International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 4
Number 2
June 2010
129
1 INTRODUCTION
The infancy and youth of radio technology was pri-
marily linked to maritime applications. Following
his invention of the first operating radio transceiver
in 1895, Guglielmo Marconi performed transmission
experiments between two Italian warships outside
the port of Spezia in 1897, where he managed to ex-
change radio messages at a distance of 22 km. Later
he continued his experiments in England, where on
Christmas Eve in 1898 he established radio telegra-
phy contact between the “East Goodwin” lightship
and South Foreland Lighthouse in South East Eng-
land. On 3
rd
March 1899 the steamship “R F Mat-
thews” collided with this lightship, which alarmed
the lighthouse ashore to obtain assistance. This was
the first time ever a distress call was transmitted by
radio from a ship at sea.
However, despite of the tremendous develop-
ments in radio technologies since that time, ad-
vancements in maritime networks are severely lag-
ging behind its land counterpart, and novel solutions
are needed to meet the imminent user requirements.
2 MARKET PULL VS. TECHNOLOGY PUSH
2.1 The ‘Northern Challenges’
The overall backdrop of the maritime communica-
tions market pull is demonstrated by Figure 1, por-
traying the ‘Northern Challenges’, exemplified by
Norway’s geographical extension and economic de-
pendability of an ocean area about 6 times the size
of its mainland. The vast geographic distances and
the economic importance of activities at sea in re-
mote areas demand novel and innovative radio-
based solutions. There are numerous unsolved re-
search challenges regarding radio communications
coverage throughout the vast region comprising e.g.
the Norwegian Exclusive Economic Zone (EEZ) and
the Arctic waters [1].
Novel Maritime Communications Technologies
F. Bekkadal
MARINTEK e-Maritime, Trondheim, Norway
ABSTRACT: Current maritime systems are to a large extent based on legacy analog VHF radios for ship-to-
shore communications near port waters, and relatively low bandwidth digital satellite communications (Sat-
Com) for long-range ship-to-ship and ship-to-shore communications. The cost of bandwidth for SatCom net-
works is expected to remain high due to the cost of launching satellites into orbit and also due to the stabi-
lizers required for presently available on-board antennas. On the other hand, the legacy VHF system compris-
es low bandwidth radios incapable of supporting applications requiring high data rates. Unlike the terrestrial
networks, advancement in maritime networks is severely lagging behind its land counterpart.
MARINTEK is the principle investigator of the MarCom project, a joint initiative between several national
and international R&D institutions, Universities and Colleges, Public Authorities and Industry, funded by the
industry itself and The Norwegian Research Council’s MAROFF program, and aiming at developing a novel
digital communication system platform to ensure the proliferation of innovative mobile network applications
presently being widely implemented on land-based wireless systems.
130
Figure 1 The ‘Northern Challenges’ exemplified by Norway‘s
geography and economic activity at sea (Source: ACIA)
2.2 MarCom scenarios and strategic initiatives
The specific market pull issues and user require-
ments pertaining to the MarCom project are investi-
gated through the following 9 scenarios/user cases:
1 Monitoring of (domestic) ferries
2 Pilotage & maintenance of fairways,
lighthouses and navigation marks
3 Integrated operations (IO’s)
4 Passenger information on trains and at roads
5 High-speed craft (HSC) operations
6 Vessel-to-Vessel Relay and Mesh networking
7 Mobile on-board LAN-solutions
8 The High North challenges
9 International shipping
Furthermore the issue of novel maritime commu-
nication technologies will be an important aspect of
the emerging e-Navigation and e-Maritime concepts
- e-Maritime being proposed by the EU Commission
(DG TREN) as an extension to the already develop-
ing e-Navigation concept originating from IALA
and IMO strategic initiatives.
Bearing in mind that the ocean waters cover
about 70% of the earth surface, that over 90% of the
world’s goods is transported by a merchant fleet
comprising around 46.000 ships, and that there are
about 4.000 viable merchant ports worldwide - liter-
ally thousands of ships are out of sight from land or
any other vessel all the time - and thus making the
global needs for reliable maritime communications
paramount.
