Dr. José-Angel Avila-Rodriguez
Dr. José-Ángel Ávila-Rodríguez joined the European Space Agency (ESA) in 2010 and is currently appointed as GNSS Evolutions Signal and Security Principal Engineer in the GNSS/Galileo Evolution Programme and Strategy Division of ESA. Between 2003 and 2010 he was a senior research associate at the Institute of Geodesy and Navigation at the University of the Federal Armed Forces Munich. Ávila-Rodríguez studied at the Technical Universities of Vienna, Austria, and Madrid, Spain, where he received a Master's degree in electrical engineering. He received a Master's degree in economics from the Spanish UNED University and a Ph.D. in aerospace engineering in signal design for GNSS from the University of the Federal Armed Forces Munich, Germany. During his career, Dr. Ávila-Rodríguez has been a key contributor to the international interoperability and compatibility efforts leading to the Galileo signal plan, supporting the Galileo program in numerous working groups of the European Space Agency, the European Commission, and the Galileo Joint Undertaking. He was recipient of the 2008 Parkinson Award and the 2009 ION Early Achievement Award, both from the U.S. Institute of Navigation. Dr. Rodriguez received on 15 June 2017 the "European Inventor Award" in the category "Research" together with its team for the invention of two new primary signals of Galileo for a better satellite navigation.
Lecture: Evolution of Galileo
Current efforts of the Galileo System towards its so-called Galileo Second Generation – G2G are presented. Various possibilities are shown in blocks and include, amongst others, discussions on new Launch Strategies (Electrical Propulsion – EP), promising new technologies in clocks, amplifiers, signal generators and other fundamental payload and platform components, Improvements of the Galileo Services in general, authentication, inter-satellite links (ISL), new orbits such as the Inclined Geosynchronous Satellite (IGSO) Orbit, etc.
Dr. Jeff Austin
Dr. Jeff Austin is currently Partner and Managing Director of Redline Leadership Associates, an international firm that specializes in leadership and management development, strategy, and team effectiveness. His consulting work includes over twenty years involvement with the space industry (including teaching in the Space Systems Engineering Masters program (SpaceTech) at Delft Technical University for 15 years and now with a new home at Technical University Graz.). Jeff recently spent seven years as Senior Vice President at TSSI, a world leader in durable medical equipment. Jeff headed up the people side of the business for this 2400 person company. Previously, Dr. Austin was Assistant Vice President for Leadership and Organizational Development at USAA, a large financial services corporation with regional offices in the United States and Europe. At USAA, he was responsible for all leadership and management education, project management education and consultation, and organizational development consulting throughout the enterprise. Prior to that, Dr. Austin was Deputy Head of the Behavioral Sciences and Leadership Department at the United States Air Force Academy. His department included undergraduate education in psychology, organizational behavior, human factors engineering, sociology and leadership.
Lecture: Leadership and Team Effectiveness
Central to the success of any engineering endeavor is the art and skill of leaders at all levels of the organization. We'll discuss leadership at the team level, look at the evolving roles from technical engineering expert, to team and project leader, and finally to senior leadership roles. We will explore the shift from process to systems thinking. Additionally, every participant will be given an assessment to begin the conversation about team leadership.
Coaching of the group project
Dr. Daniele Borio
Dr. Daniele Borio received the M.S. degree in Communications Engineering from Politecnico di Torino, Italy, the M.S. degree in Electronics Engineering from ENSERG/INPG de Grenoble, France, in 2004, and the doctoral degree in electrical engineering from Politecnico di Torino in April 2008. From January 2008 to September 2010 he was a senior research associate in the PLAN group of the University of Calgary, Canada. In October 2010, he joined the European Commission Joint Research Centre (JRC). He is a scientific technical officer in the JRC “Food Security” unit where he is supporting the European Common Agricultural Policy (CAP) through the European satellite programs, Galileo and Copernicus.
