ASIA-PACIFIC TELECOMMUNITY Document:The 21st Meeting of the APT Wireless Group (AWG-21) AWG-21/INP-59

3 – 7 April 2017, Bangkok, Thailand 27 March 2017

Japan

PROPOSED MODIFICATION TO WORKING DOCUMENT TOWARDS PRELIMINARY DRAFT NEW APT REPORT ON CURRENT AND FUTURE USAGE

OF UNMANNED AIRCRAFT

1. Background

At the last AWG-20 meeting held in September 2016, working document towards a preliminary draft new report on current and future usage of unmanned aircraft was updated and carried forward to the next meeting (AWG-20/TMP-19). APT members were invited to provide further inputs at the next meeting on this matter.

2. Proposal

Japan proposes that the following annex be considered for the modification of AWG-20/TMP-19, as indicated in section 2.2, section 3.1.1, section 3.1.2, and section 3.1.3. This document proposes an addition of a subsection concerning the frequency planning for UAS for commercial usage in Japan, and some amendments in section 3.1 on Services and applications for UAS in Japan.

Sec. 2.2 Frequency planning for UAS for commercial usage in Japan Sec. 3.1.1 E-mail delivery system through unmanned aircraft in disaster areasSec. 3.1.2 Hand-Over System of Plural Ground Stations in Plural UA OperationSec. 3.1.3 Small UA-based wireless bridge system with the satellite telecommunication system

Contact: Takako KITAHARAMitsubishi Research Institute, Inc. (MRI)JAPANXXX

Email:takako_kitahara@mri.co.jp XXX

ANNEX

Proposed modificaionmodification to working document towards a preliminary draft new report on current and future usage of unmanned aircraft.

1 Introduction

2 Current status of frequency usage for unmanned aircraft systemsCurrent status of frequency bands assigned for UAS usage in APT countries are described in the following sections.

[Editor Notes: This section describes the current status of frequency usage or regulatory status of each APT country for UAS]

2.1 Frequency planning for UAS for commercial usage in China

2.2 Frequency planning for UAS for commercial usage in Japan

August 2016, the Ministry of Internal Affairs and Communication of Japan made a regulatory amendment which deals with frequency assignment to robot usage, including UAS usage. To be exact, 2 483.5-2 494 MHz and 5 650-5 755MHz bands were additionally assigned to enable further advanced frequency usage such as high-definition/long distance video communication. In addition, 169.050-169.3975MHz and 169.8075-170MHz bands were additionally assigned as a backup circuit. Both frequency bands are subject to licensing.

The above frequency assignments were decided in recognition of the increasing demands-along with the diversification of robot usage- towards further advanced and flexible frequency usage such as for high-definition/long distance video communication. UAS users are now able to conduct data communication and image/video transmission between UA and operator using the newly assigned frequency bands.

Detailed information of intended application and technical requirements of respective frequency bands are as follows.

2 483.5-2 494 MHz and 5 650-5 755MHz bands

These frequency bands were additionally assigned to enable high-definition and long-distance image/video transmission for both uplink and downlink communication. Communication distance is expected to be as far as 5km, making it possible for UAS to fly above and send pictures or videos of restricted areas such as location affected by volcano eruption. Details on technical requirements of these bands are listed in the table below.

169.050-169.3975MHz and169.8075-170MHz bands

These frequency bands were additionally assigned for backup communication circuit. It is suited for basic control command or fundamental image transmission (such as that of black-and-white image with downgraded frame-rate). This band enables operators to conduct essential control commands for restoration purpose in case an error occurred within the main communication circuit. Details on technical requirements of these bands are listed in the table below.

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Table 2.2-1 Channels for UAS

Frequency band Maximum Transmitter Power

Variation of occupied frequency bandwidth

2 483.5-2 494MHz1W (EIRP 4W)

4.5 / 9MHz

5 650-5 755MHz 4.5 / 9 / 19.7MHz

169.050-169.3975MHz169.8075-170MHz 1W (EIRP 3.25W) 100 / 200 / 300kHz

3 Services and applications for public use of unmanned aircraft systems in some countries

3.1 Services and applications for UAS in Japan

[2.1.1] Background

[2.1.2] In Japan, there is a growing interest in the use of unmanned aircraft for measures against geographic structure inherent to island nation and natural disasters. Until now, we have developed some radio communication systems using small unmanned aircraft, and have conducted research and development to ensure communications at the time of disaster. This subsection describes the some examples of services and application using UAS in Japan.