2.3 Compiled user requirements versus available
communication capacity
The compiled user requirements derived from the
scenarios referenced in paragraph 2.1 above, along
with similar supplementary data from the EU-
projects ‘Flagship’ and ‘EFFORTS’, have identified
the application groups given in Figure 2 ([2],[3]).
Figure 2 Speed vs. integrity diagram showing compiled user
requirements in application groups [3].
It is obvious that but a few lower classes of these
application groups may be supported by the present-
ly available digital maritime communication means
depicted in Table 1, and thus novel maritime com-
munication technologies have to be introduced to the
maritime market.
3 NEW MARITIME COMMUNICATIONS
3.1 MarCom major objectives
MarCom’s major technological objectives are to:
− Extend the coverage and range at sea for both in-
use and novel terrestrial wireless systems/ tech-
nologies
− Find appropriate SatCom solutions to comple-
ment/supplement the terrestrial ones, mainly be-
yond their coverage
− Obtain seamless and continuous handover and
roaming within and between the systems
Table 1 Presently available digital maritime communications
3.1.1 Terrestrial systems
The appropriate terrestrial systems being applica-
ble for maritime use may be categorized as follows:
1 Cellular systems
2 Wireless Broadband Access (WBA)
Special purpose
applications
10 kbps
1 Mbps
100 Mbps
Low
Medium High
Reporting
(Operations &
Navigation)
Emergency
messaging
(SAR)
Technical
maintenance
Reporting
(Mandatory)
Infotainment
(Crew and passenger
communication)
Safety & monitoring
Training &
qualification
Integrity
Data rate
Special purpose
applications
10 kbps
1 Mbps
100 Mbps
Low
Medium High
Reporting
(Operations &
Navigation)
Emergency
messaging
(SAR)
Technical
maintenance
Reporting
(Mandatory)
Infotainment
(Crew and passenger
communication)
Safety & monitoring
Training &
qualification
Integrity
Data rate
100 messages /dayNAVTEX over InmarsatSafetyNET
Some
ships have digital data links via Satellite (Inmarsat, VSAT…)
Data rateCommunication formSystem
100 bits/dayShort messages (Satellite)SSAS
100 bits/hourShort messages (Satellite)EPIRB
2 x 9.6 kbpsVHFAIS
4.8 kbpsAccess via NMEA 0183GPS
1.2 kbpsVHFDSC
300 bpsHF, MFNAVTEX
100 messages /dayNAVTEX over InmarsatSafetyNET
Some
ships have digital data links via Satellite (Inmarsat, VSAT…)
Data rateCommunication formSystem
100 bits/dayShort messages (Satellite)SSAS
100 bits/hourShort messages (Satellite)EPIRB
2 x 9.6 kbpsVHFAIS
4.8 kbpsAccess via NMEA 0183GPS
1.2 kbpsVHFDSC
300 bpsHF, MFNAVTEX
131
3 Wireless Narrowband Access (WNA)
The roadmap for Cellular systems evolution to-
wards an alleged introduction of ‘Next Generation
Mobile Network’ (NGMN) is illustrated in Figure 3,
the main features being steadily increased capacity
and versatility [4]. A significant milestone on this
path is the 4G-3GPP LTE (‘Long Term Evolution’)
advancement, expected to offer peak data rates of
about 300 Mbps downlink and 80 Mbps uplink.
Actual WBA systems comprise mainly Wi-
Fi/WLAN and the emerging WiMAX technologies
in accordance with the IEEE 802.11 and 802.16
standards, respectively.
For maritime users Wi-Fi is merely applicable for
on-board purposes and close to shore (e.g. in har-
bors) due to its limited range.
However, WiMAX is considered a viable option
for medium- to long-range broadband maritime
communications, particularly if sub-GHz frequen-
cies are applied - thus supposed to be capable of
providing data rates > 20 Mbps at ranges up to 50-
100 km [5].