Lab on GNSS Signal Processing
The goal of this lab is to provide the students with hands-on experience of the various signal processing stages of a GNSS receiver. The experiments conducted during the lab will complement the notions introduced during the lectures and will allow the students to directly experiment with real GNSS data.
The lab is divided in three parts. The first two analyze acquisition and tracking, which are the two main signal processing blocks of a GNSS receiver. The students will be provided with a short dataset containing baseband GPS L1 C/A, Galileo E1 and Beidou B1C signals. Matlab scripts for acquiring and tracking GNSS signals are provided and used to process the dataset adopted for the lab.
The last part focuses on measurement generation for the results computed at the tracking stage. These measurements allow the computation of the final position solution.
The lab is divided into exercises that require the modification of the basic acquisition and tracking scripts and the addition of new functionalities.
Prof. Michel Bousquet
Prof. Michel Bousquet retired from ISAE-SUPAERO (www,isle-supaero.fr), the French Aerospace Engineering Institute of Higher Education, where he has directed masters programmes and a research team in satellite communications and navigation. With research interest covering several facets of satellite systems, Prof Bousquet participated into many national and international R&D projects. He is the author/co-author of many papers and books (e.g. Satellite Communication Systems, Wiley 6th edition). He was involved in the founding of several academic master level and continuing education programmes in aerospace engineering and management, including the “Master of Space Studies” of the International Space University (ISU) and the “International Summer School on GNSS”. Visiting lecturer with several universities such as Univ of Surrey, Univ of Roma, Graz Univ of Technology (SPACETECH master), organiser of a large number of seminars and short-course on satellite systems and technologies, he is recipient of the 2019 AIAA Aerospace Communication award for his “For his outstanding contribution and promotion of education and proliferation of knowledge on aerospace communication and navigation”.
- GNSS Radiofrequency Link
The radiofrequency link from the GNSS satellite is a key component of a satellite navigation systems. The carrier-to noise power spectral density available at the input of the GNSS receiver conditions availability and performance. Navigation data is conveyed thanks to the use of carrier modulation. Multiple access techniques allows to share the same radio ressource between different RF carriers. The lecture introduces the main concepts and parameters conditioning the link performance.
- Satellite Communications Systems / Positioning with Communications Systems.
The lecture gives a broad introduction to satellite communications systems architectures and technologies. This overview supports the description of communication satellite based augmentation systems (SBAS) to improve performances of GNSS; Basics of position determination using various communication systems technologies (WiFi, UWB, etc) conclude the presentation.
Dr. Sophie Damy
Dr. Sophie Damy is currently a Scientific Officer at the Joint Research Centre (JRC) of the European Commission, in Ispra, Italy, in the field of satellite-based navigation. Her recent work focuses on Galileo new feature, OSNMA. She graduated in 2011 from the French National School of Civil Aviation (ENAC) in Toulouse, France where she obtained a MSc in Aeronautical Telecommunications. Sophie joined the Centre for Transport Studies, at Imperial College London, UK in 2012 to conduct her PhD as a Lloyds Register Foundation scholar. After obtaining of her degree in 2017, she became a Research Associate at ICL, before joining the JRC in January 2018.
Lecture: Galileo Open Service Navigation Message Authentication
With its Open Service Navigation Message Authentication (OSNMA) protocol, Galileo is providing a mean to authenticate the data transmitted by its satellites. This lecture will provide a high-level description of OSNMA as well as explanations on the service’s motivations and possible applications. We will then take a closer look at the OSNMA protocol itself, reviewing both the dissemination of the data and their verification. Finally, a short tutorial using a Matlab script will provide you with the possibility to process of some OSNMA test vectors.
Aude de Clercq
Aude de Clercq earned a joint degree in law and translation in France before she moved to the United States to specialize in public management.
She started her career at ESA’s legal department in Paris, then moved to the Netherlands where she managed a start-up company during its incubation period at the incubator of ESA Technology Transfer Programme Office (TTPO), in ESTEC. When the start-up graduated from the incubation programme, she started working for ESA TTP as a Technology Transfer Officer.