[2.1.3] Services and applications for UAS in Japan

[2.1.4] E-mail delivery system through unmanned aircraft in disaster areas

3.1.1.1[2.1.4.1] Background and aims

In case that a great disaster happens, information transmissions including the safety confirmation will become very difficult since disconnection of communication networks is encountered. For quick provision of temporary communications to the disaster area where the communication measures are shut down, Japan has developed message storage and transporting system using unmanned aircraft (UA). In such system, the UA picks up the messages (ex. e-mails) in disaster area and return them to non-disaster area. This system has superior merit to establish the communication network quickly without influence of damage on the ground.

3.1.1.2[2.1.4.2] System overview

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Figure 3.1.1.2-1 Overview of E-mail delivery system through Unmanned Aircraft in disaster areas

Figure 3.1.2.1-1 Overview of E-mail delivery system through Unmanned Aircraft in disaster areas.

Figure 3.1.1.2-1Fig. 3.1.2.1-1 shows the overview of e-mail delivery system through Unmanned Aircraft in disaster areas. Herein, it is supposed at the refuge shelter in the disaster area that a temporary message storage with Wi-Fi AP is provided. Victims come there with their smart phone and send e-mails to the temporary message storage over Wi-Fi. The temporary message storage stores e-mails until UA coming (I). An UA has the functions of a Wi-Fi router and a message storage. The communication between the ground and UA will start, when the UA comes into Wi-Fi AP area of the temporary message storage (II). When UA returns to a non-disaster area, the gateway pushes e-mails to the Internet (III). This system can rapidly work even just after the disaster occurrence, therefore very important information such as safety confirmations can be exchanged and contribute to the rescue operation.

3.1.1.3[2.1.4.3] Summary of verification experiment

Figure 3.1.1.3-2Fig. 3.1.2.1-2 shows experiment scene that this system was verified at school ground assigned as a refuge shelter. The temporary message storage was set nearby gymnasium and the gateway was set keeping a distance with the temporary message storage as far as possible. Our system is useful for both rotary wing UA and fixed wing UA. Then, we used rotary wing UA instead of fixed wing UA because the experimental field was very limited for fixed wing UA. The delay between non-disaster area and disaster area was set virtually 30 minutes as a flight time between them.

We verified the e-mail transmission from disaster area to non-disaster area. The experimenter came nearby the temporary message storage, and sent e-mail to it. An UA came disaster area and collected e-mail over Wi-Fi. The UA returned to non-disaster area after finishing collecting e-mail. The Wi-Fi AP and message storage in UA pushed e-mail to the network in non-disaster area. We also verified the e-mail reply from non-disaster area to disaster area.

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Figure 3.1.1.3-2 Overview of verification experiment

Fig. 3.1.2.1-2 Overview of verification experiment

3.1.2 Handover System of Plural Ground Stations in Plural UA Operation

3.1.2.1 Background and aims

Recently, with the progress of UAS (Unmanned Aircraft Systems) technologies, its application is expected to expand to civilian use. It is expected to expand the use of small and medium-sized UAS and operate in a wide area in various fields including pesticide spraying, aerial survey, logistics, environment observation, data collection for survey of animal and plant life, infrastructure monitoring, and information collection at disaster. In the wide area operation of small and medium-sized UAS, it is necessary to follow the flight situations of each UA (Unmanned Aircraft) to secure the flight safety among plural aircraft (among UA, or among manned aircraft and UA in the future) which share the air space, and accordingly, a simple and lightweight flight control system should be considered for a flight control of small and medium-sized UAS.

Handover System of Plural Ground Stations in Plural UA Operation, composed of a

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communication system mounted on UA and AP (Access Points) for ground control, aims to continuously monitor plural UA and safely control the flight by managing flight information of plural UA obtained from plural APs in an UA flight control system.

