APT REPORT
on
THE POSSIBLE RADIO SERVICES AND APPLICATIONS
ONBOARD AIRCRAFT AND VESSELS
No. APT/AWG/REP-56
Edition: September 2014
Adopted by
17th Meeting of APT Wireless Group
23 - 26, September 2014
Macao, China
(Source: AWG-17/OUT-16)
APT REPORT ON THE POSSIBLE RADIO SERVICES AND APPLICATIONS
ONBOARD AIRCRAFT AND VESSELS
1
Table of Contents
Introduction .................................................................................................................................... 4
2
Background .................................................................................................................................... 4
3
Scope of work ................................................................................................................................ 5
4
The potential radio services and applications on-board aircraft .................................................... 5
4.1
4.2
Case 1: Millimetre wave broadband wireless communication between airplane and ground .... 5
4.1.1
Background ...................................................................................................................... 5
4.1.2
Application needs............................................................................................................. 6
4.1.3
Experiment ....................................................................................................................... 6
4.1.4
Results ............................................................................................................................ 10
4.1.5
Conclusion ..................................................................................................................... 15
4.1.6
Future challenge ............................................................................................................. 15
Case 2: wireless bridge system using small UAS ..................................................................... 16
4.2.1
Background .................................................................................................................... 16
4.2.2
Wireless Bridge Using Small UAS ............................................................................... 16
4.2.3
Measurement results ...................................................................................................... 18
4.2.4
Integration of wireless bridge using UAS and Relay-by-Smartphone........................... 21
4.2.5 Delay and Disconnection Tolerant Message Transmission System using UAS (in case
of using single Unmanned Aircraft UA) ..................................................................................... 24
4.2.6 Hand-Over system of multiple ground stations in multiple unmanned aircrafts
operation ...................................................................................................................................... 28
5
5.1
5.2
6
The potential radio services and applications on-board vessel .................................................... 32
Case 1: Wireless Broadband Video Transmission Systems ..................................................... 32
5.1.1
Background and Application Requirements .................................................................. 32
5.1.2
System Description ........................................................................................................ 33
5.1.3
Service Provider Cases .................................................................................................. 34
5.1.4
Market Trend ................................................................................................................. 35
5.1.5
Future challenges ........................................................................................................... 35
Case 2: Maritime Broadband Multi-hop Relay Communication System ................................. 36
5.2.1
Background and Application Requirements .................................................................. 36
5.2.2
System Description ........................................................................................................ 36
5.2.3
Verification test .............................................................................................................. 38
5.2.4
Application Services ...................................................................................................... 41
5.2.5
Market Trend ................................................................................................................. 41
5.2.6
Future challenges ........................................................................................................... 41
Summary ...................................................................................................................................... 42
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6.1
Summary of the potential radio services and applications on-board aircraft............................ 42
6.2
Summary of the potential radio services and applications on-board vessel ............................. 43
7
References .................................................................................................................................... 44
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1
Introduction
There are increasing demands for the use of radio services from wherever you are located, including
on-board aircraft and vessel. At the AWG-12 meeting held in Xia Men, China, an agreement was
reached in the Task Group Aeronautical and Maritime (TG A&M) to study the possible radio
services and applications on-board aircraft and vessel. The purpose of this report is to identify the
future needs of special communications for social, industrial and economic development which could
be satisfied by services and applications on aircraft and vessel. Several potential cases are discussed
in this report.
2
Background
To promote new wireless applications and to promote a harmonized vision of wireless
communications systems and services in the Asia-Pacific region to meet the emerging digital
convergence era are the two principle objectives of the AWG. TG A&M extends these general goals
to the aeronautical and maritime field and address the related issues.
According to the terms of reference of TG A&M, several issues of the use of mobile phone as well as
the use of other modern wireless technologies onboard the aircraft and vessels should be considered,
including:

Spectrum harmonization issues including preferred frequency bands and associated
technical characteristics;

Associated regulatory and licensing issues, when considered appropriately.

To study and review future wireless communication technologies on aeronautical and
maritime fields.
With the growth of the penetration of radio communications on business, industry and people’s daily
lives, and with the technology improvements that will make it possible for the use of higher and
wider spectrum bands, it is expected that a variety of radio services and applications will be available
for onboard aircraft and vessel in the future. For example, cellphones will be able to connect to a
pico-cell network built onboard aircraft and vessel, and further connect to a land-mobile network
switching center via satellite link or other kinds of link. Aircraft has been shown to establish a
bidirectional IP communication link with the ground environments by millimetre wave transmissions,
which enables mass volume downloading from the Internet. RFID and sensors based Internet of
vessels can dynamically sense and exchange the information between vessels and harbors, even
between vessels and cargos.
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To successfully deliver services and applications mentioned above, it depends on the supporting
features of new technologies, possible allocated spectrum resources and harmonized coexistence
with the current spectrum utilization in different Asia-Pacific countries. The factors also include
safety concerns and it need to be implemented in accordance with all relevant national and
international laws, regulations and policies. Furthermore, the service and application providers
should pay more attention to the market trends, to ensure that he can get support from the latest
infrastructures, facilities and devices. Of course, all these factors should work together, and some
specific challenges should be considered also, for example radio propagation conditions, high
mobility and time delay etc., we must consider how to deal with these challenges carefully.
3
Scope of work
The potential radio services and applications onboard aircraft and vessel are discussed in this report.
Several cases with background, application needs, success factors, experiment, future challenges,
market trends, provider information are described in the following part 4 and part 5, some
characteristics of services and applications will be addressed including operating band, geographic
range, primary/secondary feature, protection requirements and so on. For the cases have been tested,
the related experimental configuration and results will be given. The summary and conclusion of the
report and the references are given in the following part 6 and part 7.
4
The potential radio services and applications on-board aircraft
4.1 Case 1: Millimetre wave broadband wireless communication between airplane and
ground
4.1.1 Background
Demand has increased for better mobile phone and wireless local area network (LAN) access for
people on-board aircraft. Now, several airlines have started cabin use of cellular phones with a
system involving satellites. Meanwhile, in Japan, a wireless communication system on passenger
airplanes is also being studied. This study, being executed under the Commissioned Business
program of Japan’s Ministry of Internal Affairs and Communications, has led to the design of an
aero broadband system, called the aero hot spot system, using the millimetre wave band. In the
system, airplanes fly over ground tracking antennas arranged at regular intervals. As the aircraft
passes overhead, the antennas hand over service one after another to the aircraft. The National
Institute of Information and Communications Technology (NICT) and Mitsubishi Electric
investigated a broadband communication system for airplanes in which the millimetre wave (MW)
band (40 GHz band) facilitates broadband wireless communications on airplanes and on the ground.
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Some evaluations and experiments toward such a realization have been conducted by the Mitsubishi
Research Institute. The millimetre wave band, such as the over-40-GHz band, is not used heavily in
commercial applications and is expected to facilitate the broadband communication system. The
following part refers to the results of the experiments.
4.1.2 Application needs
Application needs were studied by questionnaire survey, for the purpose of arranging demands for
the communication systems for airplanes in which the millimetre wave band (40 GHz band). The
questionnaire was about utilization form of this system, flight condition of airplanes, needs for the
communication capabilities, etc. The possible users of this system were categorized four groups,
which are aerial survey and imagery, aviation-related experimental research, civil aviation services,
and fixed-wing airplane and rotary-wing airplane development. Table 4.1-1 presents the summary of
the questionnaire results.