At TTP she is now in charge of the management and exploitation of ESA’s portfolio of patents and the Network of Technology brokers deployed by the programme throughout ESA’s Member States.
Lecture and Workshop: Intellectual Property Rights (IPR) and Patents in GNSS
Introduction in Intellectual Property Rights in particular Patents, Copyright, Trademarks protection followed by examples in the field of GNSS.
Jean-Jacques Dordain has been the Director General of the European Space Agency (ESA) from 2003 to 2015. During his mandate he could contribute to the Galileo Programme from the signature of the industrial contracts to the launch of the first 10 satellites in orbit.
Before 2003, he served as Director of launchers at ESA, signing all agreements and contracts necessary to operate Soyuz from French Guiana, which has been instrumental to launch Galileo satellites.
As Director of Strategy and Technical Assessment, he has initiated the cooperation between ESA and the EU, setting the ground for the Galileo and Copernicus Programmes.
He is currently advisor of the External Action Service of the EU, Luxembourg, Switzerland and the UAE for space matters as well as member of Boards of more than ten start ups in Europe.
Lecture: Space and Europe, a matter of innovation, cooperation and education.
Space and Europe (Rome Treaty) were both born in 1957 and, since then, have developed together, making of space a dimension of Europe and of Europe a unique space power in the world.
The current changes which are transforming the world and the role of space in this new world require innovation, cooperation and education for shaping a sustainable future. Both Space and Europe have developed and practised that culture of innovation, cooperation and education and are therefore, more than ever, a garantee of future successes.
Dr. Cillian O'Driscoll
Dr. Cillian O’Driscoll received his M.Eng.Sc. and Ph.D. degrees from the Department of Electrical and Electronic Engineering, University College Cork, Ireland. He was a senior research engineer with the Position, Location and Navigation (PLAN) group at the Department of Geomatics Engineering in the University of Calgary from 2007 to 2010. He subsequently joined the European Commission from 2011 to 2013, first as a researcher at the JRC, and later as a policy officer with the European GNSS Programmes Directorate in Brussels. In 2014 he established his own consulting company and since then has been working with clients including the European Space Agency (ESA), European Commission and a number of private businesses, specializing in GNSS signal processing, anti-spoofing and authentication.
This lecture will cover the basic concepts of authentication as applied in the civil GNSS context, including navigation message authentication, signal-level authentication techniques and implications for authenticated Position, Velocity and Time (PVT). The basic cryptographic elements will be described and case studies will be made of the authentication techniques proposed for Galileo (OS-NMA) and GPS (Chimera).
Dr. Georgios Giannopoulos
Dr Georgios Giannopoulos holds a degree in Mechanical and Aeronautical Engineering, a PhD in Engineering from Vrije Universiteit Brussel and the Royal Military Academy of Belgium and a Management degree from Solvay Brussels School in Economics and Management. He is currently the Head of the Technologies for Space, Security and Connectivity Unit working on security related topics such as critical infrastructure risk and resilience, CBRNE Hybrid Threats, Galileo and 5G applications and he is also the Deputy Director of the Space, Security and Migration Directorate at the Joint Research Centre of the European Commission. He is the author of more than 50 publications and book chapters and he has trained officials in several European countries in order to support their efforts on improving the protection of their technological systems and critical infrastructures as well as countering Hybrid Threats.
Dr. Christopher J. Hegarty
Dr. Christopher J. Hegarty is a Technical Fellow with The MITRE Corporation, where he has worked mainly on aviation applications of GNSS since 1992. He received B.S. and M.S. degrees in electrical engineering from Worcester Polytechnic Institute and a D.Sc. degree in EE from the George Washington University. He is currently the Chair of the Program Management Committee of RTCA, Inc., and co-chairs RTCA Special Committee 159 (GNSS). He served as editor of the U.S. Institute of Navigation (ION)’s quarterly journal, NAVIGATION, from 1997 – 2006 and as ION president in 2008. He is a Fellow of the ION and IEEE, the recipient of the 2005 ION Kepler Award, and co-editor/co-author of the textbook Understanding GPS/GNSS: Principles and Applications, 3rd Ed.
