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Navigation: Trend and challenges

Jan 2019 | No Comment
Experts share their opinion on the trends and challenges in satellite navigation at 16th International Association of Institutes of Navigation (IAIN) World Congress 2018, Chiba Japan during 28 November – 1 December. Some of the views are presented here

Ground wave radio navigation system will be developed

Prof Yasuo ARAI

Immediate Past President of International Assoication of Institutes of Navigation (IAIN)

Navigation should be de defined not only “to move from point to point decided” but also “entirely to establish the decided Mission including moving”, so almost of vehicles should accomplish their missions such as transportation of passengers or/and cargos with one of the most important missions to observe surroundings, to detect hazards and/or to avoid them in order to move to destination with safety, security and efficiency navigation.

Bringing an end to navigation for manned/unmanned vehicles, the technology on the Positioning, Timing, Sensing and Communication should be essential. Though, first of all the latest trends on these technologies will be mentioned, and the challenges to new generation will be done.

Positioning and Timing Today it has been past quarter centuries since starting GPS operation in full running in 1990s. Now, GPS (USA): GLONASS (Russia): CDMA, GALILEO (EU): FOC and Bei Dou (China) are running as GNSS, and IRNSS (India) and QZSS (Japan) as RNSSs. Almost entirely prospects that until 2020 these all systems will be operating in full running would be done, and it would be coming into the Navigation era when it would be said not possible to navigate without GNSS. Increasing infrastructures on G/ RNSS in intensity, GNSS receivers also have been changed to multi-GNSS and multi-Sensors in an attempt to improve the vulnerability of G/RNSS.

G/RNSS will be available in the area of outdoor positioning including urban, and positioning accuracy will be sub-meters or cm order from traditional positioning accuracy 10 meters adding application of QZSS.

Ground wave Radio Navigation In case of G/RNSS, it is not possible to apply the Positioning and Timing under the ground such as subway or tube and tunnel. Though, it will be difficult to apply the traditional Ground wave Radio Navigation even such as eLoran or Loran C for land navigation. ELoran will be applied to Marine Navigation and Aviation for back up of GNSS vulnerability such as jamming and spoofing.

Multi-Sensors IMU is applied to GNSS receiver for automobile navigation according to anti-vulnerability of GNSS, but at present it is just difficult to keep required accuracy for long time depending of GNSS positioning accuracy. Error is affected by the time, so it will enlarge in case of stopping or very slow speed in long time.

Anti-Jamming/Spoofing In aviation, the development of phased array GNSS antenna is advanced for not only anti- Jamming/Spoofing but also stable platform to protect the missing satellites due to changing vehicle’s attitude.

Indoor Positioning Recently, Indoor Positioning System has been applied with WiFi System of which positioning would be done by the measuring the receiving signals’ level and several referring markers set up at known fixed points. The accuracy is said 1 meter or sub-meters at present and apply the human being movement in the building or so. Moving robots and small indoor drone will be able to contribute the safety evacuation system indoor field and advance toward seamless navigation indoor from/to outdoor.

Sensing Navigation system presents not only Positioning and Timing but also a lot of data or information related navigation for own and others, such as heading, altitudes, 2/3D velocities, yaw/ roll/pitch and others’ information. The most important information is Radar and Visual information. These systems present circumstances but the performances just also presents navigation information, so these information should be fused and introduce the solution of surrounding condition just same as expert of navigation would use any kind of information which he or she is able to make up as possible.

Communication The communication system is also most important function. 4G is fruitful mobile data communication, and presents IoT not only to fixed points but also mobile vehicles. But latency of 4G or internet is not stable, so it is difficult to apply control network system.

Next generation 5G has low latency such as 0.1 ms which is same as able to control actuators and all of functions in a car. This performance will be able to synchronize a lot of video channels at once and apply the video from desired eye points just same as moving audiences.

The limited performance of 5G is the valid area calculated by range less than latency x radio wave velocity. So, it will be possible to wireless control in large vehicle. So, next generation of network construction should be fused 4G and 5G (low latency system), and be applied to autonomous/manned vehicle navigation.

Closing this article, challenges to nest future are described as follows;

▪ Ground wave radio navigation system for land navigation will be developed, and GNSS receiver will be covered all radio navigation system, so jump to Multi-RNS (Radio Navigation System) from Multi-GNSS, and proceed Seamless Navigation.

