Lasisi S Lawal | Usmanu Dan Fodiyo University, Sokoto-Nigeria (original) (raw)

Papers by Lasisi S Lawal

Proceedings of the Satellite Division's International Technical Meeting, Oct 4, 2023

Four remarkable events are currently concurring to make possible the establishment of a very firs... more Four remarkable events are currently concurring to make possible the establishment of a very first demonstration of a preliminary DFMC SBAS service in Africa: • Galileo and GPS constellations near completion and/or replenishment ensure the provision of a significant number of operational dual frequencies (L1 & L5) navigation satellites; • The collaborative work of the Eurocae-RTCA WG-62 is well underway and DFMC MOPS are close to their finalization, while DFMC SARPs are endorsed and will be applicable by November 2023; • TAS (Thales Alenia Space) has developed an efficient DFMC navigation kernel compliant to the latest versions of those DFMC SBAS related standards; • And last but not the least, ASECNA (Agency for Air Navigation Safety in Africa and Madagascar) has officially launched its Augmented Navigation for Africa (ANGA) initiative, recognised by the International Civil Aviation Organisation, that intends to provide a full Legacy SBAS SoL service in the coming years but that is already broadcasting a demonstration service over African sub-saharian regions. More specifically, the Galileo constellation comprises 24 operational E1-E5a capable satellites since the last satellites launched in December 2021 are operational. The modernization of GPS space and ground segment is also in progress, and with the newest block III satellite operational since February 2023, the GPS constellation now comprises 18 operational L1-L5 capable satellites. GPS and Galileo have not reached the full operational capability for L1-L5/E1-E5a services, still they now offer a wide range of DFMC observability and measurements anywhere on the ground. The joint work of EUROCAE and RTCA is expected to give birth to a MOPS DFMC L5 Revision A (ED259A) in mid-2023. However, many successive work/draft versions have been produced up to now and we have based the results of this study on the latest available versions. Based on its long experience on various SBAS such as EGNOS or ANGA, TAS has developed a DFMC SBAS navigation kernel compliant with the work of the WG-62. As its Legacy SBAS L1 counterpart, this DFMC navigation kernel can be used to feed various SBAS performance studies with relevant and valuable augmentation messages. Moreover, it can also run in real time with actual GNSS stations measurements to provide an initial non safety-of-life SBAS service, very similarly to an operational SBAS system. The first part of the paper will deal with simulation studies in Africa. Under a CNES (Centre National d’Etudes Spatiales) contract, TAS has evaluated the performances of its DFMC navigation kernel using real GNSS data over a few representative African scenarios. The scenarios cover nominal and also degraded conditions (such as the loss of monitoring stations, or a depleted constellation). Two of those DFMC SBAS scenarios will be presented in the paper. They both augment GPS and Galileo constellations, they use the same network of 15 reference stations, but they differ on the time periods (December 2021 for the first scenario, and March 2022 for the second one) to evaluate the impact of the ionosphere activity on the DFMC SBAS performances. The selected network of reference stations includes stations from various agencies participating in the International GNSS Service (IGS) and stations from the SAGAIE network (Stations ASECNA pour l’Etude de l’Ionosphère Equatoriale). The stations are mainly located in the African equatorial region, and their observables have been collected from IGS or CNES servers. The preliminary analyses show very good navigation performances. The pseudorange integrity is met with high margins. The horizontal position error (95%) is below 0.9m and the vertical position error (95%) is 1.6m, with maximum safety index lower than 0.47. The 99% availability area for APVI and LPV200 services largely covers Africa, from 40°W to 80°E, and from 60°S to 60°N. Furthermore, CAT-I availability, with a 10m vertical alert limit, is available more than 90% of the time on the entire African continent. In the last part of the paper, we will describe the real time DFMC SBAS testbed that has been set up in view of the demonstration that started this Spring 2023. This testbed will use the ANGA signal broadcasted by ASECNA’s demonstration infrastructure to produce both valuable demonstration L1 and L5 augmentation messages. The Signal in Space (SiS)will be broadcasted by Nigcomsat 1-R GEO satellite. To our knowledge, this will be the first DFMC SBAS demonstration SIS to be broadcasted in Africa through NIGCOMSAT-1R SBAS GEO, and one of the first in the world. In conclusion, the paper will present the performance analysis of the ANGA DFMC demonstration signal regarding positioning accuracy, availability, continuity and integrity margins over the service area. The results will illustrate the level of navigation performances expected for a corresponding DFMC operational service over a wide service coverage area characterized by complex…