3.1.2.2 Overview of Handover System of Plural Ground Stations in Plural UA Operation

Figure 3.1.2.2-3shows the Overview of Handover System of Plural Ground Stations in Plural UA Operation. The assumed application of this system is to allow UA operated in long-range flight routes to perform physical distribution as well as observation and surveys in mountain areas where wireless communication reach can hardly be established because of the unevenness of terrain, by providing them with plural ground stations along valley pathways so that wireless links can be seamlessly maintained. This system is composed of a communication system mounted on UA and AP (Access Points) for ground control, and monitors flight information and achieves a stable flight control in a wide area by sequential handover of plural APs placed along the flight path. Thus, it is possible to continuously monitor plural UA and safely control the flight by managing flight information of plural UA obtained from plural APs in an UA flight control system.

Figure 3.1.2.2-3 Overview of Hand-Over System of Plural Ground Stations in Plural UA Operation

This section introduces a handover technology for the efficient use of frequency and the safe wide-area operation required for the flight control system above. This technology enables the implementation of a flight control system for a small and medium-sized UA which is unable to be equipped with a large flight control system such as a satellite communication system or an ATC transponder.

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3.1.2.3 Example of Operations and Features

(1) Example of Operations

Figure 3.1.2.3-4illustrates the example of operation of UA Handover System. This system consists of Control and Non Payload Communication (CNPC) mounted on UA and AP (Access Points) for simple ground control placed on the ground. Each AP is placed along the flight path of UA on the ground so that its radio coverage overlaps that of adjacent AP. When UA approaches the coverage of AP, the UA request the AP to control flight and the AP keeps the flight information of the UA, together with that of other UA within the coverage. When the UA moves to an adjacent AP, the AP seamlessly handovers the UA information to the adjacent AP, which monitors the UA continuously.

AP follows the current position, velocity, direction, altitude, and identification number of plural UA and transmits the information to an UA flight control system through a Ground Network System. Based on the information, the UA flight control system directs the distance between UA, altitude, velocity, direction, and route to a flight control system of each UA to enable safe and efficient UAS operations.

This system is intended for a small and medium-sized UA which is unable to be equipped with a large flight control system such as a satellite communication system or an ATC transponder. Therefore, on-board equipment for hand-over needs to be small, lightweight, and power-saving. For widely using UAS, AP should be portable, inexpensive, and power-saving. Achieving this allows the construction of flight control system enabling dynamic flight path setting to operate many UA simultaneously.

Figure 3.1.2.3-4 Example of Operations

(2) Features of UA Handover System

UA handover system is intended for safe flight and efficient operation of UA by always controlling the BLOS (BLOS: Beyond line-of-sight) wide-area operation of small and medium-sized UA. Therefore, this system needs to have:

high frequency usage efficiency and power-saving ground equipment;

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one wave of 5GHz for frequency based on the agreement of WRC-12;

no cutoff during handover for safe flight control, such as wireless LAN;

no large-sized ground equipment, like a base station of cell phone for easy installation;

a small, lightweight, and power-saving radio to be able to be installed in a small and medium-sized UA; and

transmission rate control that can change aircraft body information and information volume of images and sensors required for flight control, is available in response to situations such as UA take-off and collision avoidance.

(3) Features of installed algorithm

In accordance with features described in (b), the handover control algorithm and transmission rate control algorithm installed in this wireless system have the following features:

① Features of handover control algorithm

Protocol that handover is available in one wave of 5GHz band.

Wireless Communication system is Time Division Multiple Access (TDMA) where one-to-many communication is available for UA and AP.

Reliable and seamless soft-handover to new AP, by allowing UA to communicate adjacent APs simultaneously in an overlapping communication area.

② Features of transmission rate control algorithm

Transmission rate control established by altering the time slot assignment

Employed sequential transmission resource allocation that enables a gradual assignment to perform safe and secure transmission rate control.

Defined and distributed resource request values by using an application program instead of setting a fixed assignment, to allow AP to perform fair and optimum transmission resource allocation to each UA

3.1.2.4 Overview of verification test of the handover wireless system

(1) Overview of the test system

To verify performance of the above-mentioned UA handover system, a wireless system equipped with each algorithm has been developed. This system is composed of a wireless communication unit on a ground station and an unmanned aircraft (UA), both with a common configuration. Figure 3.1.2.4-5shows photographs of the completed unit.