This lecture provides an overview of digital modulation techniques used for satellite navigation systems, including direct sequence spread spectrum, binary offset carrier, and variants. Common design features of modern GNSS signals including pilot components, secondary codes, and multiplexing techniques are described. The lecture also summarizes the specific signal designs used for GPS, GLONASS, Galileo, BeiDou, QZSS, and NAVIC.
This lecture provides an overview of GNSS receiver signal processing, including a description of the basic techniques employed to acquire, track, and demodulate the navigation data from received GNSS signals. Typical hardware components of a modern, digital GNSS receiver are also described.
Francesco Menzione was born in Napoli in 1986. He received the B.E., M.E., and Ph.D. degrees from University of Naples Federico II in Aerospace Engineering and Satellite Navigation. After almost eight years working in the Aerospace sector, he joined European Commission Joint Research Centre as Technical and Scientific Officer. His main areas of research interest are navigation in Space Service Volume, precise orbit determination with high accuracy service (HAS), LEO PNT systems and other GNSS driven space applications (i.e. mega-constellation autonomous operations, EO formation flying, radio-occultation, interference monitoring)
Dr. Jihye Park
Dr. Jihye Park is an associate professor of Geomatics in the School of Civil and Construction Engineering at Oregon State University (OSU), USA. Before joining OSU, she worked as a post-doctoral researcher in Nottingham Geospatial Institute at University of Nottingham, UK. She holds a PhD in Geodetic science and surveying at The Ohio State University. Her research interests include GNSS positioning and navigation, Precise Point Positioning, Network Real-time kinematic, GNSS meteorology, GNSS-Reflectometry, and GNSS remote sensing for monitoring the earth environments, natural hazards, as well as artificial events.
Multi-GNSS Precise Point Positioning
This lecture provides the fundamentals of precise point positioning. By exploring the error budgets of multi constellation GNSS (e.g., satellite and receiver clock error, antenna bias, differential code bias, inter-system bias, atmospheric delays, tidal effects, phase windup, relativistic effects), students will learn how to mitigate each error for achieving millimeter level of positioning accuracy.
GNSS Remote Sensing
This lecture covers different types of GNSS remote sensing methods and their applications including ionospheric monitoring for various geophysical events, GNSS meteorology, and GNSS-reflectometry for water level measurements.
Matteo Paonni is Deputy Head of the Technologies for Space, Security and Connectivity Unit, within the Directorate for Space, Security and Migration at Joint Research Centre of the European Commission in Ispra, Italy. Under his position, Matteo coordinates the scientific and policy support on the EU GNSS Programmes. Matteo is also the chairman of the European Commission’s Galileo 2nd Generation Signals Task Force, under the EU Space Programme Committee. His main technical background is on GNSS signal design and optimization, GNSS security, compatibility and signal processing. From 2007 to 2013 Matteo was a research associate at the University of the Federal Armed Forces in Munich, Germany.
Eduardo Tapias is the CEO and founder of GNSS Academy, he graduated in Aeronautics from Polytechnic University of Madrid in 2002, he has more than 20 years of experience on Satellite Navigation, he spent most of his career working for the main industrial European leader companies GMV, Thales Alenia Space and Airbus DS, as well as director and consultant of start-ups in Toulouse and San Francisco, mostly involved within the algorithms design and performance core of both European Navigation Systems: EGNOS and Galileo always in critical applications such as Autonomous Vehicles and Aviation as integrity lead.