Table 4.1-1 Summary of the questionnaire results
Data
Aerial photograph, SAR,
laser measurement
data
(for measurement and
observation for
disaster)
Aviation-related
experimental data
(image, photograph,
and movie)
Flight experiments data
(data recorder)
Data transfer via the
Internet for civil
aviation services
(text data and images)
Live broadcast system
for the helicopter
Data capacity
A few dozen ~a few
hundred GB
A few dozen GB
More than a few dozen
GB
More than a few dozen
GB
Changing
altitude or
turning during
data transfer
Possible
Possible
Impossible
Possible
Aircraft type
Cessna-type plane
Helicopter
Fixed-wing airplane and Civil aircraft
rotary-wing airplane
Helicopter
Flight altitude
200m~6,000m
5km~15km
5km~15km
150m~1,000m
Communication
distance
A few hundred m ~
10km
100km~200km
200km~400km
30km~50km
Data transfer
rate
A few hundred Mbps ~
a few Gbps
More than a few
hundred Mbps
A few hundred Mbps ~
a few dozen Mbps
A few dozen Mbps
Flight velocity
200km/h~500km/h
240km/h~1.100km/h
450km/h~1,000km/h
~300km/h
Radius of turn
Cessna-type plane :
more than 4,000m
In case of 200km/h :
more than 900m
Flight hours
4h~7.5h
4.1.3
Experiment
(A)
Experiment summary
5km~25km
2~5h
Domestic: 1~2h
International: ~12
hours
More than 1 hour
The verification test using aircraft was scheduled in January 2012 on the island of Oahu, Hawaii,
USA, for the purpose of verifying mass volume downloading by bidirectional communication
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between aircraft and the ground. A small airplane was used as the airborne station. Table 4.1-2
presents an overview of the airborne verification test, and Figure 4.1-1 illustrates a diagram of the
airborne verification test. One of the key technologies of the system is to track the target terminal
antennas. To track each antenna position, the antenna system needs to consider the characteristics of
the millimetre wave and the geographical dimensions. The ground-based tracking antenna must
continuously track the aircraft with a high degree of accuracy. The on-board antenna must track the
ground-based antenna by considering aircraft attitude and location. With a reflector controlling the
antenna beam in the system, the mechanism provides a cost-effective, power-efficient tracking
antenna. The ground station has a mechanically controlled reflector to direct the antenna beam in a
specific direction by tilting the reflection disk mechanically. Furthermore, a radio wave was
separately transmitted at 44.55 GHz, in addition to the communication signal wave so that the system
could execute the mono-pulse tracking technique by monitoring the reception level of the radio wave
signal. The system uses the frequency division multiplex (FDD) method for communication. The
transmission and reception frequencies are allocated as 46.8 GHz and 44.45 GHz, respectively, for
simultaneous transmission. The data transfer rate is 141.7 Mbit/s when QPSK modulation with a
symbol rate of 78 Msps is applied. The 106.3 Mbit/s transfer rate is realized when 8PSK modulation
with a symbol rate of 39 Msps (Mega samples per second) is applied. The antenna control
information, such as the reception level and antenna directional data, is stored in the control sections.
The modem signal and the error information of Bit Error Ratio (BER) or Packet Error Rate (PER)
(circuit quality) are also stored in the modem sections at both the airborne and ground stations. The
flight data, which consists of airplane location/attitude information, is stored only on the aircraft. The
ground station treats the transmitting and receiving data through millimetre waves.
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Fig.4.1-1 Airborne verification test system
Table 4.1-2 Airborne verification test overview
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(B)
Experimental Configuration
Figure 4.1-2 shows the connection diagram on the aircraft. The aircraft system consists of antennas
for transmitting/receiving radio waves, a controller for directional control of the antennas, a modem
for modulating/demodulating data, and a power supply from the aircraft to each device. The onboard antenna consists of transmission and a reception components using active phased array
antenna (APAA) technology, which is capable of two-dimensional electronic antenna scanning. The
APAA is composed of 64 elements in an eight-by-eight array. Each element of the APAA is
connected to the transmitting/receiving module to control the antenna beam direction by changing
the phase component with 4-bit resolution. In addition, the directional control of the antenna is
limited to +/- 45 degrees as a device specification.
The configuration of the control section allows the connection of the GPS and the gyro sensor
modules to acquire the location and attitude of the aircraft. The system computes the direction to
which the antenna should be directed in the very near future to command and control the antenna for
direction to a point from the past track of the flight path based on information from the GPS and the
gyro sensor. The modem is configured to allow switching modulation between QPSK and 8PSK
using a PC. The PC is also used as a file server.
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Fig.4.1-2 Experimental configuration at the airplane side
4.1.4
Results
Table 4.1- 3 shows the items to be evaluated in the airborne verification test. Each item was
conducted using the test procedures shown in Figure4.1- 3. The following figures show the results.
Table 4.1-3 Airborne verification test evaluation item
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Fig.4.1-3 Testing procedure
(A)
Antenna pattern measurement
As shown in Figure4.1-3, the antenna pattern is measured on the basis of the reception level during
several passages of the airborne station exactly over the ground station. The antenna directivity of the
ground station is fixed straight upward and that of the airborne station is selected as either fixed
straight downward or in the programmed tracking mode during the passage by selecting patterns of
flight altitudes. The sampling interval for data acquisition is 0.1 seconds.
Figure 4.1-4 shows the results of antenna pattern measurements of the altitude of the aircraft, which
is approximately 900 m. The result of the measurement obtained in an anechoic chamber is also
depicted. As a result, the beam width of the antenna is observed at about 8 degrees in the airborne
test, while it is observed at 10 degrees in an anechoic chamber. Although the width becomes
approximately 2 degrees narrower than that of the designed value, the characteristics of the antenna
beam are almost identical. The difference in the peak values of the antenna beams is attributed to the
effect of the mounting error of the device or the influence of the fuselage.
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Fig.4.1-4 Antenna pattern measurement result
(B)
Tracking ability test
As shown in Figure4.1- 3, tracking ability was measured based on reception level during several
round trip passages of the airborne station over the ground station. The antenna directionality of the
ground station is fixed straight upward and that of the airborne station is selected as either fixed
straight downward or in a programmed tracking mode during the passage by selecting three flight
altitudes (2,500 m, 1,500 m, and 900 m). The sampling interval for data acquisition is 0.1 seconds,
and the airspeed is about 200 km/h. Figure 4.1-5 shows the reception level of the airborne station
antenna when fixed straight downward. Also, Figure 4.1- 6 shows the reception level of the airborne
station antenna in programmed tracking mode. The duration of the communicating segment, which is
specified as a segment from a point about 5 dB below the peak until that of 5 dB from the peak of
electrical power from this result, is approximately one when fixed straight downward and
approximately 3.5 seconds in programmed tracking mode. Programmed tracking mode is longer and
can be confirmed as tracking correctly. The maximum angular ground speed is 229.65 km/h at an
altitude of 785.47 m tracked at 4.7 degrees per second in calculation, which is confirmed as the
desired data to be obtained. Although restrictions on the flight altitude limit the value, a higher
tracking capability is ensured since APAA is performed during the electronic scan.
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Fig.4.1-5 Reception level of airborne station with antenna fixed in straight downward
Fig.4.1-6 Reception level of airborne station with antenna in programmed tracking mode
(C)
Communication capability test and mass volume data transfer test
Reception level and BER characteristics were obtained as shown in Figure 4.1-3 (2). The modulation
type during this acquisition is QPSK, and the flight altitude is approximately 2,000 m. Figure 4.1-7
shows the reception level and BER for the uplink. Similar results are obtained for the downlink as
well. Although the uplink and downlink have slightly different frequencies, the characteristics are
confirmed as almost identical. Indications of higher reception levels than the designed value during
uplink can be inferred as caused by the transmission signal of the downlink, which was reflected by
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the dome and diffracted to the reception side. The BER of the uplink ensured a sufficient value even
under such conditions. The BER shown here is a BER before correcting errors so that it can be
improved by this correction. It succeeds in establishing communication for approximately 2 minutes
as well as in downloading a 500 Mbytes file in approximately one minute during this communication
establishment segment even in this environment.