Also, specifications of the wireless equipment are as follows:

Service frequency: One radio wave in the band of 5030 MHz to 5090 MHz

Transmission output: 1 W

Multiple connection system: TDMA

Mass of on-board wireless unit: 1 kg maximum

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Figure 3.1.2.4-5 Handover wireless system

(2) Overview of the verification test

The verification test of handover control and transmission rate control was domestically conducted by carrying the above-mentioned wireless system on board of UA units. In this test, two UA units were equipped with the handover wireless unit as shown in Figure 3.1.2.4-6 (UA1 flight path) and Figure 3.1.2.4-7 (UA2 flight path). Designations of the units are UA1, UA2, AP1 and AP2, respectively.

In the verification of handover actions, different communication areas utilizing the mountains and flight altitude were established by making use of the topographical form of a mountain as a shield between AP and UA, and two UA units performing a turning flight with an altitude difference of 100 m. The three areas consisting of an area where communications are enabled with AP1 only, with AP2 only, and an area where communications with the both AP stations are enabled, were established to check the following actions:

① Checking the handover actions

The handover actions of one or two UA units while moving between two AP communications areas were checked.

② Checking actions of transmission rate control against plural UA units

The actions of the transmission rate control when two UA units changed their resource request value were checked.

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Figure 3.1.2.4-6 Flight path of UA1

Figure 3.1.2.4-7 Flight path of UA2

(3) Verification test results

This verification test gave the following results:

① Checking the handover actions

Handover connection transition in this verification process is shown in Figure 3.1.2.4-8.

In the flight process of UA1 in each area of AP1 and AP2, it was verified that soft handover was performed while changing the counterpart of communication in the sequence of (a) UA1 to AP2 connection, (b) UA1 to each of AP1 and AP2 stations, and (c) UA1 to AP1 connection. Likewise, it was confirmed that UA2 similarly performed the handover between

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the areas while being connecting with both AP stations, and also recognized re-connection with a link once disengaged. From the verified facts described above, plural handovers were checked to be executed by two UA units at different altitudes during the process of moving between both AP stations.

Figure 3.1.2.4-8 Handover connection transition

② Checking actions of transmission rate control against plural UA units

Rate change transition in this verification process is shown in Figure 3.1.2.4-9. In this verification, each resource request value of UA1 and UA2 were changed in order to determine how the actual transmission rate control varied. As shown in the figure, transmission rate varies according to resource request value change of UA1 and UA2. Also, as a result of analysis, the rate control was found to have been executed in a step-wise manner. Conducting controlling action via an intermediate state during such a rate control process suppresses the loss probability of communications by reducing the congestion probability, thereby enabling the allocation of communication resources with further enhanced reliability.

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Figure 3.1.2.4-9 AP1-UA1/UA2 Rate change transition

The verification test proved that UA can autonomously switch ground stations to be actually connected and that plural UA units can execute the assignment of time slots as shared resources in accordance with resource request values. Consequently, it was verified that handover algorithm and transmission rate control algorithm can be installed in compact and light-weight wireless units to be in service in an actual flight environment. These algorithms are installed mainly by using software so that maintaining both down-sizing and scalability can be achieved.

3.1.2.5 Technical challenges

The handover control technology developed in this study involve challenges such as methods of application to specific CNPC links, coexistence with on-going communication protocols, and stable operation in larger communication environment. There are also challenges for further sophistication such as collaboration with flight control system, ground station deployment method, application of optimum algorithms, control parameters extension (threshold value, action timing, modulation and coding for example), setting automation, etc.

3.1.3 Small UA-based wireless bridge system with the satellite telecommunication system

3.1.3.1 Background and aims

The most advanced and popular mobile phones become almost useless under large-scale disasters due to physical damage, electricity outage, and traffic congestion. In addition, many areas in mountains or islands may be isolated due to the total damage of roads, harbors, and communication infrastructures. Under such situation, it is desired to monitor the situation in the whole of disaster area to judge, predict, and cope with disaster details. In addition, it is more desired to provide deployable temporal communication lines rapidly to the isolated areas until the recovery of ground infrastructures. To realize the temporal communication lines, a hybrid multi-hop network to collaborate with the remaining cellular telecommunication network has

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been researched and developed by the National Institute of Information and Communications Technology (NICT) in Japan..