▪ Application of 3d Velocities by PPP receiver to gain the performance of vehicle control system. Feedback system is essential velocities (timerate of position) information.

▪ To gain the accuracy of position (velocities also), using QZSS in each region and instead Geo stationary satellite as SBAS especially at high latitudes.

▪ Development of downsizing radar for drone and automobile, and fusion of radar, visual and navigation information by sensor to increase not only accuracy but also responsibility for safety, security and economical manned/ unmanned/autonomous navigation.

Societal benefits from positioning, navigation and timing

John Pottle

Director, Royal Institute of Navigation, London President, International Assoication of Institutes of Navigation (IAIN)

We live in a fast-changing world. In the past, success was to get a position fix on a navigation receiver; then an accurate position became the goal. Now resilience is receiving attention: there is a call for continuity and integrity as well as accuracy. The routes to achieving resilience are still maturing. This is evidenced by the multiple approaches to rationalising the risks and mitigating them. Risk assessment frameworks are being developed and starting to be used more regularly, helping to rationalise the likelihood, or sometimes ease, of disruption against the severity of impact. Having rationalised the risk, appropriate mitigation choices can more readily be made.

Mitigating the risks presented by the vulnerabilities of satellite navigation systems does not always have to be complex. A directional antenna provides jamming protection; augmentation with Inertial and/ or Wi-Fi improves resilience (though not necessarily accuracy); multi-frequency receivers are less susceptible to jamming and spoofing risks. Many who rely on position, or time, are beginning to design-in security and resilience to their systems. Sophisticated approaches can sometimes be needed. But the 80/20 rule can be applied and some initial steps can deliver a major improvement.

Looking to the future, I submit that what we are seeing here is but the beginning of a revolution: more autonomy, collaborative systems, data analytics, artificial intelligence, augmented reality. We are seeing already the first steps on each of these but the revolution they can enable is to come.

At two recent conferences I have heard multiple mentions of paradigm shift. New paradigms are ahead, where the assumptions of the past and the present should not be relied upon. The basis of success for careers, companies, even nations, is shifting. We all need to change, to adapt, to remain strong and to thrive.

So how to rationalise, in this context, the value of our work? At the recent International Navigation Conference (INC2018, Bristol, UK 12-15 November) we explored the benefits to society from application of knowledge and expertise in navigation, positioning and timing. Think of the benefits that come from seismic and bridge monitoring for example; efficiency improvements from smart logistics; safety benefits from automation; the communications revolution enabled through position and precise time.

The World Trade Organisation has published 17 sustainable development goals – the blueprint to achieve a better and more sustainable future for all. Please go online and take a look at them. When you are there, consider how you can measure the impact of your next project? Perhaps you can measure benefit towards one or more sustainable development goals? If you do, I suggest that you will be more successful as you will be creating tangible societal benefit. I also see great value in sharing perspectives and insights between like-minded individuals, organisations, institutions. Together we are can do more, delivering more meaningful benefits, more quickly and more sustainably.

Civil and Commercial Aviation affected by GPS jamming

Steve Hickling

Director Marketing & Sales Enablement, Spirent

Guy Buesnel

PNT Security Technologist, Spirent

As modern civil and commercial aircraft become more reliant on GPS, it is perhaps not surprising that there has been significant increase in the number of reported incidents of systems being affected by GPS jamming.

It’s important to note that modern airliners retain legacy navigation systems that pilots can use in the event of GPS disruption caused by intentional or unintentional RF jamming. This means that the loss or degradation GNSS signals is not normally a safety-critical issue on the flight deck, but it is an operational issue as flights could be diverted, rerouted or delayed during episodes of interference that preclude the use of modern air traffic methods such as RNAV approaches.

Number of incident reports on the rise according to Eurocontrol figures

To fully appreciate that GPS interference has the potential to cause significant impact to commercial aviation an examination of recent reports of real-world disruption is helpful. In a presentation in September 2018 setting out its recommendations for protecting aviation from radio frequency interference, Eurocontrol said it had received 815 reports of GPS outages to-date in 2018 – nearly double the number experienced in 2016, the next most-disrupted year.

GPS interference causes disruption at Ninoy Aquino International Airport

A recently released report from the International Civil Aviation Organisation (ICAO) has revealed that a single airport saw over 50 incidents of GPS interference in just one 3-month period in 2016.