Observing this thriving market and the difficulties for companies to hire well qualified and prepared engineers, he founded the GNSS Academy in Toronto, Canada, in September 2019 in order to cope with this need. GNSS Academy today supports the GNSS Market from its main asset: Engineers, creating the E2C path between Engineers seeking new job opportunities and the key reference companies demanding qualified profiles. He trained more than 200 engineers in 28 different countries all over the World through industrial high-end online and in-person training programmes.
Lecture: Basics of GNSS
The main mission of GNSS is to fix a position in the right reference frame and timing in the right reference time scale. In this lecture, we will review the main principles for a receiver to get the most basic solution SPP using single or multi-constellation signals, we will develop the equations system to solve for, a good understanding of the 2 key observables built by a receiver as satellite distances: the codes and the carrier phase measurements, the different ranging error sources and the different ways to mitigate and correct them using, amongst others, the broadcast navigation message as main information source,. We will end up the talk by deep diving into the architecture of a receiver's Positioning Engine to learn how we get a fix thanks to mathematical estimation filters (e.g: WLSE) and also showing some performance sensitivity analyses on the position error using real receiver data.
Dr. Javier Ventura-Traveset
Dr Ventura-Traveset is working since more than 30 years at the European Space Agency, having been involved in multiple space programs covering the fields of satellite communication; earth observation; science; microgravity; technology transfer; lunar exploration; and notably satellite navigation.
He has been Principal System Engineer, Mission Manager and System Manager in all phases of the currently operational EGNOS Navigation System, precursor of the European Galileo system. Currently, he is the Head of the ESA Navigation Science Office, coordinating all GNSS scientific activities for the European Space Agency and ESA’s Moonlight Program Navigation Manager, managing all ESA lunar navigation-related activities, including the ESA Lunar Pathfinder and the Moonlight Programmes. He is also the Executive Secretary of the ESA GNSS Scientific Advisory Committee since 2012.
Dr Ventura-Traveset has authored or co-authored over 250 technical papers and 4 patents; he is technical co-editor and co-author of the book “EGNOS - A Cornerstone of Galileo” and of several book Chapters in the field of space engineering. Throughout his career he has received several recognitions, such as the Award for the best PhD Thesis; the “ESA inventor Award Medal”; the "ESA Team Award" on 2 occasions; the “Professional Excellence Award” from the Spanish Association of Telecommunications Engineers; and several recognitions from the US Institute of Navigation.
Dr Ventura-Traveset holds a PhD in Electrical Engineering from the Politecnico di Torino in Italy; a Master of Science in Engineering from Princeton University (New Jersey, USA); and a Master’s degree in Telecommunication engineering from the UPC University in Barcelona, Spain. He also performed the “Senior Management Program for Executives” from IESE Business School, and the "Strategic R&D Executive Management Program" from the INSEAD University, in France.
Dr Ventura-Traveset is a Member of the Royal Academy of Engineering of Spain.
Lecture: ESA Lunar Navigation strategy: Moonlight and Lunar Pathfinder:
The interest in the Moon exploration has grown substantially in the last years. The Moon exploration is now emerging as the next global strategic priority in space exploration and a large number of highly ambitious government and commercial missions are today planned. All these missions need communication and navigation functions. Given the large number of lunar missions planned a common approach for the provision of these services seems to be the most efficient, in terms of missions cost and complexity. This is the ESA view. This talk will then focus on lunar navigation services and on the ESA vision/roadmap for the provision of these services during the next 15-20 years, in the context of this new exploration paradigm. This will be illustrated with ESA concrete plans in the context of the Lunar Pathfinder and ESA Moonlight program, where the use of GNSS technologies, first from Earth and then from lunar orbit and surface assets is envisaged.
Paul Verhoef is currently retired and was the ESA Director of Navigation (D/NAV) from 15 February 2016 - 15 February 2022.