3.1.3.2 System overview

Figure 3.1.3.2-10shows an overview of the hybrid multi-hop network that combines small UA-based wireless bridge system and satellite telecommunication system. The small UA-based wireless bridge system provides the connection to the isolated area where ground infrastructures are broken. The satellite telecommunication system proves the Internet link to the small UA-based wireless bridge system via vehicle-mounted earth station. To collaborate with cellular telecommunication network at the isolated area, we used a femtocell station in the case of our research and development. The femtocell station is a small base station of cellular telecommunication that can be installed in residential environments to provide improved cellular coverage for indoor environment. In order to connect the femtocells with the main core network, we used Internet link through the hybrid multi-hop network. This configuration can provide temporal link even in a distant disaster area. However, the link quality of the hybrid multi-hop network depends on the small UA-based wireless bridge system due to the narrowband system compared with the satellite telecommunication system.

Figure 3.1.3.2-10 Overview of hybrid multi-hop network

(1) Small UA-based wireless bridge system

In the small UA-based wireless bridge system, the small UA has an on-board transceiver and relays the signal between the ground stations (GSs). The small UA circles around above the fixed area for the relay communication. Table 3.1.3.2-2 shows the specification of small UA system. The UA system consists of a small UA and a ground control station (GCS). The payload of small UA was limited to 0.5 kg due to small airframe. The nominal endurance was about 2 or

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3 hours. The control range from GCS was about 9 km. The frequency of control and non- payload communications (CNPC) was conducted in the 5060 MHz band and the signal power of CNPC was 1 W in the experimental measurement. The small UA can be launched by throwing and recovered by deep-stall landing. Therefore, special area such as runways is not needed for launch and landing. In addition, since the small-UA and GCS are easily hand-carried, we can operate them even when cars are not available due to road damage. Table 3.1.3.2-3 shows the specification of transceivers for on- board and ground station (GS) for relay communication. Each transceiver for GSs and UA were equipped with a single antenna used for transmission and reception in a half duplex manner. The weight of on-board transceiver with a battery was 0.47 kg. In the experimental measurement, the frequency band of the transceiver was 2 GHz band and the transmit power was 2 W. The maximum range for communication between UA and GS was about 20 km. In order to relay communication, it was preferable that we ensure the Line-of-sight (LOS) between UA and GSs. A snapshot of small UA-based wireless bridge system is shown in Figure 3.1.3.2-11.

Table 3.1.3.2-2 Specification of small UA system

Table 3.1.3.2-3 Specification of transceivers

Figure 3.1.3.2-11 Snapshot of small UA-based wireless bridge system

(2) Satellite telecommunication system

As satellite telecommunication system, we assumed the use of the wideband internetworking satellite WINDS (Wideband InterNetworking engineering test and Demonstration Satellite, also called KIZUNA). WINDS was developed by the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). In WINDS, Ka-band (20 GHz to 30 GHz) was used for communication use. WINDS includes Ka-band

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vehicle-mounted earth station and earth station. The earth station was installed at the NICT Kashima Space Research Center located in Kashima, Ibaraki, Japan. The user data rate of Kashima earth station was 1244 Mbps and that of the vehicle-mounted earth station was 622 Mbps. Therefore, the high-speed access to the Internet was able to be provided by WINDS.

3.1.3.3 Summary of verification experiment

We conducted a demonstration of the hybrid multi-hop network with the cellular telecommunication network in Shimanto-machi, Kouchi, Japan. The demonstration field is deep in the mountains and out of the service of cellular network system. The purpose of this demonstration was to operate the cellular telecommunication network even at the isolated area. In order to achieve our purpose, a femtocell of cellular telecommunication was installed in demonstration field.

