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1 INTRODUCTION

The main types of serious accidents in shipping are

collisions, contacts and groundings. While there are

many studies indicating that ship accidents are

influenced by many internal and external factors,

some characteristics on decision making just prior to

accidents. Statistics have shown that these categories

represent around 2/3 of all accidents in Europe [3],

Japan [8] and Canada [12]. Earlier studies [1, 6, 13]

and statistics from incident [4] and accident statistics

[3] have shown that root causes for collisions are

found in human performance, expressed by poor

communication, situational awareness, unfamiliarity

with equipment and fatigue. For contact and

grounding incidents the reasons can be found in

similar categories as for collisions with additional

Low Bandwidth Network-RTK Correction Dissemination

for High Accuracy Maritime Navigation

S. Alissa

, M. Håkansson

, P. Henkel

, U. Mittmann

, J. Hüffmeier

& R. Rylander

Lantmäteriet (Swedish Mapping, Cadastral and Land Registration Authority), Gävle, Sweden

ANavS GmbH, Munich, Germany

Research Institutes of Sweden, Göteborg, Sweden

ABSTRACT: More than half of the incidents reported to EMSA relate to nautical events such as collision,

groundings and contacts. Knowledge of accurate and high-integrity positioning is therefore not only a need for

future automated shipping but a base for today’s safe navigation. Examples on accidents include Ever Given in

the Suez Canal and HNoMS Helge Ingstad in Norway.

A Network-RTK (NRTK) service can be used as an augmentation technique to improve performance of

shipborne GNSS receivers for future positioning of manned and unmanned vessels in restricted areas, such as

port areas, fairways, and inland water ways. NRTK service providers generate RTK corrections based on the

observations of networks of GNSS reference stations which enables the users to determine their position with

centimeter accuracy in real-time using a shipborne GNSS receiver. Selection of appropriate communication

channels for dissemination of NRTK corrections data is the key to a secure positioning (localization) service. In

PrePare-Ships project, the modern maritime communication system VDES (VHF Data Exchange System) is

proposed to distribute SWEPOS (NRTK in Sweden) correction data to shipborne positioning modules. VDES is

a very reliable technique and it is compatible with most onboard functionalities. In order to minimize the

impact on the overall VDES data capacity in a local area, NRTK correction data shall only occupy a single VDES

slot with a net capacity of 650 bytes. Update rates may vary but are preferably at 1Hz. However, NRTK

correction data size changes instantly, depending on the number of visible GNSS satellites, and the data rate can

therefore sometimes reach in excess of 1000 byte/s. In this study, a smart technique is proposed to reduce size of

NRTK correction data to instantly adapt with the VDES requirements by choosing a combination of specific

signals, satellites or even constellations such that the data rate is not more than 650 byte/s, and at the same time

it achieves optimal positioning performance with the accuracy required by the PrePare-Ships project

application.

http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 15

Number 1

March 2021

DOI: 10.12716/1001.15.01.17

172

unfamiliarity with area, poor voyage plan and poor

assessment of speed.

Regarding time constrains of the operator, there is

a fundamental difference in near-grounding situations

to in near collisions/ close quarter situations. While

decisions can often be made some ten minutes or so to

avoid groundings, collisions have a much shorter

time-to-act span down to seconds [5]. Hollnagel [2]

has found that for the humans in a system “that the

reason why they sometimes fail, in the sense that the

outcome of their actions differ from what was

intended or required, is due to the variability of the

context and conditions rather than to action failures”.

Thus, the ability to minimize the variability will have

a potential to minimize the occurrence of undesired

events.

The objectives of this study within the PrePare-

Ships project is to give evidence-based criteria for

designing decision support tools based on a dynamic

ship predictor which require high accuracy

positioning information from the shipboard GNSS

receiver and the other sensors. The feedback from ship

crews implies that dynamic predictors increases the

understanding on how the future movement of the

vessel will be in different weather conditions. The

results of the literature study and data analysis

indicate that the prevailing event categories can be

influenced by decision support making the common

understanding of the current situation more visible to

the crews. Especially for collision situations, short

time spans are available to make decision, therefore a

constant prediction of how the ships will move can

support the crews in decision making and situational

awareness. Accident investigations show a significant

amount of accidents where the crews internal

situational picture deviated on the same as well as on

all bridges of the ships involved.