Institute of Navigation, 2023

Four remarkable events are currently concurring to make possible the establishment of a very firs... more Four remarkable events are currently concurring to make possible the establishment of a very first demonstration of a preliminary DFMC SBAS service in Africa:
• Galileo and GPS constellations near completion and/or replenishment ensure the provision of a significant number of operational dual frequencies (L1 & L5) navigation satellites;
• The collaborative work of the Eurocae-RTCA WG-62 is well underway and DFMC MOPS are close to their finalization, while DFMC SARPs are endorsed and will be applicable by November 2023;
• TAS (Thales Alenia Space) has developed an efficient DFMC navigation kernel compliant to the latest versions of those DFMC SBAS related standards;
• And last but not the least, ASECNA (Agency for Air Navigation Safety in Africa and Madagascar) has officially launched its Augmented Navigation for Africa (ANGA) initiative, recognised by the International Civil Aviation Organisation, that intends to provide a full Legacy SBAS SoL service in the coming years but that is already broadcasting a demonstration service over African sub-saharian regions.
More specifically, the Galileo constellation comprises 24 operational E1-E5a capable satellites since the last satellites launched in December 2021 are operational. The modernization of GPS space and ground segment is also in progress, and with the newest block III satellite operational since February 2023, the GPS constellation now comprises 18 operational L1-L5 capable satellites. GPS and Galileo have not reached the full operational capability for L1-L5/E1-E5a services, still they now offer a wide range of DFMC observability and measurements anywhere on the ground.
The joint work of EUROCAE and RTCA is expected to give birth to a MOPS DFMC L5 Revision A (ED259A) in mid-2023. However, many successive work/draft versions have been produced up to now and we have based the results of this study on the latest available versions.
Based on its long experience on various SBAS such as EGNOS or ANGA, TAS has developed a DFMC SBAS navigation kernel compliant with the work of the WG-62. As its Legacy SBAS L1 counterpart, this DFMC navigation kernel can be used to feed various SBAS performance studies with relevant and valuable augmentation messages. Moreover, it can also run in real time with actual GNSS stations measurements to provide an initial non safety-of-life SBAS service, very similarly to an operational SBAS system.
The first part of the paper will deal with simulation studies in Africa. Under a CNES (Centre National d’Etudes Spatiales) contract, TAS has evaluated the performances of its DFMC navigation kernel using real GNSS data over a few representative African scenarios. The scenarios cover nominal and also degraded conditions (such as the loss of monitoring stations, or a depleted constellation). Two of those DFMC SBAS scenarios will be presented in the paper. They both augment GPS and Galileo constellations, they use the same network of 15 reference stations, but they differ on the time periods (December 2021 for the first scenario, and March 2022 for the second one) to evaluate the impact of the ionosphere activity on the DFMC SBAS performances. The selected network of reference stations includes stations from various agencies participating in the International GNSS Service (IGS) and stations from the SAGAIE network (Stations ASECNA pour l’Etude de l’Ionosphère Equatoriale). The stations are mainly located in the African equatorial region, and their observables have been collected from IGS or CNES servers. The preliminary analyses show very good navigation performances. The pseudorange integrity is met with high margins. The horizontal position error (95%) is below 0.9m and the vertical position error (95%) is 1.6m, with maximum safety index lower than 0.47. The 99% availability area for APVI and LPV200 services largely covers Africa, from 40°W to 80°E, and from 60°S to 60°N. Furthermore, CAT-I availability, with a 10m vertical alert limit, is available more than 90% of the time on the entire African continent. In the last part of the paper, we will describe the real time DFMC SBAS testbed that has been set up in view of the demonstration that started this Spring 2023. This testbed will use the ANGA signal broadcasted by ASECNA’s demonstration infrastructure to produce both valuable demonstration L1 and L5 augmentation messages. The Signal in Space (SiS)will be broadcasted by Nigcomsat 1-R GEO satellite. To our knowledge, this will be the first DFMC SBAS demonstration SIS to be broadcasted in Africa through NIGCOMSAT-1R SBAS GEO, and one of the first in the world. In conclusion, the paper will present the performance analysis of the ANGA DFMC demonstration signal regarding positioning accuracy, availability, continuity and integrity margins over the service area. The results will illustrate the level of navigation performances expected for a corresponding DFMC operational service over a wide service coverage area characterized by complex and challenging ionosphere conditions.