In addition, a similar result was confirmed during the turning flight as shown in Figure 4.1- 3 (3).
During the turns, a test was conducted with modulation type QSPK, as well as switched to 8PSK. As
a result, characteristics identical to those during straight flight were obtained without dependence on
the modulation type. The system succeeds in establishing communication for approximately 20
minutes in the combination of QPSK and 8PSK type, as well as in downloading a 500 Mbytes file
for both the QPSK and 8PSK during this communication establishment segment of the flight. These
results can be considered verification of mass volume downloading with bidirectional IP
communication.
Fig.4.1-7 Reception level during uplink and BER
(D) Communication distance test
We calculated the communication distance from the result obtained in the test in (C). Figure 4.1-8
shows the results of the communication distance obtained during straight flight. The results indicated
that communication was established for a horizontal distance of 2,380 m and a flight altitude of
1,816 m, thus the communication distance was approximately 3 km. At this time, the angle of
elevation sighting the airborne station from the ground station is 38 degrees, which was confirmed as
a minor difference compared to the device specification of 45 degrees for the beam scan range of the
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APAA used on the airborne station. This scan range influences the restriction of communication
distance. This result confirms that the communication distance corresponding to the beam scan range
of the antenna for an airborne station is ensured.
Fig.4.1-8 Communication distance calculation result (during straight flight)
4.1.5 Conclusion
The experiments regarding a broadband communication system for airplanes using the millimetre
wave (MW) band (40 GHz band) proved the effectiveness of broadband wireless communications in
airplanes and on the ground. The results confirm the success of the airborne verification test using a
small airplane. Application of this result to various aircraft shall establish an environment that
enables mass volume downloading with bidirectional IP communication. The range of application of
this system can be the aircraft Internet service on commercial airlines to a system handling volume
data, such as aerial surveys. It is also considered to be possible to apply the broadband
communication system to terrestrial communication system such a train communication system. Its
prospective future development is awaited.
4.1.6 Future challenge
We experienced a serious damage caused by the Great East Japan Earthquake in 2011. After such
damage, it is essential for relief, restoration and reconstruction from the earthquake to grasp the
situation. A broadband communication system for airplanes using the MW band can be used for
transmitting videos and pictures obtained by airplanes to grasp the damages in affected areas.
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Therefore, we will explore the possibilities of applying the technology in a practical way for disaster
rescue and relief.
4.2 Case 2: wireless bridge system using small UAS
4.2.1 Background
The crisis of the 3.11 Great East-Japan Earthquake in 2011 reminded us that the most advanced and
popular mobile phones becomes almost useless under large-scale disasters due to physical damage,
electricity outage, and traffic congestion. The loss of communication caused confusion, bad decision,
and even increase of the number of victims in evacuation and rescue process. In addition, many areas
in mountains or islands were isolated due to the total damage of roads, harbors, and communication
infrastructures. Although such a disaster would not happen frequently, we cannot deny that the
earthquake or tsunami of about the same scale would hit populated metropolitan area in very near
future.
Based on the lessons learned from the above experiences, we started R&D on disaster-resilient
wireless bridge using small unmanned aerial system (UAS) in order to ensure the communication
infrastructure between the isolated and the non-isolated areas. The UAS and satellite link provides
temporal communication lines rapidly deployable to the isolated areas until the recovery of ground
infrastructures.
We developed the disaster-resilient wireless bridge using small UAS and the first demonstration test
of wireless bridge using UAS was successfully conducted in the end of March 2013. This document
provides a brief overview of wireless bridge using UAS and the report of experiments and
demonstration tests.
4.2.2 Wireless Bridge Using Small UAS
The small UAS used in the system consists of a small unmanned fixed-wing aircraft and ground
control station (GCS). The aircraft has an avionics computer system, two-way wireless control link,
and some sensors such as a GPS receiver, an acceleration sensor, a gyro sensor and an altimeter. It is
an autonomous aerial robot, which flies according to pre-programed waypoints and returns to a preprogramed landing point after the completion of mission. Conventional manned aircrafts could be
used in the disaster situations not only for wireless relay and monitoring, but also for transportation
of people and goods. However, the cost to operate small UAS would be much lower than that for
manned aircrafts, if the mission is limited to wireless relay and monitoring.
The specifications of the small UAS are shown in Table 4.2.1. We can operate it even when the cars
are not available due to road damage, heavy traffic jam, or gasoline shortage since the aircraft and
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GCS are easily hand-carried. In addition, special area such as runways is not needed for launch and
landing since it can be launched by throwing and recovered by deep-stole landing.
The UAS flies and circles around a certain point to provide a bridge between an isolated area due to
the damage of infrastructures and a survived area by on-board wireless relay station (OWRS). In
order to extend the range of the bridge, we can add another UAS to form a double-hop relay given by
the UAS-to-UAS direct communication link as shown in Fig. 4.2.1. Two ground telecom stations
(GTS) are setup on the ground using tripods: one is in the isolated area where the normal networks
are not available and the other is in the survived area where the GTS is connected to the Internet or
the private network. The users in the isolated area can access to the Internet or the private network by
using their own Wi-Fi terminals such as smart phones or PCs via a Wi-Fi access point delivered
along with the GTS. One UAS would cover an area of about 5 km in radius. Therefore the possible
communication range between two GTS would be more than 10 km with the double-hop formation.
The specifications and the view of the OWRS are shown in Table 4.2.2 and Fig. 4.2.2, respectively.
Fig. 4.2.1 Wireless bridge using UAS.
Table 4.2.1 Specifications of the small UAS.
Name
Wingspan, Weight
Payload
Flight time, range
Wind speed
Max. flight celling
Power, operation
PUMA-AE (AeroVironment, UAS)
2.8m, 5.9kg
0.5kg
2-4 hours, 15-20 km
25 knots (13m/s)
5000 m (200~400m in the demo)
Electric, hand launch, deep-stole landing,
autonomous flight by GPS and other sensors,
water proof
Table 4.2.2 Specifications of the OWRS.
Frequency/Bandwidth
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TX power
2W
Modulation/MAC
MSK/TDMA/TDD
Antenna
λ/4 whip (omni-directional)
Number of hops
Single or double
Air bit rate/Throughput(*)
6Mbit/s/500kbps
Synchronization
GPS receiver in GTS
Size (w/o antenna)
W90 x D100 x H116 (mm)
Weight
500g
Fig. 4.2.2 On-board wireless relay station (OWRS).
4.2.3 Measurement results
4.2.3.1. Sendai
First experiment on the relay communications using an unmanned aircrafts (UA) was conducted in
Sendai city, Miyagi prefecture, Japan, in March 2013. The purpose of conducting this experiment
was to measure basic characteristics on the system, including received signal strength (RSS) at
ground station (GS) during a flight, correlation of measured RSS with flight characteristics like
posture angles of the aircraft, and so on. Fig. 4.2.1 shows an illustration on the system’s deployment
at this experiment; two GSs, GS-A and GS-B, were deployed with distance of 900 meters. These
GSs are settled so that line-of-sight (LOS) with the UA is maintained along a pre-determined flight
route. The flight route of the UA is displayed by a red curve in Fig. 4.2.3-1. The altitude of the
deployed UA was set to around 170 meters against the ground level (AGL), and its radius was set to
around 100 meters.
A control station for the UA was located close to the GC-A, at which the average distance against the
UA is around 400 meters.
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Fig. 4.2.3-1 System deployment for experiment on the relay communications using UA
conducted in Sendai city
As a measurement result, Fig. 4.2.3-2 shows RSS measured at the GSs while the UA were flying. As
shown in this result, the RSS is periodically changed due to the periodic flight route of the UA in this
experiment. This result suggests that characteristics of radio communications in UAS are highly
affected by its deployment that includes flight operation of UAs. From applications viewpoint, we
confirmed that the relay communications establishes communications link with throughputs of up to
500 kbps, and also web browsing with the Internet was achieved through the relay communications
with a UA.