The high-accuracy GNSS positioning technique is

widely used in marine navigation. In general, there

are several techniques for providing GNSS corrections

that can be used to achieve high precision positioning

like e.g. DGPS, SBAS, RTK and PPP. In the PrePare-

ships project we are working to develop methods in

order to use Network-RTK and PPP for positioning of

ships. As NRTK technology requires land-based

reference stations it will focus on positioning in

inshore areas. Since the core of fast and high-accuracy

NRTK positioning is the ability to provide the

correction data for all constellations, satellites and

signals, this study focuses on the NRTK accuracy

performance when it provides the correction data to

the shipboard GNSS receiver.

2 GNSS NRTK POSITIONING FOR SAFE

NAVIGATION IN THE RESTRICTED WATERS.

In order to decrease the risk of ship collisions, the

situational awareness can be increased by predicting

future positions and exchanging them with the

surrounding. Therefore, the PrePare-Ships project

develops a robust and accurate navigation solution

based on the features of Galileo signals in

combination with NRTK corrections and other in-ship

sensors. The solution reduces the risk for ship

collisions, provide decision-support in fairway

navigation, decrease environmental impact and

emissions and provide a cornerstone for future

automated navigation. The PrePare-Ships System will

receive position, attitude and velocity data from the

ANavS GNSS receiver using the Galileo Open Service.

The ANavS receiver use the signals from Galileo

satellites, the carrier-phase positioning corrections

from Network-RTK supported from SWEPOS, and

information about the integrity of the RTK

corrections. SWEPOS is the national CORS network of

Sweden operated by Lantmäteriet (the Swedish

Mapping, Cadastral and Land registration authority).

By that, ANavS provides a reliable positioning service

using sensor fusion.

The network RTK service in the project is based on

SWEPOS. The Swedish GNSS reference station

network has been developed in different stages to be

able to meet the requests on better positioning

uncertainty, reliability and availability. In general,

SWEPOS is based on:

− Physical infrastructure (permanent reference

stations and hardware of the control center);

− Distribution infrastructure capable of

disseminating real-time data flow from the stations

to the control center and from this to the user

according to RTCM SC 104 (Radio Technical

Commission for Maritime Services Special.

Committee 104) standard [11];

− Processing infrastructure, consisting of third party

software that improve the estimation of the various

errors and make them available to users spread

over the coverage area.

The current SWEPOS NRTK Service is based on

the Virtual Reference Station (VRS) concept, with two-

way mobile network communication between the

processing center and the NRTK users. The VRS

technique is currently the most popular/used NRTK

technique due to its compatibility with existing

software. The shipborne EGNSS receiver applies the

standard differential positioning of its observations

with observations from the VRS. Based on the

observations from the surrounding Physical Reference

Stations (PRS) in the area, the SWEPOS control center

will interpolate and generate a set of GNSS

observations/corrections calculated as if they were

acquired by a hypothetical receiver placed at the

required reference position, thus obtaining a VRS. The

network computing center is located in Lantmäteriet

(Gävle) and it generally perform the following steps:

− Determine various errors of different origin,

including atmospheric errors, clock errors, and

local multipath with cm-accuracy by fixing the

ambiguities of the baselines within SWEPOS

network,

− Simulate the position of the VRS by geometrically

displacing the data of the reference station closest

to the rover,

− Interpolate the estimated errors at the VRS location

using mathematical models,

− Transmit the corrections to the users in real-time.

The current SWEPOS infrastructure consists of

approximately 460 permanent GNSS reference

stations located as shown in Figure 1. The distances

between these stations can be classified into the

following configurations [9].

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− Normal Configuration (NC): It’s the original form

of SWEPOS NRTK which was built through

establishing NRTK service in 2002-2010. The

distances be-tween the stations are 70 km.

− Densified Configuration (DC): It’s the densified

form of NRTK service. The distances between the

stations are 35 km. The densification from 70 to 35

started in 2010 for improving the network

performance.

− High-Densified Configuration (HDC): It’s a special

form of NRTK service and implemented for the

areas that need very high performance (project-

oriented positioning services). The distances

between the stations are 10 km.

Figure 1. Map of SWEPOS reference stations.

All SWEPOS stations are equipped with very

modern GNSS receivers which can receive and

process the signals/frequencies from all current GNSS

constellations (GPS, GLONASS, Galileo, Beidou,…).

Figure 2 shows two types of GNSS receivers (Trimble

Alloy and Septentrio PolaRx5) which are the most

common types on the SWEPOS stations. Data is

collected every second and a 5 degrees elevation mask

(in data processing software) is used. A Choke ring

antenna of Dorne Margolin design mounted under a

radome is used at every SWEPOS reference station.

