The communication device according to (4). (6) The block format is a format composed of an error correction block encoded by a block code. The communication device according to (5) above. (7) The block format is a format composed of an error correction block encoded by a product code. The communication device according to (6). (8) the block format is a format composed of an error correction block encoded by a Reed-Solomon product code; The communication device according to (7) above. (9) The interleaving unit determines the interleave length based on information regarding a transmission path of the spatial optical communication used for transmitting the transmission data. The communication device according to any one of (1) to (8). (10) The interleaving unit determines the interleave length based on at least information indicating whether the free-space optical communication is communication between a ground station and a satellite station or communication between satellite stations. The communication device according to (9). (11) The interleaving unit determines the interleaving length based on information of an error rate in communication with a receiving side of the spatial optical communication. The communication device according to (9) above. (12) The transmission data includes, in addition to first data which is payload data, second data used for exchanging control information between communication devices of the free-space optical communication; The interleaving unit determines the interleaving length based on the second data. The communication device according to any one of (1) to (11). (13) A detection unit that detects an interleave length of received data that is received by spatial optical communication and is shaped so that an interleave length can be detected; a deinterleaving unit that deinterleaves the received data based on the detected interleave length. Communications equipment. (14) determining an interleave length of transmission data to be transmitted by the free space optical communication; Interleaving the transmission data with the determined interleave length; The interleaved transmission data is shaped so that the interleave length can be detected at a receiving side of the spatial optical communication. Communication methods. (15) Computer, an interleave unit that determines an interleave length of transmission data transmitted by the free space optical communication and interleaves the transmission data at the determined interleave length; a shaping unit that shapes the interleaved transmission data so that the interleave length can be detected at a receiving side of the spatial optical communication; A communications program to function as a [Explanation of symbols]

[0167] 1. Communication Systems 10 Terminal Equipment 20 Server device 30, 40 Communication equipment 11, 21, 32, 42 Communication Interface 31, 41 Optical Space Communications Department 311, 411 Receiving processing unit 312, 412 Transmission processing unit 12, 22, 33, 43 storage section 13, 23, 34, 44 Control section 341, 441 Acquisition Department 342, 442 Plastic surgery department 343, 443 Error Correction Unit 344, 444 Interleave Section 345, 445 Transmission control section 346, 446 Detector 347, 447 Deinterleave section 348, 448 Reception control section

Claims

1. an interleave unit that determines an interleave length of transmission data transmitted by the free space optical communication based on information about a transmission path of the free space optical communication, and interleaves the transmission data based on the determined interleave length; a shaping unit that shapes the interleaved transmission data so that the interleave length can be detected at a receiving side of the spatial optical communication, The information on the transmission path of the spatial optical communication includes at least information indicating whether the spatial optical communication is communication between a ground station and a satellite station, communication between satellite stations, or communication between ground stations. Communications equipment.

2. The shaping unit shapes the interleaved transmission data based on a block format configured of one or a plurality of data blocks; The block format is composed of one or more data blocks with a synchronization code arranged at a block boundary, The shaping unit arranges the synchronization code at the block boundary based on the determined interleave length. The communication device according to claim 1 .

3. The block format is a format composed of an error correction block encoded by a block code. The communication device according to claim 2 .

4. The block format is a format composed of an error correction block encoded by a product code. The communication device according to claim 3.

5. the block format is a format composed of an error correction block encoded by a Reed-Solomon product code; The communication device according to claim 4.

6. The interleaving unit determines the interleaving length based on information of an error rate in communication with a receiving side of the spatial optical communication. A communication device according to any one of claims 1 to 5.

7. determining an interleave length of transmission data transmitted by the free space optical communication based on information regarding a transmission path of the free space optical communication; interleaving the transmission data based on the determined interleave length; The interleaved transmission data is shaped so that the interleave length can be detected at a receiving side of the spatial optical communication; The information on the transmission path of the spatial optical communication includes at least information indicating whether the spatial optical communication is communication between a ground station and a satellite station, communication between a satellite station and another satellite station, or communication between a ground station and another ground station. Communication methods.

8. Computer, an interleave unit that determines an interleave length of transmission data transmitted by the free space optical communication based on information about a transmission path of the free space optical communication, and interleaves the transmission data based on the determined interleave length; a shaping unit that shapes the interleaved transmission data so that the interleave length can be detected at a receiving side of the spatial optical communication; The information on the transmission path of the spatial optical communication includes at least information indicating whether the spatial optical communication is communication between a ground station and a satellite station, communication between a satellite station and another satellite station, or communication between a ground station and another ground station. Communications program.

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