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Shikoku Bureau of Telecommunication hosted the ex-periment, Shimanto-cho, Kochi supported it, and NICT conducted it in cooperation with mobile phone business operators—NTT docomo, KDDI and SoBank Mobile— in February 2015. e experiment site was a resident area in a so-called Hilly and Mountainous area in Shimanto-cho, Kochi. We set the experiment conguration and scenario as follows: we placed a mobile phone hub station, a drone link ground station, and a WINDS vehicle-mounted satel-lite earth station in an area where mobile phone services are unavailable; we launch the drone using a tiny space in a rice eld—where harvest is completed; the drone went up along a valley, then the drone moved to a link point around where the drone was to create a wireless link—the point is about 2 km horizontal distance away from, and about 1,000 m high above, the place where the drone is to be launched—and circled around the link point. Note that the drone ew under beyond line-of-sight conditions, while the wireless link connection was maintained. e signals from the femto-cell hub station were connected to mobile phone networks via the drone link and the satellite link.Although the link was in a slight unstable condition due to the limitation of communication capacity and the uctuations in the drone’s location or attitude, we success-fully conrmed that bidirectional voice communications are available, proving, for the rst time in the world, that aerial space relay technically enables mobile phone conver-sation.Beside the proof-of-concept experiments described above, in collaboration with municipalities, we conducted experiments to use drones for capturing action traces of harmful animals from high places above the ground—we attempted chasing wild boars in Fukushima and monkeys in Tokushima in cooperation with Circuit Design, Inc. We mounted small transmitters the animals equipped with GPS devices to capture signals from those transmitters up in the air and transmit down to the ground for the extrac-tion of animal action traces. We have found in such ex-periments several system problems to solve. So, we are preparing plans for conducting studies on those problems. In addition, we received an order from Hitachi High Tech Solutions Ltd for measurement of the radio environment in a coast area, where the total length of the ight course is about 13 km—Fukushima Prefecture has been develop-ing, in Minami Soma, the “Fukushima Robot Test Field” for the performance evaluation of robots or drones to be used in a disaster situation and others. e area where we conducted the measurements includes the test eld. So, in February 2017, we conducted radio wave measurements using a Puma AE, which is capable of performing long-duration beyond line-of-sight ight (with wireless connec-tion maintained) [5]; the Puma AE, loaded with a small spectrum analyzer in its payload, cruised in each of three ight sections of about 4 km—the 13 km course was di-vided into such three sections—, made measurements of noise levels in the bands of 169 MHz, 920 MHz, 2.4 GHz, and 5.7 GHz, at two elevations from the ground of 100 m and 150 m; and the measurement results were publicized on Fukushima Prefecture’s webpage [6]. Note that we conducted the ight under permission of “a ight without standard method specied” from the Ministry of Land, Infrastructure, Transportation and Tourism (in our case, we made beyond line-of-sight ight), and with regard to the contract research from the Ministry of Internal Aairs and Communication, which will be described later, the measurement conditions are similar to those in this case. So, because a Puma AE is suitable to wide-area aerial measurements of radio wave environments or wave propa-gation characteristics too, we will use the drone for such measurements.3Contract research from the Ministry of Internal Affairs and CommunicationsIn 2012, while worldwide eorts for the utilization of drones had become active, the World Radiocommunication Conference (WRC- 12) agreed on the use of the 5 GHz band (5030 to 5091 MHz) frequencies for control-and-non-payload communication—CNPC link or C2 link—to con-trol drones (transmitting commands) or monitor drones (receiving telemetry signals). Furthermore, in 2015, in WRC 15, they approved the conditional use of satellite-link FiF6　Experiment of mobile phone link by air to space relay (Shimanto-cho, Kochi, February 2015)Femtocell communication zoneSmall UAV Puma-AE,flight at altitude of 1000m)Wideband Internetworking Engineering and Demonstration Satellite（WINDS）InternetKashima Space Research Center, NICT (Kashima, Ibaraki)Isolated disaster area (under experiment scenario)Vehicle mounted satellite earth stationMobile phone company’s networkProving first the possibility of mobile phone relay linkFemtocell hub station612-9 Wireless Communication Technology for Small Unmanned Aircraft Systems ~Towards the deployment of IoT in the Sky~