Human resource management research, 2013

United Kingdom’s Brexit from the European Union implies restricted access to the European Global ... more United Kingdom’s Brexit from the European Union implies restricted access to the European Global Navigation Satellite System (GNSS) System - Galileo; with no access to the secured and encrypted signal used for defense and government purposes, which is restricted to European Union (EU) members. To mitigate this issue, the United Kingdom can, as a matter of urgency, launch a payload on a national military Communications Satellite to provide Navigation Overlay Services for the United Kingdom territory, surrounding waters and neighboring ally countries to meet the requirements of: Defense systems, Aviation, Maritime requirements and the effectiveness of Location-based Services for Emergencies and Crisis management etc. The United Kingdom can deploy a low-cost Satellite-Based Augmentation System(SBAS) as a navigation overlay service (NOS) on a hosted national geostationary satellite utilizing GNSS, especially GPS and Galileo as an alternative to the Galileo’s PRS. This paper describes the design of a navigation overlay service system as a hosted payload on a national satellite and the required supporting ground infrastructure, highlighting various applications, services and solutions.

International Journal of African and Asian Studies, Dec 20, 2018

Satellite-Based Augmentation System (SBAS) arose from the need to provide continuity, availabilit... more Satellite-Based Augmentation System (SBAS) arose from the need to provide continuity, availability, integrity and accuracy of global positioning signals to eliminate errors and compensate for discrepancies associated with GPS signals and other navigation systems. The NIGCOMSAT-1R Project is the insurance replacement of the NIGCOMSAT-1 satellite, which was de-orbited on 10th of November 2008 due to an irreparable single point of failure on-board the satellite. The NigComSat-1R Navigation (L-band) payload is a Space Based Augmentation System meant to provide a Navigation Overlay Service (NOS) similar to the European Geostationary Navigation Overlay Service (EGNOS). The paper seeks to examine some of humankind's triumphs in navigation, from mechanical clocks to the critical role that Space-Borne Oscillators play in improving Performance of Satellite-Based Augmentation Systems and the strategic role of NIGCOMSAT-1R, the nascent African contribution to the Global Navigation Satellite System.

Springer eBooks, 2012

Africa remains the least wired continent in the world in terms of robust telecommunications infra... more Africa remains the least wired continent in the world in terms of robust telecommunications infrastructure and systems to cater for its more than one billion people. Based on the ICT Development Index (IDI) of all countries in Africa, as reported in the ITU 2010 report (Measuring the information Society), Africa is still at an early state of ICT development as verified by the relatively low IDI values of all countries in the African region. In developing nations, where Africa squarely belongs; mobile broadband subscriptions and penetration between 2000-2009 was increasingly more popular than fixed broadband subscriptions. To achieve the goal of universal access, this paper examines and identifies the growing need for wireless communications (Communication Satellites, CDMA, GSM, WIFI, LTE, WIMAX, Radio Links etc) in Africa which is the cornerstone for rapid implementation of ICT infrastructure to complement the sparsely distributed terrestrial networks in the hinterlands. Also discussed and examined are the needs for: regional and cross border connectivity, existing regional infrastructure, the competitive advantage of communication satellites and terrestrial wireless network systems, challenges and limitations including ways of overcoming them.