The radomes are made of clear acrylic. Figure 3 shows

an example of the class A station.

Figure 2. GNSS receivers used in most of SWEPOS stations.

Figure 3. The SWEPOS station Leksand.

The transmission infrastructure is a very important

part in Network-RTK. It should be capable of

disseminating a real-time data flow from the stations

to the processing center, and from the center to the

ship according to own protocols or standard ones.

The NRTK correction data is generally transmitted

to the ship via the RTCM format. The RTCM SC 104

on Diﬀerential GNSS (DGNSS) provides the standards

for disseminating the diﬀerential GNSS and RTK

information from the service provider to the users (the

shipborne GNSS receivers in our case). The RTCM

was mainly used for disseminating the correction data

in PrePare-ships project. The data transmission from

the reference stations to the control center server and

from the control center server to the user for RTK

corrections is mostly carried out via the Network

Transport of RTCM via Internet Protocol (NTRIP)

[10].

3 DISSEMINATION OF NRTK CORRECTION

DATA VIA VDES.

As 4G and future 5G does not fulfil the maritime

reliability requirements, the maritime Automatic

Identification System (AIS) is used world-wide for

exchange of position reports and other data between

ships and between ships and shore based base

stations. The system operates on dedicated VHF

channels within the maritime band and is based on

the concept of time multiplexed transmissions

(TDMA) enabled by the availability of a common time

reference from GNSS. Carriage of AIS transponder

equipment is required for the majority of commercial

ships and AIS base stations are employed by most

coastal nations.

The dynamic predictor which proposed in the

PrePare-ships project requires substantial

communication bandwidth to sustain accurate and

timely predictions ship to ship. AIS cannot deliver

this bandwidth so the research in the project will be

performed using VHF Data Exchange System (VDES)

as communication channel. VDES is the next

generation AIS with up to 32 times the bandwidth

compared to AIS [7]. The VDES terrestrial link

denoted VDE-TER link ID 19 can deliver 702 bytes per

slot after FEC (Forward Error Correction) and the

PrePare-ships project has selected this link as the

primary link for the dynamic predictor research. An

alternative, but discarded solution, could be VDE-

ASM with link ID 5 that can deliver 36 bytes after FEC

174

per slot. There are 2250 slots/minute in the AIS/VDES

communication system with 37.5 slots per second.

With VDE-TER link ID 19 the dynamic ship predictors

“payload” limit has been set to 650 bytes/slot as an

initial assumption and the rest of the bytes (52) have

been reserved for link management.

VDES is a broader concept subject to on-going

international standardization and development

efforts. The goal is to enhance the amount of data that

can be transmitted and to enable world-wide rather

than line of sight communication capabilities, by

introduction of a satellite segment. VDES is intended

to be an enabler for new functions aimed to improve

safety and efficiency for shipping operations.

To ensure better availability of GNSS correction

data, a novel way of dissemination was developed

within the PrePare-Ships project. This approach

builds upon the approach previously discussed,

dissemination via internet and NTRIP by adding an

additional layer after the NTRIP Caster mountpoints

user. Several additional considerations need to be

taken into account for VHF and VDES dissemination.

These can be divided into adapting the GNSS

correction data stream content, and preparation and

restoration of the correction data before transmission

and after reception with regard to synchronization

with the VDES protocol. Figure 4 shows the diagram

for this method.

Figure 4. Dissemination of GNSS correction data via VHF

and VDES.

The emerging capabilities of VDES are exploited

by the PrePare-Ships project for transmission of

network RTK data from shore to ship as well as for

exchange of prediction information between ships.

For this purpose, prototype VDES transponders are

installed on the participating ships and a shore based

VDES base station is provided with coverage of the

intended test area.

The TDMA concept for VDES and AIS is based on

slots. A slot is defined as a 2250th of a minute or

approximately 26.7 ms. It is estimated that one slot

per second is a reasonable load on the VDES link that

can be dedicated for transmission of NRTK

corrections. With allowance for some overhead, this

translates to the 650 bytes/s limit required for the

RTCM data stream.

The VDES base station integrates with an NTRIP

client for acquisition of the compact RTCM data from

SWEPOS. The received packages are formatted and

broadcast as one slot messages on a VHF channel

dedicated for the purpose. The transponder on a

participating ship strips the received data from VDES

overhead and restores the RTCM content as provided

by the NTRIP client.