According to the report, flight crews reported more than 50 incidents of harmful GPS interference at Ninoy Aquino International Airport in Manila, Philippines, between March and May 2016.

Flights coming in to land on Runway 24 frequently experienced total loss of GNSS reception in the critical instrument approach phase. According to the report, this “sometimes led to missed approaches”, forcing flight crews to go around and re-approach the runway using back-up navigation systems.

What’s more, interference to the GPS signal meant incoming aircraft couldn’t accurately broadcast their position to air traffic control via the global ADS-B aircraft position identification system. Sometimes the onboard ADS-B couldn’t report a position at all, and sometimes the position it reported was massively at odds with the aircraft’s true position. Similarly, pilots reported issues with their ground proximity warning systems (GPWS) once location awareness was lost by the automated system.

Individual Pilot Reports highlight on-board operational issues

Some reported incidents of GPS disruption contain a lot of information about the impact of the problems. Whilst its not certain that the incident below was caused by GPS interference, the symptoms that the flight crew experienced are certainly very suggestive of an interference event

“An Air France Airbus A319-100, registration F-GRHB performing flight AF-1123 from Munich (Germany) to Paris Charles de Gaulle (France), was in the initial climb out of Munich’s runway 26L when the crew reported they had lost their positioning system, they were maintaining runway heading and needed radar vectors to return to Munich. The aircraft stopped the climb at 5000 feet, was vectored for the approach and landed safely back on runway 26L about 20 minutes after departure.

According to information The Aviation Herald received both GPS systems showed a fault.

The aircraft remained on the ground for about 2:45 hours, then was able to depart and reached Paris with a delay of 3.5 hours. “

In the USA, NASA administers a voluntary Aviation Safety Reporting System (ASRS). The ASRS collects reports of aviation incidents or situation reports from pilots, controllers or others. Since 2013, there have been more than 250 incidents reported to ASRS relating to GPS disruption.

In one such incident, documented in 2017, a pilot reports that the GPS signal is briefly lost (for around 30 seconds). The pilot wonders whether it was interference caused by a Personal Protection Device (Cigarette Lighter type jammer). The pilot continues into rain, clouds and turbulence but once again encounters GPS signal failure. The pilot report continues, “then all hell broke loose, GPS signal failure, ADSB failure, multiple cascading messages on the GTN.” It’s a very graphic report and details the impact of what probably was GPS interference, on multiple on-board aircraft systems.

GPS jamming exercises highlight system issues

Often, pilot reports of incidents most likely caused by GPS interference, coincide with GPS jamming exercises conducted by the military. A report from the Radio Technical Commission for Aeronautics (RTCA) highlights the worsening impact of military GPS jamming exercises on commercial aviation in the US, due in part to a sharp increase, from 43 exercises in 2012 to 127 in 2017, with the number of affected locations increasing from 16 to 37.

The report identifies 13 different potential impacts on commercial aircraft systems, ranging from loss of GPSbased navigation, which can result in missed runway approaches, to impairment of the ADS-B system, which reports an aircraft’s location to air traffic control and other aircraft nearby.

In several cases (24 in 2017), air traffic controllers have had to activate a so-called “stop buzzer” – a request to the organisers of the military exercise to pause the jamming to allow a particular aircraft, such as an air ambulance, to operate unimpeded.

The RTCA report highlights the needs for the whole aviation industry to understand the risks associated with GPSbased navigation, and to address any shortcomings in systems and procedures.

Mitigation

GPS interference detectors exist that if deployed around airports could lead to operational improvements and mitigations. Also, the frequency of interventions would suggest that better co-ordination between the military and ATC during GPS jamming exercises would be helpful.

Commercial aviation already has legacy networks of conventional radio navigation aids and ILS landing systems, a worldwide infrastructure that can be used alongside GPS to provide assured navigation and this has prevented GPS disruption from becoming a major Safety of Life Issue.

However, reliance on these systems prevents use of modern techniques required to obtain much needed improvements in capacity and efficiency and designed to exploit GNSS accuracy and ubiquity.