Fig. 4.2.3-2 Received signal strength (RSS) measured at deployed GSs along the flight route
shown in Fig. 4.2.3-1.
4.2.3.2. Taiki-cho in Hokkaido
Second experiment on the relay communications using an unmanned aircrafts (UA) was conducted
in Taiki-cho, Hokkaido, Japan, in June 2013. The purpose of this measurement is to test the long
distance relay communication. Fig. 4.2.3-3 shows an illustration on the system’s deployment at this
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experiment; two GSs, GS-A and GS-B, were deployed with distance of 1500 meters. These GSs are
settled so that line-of-sight (LOS) with the UA is maintained along a pre-determined flight route. The
flight route of the UA is displayed by a red curve in Fig. 4.2.3-3. The altitude of the deployed UA
was set to around 300 meters against the ground level (AGL), and its radius was set to around 100
meters. A control station for the UA was located close to the GC-A, at which the average distance
against the UA is around 400 meters.
As a measurement result, Fig. 4.2.3-4 shows RSS measured at the GSs while the UA were flying.
The RSS of this experiment is periodically changed due to the periodic flight route of the UA
similarly to the experimental 1. The average RSS of GS-B is 20 dB lower than that of the GS-A due
to the path loss decay. However, we confirmed that web browsing with the Internet was achieved
through the relay communications with a UA. It indicates he possibility that wireless bridge using
small UAS can realize the relay communication between the two GSs with distance of 3000 meters.
As a conclusion, the relay communications using UA was experimentally demonstrated that the
system establishes a communications for saving disruptive areas from network failures due to
massive disasters like earthquake, tsunami, avalanche, and so on.
Fig. 4.2.3-3 System deployment for experiment in Taiki-cho, Hokkaido, Japan
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Fig. 4.2.3-4 Measured RSS level at the deployed GSs along the flight route shown in Fig.4.2.3-3.
4.2.4 Integration of wireless bridge using UAS and Relay-by-Smartphone
4.2.4.1. Applications and characteristic of relay-by-smartphone
By developing a novel multi-hop routing technology, a network architecture that can be used for
infrastructureless message transmission, “Relay-by-Smartphone” is created. Relay-by-Smartphone is
applicable in many situations, such as distributing advertisements or distribution of information
documents in meeting or conference. However, one application that it especially excels at is disaster
oriented network. Tragic disasters like tsunamis or earthquakes would often leave the affected areas
with damaged transportation infrastructure, insufficient power and water, and most importantly
damaged communication infrastructure. Without communication infrastructure, most communication
devices, such as cellular phones, laptop computers, or personal tablets, are rendered unusable. As a
result, disaster victims are unable to contact their family, friends, or associated authorities to report
their safety or request aids. Relay-by-Smartphone aims to solve this problem by establishing
infrastructureless communication from disaster victims’ mobile communication devices. When a
disaster victim participating in Relay-by-Smartphone system sends a message, the message will
propagates through other devices until the destination is finally reached. Thus, making message
delivery inside the disaster affected area possible. Additionally, Relay-by-Smartphone can also have
a special device, which acted as a gateway between Relay-by-Smartphone network and other
networks. Therefore, once the message arrived at the gateway, the message can be forwarded into
Internet or other network and thus making communication to and from outside network possible.
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4.2.4.2. Integration of wireless bridge using UAS and Relay-by-Smartphone
The flexibility of Relay-by-Smartphone system means that it is possible to interconnect this system
with other communication network such as satellite communication systems, Unmanned Aircraft
Systems (UAS), and optical fiber networking. Similar to other wireless multi-hop networks, Relayby-Smartphone relied on network participants who are uncontrollable. As a result isolation problem
may surfaces when a Relay-by-Smartphone network is too far away from the closest gateway. Even
when isolation problem may not pose any problem for those that want to send message locally, it
prevent Relay-by-Smartphone network from delivering messages to the outside networks. However,
we can overcome the isolation problem by integrating Relay-by-Smartphone and UAS.
Unmanned Aerial Vehicles (UAVs) are automated aircraft of various shapes and sizes, which are
commonly utilized in reconnaissance, scouting hazardous areas, collect data from mobile sensors
networks, and so forth. We focus on an application of UAV referred to as Unmanned Aircraft
System (UAS) based relay system, which is a network made up of multiple UAVs interconnecting to
form an Adhoc like network that can provide communication services in a large area. With UAS
based relay system, multiple Relay-by-Smartphone networks can be connected through series of
UAV. Due to the extraordinarily large area coverable by UAS based relay system, it is very practical
to utilize UAS based relay system to interconnect multiple Relay-by-Smartphone networks. By
integrating multiple UASs and Relay-by-Smartphone networks isolation problem can theoretically be
eliminated through the placement of UAS’s base stations as shown in Fig. 4.2.4-5. The experiment to
show the practicality of this concept was conducted at Tohoku University’s Aobayama campus and
Katahira campus. Aobayama campus was assumed to be an area affected by disaster while Katahira
campus was assumed to be unaffected area as shown in Fig. 4.2.4-6. Additionally, each campus has a
ground station with a Relay-by-Smartphone gateway connected are deployed. The message was sent
from a participant at Aobayama campus and propagated through other participants’ smartphone
before arriving at the gateway. The message is then forwarded to PUMA-AE unmanned aerial
vehicle (UAV), which in turn transmits the message to the gateway residing at Katahira campus
resulting in a successful transmission over approximately 3 kilometers distance without any need for
infrastructure. Additionally it is observed that the delivery delay increases with the increase in data
size as shown in Fig. 4.2.4-6.
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Fig. 4.2.4-5 An overview of a system integrating UAS based relay and multiple Relay-bySmartphone systems
Fig. 4.2.4-6 An outline of the experiment conducted at Tohoku University to evaluate the
performance of Relay-by-Smartphone and UAS integration system
Fig. 4.2.4-7 Experimental result shows that deliver delay increases with the data size
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4.2.4.3. Future considerations and conclusion
Relay-by-Smartphone system has significant potential in providing communication service in an area
without established infrastructure. However, many challenges still need to be addressed to achieve a
system that can serve in dire situation such as after disaster. Due to the diversity of mobile devices, it
is necessary to be able to make Relay-by-Smartphone work on different mobile devices, which may
have different hardware specifications or different operating systems. In order to unleash the full
potential of Relay-by-Smartphone, interconnectivity to other communication networks, such as UAS
networks need to be improved. Currently, essential functionalities, such as routing protocol are
implemented separately in both Relay-by-Smartphone and UAS networks. It is necessary to develop
a robust routing technology that integrates the characteristics of both Relay-by-Smartphone and UAS
networks in order to provide optimal performance when both systems are utilized to their full
potential.
In conclusion, Relay-by-Smartphone system is a practical infrastructureless communication system
aims to deliver message over a long distance. The system can be enhanced by interconnecting it with
other communication network such as UAS networks to further increase the coverage area.
4.2.5 Delay and Disconnection Tolerant Message Transmission System using UAS (in case of
using single Unmanned Aircraft UA)
4.2.5.1. Overview of delay and disconnection tolerant message transmission system
Due to natural disaster such as earthquake, tsunami and typhoons, it is feared that small villages,
which are in the mountain region, by the river or nearby shore, are isolated from other areas. The
Unmanned Aircraft Systems (UAS) will be useful for such extraordinary situation. In the initial state
of the disaster relief, available number of Unmanned Aircraft (UA) will not be enough.
This section describes the delay and disconnection tolerant message transmission system using the
single UA, which provides the exchange of the electric messages such as E-mails, short messages,
and files, between the surviving region and isolated area.