The VDES transponder is interfaced with other

equipment on the ship by means of an Ethernet

network interface compliant with IEC 61162-450. This

standard dictates the required properties of the

network and methods of data exchange for usage with

maritime communication equipment and systems on

ships.

The IEC standard does not specify any data format

intended for transmission of GNSS corrections over

the network. However, it is generally open for co-

existence of standardized messages and messages

with arbitrary data formats as long as a set of

minimum requirements are fulfilled.

The transport layer used for transmission of

IEC61162-450 messages is the UDP multicast protocol.

This makes it possible to transmit the RTCM packages

from the VDES transponder to the navigation sensor

as a UDP payload without any additional formatting.

The VDES transponder thus transmits the RTCM

correction data received from the base station over the

Ethernet network on the ship. The navigation system

retrieves the corrections from the network with

knowledge of the agreed IP address and port number

used by the multicast protocol.

Figure 5. Transfer of GNSS NRTK corrections via VDES.

Distribution of RTK correction via VDES according

to the principles described are suitable for generic

port installations. A VDES base station service

provider may thus provide access to high

performance positioning without need for dedicated

communication equipment on the ships.

4 ADJUSTMENT OF NRTK (RTCM MESSAGES)

CORRECTION DATA.

When adapting the correction data stream for VDES

transmission the following factors must be

considered:

− Utilization of only one VDES slot gives an upper

limit for the data rate of 650 bytes/s.

− The coverage area of the VHF transmitter is

considerably larger than the area where correction

data from one single VRS may be utilized, derived

from maximum distance between user and VRS

due to positioning accuracy requirements.

175

In VDES, multiple communication channels

between ships and land-based transceivers are

handled by dividing the communication over a

specific number of slots (time intervals) each second.

As all communicating parties within communication

range share the same slots, where only one party may

transmit within each slot, communication must be

kept at a minimum. Thus, the solution in PrePare-

Ships is to utilize only one of the available slots each

second. This gives a bandwidth limitation for the

transmission of GNSS correction data corresponding

to 650 bytes/s. Typical data rate for corrections

including GPS, GLONASS, and Galileo is between

700-1000 bytes/s. Adding corrections for BeiDou and

the integrity data will of course increase this number

further. As a consequence, the size of the GNSS

correction data has to be reduced by applying some

filtering. This especially applies for situations when

corrections for several GNSS constellations are

transmitted.

Additionally, the range of the VHF transmitter

greatly exceeds the maximum range between the

GNSS correction data user and the VRS position. In a

solution where GNSS correction data is broadcasted

for a grid of VRSs[14], this mean that each VHF

transmitter may have to transmit GNSS corrections for

more than one VRS. This is in the PrePare-Ships

solution solved by serializing correction data from

several VRSs into the same data stream. At the same

time correction data from each VRS is down sample in

order not to increase the bandwidth requirements of

the transmitted corrections. This means, that if

corrections for several VRSs are sent in the same

correction stream, the frequency of the observation

messages for each VRSs is down sampled by the

number of VRSs included in the stream.

To comply with the above-mentioned conditions,

the Lantmäteriet Adjustment Solution (LAS) for GNSS

correction data adjustment was developed. The

responsibility of this software is to produce a

correction data stream that complies with the

bandwidth limitation of 650 bytes/s and have the

capability to combine several correction data streams

from several VRSs into one single correction data

stream. Figure 15 depicts the data flow between caster

(black square), adjustment software (pink square), and

the VHF transmitter (brown square). TCP/IP is used

for transmission of correction data between these

components. For dissemination via VHF and VDES,

the developed adjustment software connects to the

same mountpoints and performs combining, down

sampling, and removal of correction data to comply

with the above-mentioned conditions. The resulting

correction data stream is refed into to the caster and

served for the mountpoint labelled PREP in the figure

6. From this point, the VHF transmitter can connect to

the mountpoint and transmit the correction data

stream. The same process is repeated for other VHF

transmitters and additional VRSs.

Figure 6. Data flow of GNSS correction data before

dissemination via internet and VHF

Tests that demonstrates the feasibility of using

GNSS correction data processed for VDES

transmission have been performed in cooperation

with RISE (Research Institutes of Sweden). These tests

were performed for statically located antennas only.

Future tests will also be done for moving antennas.