We would do well to not ignore legacy technologies

Simon Gaskin

Secretary General, International Association of Institutes of Navigation

Ever since mankind started developing means of transport there has been a requirement for the operator to know their present location relative to the destination and hazards or obstacles on the route. Technological developments eventually resulted in a variety of systems by which to achieve that in most environments. Navigators learnt to constantly compare and contrast the outputs of different systems in order to satisfy themselves that those outputs were essentially in agreement or identify whether one (or more) of the systems was in error. Then came the GNSS ‘gift’ of increasingly accurate absolute position. Overnight, it seems, we unlearnt all the best practices for navigating acquired over centuries and placed our belief in a single method of determining position that is vulnerable to disruption, malicious manipulation, or even denial. Nor has the requirement for quality relative positional information gone away. Could it be that the necessity for autonomous platforms to be permanently certain of the time, their position and attitude without the benefit of a ‘person in the loop’, will finally be sufficient incentive for the successful introduction of viable alternative systems that will ensure the capability of vehicles to derive that information is resilient?

Trends

A brief look at the titles of papers recently submitted to the Royal Institute of Navigation’s ‘Journal of Navigation’ reveals some of the methods being examined for their potential to contribute to Resilient Navigation: Visual Shoreline Navigation, Multi-antenna GNSS and INS Integrated Position and Attitude Determination without Base Station for Land Vehicles, Asynchronous Wide Area Multi-Lateration with Irregular Pulse Repetition, A Passive Acoustic Positioning Algorithm Based on Virtual Long Baseline Matrix Window. One of the quests of research is an (almost) error free sensor onboard a vehicle, independent of external signals – the ultimate Inertial Measurement Unit (IMU). But still, the very best are burdened by significant error accumulation and commercially unaffordable price-tags. Much is expected of quantum technology to solve this but a usable solution remains a long-term aspiration. Recently, much navigation was done by eye. Given the developments in imaging, another avenue for determining relative position ought to be the utilisation of cameras (visual spectrum, lowlight, Infra-red, thermal – (think the burgeoning, wondrous camera imaging of nature)) – onboard, independent and difficult to mislead, but not infallible.

Another possibility is to make use of ‘signals of opportunity’ (SOOPs), that is to say, signals transmitted for other purposes but which might be made use of to determine relative position.

However, the very nature of SOOPs is that they may not be the same everywhere a vehicle travels. Thus, either a receiver must be capable of making use of any signal – a big ask, or a suite of receivers will be required in order to enable the continuous determination of position from an ever changing array of signals with concomitant costs. The automotive industry in particular has been developing the Simultaneous Location And Mapping (SLAM) technique of comparing the vehicle’s ‘sense’ of location with a map of its operating area in order to derive where it is on that map. Their objective being to employ both SOOPs and SLAM to locate a vehicle.

We would do well to not ignore legacy technologies, which still have much to contribute, especially with a little 21st Century make-over. There are ongoing studies into the possibilities for extracting more information from radar, but this is very much in its early stages and not without weaknesses. But every ship (at least) already carries one, or more, radar systems so, if there is added value to be obtained from this tried and tested method, its adoption by just one navigation community should not involve great expense or complex regulation.

There is at least one older, well proven, terrestrial-based radio system capable of providing position and, crucially, time of sufficient accuracy for not only platform navigation but also the operation of regional, national and international networks for which uninterrupted access to continuous and precise time is a fundamental requirement. Unfortunately, much of the infrastructure for one such system in Europe has been dismantled, but it continues to be used in other regions and, indeed, some nations intend to build new systems.

Challenges

Quite apart from any technical or physical challenge, it is my perception that, whilst the User community has generally begun to recognise the need for resilient navigation, one of the biggest challenges is still that, with some exceptions, owners, operators, Authorities and regulators are reluctant to recognise that multiple GNSS constellations alone do not provide resilient navigation and that it is imperative that alternative, non space-based, positioning and timing systems together with the sensors to utilise them, are developed, adopted and utilised. Beyond that are the more prosaic issues: penalties (financial, both in terms of outlay and who pays; technical, the complexity of installation and operation and regulatory); coverage (local, regional or global); whether to pursue one solution to fit all (easier to regulate and cheaper to install), or a plethora of solutions in different locations, each only appropriate to part of the User community (far more complex, far more difficult to regulate, more expensive for the owner/operator and therefore unlikely to be popular); the preparation of standards for operational performance and means of testing so that manufacturers know what they are attempting to produce; the development of navigation suites which will automatically and continuously compare and contrast the outputs of different positioning systems in order to detect divergence, perhaps utilising machine learning, or maybe under the watchful eye of a remote operator – such systems will be sine qua non in autonomous vehicles and they will ease the mental load on operators in manned platforms.

