What is SBAS?
The Satellite Based Augmentation System (SBAS) consists of a small set of geosynchronous satellites that broadcast positioning corrections calculated using a network of geographically distributed reference stations. These corrections improve the accuracy and reliability of the Global Navigation Satellite Systems (GNSS) constellations, its main four instantiations being: GPS (United States), Galileo (European Union), GLONASS (Russia) or Beidou (China). GNSS use several satellites to triangulate the position and accumulate errors due to perturbations of signals.
The position accuracy of GNSS standalone, typically in the range of 5-10 meter horizontally and 8-20 meter vertically, can be improved down to 1 and 2 meters respectively with SBAS. Besides, GNSS do not provide information on how reliable the position is, whilst SBAS does bring this safety-critical information.
For many applications, the performance of stand-alone GNSS is insufficient from accuracy or reliability perspectives. To solve this, a GNSS-augmentation service must be provided. From a general point of view, there are two different approaches to implement an augmented positioning and navigation service for a specific application at a certain location:
- Deploy a localised system: GNSS corrections are computed locally or retrieved from the network (very sparse in Africa). Systems that compute corrections locally are Differential GNSS (DGNSS) and Real Time Kinematics (RTK) whereas Precise Point Positioning (PPP) retrieves it from the network.
- DGNSS: offers meter level precision. It requires a dedicated base station with a resulting coverage area limited to 100km, loosing 1m accuracy each 150km up to 500km.
- RTK: offers precision to centimeter level, but a dedicated base station needs to be installed and the coverage area is limited to 50-150km.
- PPP: precision can range from various meters (1-5m) to under a meter depending on the network density, requiring connection and subscription with a commercial provider.
- Use SBAS: GNSS corrections are computed in strategically positioned locations throughout the continent, and broadcasted over satellite. The precision is as good as 1 meter and any application at any location in the service area can be served, only requiring a GNSS/SBAS receiver that can move with the final user. The coverage area can extend over a continent, including the ocean.
After the United States and Europe pioneered and operationalised their own SBAS systems some years ago (called WAAS and EGNOS respectively) and other regions are progressing in their initiatives, it is Africa’s turn as well to deploy its own system and achieve an autonomous provision of SBAS services.
Source: International Civil Aviation Organization (ICAO), European Space Agency (ESA)
SBAS as a key contributor to African strategic economic sectors
Africa is a very singular continent. It is the second continent in size and population and, along with Asia, these two continents are forecast to be the highest areas of world population growth in the coming decades. Additionally, Africa has vast remote areas which are often difficult to access and that would be costly, unsustainable or even impossible to equip with ground infrastructure.
Consequently, SBAS unfolds as the most suitable all-in-one solution to satisfy the majority of user needs and requirements. More importantly, SBAS is indispensable in applications where people’s lives are at stake or where a certain degree of liability or guarantee is required. That is why SBAS originally emerged as a solution for aviation where a safety critical positioning and navigation service was required. The so-called SBAS Safety of Life (SoL) service, already improving flight safety and efficiency in Europe, is anticipated to do so to a larger extent in Africa, solving the lack of local ground-based navigation aids and landing systems at airports. This SBAS service designed for a safety-critical application can be extended to other markets where the reliability of the GNSS signal is indispensable, such as maritime, drones, rail and automotive applications.
Nevertheless, SBAS can also include an open service beyond aviation and other mass-market sectors, benefiting to the economy and bringing various societal benefits. Indeed, it will stimulate innovation, attract inward investment, create high-value jobs, reduce imports and open up new export markets, save lives, increase productivity, improve the environment, reduce inequality, encourage social cohesion in rural communities and overall contribute to enhance the standard of living for the African society.
The potential benefit generated to strategic economic sectors in the African continent such as aviation, maritime, agriculture, road, rail, geo-information, consumer location based services, as well as two emerging transversal markets which are drones and 5G & Internet of Things (IOT), have been the focus of several market assessments conducted recently, that revealed some highlights of the use of SBAS for all the aforementioned sectors in Africa:
AVIATION – SBAS is a key enabler of the operationalisation of the Single African Air Transport Market (SAATM) flagship programme of the African Union and its Agenda 2063. In Africa, 65% of the aerodromes are not equipped with an adequate navigation infrastructure. In addition, about 21% of airports and aerodromes are not equipped with precision navigation aids, resulting in only about 14% which are equipped with ILS, some of them only in 1 runway end. All of them will benefit from SBAS as a primary navigation aid or as a backup, without the need of investing in airport infrastructure CAPEX. This will remarkably contribute to boost domestic and intra-regional air connectivity, as well as reduce the African accident rate, currently the highest in the world with 7.5 accidents/1M departures, largely above the world average of 3.0 in 2019 (source: ICAO). There were around 3.8 million movements in 2019, and expected to grow significantly after the covid-19 recovery period, thus being a large market to benefit from SBAS in the en-route, approach and final approach phases. The baseline organic growth would be boosted thanks to SBAS allowing access to more airports and helping lower the ANSPs and airline costs.
MARITIME – SBAS can support the efficiency, safety and optimisation of oceanic and coastal navigation, inland water navigation, port operations, search and rescue and container inventory management, identified as the applications that contribute most to the reduction of ship navigation casualties, pollution and optimization of security. Africa holds more than 40,000km of coastline and a large market in terms of vessels and operations, being the cargo market the most relevant segment. The current network of ground infrastructure along the coastline and rivers is scarce and SBAS can fil the gap in service provision to maritime users and authorities. Together with the deployment of the required infrastructure, precise navigation services with SBAS in rivers like Congo or Niger could be key to its development.