The results support that processed GNSS correction

data with a byte transmission limit of 650 bytes/s,

including correction data for one or several GNSS

constellations, and containing at least 3 VRSs, can be

employed by a RTK capable GNSS receiver to obtain

positioning solutions with resolved carrier phase

integer ambiguities and centimeter level positioning

accuracy.

The adjustment software has the capability to filter

GNSS correction data in the RTCM 3 format

constellation-wise, satellite-wise, and signal-wise as it

shown in Figure 16. The objective is to achieve

optimal performance in terms of accuracy for the

user’s precise positioning solution, while at the same

time adhering to constraints that might apply locally

for individual transmitters.

Constellation-wise filtering is achieved simply by

instructing LAS about which RTCM MSM observation

messages to forward. This is possible because RTCM

MSM has specific RTCM number ranges for each of

the constellations, e.g. 107x for GPS, 108x for

GLONASS etc., where x is the MSM message type 1-7.

Satellite-wise filtering can be achieved in several

ways, and the LAS supports several options regarding

this.

1 1. Applying an elevation mask of specified angle

2 2. Removing satellites not supporting certain

signals

3 3. Removing satellites at the lowest elevations until

specified maximum transmitted size or number of

satellites requirement is satisfied.

4 4. Removing satellites such that the satellite

geometry is optimized in terms of DOP.

Optimization of PDOP (3D), HDOP (2D), and

VDOP (vertical) are supported.

5 EXPERIMENTS AND TESTING.

In order to provide a NRTK service that meet the

requirements of the PrePare-Ships project in the test

area (Gothenburg, Sweden), SWEPOS has established

three new sites (located in Vinga, Hällsvik and Styrsö)

for reference stations to support the current

infrastructure of SWEPOS in the test area and one

monitor station (located in Fotö) to provide the

176

required integrity data (the data which will send in

parallel with SWEPOS correction data to the

shipborne GNSS receiver to describe the correction

health or warnings when the system should not be

used for navigation). The locations of four new

stations (in black) are shown in Figure 7 as well as the

existing stations (in blue).

Figure 7. SWEPOS stations in the test area of PrePare-ships

project.

The Choke-ring antenna has been chosen as a

GNSS antenna at every station for its ability to

attenuate multipath signals. Figure 6 shows the

antenna in Vinga station and the Figure 7 shows the

antenna in Hällsvik station. The Septentrio ’PolaRx5’

was selected as a GNSS receiver for all stations. The

PolaRx5 is a robust multi-frequency GNSS reference

receiver and its tracking techniques provides

measurements with low noise constantly monitoring

and protecting against multipath, interference, and

other environmental effects. SWEPOS have used two

PolaRx5 receivers at each station to increase the

station/system redundancy and reliability. Figure 8

shows the hut of the Styrsö station and its two GNSS

receivers.

Figure 8, Vinga station antenna

Figure 9. Hällsvik station antenna

Figure 10. Styrsö station hut.

The test drive with the ship took place off the coast

of Gothenburg (Sweden) and is shown in Sea chart in

Figure 11. It started at Hönö Island and ended around

5 km from Gothenburg. During the drive, the bridge

between Solvik and Donsö shown in Figure 12 was

passed. After passing the bridge, the ship returned

and passed it a second and third time. Also, a

maneuver was performed, which consists of multiple

turnarounds.

Trials (3 September 2020) on the sea for testing of

the VRS were performed at different test

environments such as those in non-line-of-sight

scenarios for GNSS below bridges (see Figure 12) and

in narrow passageways have been considered. The

pilot boat used for the trial was made to take rotations

with minimum possible radii in the sea at around 10

km from the VRS to study the positioning capabilities

of the onboard ANavS Multi-sensor RTK module with

its GNSS/INS tightly coupled RTK positioning and

attitude determination.

Figure 13 shows the shipping route as determined

by the ANavS Multi-sensor RTK module. The color

denotes the availability of a fixed RTK solution, i.e.

green sections refer to a fixed RTK solution and red

sections refer to a float RTK solution.

Figure 14 shows the heading over time as

determined by the ANavS Multi-Sensor RTK module.

The enlarged section refers to several turns with a

variation of the heading angle between 0° and 360°.

Figure 15 shows the precision of the position

solution over time. It is better than 5 cm for a fixed

177

RTK solution, which is obtained for most of the time.

The accuracy degrades to a few decimeters for a float

RTK solution.

Figure 16 shows the precision of the 3D velocity

estimates. It varies between 5 cm/s and 8 cm/s for a

fixed RTK solution.