Relevant WNA systems are Digital VHF (D-VHF)
and (partially) AIS, but the latter is presently offer-
ing only 2 x 9.6 kbps, and thus of no interest to the
bandwidth-demanding services in Figure 2.
As the 1
st
generation of D-VHF systems Telenor
Maritime Radio (TMR) devised a technology
providing a.o. a ‘broadband’ service of 133 kbps by
utilizing 9 x 25 kHz VHF channels, with a range of
∼130 km. TMR has deployed this system to cover all
of the 2.400 km long Norwegian coastline, together
with parts of the North Sea and the Norwegian Sea.
However, as a part of harmonizing the maritime
D-VHF services a significantly more spectral-
efficient solution has been introduced, indicating
that the 2
nd
generation might increase the D-VHF’s
capacity by a factor of 3 -10 [6].
3.1.2 Future trends – terrestrial wireless systems
convergence or coexistence?
WiMAX is designed to deliver multiple types and
levels of service through a flexible IP network archi-
tecture, authentication and Quality-of-Service (QoS)
mechanisms. WiMAX can be implemented as a flat
‘pure IP’ network or as a part of a multimode service
environment through application servers, network
gateways and IP Multimedia Subsystem (IMS).
LTE is now heading in a similar direction in cre-
ating Orthogonal Frequency Division Multiple Ac-
cess (OFDMA) based networks, adaptive to various
channels and signal conditions, and based on stand-
ards that comprise a framework allowing significant
change and extension without breaking, an approach
now looking obvious.
However, although several telecom advisers are
predicting a convergence towards a NGMN concept
as depicted in Figure 3, there are various reasons to
believe that their coexistence will continue for sev-
eral years to come.
Figure 3 Wireless terrestrial systems evolution roadmap
3.2 SatCom systems
MarCom’s objective is to find appropriate SatCom
solutions to complement terrestrial technologies,
mainly beyond their coverage - and the most suitable
are hence being sought among systems utilizing
GEO, LEO and HEO orbits (see Figure 4).
A GEO satellite appears to be in a fixed position
to an earth-based observer, since it is revolving
around the Earth at a constant speed once per day at
an altitude of about 36.000 km over the equator. 3-4
satellite constellations are generally used to obtain
nearly ‘global’ coverage - however excluding a.o.
the polar regions (!).
Height [km]
200 – 2.000
MEO: Medium Earth Orbit
2.000-GEO;
normally: 10.000-20.000
35.786
500-50.000
Figure 4 Satellite orbits and their main features
Inmarsat is internationally recognized as pioneers
in mobile satellite services, being founded 30 years
Molniya
Tundra
Molniya
Tundra
GEO
GEO
MEOMEO
LEOLEO
HEOs
Apogeum
Perigeum
132
ago to ensure that ships could stay in constant touch
by telephone via GEO satellites.
Over the years Inmarsat has continued to intro-
duce new technologies and services, particularly to
the maritime community: Inmarsat-A, -B, -C, -M,
Mini-M, GAN, -D/D+, MPDS and the Fleet family
(Fleet77, 55 and 33), based on older technologies
termed "Existing and Evolved", mostly providing
fax/data services with rates up to 9.6 kbps and medi-
um/’high’ speed data up to 128 kbps.
Recently Inmarsat introduced the novel BGAN
concept, which benefits from the new I-4 satellites to
offer a shared-channel IP packet-switched service of
up to 492 kbps, and a streaming-IP service from 32
to 256 kbps. The BGAN family includes Fleet
Broadband, a service planned for ships and the mari-
time community.
Another GEO-based alternative is represented by
the various VSAT systems, utilizing satellite stations
with typically dish antennas smaller than 3 m in di-
ameter (most VSAT antenna diameters ranging from
75 cm to 1.2 m) to obtain data rates generally from
narrowband up to 4 Mbps (46 Mbps being presently
the fastest one [7]).
