Masayuki Oodo

Sharing and Compatibility Study between Fixed Service Using High Altitude Platform Stations (HAPS) and Other Services in the 31/28 GHz Bands

In the World Radiocommunication Conference 2000 (WRC-2000), use of the 31 GHzand 28 GHz bands was permitted for the fixed service (FS) by using highaltitude platform stations (HAPS) in some countries. This paper examines thesharing and compatibility of the HAPS-based FS with the other services usingthe same and adjacent frequency bands and establishes the conditions of thecoexistence with those services. Feasibility of dynamic channel assignment(DCA) scheme among the different communication systems to facilitate thecoexistence is also studied.

Experiments on IMT-2000 using unmanned solar powered aircraft at an altitude of 20 km

Several countries are keenly interested in the research and development of novel wireless communication systems using high altitude platform stations (HAPS) because of their great potential benefits. In June and July 2002, we carried out the worlds first experiment on International Mobile Telecommunication 2000 (IMT-2000) by radio relay via transponders onboard an unmanned solar powered aircraft at an altitude of 20 km. This experiment demonstrated for the first time the feasibility of applying the IMT-2000 system using a HAPS and a compact cellular phone designed for terrestrial cellular systems. Two experiments were carried out over Kauai Island in Hawaii, USA. In the first experiment, we were unable to establish an IMT-2000 link connection via the aircraft at 20 km because the onboard transponder for the reverse link received unexpected signals from a terrestrial cellular system in commercial use 200 km away on Oahu Island. However, we managed to establish the link by connecting a high gain external antenna to the cellular phone. After the first flight experiment, we developed an onboard receiving antenna with a low sidelobe level to suppress interference signals. In the second experiment, we successfully achieved IMT-2000 video communication with a cellular phone. This paper presents the experimental results and analysis of these IMT-2000 communication experiments.

Experiment of telecom/broadcasting mission using a high-altitude solar-powered aerial vehicle Pathfinder Plus

A series of telecommunication and broadcasting tests using a high-altitude platform in the stratosphere at an altitude of 20 km was carried out on the Hawaiian island of Kauai in June-July 2002. For the high-altitude platform, we used a NASA solar-powered unmanned aerial vehicle (UAV), Pathfinder Plus. The tests were successfully completed, and the first in the world. This paper provides the configuration of the tests and reports some of their results.

Effect of Antenna Beam Pattern and Layout on Cellular Performance in High Altitude Platform Communications

High Altitude Platforms may offer high spectrum efficiency by deploying multi-beam, multi-cell communications networks. The properties of the antennas carried by the HAP payload are key to the effective exploitation of these benefits. This paper compares different models for the antenna sidelobe region and quantifies, in each case, the carrier to interference ratio for a 3 channel re-use plan. Networks of 121 and 313 cells are compared. We show how the ITU recommended pattern for the 47/48 GHz band leads to pessimistic results compared to an adapted pattern which fits that of measured data for an elliptic beam lens antenna. The method is then extended to consider other radiation patterns. Spectrum sharing issues are explored with reference to further ITU recommendations and comparison with measurement data. Finally, an ITU type cellular layout which uses the same antenna for each cell is compared to an alternative hexagonal layout where each cell has equal size.

Greater reliability in disrupted metropolitan area networks: use cases, standards, and practices

Unlike most general wireless users enjoying broadband access to the Internet and so on, a number of mission-critical applications such as PPDR are using narrowband systems that are only capable of transmitting voice and low-rate data. Broadband wireless networks with greater reliability are increasingly demanded by these applications including the emerging Smart Grid. With this vision, the IEEE 802.16 Working Group completed two standard amendments recently, IEEE Std 802.16n-2013 and IEEE Std 802.16.1a-2013. 802.16 network reliability is significantly increased by technical developments dealing with failures of network infrastructure stations, radio path and backhaul connectivity, and so on. This article serves to analyze the envisaged typical use cases of greater reliable broadband wireless networks, outline the main technical developments of the two standards, and introduce a recently developed practical system for PPDR applications in Japan.

Current status of 200 MHz-band public broadband wireless communication system in Japan

In 2013, Japan launched for practical use of the worlds first VHF-band broadband wireless communication system for “Public Protection and Disaster Relief (PPDR)”. NICT has been promoting research and development (R&D) and standardization regarding this new wireless system or public broadband (PBB) wireless communication system. This paper presents the outline of this system and the current status of R&D and standardization.

Experiment of IMT-2000 using stratospheric-flying solar-powered airplane

In June and July 2002, we conducted the worlds first experiments on digital TV broadcasting and third-generation mobile communications system (IMT-2000) by radio-relay at an altitude of 20 km using unmanned stratospheric-flying solar-powered aircraft. These experiments demonstrated that future broadcasting/telecom systems by high altitude platform station (HAPS) are feasible and useful. This paper describes the experimental and analytical results of the IMT-2000 experiment.

DIGITAL BROADCASTING EXPERIMENT USING A HIGH-ALTITUDE UNMANNED AERIAL VEHICLE

Using the Pathfinder Plus high-altitude unmanned aerial vehicle, we did a digital broadcasting experiment. In the experiment, Japans digital terrestrial broadcasting standard, ISDB-T, was used in the UHF band. From an altitude of 20 km, a radio station installed under a Pathfinder Plus wing transmitted the signal. Reception was successful at the ground station even when we used the parameter set that was least robust under poor channel conditions. The receiving power level of the ground station was measured and agreed with the expected value under the assumption of free space propagation.

Receiver diversity evaluation for a VHF band broadband mobile communication system

In this paper, diversity receiver performance at base station for VHF-band broadband mobile communication systems is examined by using measurement results. Diversity gain of two RX antennas for link budget calculation has been calculated by using a selective combining and an equal gain combining schemes. By analyzing the diversity gain statistically, it is found that the diversity gain of selective combining and its variation are increased in larger antenna separation and shorter transmission range. On the other hand, the diversity gain of equal gain combining and its variation are decreased in larger antenna separation and in shorter transmission range. In addition, a path loss model has been developed for a link budget design. The path loss model parameters are extracted for over 1 km transmission range. By considering the path loss model with analytically-extracted constant diversity gains for BS antenna separation lengths of 1, 5, and 10 wavelengths, the system service coverage can be estimated.

Power delay profile measurement for VHF-band broadband mobile communication system

This paper presents measurement and analysis results of power delay profiles and fading characteristics for “Public Broadband Wireless Communication (PBB) System” in VHF band. The PBB system was proposed to utilize a portion of vacant spectrum in VHF band due to the frequency reallocation plan in Japan, and the system was standardized as ARIB STD-T103 as well as IEEE802.16n. The purpose of this study is to evaluate the applicability of the system for non-line-of-sight urban environment and characterize the 200 MHz band broad band radio channel. The measurement is conducted by using a developed device which is compliant with the ARIB STD-T103 as a transceiver, and received signal is captured as complex IQ signals by using a signal analyzer. In order to obtain the power delay profile, impulse responses are analyzed by calculating sliding correlation between reference signal and measured signals. For the evaluation of delay characteristics, RMS delay spread is calculated using the power delay profile. In addition, fading characteristics is also shown to confirm the behavior of VHF band mobile propagation channel.