Conclusion

Prof. Brad Parkinson advocates that GNSS be Protected, Toughened and Augmented. Only augmentation, by whatever system, or system of systems, industry can deliver, will truly ensure that the navigation of manned or autonomous vehicles, in all environments, is sufficiently resilient to ensure uninterrupted, safe, secure, precise and efficient operations.

We actually feel the GNSS vulnerability in South Korea and we know it is real

Jiwon Seo

Assistant Professor, Yonsei University, South Korea Member of the eLoran Advisory Committee, Ministry of Oceans and Fisheries (MOF), South Korea

What is your opinion about GNSS vulnerability especially in the context of South Korea?

It is widely known that GNSS is vulnerable to radio frequency interference, but the large-scale intentional GPS jamming that South Korea has experienced for the past years is not common. The most recent jamming from the North lasted six days and impacted several hundred kilometer areas. During the period, 1,794 cell towers, 1,007 airplanes, and 715 ships experienced GPS disruptions. We actually feel the GNSS vulnerability in South Korea and we know it is real.

What is your take on GNSS back up?

Because a large-scale GNSS jamming can occur anytime in Korea and its impact is potentially hazardous, it is wise to have a back-up strategy. After realizing the vulnerability of GNSS, the Ministry of Oceans and Fisheries (MOS) of South Korea searched for a proven GNSS back-up technology that is deployable in a short time frame. Among several candidates, enhanced long-range navigation (eLoran) became the winner, and MOF initiated the Korean eLoran program.

Please explain the rationale and the objectives of the Korean eLoran Testbed Project?

The Korean eLoran testbed project that is led by the Korea Institute of Ships and Ocean Engineering (KRISO) began in 2016 and intends to demonstrate the maritime navigation capability of eLoran in the northwest area of South Korea by the end of 2020. The original Korean eLoran program that I first announced at the European Navigation Conference 2013 planned to deploy a nationwide eLoran system with three eLoran transmitters in addition to the existing two Loran-C transmitters, but the plan was changed later to a two-phase plan toward a nationwide coverage. The Korean eLoran testbed project is the first phase, which deploys one eLoran transmitter for performance verification.

What are the key features and the status of the Korean eLoran Testbed Project?

The Korean eLoran testbed constitutes one eLoran transmitter and two differential correction stations (DLoran stations) in addition to the existing two Loran-C transmitters. The project requirement is to demonstrate a 20-m maritime navigation accuracy within a 30-km range from DLoran stations. The contract of procuring an eLoran transmitter was signed last year, and an NL-40 transmitter from UrsaNav and Nautel is expected to be installed in September 2019. The KRISO Consortium also independently develops an eLoran transmitter, which is a part of the project requirement. The performance of a prototype transmitter was demonstrated in December 2018.

What are the challenges you face while implementing the project?

The key challenge is not a technology issue. Securing permanent land with a 150-m radius to install a 137-m antenna of the original design is the most difficult task. Most part of South Korea has mountainous terrain, and large and flat land is very limited and already developed. For the performance verification purpose, a smaller-size antenna will be temporarily installed on a 170-m by 60-m area on the Ara West Sea Lock in Incheon. Because of the reduced antenna size, the effective radiated power will be also reduced.

Science, technology and practice to resilient navigation

IAIN World Congress, 28 November – 1 December 2018, Chiba – A report

The 16th World Congress of the International Association of Institutes of Navigation (IAIN) was held at Chiba Japan during November 28 – December 1, 2018. The theme was “Science, Technology and Practice to Resilient Navigation”. The World Congress is held in different regions every three years to discuss technical navigation issues since 1976.

In his keynote address on Towards Resilient PNT and Intelligent Navigation Dr Hiroyuki Yamato, National Institute of Maritime, Port and Aviation Technology, Japan, highlighted two big challenges in Marine and air transport industries, which bear a heavy responsibility of international trade.