DVB-RCS represents a novel broadband VSAT-
type multi-user design included in the Digital Video
Broadcasting (DVB) family, and thus being the only
open international standard for satellite networks
with two-way communications, providing high ca-
pacity towards the user (∼40 Mbps downlink) and
more moderate capacity from the user (∼2 Mbps up-
link). DVB-RCS technology allows for star and
mesh topologies with 10.000's of VSATs per net-
work. Over 100 DVB-RCS systems are operating
worldwide today - going mobile with handover from
satellite to satellite, and numerous trials including
train-, aircraft- and vessel-mounted terminals.
The only seemingly interesting LEO alternative is
the Iridium constellation, using 66 cross-linked sat-
ellites in near polar orbit inclined 86.4° to the equa-
tor at an altitude of 780 km - and accordingly an or-
bit period of about 100 minutes - providing allegedly
‘true’ global coverage.
The nominal data rate of an Iridium ‘channel’ is
4.7 kbps, with latency for data connections about 1.8
s (round-trip) using small packets [8]. Iridium is also
advertising a "Direct Internet" at 10 kbps, but this
throughput is seemingly attainable only with com-
pressible data subjected to Iridium's proprietary (re-
mote) compression software.
The recent service offered by Iridium is Open-
Port, claiming IP-based data rates of 9.6 -128 kbps
(configurable), featuring allegedly global gap-free,
pole-to-pole coverage, with low-profile omnidirec-
tional antennas independent of stabilization plat-
forms.
Iridium is also planning a new generation of sat-
ellites - ‘Iridium NEXT’, to be operational by 2016,
and expected to provide date speeds up to 1 Mbps
(transportable K
a
-band up to 10 Mbps (?)) [9].
Contrary to GEOs and LEOs the HEOs are char-
acterized by a relatively low-altitude perigee and a
high-altitude apogee. These elongated orbits have
the advantage of long dwell times near a point in the
sky during the approach to and descent from apogee
- a phenomenon known as the ‘apogee dwell’ in ac-
cordance with Kepler’s second law. The orbital ec-
centricity is adjusted to the rotation of the Earth in
order to make the satellites operating near the apo-
gee and moving with nearly the same speed as the
Earth, thereby maintaining a fixed position in rela-
tion to a point on the ground.
During the early 1960's Soviet Union aerospace
engineers devised the Molniya HEO, which is simu-
lating the convenience of a GEO while simultane-
ously servicing the extreme northern regions, with
an inclination of (ideally) 63.45° relative to the
Earth’s equatorial plane, and an orbital period of ½ a
sidereal day. During this orbital period the Earth
makes ½ a turn, and thus the apogeum will be at the
very same position relative to earth twice a day.
Seen from the Earth a Molniya orbit satellite will
thus apparently be in zenith about 39.750 km above
two positions (at latitude 63.45°- see Figure 5) dur-
ing roughly 8 hours twice each day, the perigee
height being only about 500 km. Accordingly 2 sat-
ellites would provide continuous coverage of the
northern hemisphere, but a 3-satellite constellation is
preferable [10].
Apart from the evident Russian applications, sev-
eral studies on utilizing Molniya orbits for quite a
few applications have been carried out, recognizing
their apparent benefits in:
− Providing a quasi-stationary perspective with an
apogee height approximating the GEO, and thus
GEO technologies can be reused (slightly modi-
fied) to a.o. reduce costs and risks
− Giving an optimum high-latitude coverage per
satellite with no LEO-like latitudinal coverage
gaps, and little time “wasted” over lower latitudes
adequately seen from GEOs
− Simple ground segment; real-time communi-
cations can be achieved with a single primary
ground station, as for GEO
− More cost-effective than GEO systems for the de-
livery of satellite-based mobile multimedia in Eu-
rope [10].
133
Figure 5 The Earth seen from GEO and HEO (Molniya) satel-
lites, respectively
However, an inconvenience with the Molniya or-
bit is its satellites passage through the ‘van Allen ra-
diation belt’ twice per revolution, requiring addi-
tional mass to obtain protection of e.g. the solar
panels.