2022 International Conference on Electrical, Computer, Communications and Mechatronics Engineering (ICECCME), Nov 16, 2022

Social Science Research Network, 2022

8th International Conference on Mechatronics Engineering (ICOM 2022)

IET, 2022

Telemedicine provides a means to transcend time, geographic and cultural barriers in the delivery... more Telemedicine provides a means to transcend time, geographic and cultural barriers in the delivery of healthcare services. It is also a great tool for the realization of the United Nations Sustainable Development Goals (SDGs No. 3) in ensuring healthy lives and promotion of well-being for all, at all ages. However, despite its obvious benefits, most developing countries especially in Sub-Saharan Africa are still lagging behind in the adoption of telemedicine for their citizenry. This article reviews the past and present practice of telemedicine, the influence of the COVID-19 pandemic on the growth of telemedicine, and its potential to solve healthcare challenges in developing nations. This study establishes that despite the plethora of solutions offered by telemedicine, its slow adoption in most developing countries in Sub-Saharan Africa could be attributed to: the high initial cost of its establishment, unavailability of reliable internet connection, irregular power supply and resistance to new technology and approaches.

Proceedings of the Satellite Division's International Technical Meeting, Oct 4, 2023

Institute of Navigation, 2023

Four remarkable events are currently concurring to make possible the establishment of a very firs... more Four remarkable events are currently concurring to make possible the establishment of a very first demonstration of a preliminary DFMC SBAS service in Africa:
• Galileo and GPS constellations near completion and/or replenishment ensure the provision of a significant number of operational dual frequencies (L1 & L5) navigation satellites;
• The collaborative work of the Eurocae-RTCA WG-62 is well underway and DFMC MOPS are close to their finalization, while DFMC SARPs are endorsed and will be applicable by November 2023;
• TAS (Thales Alenia Space) has developed an efficient DFMC navigation kernel compliant to the latest versions of those DFMC SBAS related standards;
• And last but not the least, ASECNA (Agency for Air Navigation Safety in Africa and Madagascar) has officially launched its Augmented Navigation for Africa (ANGA) initiative, recognised by the International Civil Aviation Organisation, that intends to provide a full Legacy SBAS SoL service in the coming years but that is already broadcasting a demonstration service over African sub-saharian regions.
More specifically, the Galileo constellation comprises 24 operational E1-E5a capable satellites since the last satellites launched in December 2021 are operational. The modernization of GPS space and ground segment is also in progress, and with the newest block III satellite operational since February 2023, the GPS constellation now comprises 18 operational L1-L5 capable satellites. GPS and Galileo have not reached the full operational capability for L1-L5/E1-E5a services, still they now offer a wide range of DFMC observability and measurements anywhere on the ground.
The joint work of EUROCAE and RTCA is expected to give birth to a MOPS DFMC L5 Revision A (ED259A) in mid-2023. However, many successive work/draft versions have been produced up to now and we have based the results of this study on the latest available versions.
Based on its long experience on various SBAS such as EGNOS or ANGA, TAS has developed a DFMC SBAS navigation kernel compliant with the work of the WG-62. As its Legacy SBAS L1 counterpart, this DFMC navigation kernel can be used to feed various SBAS performance studies with relevant and valuable augmentation messages. Moreover, it can also run in real time with actual GNSS stations measurements to provide an initial non safety-of-life SBAS service, very similarly to an operational SBAS system.
The first part of the paper will deal with simulation studies in Africa. Under a CNES (Centre National d’Etudes Spatiales) contract, TAS has evaluated the performances of its DFMC navigation kernel using real GNSS data over a few representative African scenarios. The scenarios cover nominal and also degraded conditions (such as the loss of monitoring stations, or a depleted constellation). Two of those DFMC SBAS scenarios will be presented in the paper. They both augment GPS and Galileo constellations, they use the same network of 15 reference stations, but they differ on the time periods (December 2021 for the first scenario, and March 2022 for the second one) to evaluate the impact of the ionosphere activity on the DFMC SBAS performances. The selected network of reference stations includes stations from various agencies participating in the International GNSS Service (IGS) and stations from the SAGAIE network (Stations ASECNA pour l’Etude de l’Ionosphère Equatoriale). The stations are mainly located in the African equatorial region, and their observables have been collected from IGS or CNES servers. The preliminary analyses show very good navigation performances. The pseudorange integrity is met with high margins. The horizontal position error (95%) is below 0.9m and the vertical position error (95%) is 1.6m, with maximum safety index lower than 0.47. The 99% availability area for APVI and LPV200 services largely covers Africa, from 40°W to 80°E, and from 60°S to 60°N. Furthermore, CAT-I availability, with a 10m vertical alert limit, is available more than 90% of the time on the entire African continent. In the last part of the paper, we will describe the real time DFMC SBAS testbed that has been set up in view of the demonstration that started this Spring 2023. This testbed will use the ANGA signal broadcasted by ASECNA’s demonstration infrastructure to produce both valuable demonstration L1 and L5 augmentation messages. The Signal in Space (SiS)will be broadcasted by Nigcomsat 1-R GEO satellite. To our knowledge, this will be the first DFMC SBAS demonstration SIS to be broadcasted in Africa through NIGCOMSAT-1R SBAS GEO, and one of the first in the world. In conclusion, the paper will present the performance analysis of the ANGA DFMC demonstration signal regarding positioning accuracy, availability, continuity and integrity margins over the service area. The results will illustrate the level of navigation performances expected for a corresponding DFMC operational service over a wide service coverage area characterized by complex and challenging ionosphere conditions.