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UAS with Wi-Fi Router and
Onboard Message Storage
Wi-Fi
Surviving region
Disaster area
Temporary Wi-Fi AP
with Message Storage
Wi-Fi,
WiMAX,
LTE
Wi-Fi
Shelter A
User Terminal(s)
Internet
Dedicated Message
Storage
Shelter B
Shelter C
Figure 4.2.5-1 Overview of delay and disconnection tolerant message transmission system
Fig. 4.2.5-1 shows the overview of delay and disconnection tolerant message transmission system,
using the single UA. Herein, it is supposed at the shelter in the disaster area that temporary Wi-Fi
APs (Access Points) with the message storage are provided. In the surviving region, the dedicated
mail servers are operated to exchange the messages between the Internet and the disaster area,
through the UA. The UA has the functions of the Wi-Fi router and the message storage. The
communication between the ground and UA will start, when the UA comes into the coverage area of
Wi-Fi AP or WiMAX/LTE base station. By such network configuration, the delay and disconnection
tolerant system can be achieved. This system can rapidly work even just after the disaster occurrence,
therefore very important information can be exchanged and contribute to the rescue operation.
On the shelter side in the disaster area, the operation of user terminal is the same as in daily use,
therefore no special technique and communication engineer is necessary. The UAS is so widely
useful for the residents in the disaster area.
4.2.5.2. Possible radio services and applications
(a) Use scenario
Figure 4.2.5-2 depicts examples of use scenario of the indicated message transmission system. The
aim of the system is to provide reliable communications among various facilities such as shelters,
city halls and hospitals, during the failure of infrastructure communications caused by the disaster.
When the disaster occurs, the communication function fails between the isolated disaster area and
surviving region. As aforementioned, the UA flies and conducts information exchange between those
areas. The information exchange is implemented by the Wi-Fi and existing devices such as smart
phones and PC. No additional communication devices are necessary. For example, smart phones can
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be used to provide emergency information exchange for personal safety check and necessary medical
care. The Personal computer in the city hall monitors the water level and informs it to all shelters if
there is a risk of floods.
(b) Functions of the message transmission system
The message transmission system is intended to bring rapid relief to isolated disaster area caused by
disaster. The system should consist of several functions in the UA, isolated area and surviving region.
Only the surviving region has Internet capability. The UA should be equipped with very light
weighted and battery driven Wi-Fi router and message storage device. These devices should be
energy efficient to extend battery life of the UA. In the disaster area, such function is needed to
gather and store the resident messages via Wi-Fi and push them to UA. The function to receive
messages from the UA and distribute them to the proper user terminals, is also required. In the
surviving region, such function should be established that the server in the Internet is connected to
the Wi-Fi router in the UA. As this function needs no additional hardware, it can be equipped in the
cloud system for example.
hospital
Unmanned Aircraft (UA)
shelter
shelter
city hall
FAX
personal smart phone
Mr. ABC is safe ?
PC for management
Is there any shelter that needs blanket ?
There are many injured people.
Is the doctor available ?
The water level of the
river is so high.
Inform it to all shelters !
Figure 4.2.5-2 Example of use scenario
The protocol sequence of the message transmission system is shown in Fig. 4.2.5-3.For example, it is
supposed that the users in the surviving region (disaster countermeasures organization, person to
require safety confirmation, and so on) send the message to the end user in the disaster area. The
commercial mail server receives the message and transfers it to the temporary message storage. Then,
the messages are sent to the storage in the UA via radio connection when the UA comes in the
coverage range. The UA flies back and forth between surviving region and disaster area. When the
UA reaches the disaster area, the UA pushes the messages towards the temporary AP via the Wi-Fi
connection. Then, the AP saves the messages in the storage device, and the smart phone of the end
user picks the message via the Wi-Fi connection.
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Step.1:
The temporary message storage[A] in the surviving region
receives messages from users (disaster countermeasures
organization, person to require safety confirmation, etc) via
Internet, which is directed for the users in the disaster area.
Then, when UA comes in the BS service range,
Step.2:
The messages are sent to storage in the UASvia radio
access (Wi-Fi, WiMAX, LTE etc.).
3
Step.5:
The AP saves the messages in the
storage device equipped.
Step.6:
From the AP, the smart-phone
picked up the messages via Wi-Fi.
4
2
BS
Step.4:
UA pushes messages towards the
temporary AP in the shelter via Wi-Fi.
Step.3:
UAS carries the messages toward
the diasater area.
Internet
Temporary
AP
B
5
A
1
6
Note :
Reverse direction (from
disaster area to surviving
region) is also configurable.
Figure 4.2.5-3 Protocol sequence of the message transmission system
4.2.5.3. Technical issues to be studied
(a) Establishment of message routing
In the indicated transmission system, the message is exchanged during the fling transfer of the UA.
Therefore, it is not easy to obtain the continuous end-to-end communications. The important
technical issues of the messages routing and message delivery confirmation are described as follows.
 Messages routing
To send mails to users in the disaster area, it is necessary to manage locations of the user
terminals. This function can be achieved by referring to the access history of user terminals,
which is processed in the temporary message storage in the surviving region. Based on such
processed information, the destination of the message can be decided, which includes UA
identification number and disaster area number for example.
 Message delivery confirmation
Although the message is transmitted according to the message routing scheme, the message
may not be received due to mobility of user terminals. Therefore, it is necessary to monitor
the message delivery confirmation. If the message is sent to improper destination, it is
required to retransmit messages to other UA and other disaster area.
(b) Wi-Fi direct connection between the UA and ground
As for the indicated system, we suppose that the dedicated relaying devices such as temporary AP
are deployed on the disaster area. In the future next system, direct communication between the user
terminal and the UA is envisaged. In such case, the following issues are needed to be considered.
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 The received power will be low when the height of UA is large of hundred meters and the
communication coverage is broad.
 The UA will suffer from the interference from many terminals in broad area.
 The hidden terminal problem will frequently happen.
 The quality of the wireless link will drastically change due to high speed of the UA flight.
 It will be necessary to measure the quality of the wireless link of the upper air to clarify
the difference between the ground and upper air, in the case of cloudy or rainy weather.
4.2.6 Hand-Over system of multiple ground stations in multiple unmanned aircrafts operation
4.2.6.1. Overview of hand-Over system of multiple ground stations in multiple UAs
Recently, with the progress of unmanned aircraft (UA) system technologies, some applications are
expected to expand to civilian use. It is also expected to expand the use of small and medium-sized
UA and operate it 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 mediumsized UA (Unmanned Aircraft), it is necessary to follow the flight situations of each UA (Unmanned
Aircraft) to secure the flight safety among multiple aircrafts (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 UA.
Figure 4.2.6-1 shows an overview of hand-over system of multiple ground stations in multiple UAs
operation. This system is composed of an on-board transceiver and access points (APs) for ground
control. This system monitors flight information and achieves a stable flight control in a wide area by
sequential hand-over of multiple APs placed along the flight path. Thus, it is possible to continuously
monitor multiple UA and safely control the flight by managing flight information of multiple UAs
obtained from plural APs in an air traffic control system.
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Figure 4.2.6-1 Overview of hand-over system of multiple ground stations in multiple UAs operation
This section introduces a hand-over technology for the efficient use of frequency and the safe widearea 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 (Air
traffic control) transponder.
4.2.6.2. Example of operations and features
(a) Example of Operations
Figure 4.2.6-2 illustrates an example of operation of UA hand-over system. This system consists of a
control and non-payload communication (CNPC) system mounted on an UA and AP (Access Points)
for simple ground control placed on the ground level. 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 requests 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 new adjacent
AP, the AP seamlessly hand-overs the information of UA to new 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 ATC system through a ground network system. Based on the
information, the ATC 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.
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This system is intended for a small and medium-sized UA which is unable to be equipped with a
large-size 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. In the future, when UA shares the air space with manned aircrafts, the integrated
control of manned and unmanned aircraft can be attained by information sharing between the UA air
traffic control system and the manned aircraft air traffic control system.