Figure 17 shows the number of available double

difference carrier phase measurements (scale on the

left y-axis) and the precision of the horizontal

positioning accuracy (scale on the right y-axis) during

three passages below bridges. Obviously, the number

of available measurements drops significantly below

the bridges but the positioning accuracy remains

better than 10 cm due to the GNSS/ INS tight

coupling.

Figure 11. Sea chart showing the area suitable for a planned

positioning test site.

Figure 12 The pilot boat when passing the bridge.

Figure 13. Shipping route of 2 hours in Gothenburg area.

The color denotes the availability of a fixed RTK solution,

i.e. green sections refer to a fixed RTK solution and red

sections refer to a float RTK solution.

Figure 14. Heading solution over time. The enlarged section

shows the variation of heading during some turns.

Figure 15. Precision of RTK solution over time during 2

hour shipping route: The precision is better than 5 cm for a

fixed RTK solution, and degrades to a few decimeters for a

float RTK solution. A fixed solution is obtained for most of

the time. Position accuracy when performing the maneuver.

178

Figure 16. Precision of 3D velocity solution in local

vessel coordinate frame over time. The precision

varies between 5 cm/s and 8 cm/s for a fixed RTK

solution and degrades to 25 cm/ s for a float RTK

solution.

Figure 17. Number of double difference carrier phase

measurements and horizontal positioning accuracy

during three passages below bridges.

6 DISCUSSION OF TEST RESULTS

The positioning results of the vessel show that a fixed

RTK solution with a precision of 5 cm was obtained

for most of the time. Similarly, a fixed attitude

solution was obtained for most of the time. The

precision was mainly limited by phase noise and

multipath during fixed RTK solutions.

A temporal degradation in precision was

observable and clearly related to temporal losses of

the 4G communication link. The latter one was used

to obtain the RTK corrections. There were several

communication outages in the order of one minute

with a maximum outage of 1.7 minutes (Figure 18).

Figure 18. Outages of the RTK correction data.

The RTK corrections can be predicted to some

extent during GNSS outages. However, small changes

of atmospheric delays of only a few centimeters are

sufficient to lose an ambiguity-fixed solution. In this

case, the ambiguity estimates are set to float and are

re-estimated within the Kalman filter. This leads to a

weaker model and, thereby, to a larger uncertainty

until the float ambiguity estimates are fixed again to

integer numbers. Similarly, the RTK positioning

accuracy decreases with an increasing distance to the

VRS as differential atmospheric delays increase with

the distance. Differences in atmospheric delays are

caused by differences in the mapping function and/ or

by differences in the zenith delays. The ionospheric

activity was low during the test drive and did not

impact the positioning performance.

Future enhancements are two-fold: On the one

hand, VDES will be used for a more reliable

communication link. On the other hand, a Precise

Point Positioning (PPP) solution will be used for a

stand-alone absolute positioning solution

7 CONCLUSIONS

Trials on the sea for testing of the VRS indicate that

statistical uncertainties in the order of 5-10 cm can be

achieved within a distance of 12 km from the virtual

reference station, which may be compared to an

accuracy of around 5 m with standard equipment

used in the maritime industry today. The test results

proved that we can get the same required positioning

accuracy by using the LAS solution which proposed

to reduce size of NRTK correction data to instantly

adapt with the VDES requirements.

These results proved that the chosen system design

(The proposed positioning service in this study and

the proposed predictor in the project) should scale

well for worldwide implementations in areas of heavy

traffic, where avoidance of congestion in the

AIS/VDES system is crucial. The performance

enhancements in Positioning Navigation and Timing

(PNT) achieved in the PrePare-ships project are not

limited to the shipping sector but are a cornerstone for

future shapes of shipping that we now are at the dawn

of. Today it can enhance maritime constructions,

automated mooring, cybersecure local position

179

corrections, more accurate information to pilots and

officers in narrow fairways or heavily trafficked areas.

It enhances the capabilities of Search And Rescue

(SAR), resilient PNT, enables concepts like remote

operation/assistance of ships and even a future

scenario of autonomous shipping.

ACKNOWLEDGEMENT AND DISCLAIMER

The research leading to these results has received funding

from the European GNSS Agency under the European

Union’s Horizon 2020 research and innovation programme

under grant agreement No 870239. The content reflects only

the author’s view. The Union is not liable for any use that

may be made of the information contained therein.

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