Another attractive HEO avoiding this hindrance
is the more low-eccentric ‘24-hours’ Tundra orbit,
which is more comprehensively described in [1].
4 THE HIGH NORTH CHALLENGES
The fragile environment of the High North is decid-
edly dependent on a sustainable ecosystem balance.
Safeguarding this balance calls for a highly devel-
oped communication infrastructure and sophisticated
surveillance systems, which are presently unavaila-
ble. Reliable broadband radio communications in the
Northern and Arctic Region is vital for fast reporting
of status and evolution of the environment, and early
warning of pollution threats. Additionally, these
technologies are decisive for efficient handling of
hazards and accidents intimidating people and/or the
environment.
Broadband radio communications with data rates
of several Mbps is anticipated to be needed by sev-
eral activities in this vast area, out of which the more
important are:
− Fisheries, including resource investigations and
protection
− Oil and gas offshore activities
− Fishfarming, aquaculture installations and
associated activities
− The Coast Guard’s law enforcement of environ-
mental crime and other illegal activities
− Homeland security and defense activities
− Research activities (ice studies, meteorological
and hydrological research and monitoring etc.)
− Coastal water activities (ferries, cruise ships, sup-
port ships, fishing, fishfarming etc.)
The terrestrial systems outlined in paragraph
3.1.1 needs further thorough investigations regarding
feasible utilization in the High North, but the com-
mercial aspects are most likely to override the tech-
nical challenges, since the initial number of users are
supposed to be fewer than commercial operators
would consider satisfactory.
However, our preliminary findings indicate the
coastal areas (including the Northeast and Northwest
passage) to be adequately covered by terrestrial sys-
tems, where sub-GHz WiMAX and enhanced D-
VHF are considered the most promising alternatives.
In order to cover the passage North of Russia or
Canada, or the area near Svalbard, a “chain” of per-
tinent base stations with an appropriate backhaul in-
frastructure would be required. The cost and com-
plexity of such a system would necessitate a detailed
study of a.o. the area’s topography. But even if such
systems could be favorably deployed, vast areas
would still be left uncovered, demanding other solu-
tions to complement these coastal area systems.
The crucial limitations of traditional SatCom sys-
tems are illustrated in Figure 6:
Figure 6 Traditional SatCom limitations in Polar regions
− Although Iridium claims the OpenPort service to
provide IP-based data rates of 9.6-128 kbps, fea-
turing allegedly global gap-free, pole-to-pole
coverage, this system is judged inadequate as a
more permanent solution to the High North
− GEO satellites are invisible at latitudes exceeding
about 80° N
− Even relatively advanced maritime SatCom ter-
minals with stabilized antennas require elevation
angles preferably >5°, and are thus rendered in-
adequate at latitudes exceeding about 76°N.
− Stabilized antennas must lock onto the intended
satellite for proper operation, but several condi-
tions, including the vessel’s unpredictable gyra-
tions, can instigate a stabilized antenna to drift
from the intended satellite and cause signal drop-
out and/or harmful interference to adjacent satel-
lites. Due to rather severe roll, pitch and yaw
movements of a vessel during adverse weather
conditions even larger elevation angles are re-
134
quired, and thus practical problems with ‘stand-
ard’ SatCom terminals may be expected to arise
at latitudes beyond about 70°N. Layers of
(mixed) saltwater, sleet and ice on the antenna ra-
dome will certainly not diminish such problems,
and thus adding up to the unsatisfactory situation
illustrated in Figure 7.
Figure 7 Illustration of the inadequate GEO coverage in the
High North
Consequently it seems evident from our prelimi-
nary findings that HEO’s would provide the only
technically viable alternative for adequate SatCom’s
in the northern areas - in fact to the northern hemi-
sphere on the whole (which accordingly also applies
to the southern hemisphere if the orbits are ‘re-
versed’). However, thorough investigations are re-
quired to reveal the cost/performance figures of per-
tinent systems, along with their success factors [1].