The first challenge is automation or autonomization of navigation which realizes safe and labor-saving transportation and better working environment for watch officers and pilots. The second challenge is the pursuit of the economically effective and energy saving navigation to realize environmentally friendly transportation. Shipping companies and air lines are also making efforts to strengthen their competitiveness in this regard. These challenges require digitalized optimal navigation taking into account of the effect of navigation environment based on real time performance measurement of individual ships and planes. Resilient and accurate Position, Navigation and Timings (PNTs)and intelligent navigation technologies are expected to play a big role in the measures to the two challenges.

Dr Izumi Mikami, Satellite Positioning Research and Application Center made a presentation on“Higher Accuracy Positioning Enabled by GNSS and its Guide toward “New World”. He said that the QZSS’s service will realize centimeter level accuracy, while the others target about 20 centimeters through 1 meter range accuracy. These services are readily applicable to the autonomous vehicles driving as the most intuitive and straightforward example. These must, however, incubate countless and inconceivable applications in our daily life, should the services be suitably combined with other new technologies such as AI, 5G, IoT, the robotics, the cloud computing, the big data, and so on. The navigation method itself of any mobile things including space vehicles should also change drastically depending on the GNSS service progress. The concept of “New World” of navigation guided by the GNSS precise positioning services is worth foreseeing.

Mr James Joeseph Miller, NASA Headquarters spoke on International Cooperation in the GNSS Space Service Volume (SSV). He elaborated on a number of on-going efforts to engage GNSS providers and space agencies to pursue compatibility and interoperability among these systems to support space operations.

Dr John Raquet, The Air Force Institute of Technology made a presentation on UAVs vs Natural Autonomous Vehicles (NAVs) — Are We Closing the Gap? In view of many significant advancements in UAV technology over the past 10-15 years, in this presentation, Dr Raquet evaluated on how well we are really doing in this area by comparing performance of UAVs with those of Natural Autonomous Vehicles (NAVs), defined as entities that fly but are not designed, built, or controlled by a humans (birds, for example). Performance was evaluated according to eight different metrics, and the “best in class” UAVs and NAVs for each metric are directly compared. The picture that emerged provided insight into where to put our UAV development efforts as we move toward the future.

Dr Dorota A Grejner-Brzezinska, The Ohio State University in her presentation on PNT in Smart Cities – Are We Ready for Autonomous Driving? introduced the concept of smart and connected communities and smart cities, and discussed the trends that guide the advances in the implementation of these concepts worldwide. She also discussed the various aspects of autonomous driving in a smart city with examples of research performed at The Ohio State University.

Mr Dana A Goward, President, Resilient Navigation and Timing Foundation made a presentation on “Resilient PNT –Protect, Toughen, and Augment GNSS”. He said that a holistic approach focusing on user needs and an architecture that is able to reliably fill them is required to achieve resilient navigation. In this light, relying entirely upon weak GNSS signals is insufficient. At the moment the space portion of that architecture is sufficient, though it is being increased regularly. We must do everything we can to protect navigation signals from space, ensure our ability to use them is maximized with toughened receivers, and augment space signals with other signals and autonomous systems. The presentation discusses ways in which efforts to protect, toughen, and augment GNSS are being pursued in various countries and other initiatives that should be undertaken.

In the award ceremony, several awards were presented. The John Harrison Award for outstanding contribution to navigation was presented to Dr Dorota A Grejner-Brzezinska, Ohio State University, and the Necho Award for long term contribution to the field of navigation to given to Prof Bernhard Hofmann-Wellenhof of the Austrian Institute of Navigation. The Honorary Membership was awarded to Capt Rein van Gooswilligen. Taro Suzuki, Assistant Professor, Waseda University received IAIN’s Sedak Award for presentation of his paper “Evaluation of Precise Point Positioning of Small UAVs using L6E Signal via QZSS.”

There was an interesting and lively discussion in Plenary Panel on Resilient Navigation. The session was chaired by Mr Dana A Goward, President, Resilient Navigation and Timing Foundation. The panelists were Mark Dumville, Nottingham Scientific Ltd (UK); Steve Hickling, Spirent; Michael Jones, Roke Manor; Prof Jiwon Seo, Yonsei University; and Francis Zachariae, International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) General Secretary.

Over 250 delegates attended the congress from 27 countries. The congress had over 100 presentations. The IAIN World Congress 2021 is scheduled to be held at Edinburgh, UK during 15 – 18, November 2021.

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