Figure 3.1.3.3-12and Figure 3.1.3.3-13 show examples of deployment and the trajectory of UA in the experimental measurement. The area for experimental demonstration is located in the depths of mountains (1400 feet above sea level) in Kouchi, Japan, and it is out of the coverage of cellular telecommunication network. The two GSs (denoted by GS1 and GS2) were separated by about 600 m. There is no direct communication link between GS1 and GS2, thus information was able to be delivered only through the relaying UA. We assumed that the area of GS2 was the isolated area and that of GS1 was the non-isolated area. In the isolated area, the femtocell was located within a house close to GS2. In the non-isolated area, the vehicle-mounted earth station was located near GS1. The GS1 connected the vehicle-mounted earth station with the satellite telecommunication over the cable.

Figure 3.1.3.3-12 Case A: average of wind speed is 8 m/s

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Figure 3.1.3.3-13 Case B: average of wind speed is 2 m/s

In this experimental measurement, we conducted voice testing using a speech quality measurement tool, such as Perceptual Evaluation of Speech Quality (PESQ). PESQ analyzes the speech signal sample-by-sample after a temporal alignment of corresponding excerpts of reference and test signal, and PESQ results principally model mean opinion scores that cover a scale from 1 (bad) to 5 (excellent). In general, the score of 2.5 means the audible level. We measured the PESQ score using 3G mobile terminals, LTE mobile terminal and Skype application on LTE terminal since PESQ scores vary widely even among quality terminals. Moreover, the bit rate of the Skype application was fixed to 30 kbit/sec.

Figure 3.1.3.3-14 and Figure 3.1.3.3-15 show PESQ scores f for various cases of mobile terminal in the demonstration system, where the case of only satellite telecommunication was used is plotted as a target for comparison. The latter case is plotted in the graph as a comparison. Ten difference sentences of voice every terminal are inputted to the demonstration system and the scores are measured at terminal of femtocell side. Moreover, we measured PESQ scores of two cases (case A and B) from the satellite telecommunication point of view (Satellite), the PESQ scores of two cases (case A and B) denote the same tendency and those scores depend on the mobile terminals.

On the other hand, in the hybrid multi-hop network (satellite and UA), the PESQ scores depended largely on the environment influence. The communication link between GSs was often disconnected due to strong wind speed in the case identified in Figure 3.1.3.3-14. Therefore, we could not measure the PESQ scores of all sentences in this case. In the case indicated in Figure 3.1.3.3-15, it was observed that the PESQ score of the hybrid multi-hop network exceeded 3.0 (fair) several times. However, the variance of the PESQ score of the hybrid multi-hop network is larger than that of only satellite telecommunication system due to the moving relay of UA. In order to ensure reliability, it is necessary for the small UA-based wireless bridge system to improve the link quality.

Figure 3.1.3.3-16 and Figure 3.1.3.3-17 show one-way delay for various cases of mobile terminal in the demonstration system, where the case of only satellite telecommunication was used is plotted as a target for comparison. The one-way delay properties are measured at terminal of femtocell side when the 10 difference sentences of voice every terminal are inputted to the demonstration systems. Theoretically, the one-way delay of only satellite telecommunication system was below 200 msec, and the minimum delay of small UA-based wireless bridge system was 200 msec. Therefore, the minimum delay was estimated 900 msec or

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under at the most even if we take into account the intrinsic delay of femtocell. In Figure 3.1.3.3-16, we could not measure all sentences of one- way delay, in the same matter as shown in Figure3.1.3.3-14. However, in Figure 3.1.3.3-17, it was observed that the delay of the hybrid multi-hop network varied from 740 msec to 910 msec in the case of 3G or LTE terminal. Moreover, the maximum delay of Skype application with LTE terminal reached the edge of 1200 msec due to the addition of the processing delay within the Skype application.

From these results, we were able to confirm the validity of the hybrid multi-hop network as telecommunication system between an isolated and non-isolated area in the case of disaster while the communication quality depends on the flight environment of small UA.

Figure 3.1.3.3-14 PESQ scores in the case A

Figure 3.1.3.3-15 PESQ scores in the case B

Figure 3.1.3.3-16 One-way delay of case A

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Figure 3.1.3.3-17 One-way delay of case B

4 Conclusions

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