Figure 4.2.6-2 Example of hand-over operation
(b) Features of hand-over system
The hand-over system is intended for safety flight and efficient operation of UA by always
controlling the beyond line-of-site (BLOS) wide-area operation of small and medium-sized UA.
Therefore, this system needs to have:

High spectral efficiency and power-saving ground equipment;

Single channel of 5GHz frequency band based on the agreement of WRC-12;

No cutoff during hand-over for safe flight control, such as wireless LAN;

No large-sized ground equipment;

Small-size, lightweight, and power-saving radio to be able to be mounted in a small and
medium-sized UA.
To meet these requirements, this system shall have the following features:
(1).
Protocol that hand-over is available in single channel of 5GHz frequency band.
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(2).
Protocol that time-division multiple access (TDMA) and time division duplex (TDD)
where one-to-many communication is available for UA and AP.
(3).
Reliable and seamless hand-over to new adjacent AP, by allowing UA to
communicate adjacent APs simultaneously in an overlapping communication area.
(4).
To improve the robustness of communication continue the communication as long as
possible, not disconnecting the communication with the current AP immediately after
establishing the communication with the adjacent AP (See Figure 4.2.6-3 ②).
①
②
③
Figure 4.2.6-3 Example of basic hand-over by single UA
(5). Establish hand-over only by communication between each AP and UA without any ground
station such as a radio network control equipment that controls AP to control hand-over.
(6).
Power-saving design. When there is no nearby UA for requesting hand-over, AP stops
sending to reduce power consumption.
This hand-over system is that UA sends a call to AP, and AP gives a transmitted packet to UA. Then,
using the packet, UA communicates with AP. Transmitted packet to be given to one AP is limited
and divided into three as shown in Figure 4.2.6-4. By dividing into three, hand-over can be done
without congestion (See Figure 4.2.6-5).
Set-A Packet call with AP
Set-B Packet call with AP
Set-C Packet call with AP
Initial packet call
Figure 4.2.6-4 TDMA-TDD format of hand-over algorithm
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Figure 4.2.6-5 Example of hand-over operation using TDMA-TDD format
4.2.6.3. Technical issues
(a) Adaptive control of transmission rate
According to situations of take-off and landing and collision avoidance of UA, image information
and sensor information necessary for flight control as well as airframe information are required to be
transmitted. However, in case of transmission through TDMA-TDD in limited frequency band, if
packets are fixedly applied to multiple AP or UA, the packets are fragmented and CNPC information
cannot be transmitted efficiently. It’s a challenge to develop a transmission rate adaptive control
system which transmits the most appropriate CNPC information amount effectively in the limited
band and frequency.
(b) Automated setting of APs
In the UA hand-over system we introduced here, it is necessary to locate AP along the flight path in
the predetermined order. However, when a path is extended or urgently set due to, for example,
disaster, AP should be located without any mismatch of relation between setting and location for
each other. It’s a challenge to develop a function to set AP automatically without any restriction.
5
The potential radio services and applications on-board vessel
5.1 Case 1: Wireless Broadband Video Transmission Systems
5.1.1 Background and Application Requirements
The maritime transport regulatory systems includes Vessel Traffic Service(VTS) and Automatic
Identification System (AIS).Such systems provide great help for administration routines. But there
are certain deficiencies in these systems. For example, there are cases that the VTS radar is often
influenced by the horizontal width of the beam, which result distorted images, and cases that radar is
susceptible to interferences like the thunder and snow clutter, sea clutter, identical frequency clutter.
Therefore, the scan will be easily blocked by the object so that a blind spot will come out.
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When the dangerous accidents take place in waters far away from the ports, the search and rescue
coordination center will fail to offer accurate instructions based on the actual situations. To improve
this situation, we need the other systems as a complement of the maritime traffic regulation, and the
wireless broadband video transmission systems will be a good choice. With the wireless broadband
video transmission system, we are able to know exactly in real time what is happening to the vessels,
to find disasters or hidden troubles as soon as possible, and to provide the basis for rapid decisionmaking of the coordination center.
The wireless broadband video transmission systems should be capable of safe and reliable
transmission of video signals (including speech signals), and at the same time should be able to
ensure stable operation of the mobile terminal with excellent performance in a high-speed voyage.
We has made some attempts on the wireless broadband microwave transmission, and have performed
practical application in the search and rescue drills of the vessels in distress.
5.1.2 System Description
China has constructed a set of wireless broadband access communication system for the maritime
video transmission in Dalian Port area, which is composed of four base stations, a number of vesselborne or vehicle-mounted mobile terminals and servers as described in figure 5.1-1. The system take
use of advanced non-line-of-sight (NLOS) wireless broadband transmission equipment, non-line-ofsight (NLOS) radio base stations and mobile terminals supporting 5.8GHz and several other
microwave bands, in application of OFDM-4/16/64QAM modulation scheme and a time division
duplex (TDD) transmission protocol, with a maximum output power of 5W for base station,
2W
for mobile terminal. It achieves a good signal coverage within 20 nautical miles away from the
coastal line, with a data transfer rate up to 2Mbits/s. The main advantage of the system follows that a
mobile terminal can ensure a real-time transmission of multimedia information back to the
coordination center in a state of high-speed mobile, so as to provide a convenient link for decision
making for command and dispatch and distress relief.
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Vessel 1
Vessel N
Base-station1,2
Base-station3,4
Server
Coordination Center
Fig.5.1-1 Wireless Broadband Video Transmission System Diagram
5.1.3
Service Provider Cases
The wireless broadband video transmission systems had been applied in joint maritime search and
rescue drills in recent years, providing a command ship, a vessel in distress, two search and rescue
ships and a helicopter with wireless data transmission ，Specific configuration is as follows:
Command ship: a wireless transmission base station, a set of signal processing equipment, 1 video
camera .Vessels in Distress: a mobile terminal, two sets of signal processing equipment, 2 video
cameras. Search and Rescue ships: a mobile terminal, one set of signal processing equipment, 1 fixed
video camera. Helicopter: a mobile terminal, two sets of signal processing equipment, 1 video camera.
In such a search and rescue drill, the command ship can accurately locate of the vessels in distress and
the surrounding situations by the received wireless video signals from the vessels in distress, search
and rescue vessels and helicopters, and through the wireless broadband video transmission system to
carry out a successful rescue of the vessels in distress. The wireless broadband video transmission
system plays an important role in the exercise.
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Fig.5.1-2 Wireless Broadband Video Transmission System for Maritime Rescue Exercise
5.1.4 Market Trend
From a technical perspective, the video technology and wireless transmission technologisare already
quite mature, with lower construction cost.
The maritime wireless broadband video transmission can effectively enhance the safety of the vessels,
to provide a basis for decision making for search and rescue of the vessels in distress. The maritime
wireless broadband video transmission is the inevitable trend of the development of maritime transport
safety communication, and has a broad market prospect.
5.1.5 Future challenges
With the tremendous development of maritime transport, fisheries, and maritime mining operations,
etc. the wireless broadband video transmission system which can report the situation in real-time will
be used more and more frequently. However, the smaller transport vessels and fishing boats cannot
afford a wireless video transmission system. A larger market size should be able to reduce the cost.
While the large vessels with the systems mentioned above can only realize the video transmission in
the waters within 20 nautical miles offshore . The satellite transmission can be an alternative.
However, as the cost is much higher, it is difficult to promote the use of satellite links on the vessels.
Since better communication quality, lower communication cost, and longer communication distance
are the eternal theme and challenges for maritime radio communication, Innovative systems and stateof-the-art communication technologies are summoned to meet the demands.