ROAD – GNSS is widely used in the automotive industry for navigation purposes but SBAS can enhance the efficiency and safety of road transportation and fleet management. Additionally, the emergence of automated and connected vehicles is driving the industry towards more stringent accuracy requirements where SBAS can have an important role. In Africa, potentially 68 million cars could benefit from SBAS as a source of positioning and navigation, expected to grow significantly as population and earnings per capita grow as well during the next couple of decades.
RAIL – The use of an SBAS receiver in combination with other sensors could result in the provision of an accurate and reliable position to be used by railway signalling systems in safety-critical applications. This could unleash an overall improvement in the railway system in Africa, where many regions, especially land-locked countries, could significantly benefit from a more efficient railway system. Africa holds already more than 82,000 km.
AGRICULTURE – The mechanisation of agriculture through machinery guidance, biomass monitoring, livestock tracking, harvest and yield monitoring, can greatly increase the capacity of small and large farmers and although still limited in Africa, is deemed to progressively be adopted in Africa. GNSS is becoming an integral part of smart farm management solutions and SBAS can be a cost-effective enabler of precision agriculture applications such as farm machinery guidance or variable rate technologies. The effect of increased agricultural productivity can be crucial in Africa, where the sector represents 15% of the continent’s GDP. In terms of potential users that could benefit from SBAS, there could be currently around 1.5 million tractors (Source: ALG analysis), a number that has been growing at a significant growth rate of 3.2% and which still has an untapped potential as mechanisation is envisaged a priority in the next years, and all together key to food security.
GEO-INFORMATION – Rural Africa stands currently with a mere 10% of surveyed land. SBAS can be used to provide land management services and ensure an effective solution where high-accuracy low-cost service is required (e.g. mapping). Besides, it can improve the cadastral management providing an improved (and African-wide) accuracy especially for rural parcels. Other key applications for the use of SBAS are construction and mining surveying, in view of the great potential of both segments in Africa for the next decades.
LOCATION BASED SERVICES (LBS) – SBAS is capable of improving the positioning at every smartphone, tablet, wearable or asset tracking device, which constitutes a mass market that holds an untapped potential in Africa. With an estimated 335 million smartphones in the whole continent and 270 million mobile internet users in Subsaharan Africa in 2019 (source: GSMA), the market could double in the next decade going from penetration rates around 25% to 40-50%. Enhanced LBS based on GNSS and SBAS could be: improved route planning and turn-by-turn instructions, smart parking, real-time public transport information, workforce management or tracking of valuable goods.
TIMING AND SYNCHRONISATION – SBAS goes hand in hand with GNSS for the provision of cost-effective and accurate timing and synchronisation services for telecom networks, financial applications such as stock exchanges, and energy production plants, as an alternative to more expensive atomic clocks, used for the synchronisation between computer systems.
DRONES – SBAS will provide higher accuracy and integrity to ensure routing and vertical landing efficiency and safety. The use of drones is envisaged to dramatically increase and can stimulate various markets, the main applications being: the transport of goods and people, mapping, infrastructure surveying and agricultural operations. Africa is becoming a reference in the drone sector, with transport corridors for medical and humanitarian purposes being served by drones, important considering the lacking ground infrastructure in some regions. In the continent, around 27,000 drones are expected in 2025, which will need regulations and services in place, as well as the required capacities for its operation.
Drones use cases are vast, with substantial economic opportunity in the areas of commercial delivery, agriculture, and health supply chain. Drones will support medial organisations with logistics and access to the facilities they serve across Africa. Besides, drones are capable of helping remote, smallholder farmers solve problems and enhance their productivity at reduced costs. In the mapping and survey domain, drones will help develop cadastres, inspect critical infrastructures or monitor large areas having suffered natural phenomena such as floods.
5G / INTERNET OF THINGS (IoT) – SBAS can be crucial in the view of a hyper- and inter-connected future. IoT will be present almost everywhere, being the wearables, asset trackers and telematics the device categories with the highest potential as will require an enhanced positioning. In fact, accurate and reliable positioning data will represent a large share of the data to be transmitted and achieve the intended outcome of a large amount of applications based on the location of objects.
The African SBAS is to become soon a reality
Africa is not far from achieving its own SBAS system. ASECNA is committed to the autonomous provision of SBAS services in the airspace of the Africa & Indian Ocean (AFI) Region, as per the mandate given by its Member States. This initiative is already recognised by the International Civil Aviation Organisation (ICAO) under the Annex 10 to the Chicago Convention.
The SBAS full infrastructure is under development and deployment in view of the provision of operational services in the next years. A recent milestone completed by ASECNA in September 2020 was the successful broadcast of the first ever SBAS pre-operational signal in this part of the globe. In fact, this milestone has marked the completion of the Phase B of ASECNA’s SBAS programme, which started in 2019. The programme will continue with phases C and D towards achieving the first operational service in 2024.
This promising scenario, where the technical part keeps advancing at a good pace, requires now of an effort to support the decision-making process of stakeholders towards the adoption of SBAS. On the one hand, there is a need to define the governance and institutional schemes of the African SBAS provider. On the other hand, users need to be timely informed about the benefits that SBAS can bring to their businesses. It is pivotal for them to count on a reference and reliable continental Cost-Benefit Analysis (CBA) as well as with tailored business cases applied to their specific vision, needs and operations.
Disclaimer: The data contained in this article may contain estimations and predictions based on current data and historical trends. Any such modelisation of data or predictions are subject to inherent risks and uncertainties.
About the authors
Pol Olivella holds a MSc in Aeronautical Engineering and is a Consultant at ALG. email@example.com
Vladimir Coca holds a MSc in Telecommunications and Aeronautical Engineering and is Senior Manager at ALG. firstname.lastname@example.org
Joan Miquel Vilardell holds a PhD and MSc in Civil Engineering and holds a MBA. He is partner at ALG. email@example.com
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