Human resource management research, 2013

International Journal of African and Asian Studies, Dec 20, 2018

Springer eBooks, 2012

2022 International Conference on Electrical, Computer, Communications and Mechatronics Engineering (ICECCME), Nov 16, 2022

Social Science Research Network, 2022

8th International Conference on Mechatronics Engineering (ICOM 2022)

IET, 2022

B P International, 2021

The oscillators, which are essential for precise timing, are at the heart of a satellite-based na... more The oscillators, which are essential for precise timing, are at the heart of a satellite-based navigation system. The purpose of this research is to investigate the crucial role that space-borne oscillators play in increasing the performance of GNSS and satellite-based augmentation systems (SBAS). The African contribution to the SBAS, the NIGCOMSAT-1R navigation payload, which uses externalised 10 MHz Master Oscillators in a 3 X 4 hybrid array configuration, examines the efficacy of Location Based Services using Navigation for Emergency and Crisis Management, among other applications.

UNESCO 9th African Engineering Week organised by the Federation of African Engineering Organisations , 2023

Maintaining the stability and reliability of power grids is critical, and situational awareness (... more Maintaining the stability and reliability of power grids is critical, and situational awareness (SA) is a key element in achieving such in power systems. Adopting Phasor Measurement Units (PMUs) in providing real-time monitoring and control of power systems is fundamental, sustainable, efficient, and commendable. This paper presents a comprehensive overview of PMU technology, its role in enhancing SA, and its impact on improving power system stability and efficiency. PMUs are sophisticated monitoring devices that offer high-speed and synchronized voltage and current phasors measurements: This enables power systems to be monitored and controlled in real-time. Our discussion covers the fundamental principles of PMU technology, its various applications, its implementation in power systems, and the challenges and limitations of its use. In addition, the paper explores current and future research on PMUs and highlights the benefits of their implementation, including enhanced reliability, improved security, better power quality, and increased efficiency. Through a detailed presentation of the capabilities and advantages of PMUs in power systems, we offer valuable insights for researchers, practitioners, and decision-makers in the power industry.

KENYA SPACE EXPO AND CONFERENCE 2022, 2022

Space technology is a comprehensive engineering discipline that explores, develops and utilizes s... more Space technology is a comprehensive engineering discipline that explores, develops and utilizes space and astronomical bodies as well as design, manufacture, testing, launching, controlling, managing and utilization of space systems especially space based satellites and space transportation systems. Practice of space engineering requires application of many fields of sciences and engineering for realistic results. Spacecraft Technology is an important component of Space Technology which focuses on design, manufacturing and testing. Spacecraft integration is the final phase of spacecraft development after the design processes. It is the overall process of delivery of products for each subsystem that enables the integration and completion of the total assembly. The final assembly must be tested to enable delivery of an acceptable spacecraft product to the launch pad. The phase of integration, assembly and test (AIT), aside design exerts a direct and important influence on the general performance, functions and reliability of spacecraft and its mission.
The paper examines the huge impact of the implementation of Small Satellite Design, Assembly, Integration and Test Center (DAITC) in developing nations as it concerns utilization of satellite and space technologies for the national economy, defense, culture and scientific research, United Nations Sustainable Development Goals (SDG) and most importantly, a technology hub for the transfer of practical satellite and space engineering skills to engineering students, graduates and workforce for the space industry and value chains.