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5.2 Case 2: Maritime Broadband Multi-hop Relay Communication System
5.2.1 Background and Application Requirements
Nowadays, the demand for the various broadband multimedia services in the telecommunications
industry has increased and is intensified sharply due to smart phones. This trend toward faster data
transmission rate and broader frequency band than the existing systems in the terrestrial wireless
communication environment also applies in maritime communication environment. Some wireless
communication infrastructures in littoral zone are necessary in order to provide broadband
multimedia services between ship and ship or between ship and shore to conform to this trend.
Many ships have the facilities to provide the maritime wireless communications service in MF, HF
and VHF frequency bands, and/or to provide satellite communication services. And also some ships
in a few km from the coast within the service coverage of LTE or WCDMA are able to use the
terrestrial mobile service such as LTE or WCDMA. However, the frequency bands of MF, HF and
VHF communication systems are too narrow to provide the broadband multimedia services, the
satellite communication systems are too expensive to provide the broadband multimedia services
freely, and the communication coverage of LTE or WCDMA systems can’ t be beyond several km.
The maritime broadband multi-hop relay communication system proposed by Korea has the
characteristics that are able to provide up to 100km of the communication coverage in littoral zone
and 1Mbit/s of end-to-end transmission data rate with low cost of the communication services.
Most of ships are operated at around 30km from the coastline, but there is a need to expand the
communication coverage to protect ship accidents in offshore, especially in open seas and to test new
building ships in the area around 100 km off and to send the test data to the ship building yards. The
ship's safety and economic operation and ship management services for a variety of applications are
considered based on this maritime broadband wireless data communication and the data exchange
protocols.
5.2.2 System Description
The maritime broadband multi-hop relay communication system and the ship’s safety related
services have been developing by ETRI in Korea for 4yeas since December 2010. The final goals of
this project are to implement the wireless system which is able to operate in the frequency band of
2.4/5.8 GHz and to have the characteristics of the communication coverage of 100km from the
coastline and the end-to-end data transmission rate of 1 Mbit/s at least.
The concept diagram of maritime broadband multi-hop relay communication system is shown in
Fig.5.2-1.
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Fig.5.2-1 Concept Diagram of Maritime Broadband Multi-Hop Relay Communication System
In these goals, the system is adopted the multi-hop relay scheme to expand the communication
coverage of 100km, and applied to the two wireless communication schemes such as the terrestrial
mobile communication scheme (LTE or WCDMA) and IEEE 802.11a scheme (WLAN) for the
transmission capacity. LTE or WCDMA scheme is applied to access between shore and the first ship
for data transfer and W LAN scheme is used between the first ship, called by Master Ship Station
(MSS), and other ships, called by 1st Slave Ship Station (SSS), 2nd Slave Ship Station, and 3rd Slave
Ship Station and so on. The configuration diagram of this system is as follows:
Fig.5.2-2 Configuration Diagram of the Maritime Broadband Multi-Hop Relay Communication
System
The maritime broadband multi-hop relay communication system is composed of 2 sub-systems
largely such as Control Station on shore and number of Ship Stations at sea. Control Station is to
control, monitor and manage Ship Stations, and a maritime broadband multi-hop relay
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communication network on shore, and Ship Station is to send and receive user’s information to
several Internet portal servers or Control Station and several control signals from Control Station on
shore, respectively. Each Ship Station is again consist of 3 modules which are a communication
module toward land which has a LTE or WCDMA function for Master Ship Station and WLAN
function for Slave Ship Station, a communication module toward the sea which has a WLAN for
Ship Station, and a bridge module which can connect between LTE or WCDMA communication
module and WLAN communication module and between WLAN communication modules. The
characteristics for this system are as follows:
Table 5.2-1. Characteristics of the Maritime Broadband Multi-Hop Relay Communication System
Items
Data transmission rate
Communication coverage
Characteristics
Remark
Min. 1 Mbit/s
end-to-end
100 km
from onshore
with the multi-hop relay
Ship speed
RF Frequency band
RF Power
Multiple access
Modulation scheme
Multiplex
<= 15 knot
<= 30km
2.4 GHz / 5.8GHz
WLAN frequency band
800MHz / 1.8 GHz / 2.1 GHz
LTE frequency band
1W
0.1W for 2013
OFDMA
WLAN
QPSK/16QAM/64QAM
(commercial products
TDD
available)
OFDMA/SC-FDMA
LTE
QPSK/16QAM/64QAM
FDD/TDD
The terrestrial communication schemes can be applied to the same way as the maritime
communication systems because of having a sufficient performance for the performance of the
maritime communication.
5.2.3 Verification test
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5.2.3.1. Configuration for the test
The verification test of the maritime broadband multi-hop relay communication system was
conducted through measuring the throughput of the above system on October 2013 near offshore of
Okpo in Geoje Island which is about 400 km southeast away from Seoul. The test configuration is as
shown in Fig.5.2-3. The test was conducted at 4 Test Points (TP): TP1 and TP2 were the first WLAN
base station at the top Oknyeobong peaks and the second WLAN base station at the top Seoyimal
lighthouse about 6km away from Oknyeobong peaks, respectively. TP3 and TP4 were the first ship
station and the second ship station in a drillship, respectively. The test was performed on three
routes. The first test was one-hop route (e.g. TP3 →TP2, TP4→TP2 and TP2→TP4), the second test
was two-hop route (e.g. TP2 →TP3 →TP1) and the final test was three-hop relay route (e.g.
TP4→TP2→TP3→TP1). The throughput was measured in the drillship using IPERF tool. And also
the test of internet access to various Internet portal servers was performed. On the other hand, the
LTE throughput tests of the commercial mobile services (LTE or LTE-A) weren’t conducted due to
the limitation to control the coverage of the mobile base stations over the coast.
Fig.5.2-3 Test Configuration for the Maritime Broadband Multi-Hop Relay Communication
System
A terminal of the maritime broadband multi-hop relay communication system was installed in each
TP, which consist of Bridge module, Modem module, and RF and Antenna module (See Fig.5.2-4).
The antenna installed in the drillship is shown in Fig.5.2-4 and the antenna in the tugboat had the
same configuration as in the drillship.
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(a) System Configuration
(b) Antenna
Fig.5.2-4 System Configuration and Antenna installed in Drillship
5.2.3.2. Results of the experiment
The results of throughput measurement using IPERF for one-hop route, two-hop route, and three-hop
route are as shown in Fig.5.2-5. The throughput in one-hop route is from 1.07 Mbit/s to 7.47 Mbit/s.
The throughputs in two-hop route and three-hop route are 1.03 Mbit/s~2.87 Mbit/s and 1.13
Mbit/s~2.55 Mbit/s, respectively. The results indicate that three-hop wireless relay in the maritime
broadband multi-hop relay communication system could achieve throughput over at least 1 Mbit/s,
though it has a wide span due to drift status and/or other passing ships around the drillship at the
time. It is expected that the coverage of the maritime broadband multi-hop relay communication
system would increase as wide as the coverage of LTE or LTE-A if terminals of LTE or LTE-A be
participated in the test.
Fig.5.2-5 Throughputs measured by IPERF
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5.2.4 Application Services
The application services can include the safe related services of ship’s operation which are to
monitor the fire detection of ship and the equipment state of ship, to manage and estimate the engines
of ship remotely, to update the nautical charts automatically and to control ship arrival and departure
safely. An application service to test for the new building ships at sea can also be considered to
exchange the data and the information through this system for ship building yards. Further, the
broadband wireless communication infrastructures can be applied to provide the control and monitor
services between the offshore plants 200 or 300 km away and the control centers on shore and to
give the Internet services between the offshore plants and Internet portal servers on shore with lower
cost.
