HTML5 Webook

63/182

it is continuously operable for about 1.5 hours.e following are the details of transmission perfor-mance:It uses, for multiplexing, TDMA / TDD;the error correction code eciency is 1/2, so its eec-tive transmission speed is approximately 400 kbps—we conrmed communication between a drone and a ground station at a direct distance of longer than 15 km. On the other hand, because each of the two ground stations mutu-ally linked via a drone has a LAN interface in it, by using the LAN port of one of the ground stations as the wireless LAN access point and connecting the other to the internet, we are able to easily establish a temporary wireless LAN (Wi-Fi) zone covering isolated areas, and use the internet connection for mail, IP telephone, and other applications for safety conrmation. In addition, although this will be discussed later, we successfully established a backhaul link by connecting our system, instead of to the internet, to a “femto cell,” which is a micro hub station of a mobile phone network.Puma AE is a battery-powered xed wing unmanned aircra with a wingspan of 2.8 m, a length of 1.4 m and a weight of 5.9 kg. It has several features as follows:it is capable of autonomously performing a long ight at a low speed along a predetermined ight course and it can be in the air for two to three hours in a ight;when taking o, it is thrown into the air from a su-ciently wide ground or open space (Fig. 3), or launched by a spring-powered launcher. Flying in rainy weather is not a problem because the aircra and a ground station are waterproofed.e wireless system works as follows:the airframe control wireless system transmits, as well as control signals, command signals and telemetry signals, videos of VGA quality taken by an aircra mounted cam-era at a rate of 30 FPS—the 2 GHz band has been used since it was rst introduced;the aircra mounted wireless system (air station) and the ground stations are operated with an experiment radio station license permitting an output power up to 1 W, so the outreach distance of the wave transmitting command/video/telemetry signals is longer than 15 km under a line-of-sight condition. e system does not use the 2.4 GHz band—no license is required, and is the most widely used band for radio-controlled hobby cra or multi-rotor type drones;on the hand controller used by an operator, the airframe telemetry information and the mounted camera videos are displayed in real time, so the operator can, if the wireless link is connected, navigate the aircra in a situation where the operator cannot see the aircra directly—such naviga-tion is very similar to instrument ight rule (IFR) of a manned aircra.On the other hand, at the ITU World Radiocommunication Conference 2012 (WRC 12), the recommendation that the 5 GHz band (from 5030 to 5091 MHz) should be added to the frequency bands for un-manned aircra control was agreed [3].However, in order to make the frequency band appli-cable in actual situations, we need to study technological problems and nalize technical standards—we have to clarify the propagation characteristics in the frequency band, develop the technologies for avoiding interference in the band and to and from the adjacent bands, and develop the technologies for frequency sharing. For the purpose of contributing to such international activities, we acquired an experiment radio station license of the 5 GHz band (with the same output power as that of 2 GHz) to operate the wireless control link of two aircras of the three we introduced, having been conducting. During ight opera-FiF2　Schematic diagram of 2-drone-relayed communication linkGround station BWi-FizoneGround station BNetwork existence place (municipal office etc.)The Internet or othersFamily member remainDrone(Small unmanned aircraft system)Smart phones, PCs, and othersDrone operation leads to safe confirmation of family membersIsolated community or shelterWi-Fi connections by drone-link makes safe confirmation, mail or telephone availablePromptly deployableFiF3　Throwing launch of communication-link drone592-9 Wireless Communication Technology for Small Unmanned Aircraft Systems ~Towards the deployment of IoT in the Sky~