5 RADIO ENGINEERING CHALLENGES IN
MARITIME ENVIRONMENTS
In order to meet MarCom’s major objective of ex-
tending the coverage and range at sea for both in-use
and novel terrestrial wireless technologies, several
radio engineering challenges are to be met, such as:
− The characteristics of radio signal propagation
over the sea must be known
− Appropriate frequency resources must be (made)
available
− Improved antenna systems need careful attention
− Investigations of additional means to extend the
coverage and range are required, such as:
− Repeaters; passive, active and regenerative
− Mobile Multi-hop Relay (MMR)
− Mesh networking
The ability to accurately predict radio propaga-
tion behaviour for wireless services is becoming
crucial to system design. Numerous studies have
(unsurprisingly) been conducted for densely popu-
lated areas, but very few have been focusing coastal
waters, which are exhibiting physical layer struc-
tures quite dissimilar to urban surroundings. Conse-
quently reliable radio channel models for propaga-
tion over sea are required to make appropriate
range/coverage predictions, and particularly to ena-
ble improvements of system performance by apply-
ing e.g. diversity and/or advanced antenna systems
techniques. Both theoretical studies and experi-
mental trials are required to determine such models.
The overcrowded radio frequency spectrum rep-
resents a crucial challenge to wireless services in
general, and to maritime applications in particular.
However, ITUs World Radiocommunication
Conference 2007 (WRC-07) approved the identifica-
tion of the 450-470 MHz and 698-862 MHz fre-
quency bands for International Mobile Telecommu-
nications (IMT) services. These frequency bands are
being referred to as the ‘digital dividend’ - the free-
ing up of spectrum brought about by the terrestrial
TV distribution switch from analogue to digital
technology.
These frequencies are also being referred to as a
part of “the spectral sirloin”, since, in addition to ex-
hibiting attractive propagation characteristics, they
also facilitate relatively undemanding development
and low-cost production of RX/TX radio equipment
with reasonable size and weight. The upper UHF
band (698-862 MHz) is thus a target band for the
WiMAX Forum, and the earliest applicable (recon-
figurable) sub-GHz WiMAX products are already
commercially available [5].
The utilization of these sub-GHz frequencies
would facilitate the novel wireless terrestrial systems
extension of coverage and range at sea, which is il-
lustrated by the fact that e.g. covering the same area
require only 2 base stations at 450 MHz compared to
30 at 3.5 GHz [5] - i.e. also an economical ad-
vantage factor of about 15 (!), and thus being highly
beneficial to maritime applications.
However, each country has the authority to man-
age their frequency resources, and an international
harmonization would consequently be needed to
provide the maritime community with the most fa-
vourable solution.
Antennas (and RF transceivers) comprise crucial
sub-systems to any radio system. Numerous anten-
nas presently being applied in wireless systems are
rather outdated, and accordingly system perfor-
mance can be significantly enhanced by utilizing
more sophisticated antenna designs. Emerging smart
antenna technologies also enabling cost-effective
shipborne solutions represents an area to which ex-
tensive R&D resources should definitely be allocat-
ed.
Other means to enhance range/coverage are Re-
peaters, MMR and Mesh networking, all referring to
different concepts for conveying user data, and pos-
sibly controlling information, between a base station
135
and a mobile station through one or more relay units
- to be utilized along with the other appropriate
techniques and methods discussed in this paper to
realize the suggested ‘Wireless Coastal Area Net-
work’ (WiCAN) concept illustrated in Figure 8 [1].
In order to facilitate seamless and continuous
handover and roaming within the heterogeneous
WiCAN environment, a ‘smart mobile router’ would
represent a crucial component, having been termed
an ‘Agile MarCom Communication Adapter’ (AM-
CA) in the MarCom project.
Figure 8 Illustration of the suggested ‘Wireless Coastal Area
Network’ (WiCAN) concept
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