5.2.5 Market Trend
IMO (International Maritime Organization) has been leading to make of IMO’s policy for eNavigation for safety and security at sea and protection of the marine environment until 2014. ENavigation can be achieved from the key infrastructures which are called 4S (ship-to-ship and shipshore). In the near future, large ships more than 300 tons have to be built 4S communication
infrastructures in accordance with the International Sailing Rules. And also many small ships below
300 tons don’t have the communication equipment in terms of cost and security, but they have also
risk of an accident because of this. Therefore it’s important for small ships that the cost of building
the wireless communication equipment would be low.
This maritime broadband multi-hop relay communication system can be consistent on the
requirements for e-Navigation. Various ship safety and security services can be provided through the
maritime broadband multi-hop relay communication system to ship-to-ship and ship-to-shore. In
addition, this system would be contributed to the realization of e-Navigation policy, the cost
reduction for communication services and the welfare improvement in ship from the current
communication environment with high-cost and low-data transmission rate.
5.2.6 Future challenges
The need for the maritime broadband wireless communication infrastructures is increasing, but there
are a lot of challenges to overcome in terms of technical aspects and non-technical aspects to provide
the maritime broadband wireless communication services.
There are the technical challenges to solve as follows:
-
Propagation characteristics analysis at sea in UHF band(e.g. frequency band above 1 GHz):
There are few reports on the analysis of propagation characteristics at sea in UHF band. That is, it
is difficult to estimate the attenuation of signals and to simulate the transmission RF channels at
sea
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-
Propagation tracking and maintenance technologies:
Ships are constantly moving at sea though there are some differences depending on the sea and
weather conditions. In order to send the signal to the destination stations (Control Station on shore
or Ship Station at sea) seamlessly, it needs to maintain an autonomous movement of the ships due
to the motion of the antenna.
-
RF and antenna technologies:
HPA and LNA for 2.4/5.8 GHz frequency band and the MIMO design technologies to expand the
communication coverage
-
Mobile IP technologies :
The Mobile IP routing and networking technologies need to maintain the connectivity between
Ship Stations seamlessly and to connect the other new route quickly instead of the disconnected
route in the environment of the unstable maritime wireless networks.
-
Buoy or relay facilities at sea:
Most of ships are moved within 30km from the coastline and any ships within this range can be a
relay station. However, there are few ships beyond 30 km and it’s difficult to find a relay station.
Buoy systems, lighthouses and son on are ones of the candidates for the relay station.
In the non-technical aspects, any frequency allotments to the maritime broadband wireless services do
not exist for services providers to do business. It would be taken a long time, but it’s necessary to allot
the frequency bands for the maritime broadband wireless communication services.
6
Summary
6.1 Summary of the potential radio services and applications on-board aircraft
As the first case of the potential radio services and applications onboad aircraft, a broadband wireless
communication system using millimetre wave between airplane and ground was introduced. As the
demand for better mobile phone and Internet access for people on-board aircraft has increased,
several airlines have started cabin use of cellular phones, personal computers and smart phones with
a system involving satellites. A new system for airplanes using the millimetre wave band (40 GHz
band) was introduced to realize the broadband wireless communications between airplanes and the
ground. Several experiments using the proposed system were conducted and proved the effectiveness
of broadband wireless communications in airplanes and on the ground. The range of application of
this system can be the aircraft Internet service on commercial airlines to a system handling volume
data.
As for the second case, wireless bridge system using small unmanned aircraft system (UAS) and
several possible radio services and applications using UAS were introduced. The wireless bridge
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system can establish a communications link for saving disruptive areas from network failures due to
massive disasters like earthquake, tsunami, avalanche, and so on. Moreover, the integration system
that combines the wireless bridge system with Relay-by-Smartphone was introduced. It was shown
that the coverage area of radio service could be enhanced by the integration system. As possible
radio services and applications using UAS, the delay and disconnection tolerant message
transmission system and the hand-over system of multiple ground stations in multiple UAs were
introduced. The delay and disconnection tolerant message transmission system can rapidly work
even just after the disaster occurrence, therefore very important information can be exchanged and
contribute to the rescue operation. On the other hand, the hand-over system can be able to
continuously monitor multiple UA and safely control the flight by managing flight information of
multiple UAs obtained from multiple access points in an air traffic control system in order to operate
small UA in various fields including pesticide spraying, aerial survey, logistics, environment
observation.
6.2 Summary of the potential radio services and applications on-board vessel
The wireless broadband video transmission system was introduced as the first case of the potential
radio services and applications on-board vessel. To improve the performance of maritime traffic
regulation, the wireless broadband video transmission system was introduced as a complement of
existing maritime transport regulatory systems including Vessel Traffic Service (VTS) and
Automatic Identification System (AIS). The proposed system is capable of realizing safe and reliable
transmission of video signals (including speech signals) as well as providing stable operation of the
mobile terminal with excellent performance in a high-speed voyage. Results from experimental
system shows that real-time transmissions of video signals from high-speed mobile terminals back to
the coordination center. Thus, convenient links are built to help decision making for command,
dispatch and distress relief.
The second case of the potential radio services and applications on-board vessel, the maritime
broadband multi-hop relay communication system, has also been introduced. As the demand for
various broadband multimedia services in the telecommunications industry increases, faster data
transmission rate and broader frequency band are required in not only terrestrial wireless
communication environment but also maritime communication environment. Following this trend,
the maritime broadband multi-hop relay communication system is proposed to provide broadband
multimedia services between ship and ship or between ship and shore. The proposed system is able
to provide high end-to-end transmission data rate with low cost of the communication services, and
more importantly large communication coverage to protect offshore accidents for ships in littoral
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zone. The maritime broadband multi-hop relay communication system and the related services have
already been developed. Experiments verified the effectiveness of maritime broadband multi-hop
relay communication system through throughput measurements.
7
References
[1] Document AWG-12/INP-81 “Proposed update terms of reference and workplan of task group
aeronautical and maritime”, by PT Telekomunikasi Indonesia, Indonesia, China, April 2012.
[2] Document AWG-13/INP-10 “Report of studies for modern wireless technologies on-board
aircraft and vessels using the millimetre wave broadband wireless communication system”, by
NICT, Japan and Mitsubishi Research Institute, Inc., Vietnam, September 2012.
[3] Document AWG-13/INP-72 “The proposed structure of the working document towards
preliminary draft new report of the possible radio services and applications on-board aircraft and
vessels”, by China, Vietnam, September 2012.
[4] Document AWG-13/TMP-13 “Meeting report of task group on aeronautical and maritime”, by
Chairman, Task Group – Aeronautical and Maritime, Vietnam, September 2012.
[5] Document AWG-14/INP-10 (Rev.1) “Propose modification to working document towards
preliminary draft new report of the possible radio services and applications on-board aircraft and
vessels”, by NICT, Japan and Mitsubishi Research Institute, Inc., Thailand, March 2013.
[6] Document AWG-14/INP-54 “Proposed modifications of the working document towards draft
new apt report of the possible radio services and applications on-board aircraft and vessel”, by
China, Thailand, March 2013.
[7] Document AWG-14/INP-73 “Proposed modifications to working document towards preliminary
draft new report of the possible radio services and applications on-board aircraft and vessels”, by
China, Thailand, March 2013.
[8] Document AWG-15/INP-38 “Propose modification to working document towards preliminary
draft new report of the possible radio services and applications on-board aircraft and vessels”, by
Japan, Thailand, August 2013.
[9] Document AWG-15/INP-62 “Proposed addition for working document towards preliminary
draft new report of the possible radio services and applications on-board aircraft and vessels”, by
Republic of Korea, Thailand, August 2013.
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[10] Document AWG-16/INP-54 “Propose modification to working document towards preliminary
draft new report of the possible radio services and applications on-board aircraft and vessels”, by
Japan, Thailand, March 2014.
[11] Document AWG-16/INP-95 “proposed modifications to working document towards a
preliminary draft new report of the possible radio services and applications on-board aircraft and
vessels”, by Republic of Korea, Thailand, March 2014.
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