Paul Verhoef has a Masters degree in electrical engineering from Eindhoven Technical University. During his studies, he spent a year working for Philips Electrical Industries in New Zealand. In his earlier career, he worked for the United Nations in the South Pacific, based in Suva, Fiji, where, among other things, he supervised the installation of the first satellite Earth station in Papua New Guinea used for international communications links.
In the late 1980s, he worked as ground segment engineer at Eutelsat in Paris on the procurement of the ground segment for the Eutelsat-II satellites. Following that, he set up the Olympus Payload Utilisation Secretariat within ESA’s Telecommunications Department at ESTEC in Noordwijk, from where the coordination of new communications experiments with the Olympus payloads was undertaken.
Since the early 1990s, Paul Verhoef has worked for the European Commission, starting with responsibility for satellite communications policy in the telecommunications policy Directorate, and subsequently with a variety of policy functions in the areas of space, telecommunications, electronic commerce and internet.
He represented the Commission in the G8 Digital Opportunities Task Force (DOT Force), and coordinated the EU position in the first World Summit on the Information Society in 2003. He was seconded for a year and a half as Vice President to ICANN, the non-profit organisation overseeing development and technical coordination of the internet domain names and numbering policies.
From 2005 to 2011, Paul Verhoef was the European Commission's programme manager for the EU Galileo and EGNOS satellite navigation programmes and was responsible for setting up the implementation of the programmes in close cooperation with ESA.
Before taking on his responsibility as ESA Director of Navigation, Paul Verhoef set up a new Research and Innovation team in DG Transport and Mobility (MOVE) of the European Commission and was Head of Unit for ‘Renewable energy sources’ in DG Research and Innovation (RTD)
Dipl. Math. Stefan Wallner
Dipl.-Math. Stefan Wallner is Galileo 2nd Generation Space-to-Ground Interface Engineer in the Navigation Directorate at ESA/ESTEC. He is involved in the Galileo Program since 2003 when he joined the University of the Federal Armed Forces, Munich, and supported the Definition of the Galileo signal structure and their international Radio Frequency Compatibility (RFC) coordination through the Galileo Signal Task Force and the Galileo Compatibility, Signals and Interoperability Working Group. Since 2010 he is involved in the preparation of the 2nd Generation of Galileo covering important evolution directions like Signal and System Robustness, the evolution of the Galileo User Signals including Signal Authentication and Novel Integrity Solutions, for which he was co-chairing the EU/US WG-C Subgroup on ARAIM. Stefan is co-chairing the Working Group on Enhancement of GNSS Performance, New Services and Capabilities in the frame of the United Nations International Committee on GNSS (ICG). Stefan holds a patent application on Spreading Codes for Navigation Systems.
- Satellite-based Augmentation System (SBAS) and Receiver Autonomous Integrity Monitoring (RAIM, ARAIM)
Safety-of-Life (SoL) related applications (e.g. Aviation, Maritime, Rail) have dedicated requirements that demand specific solutions. Space-Based-Augmentation-Systems (SBAS) and Receiver Autonomous Integrity Monitoring (RAIM) have been developed in order to exploit GNSS signals and services for SoL applications without requiring at the location where the operation shall be conducted local ground installations. This lecture introduces relevant SoL performance metrics and requirements for aviation and maritime users, followed by an outline of the SBAS and RAIM principles, their existing implementations and achieved performance levels. In addition also the future evolution of SBAS towards Dual Frequency Multi Constellation (DFMC) SBAS is presented together with its expected benefits for users. Exploiting the existing interoperability of GNSS signals can enable Advanced RAIM (ARAIM) solutions in the future. These are currently engineered at international level for the provision of horizontal (H-ARAIM) and vertical (V-ARAIM) capabilities. The principles and advantages of ARAIM are discussed in this lecture together with possible implementation solutions.
- GNSS Space Service Volume and Deep Space Navigation
The vast majority of GNSS users are located at the surface of the earth or close to it and GNSS systems are primarily designed to serve these users. However, GNSS signal emissions also extend beyond the earth and are exploited also for positioning and operating satellites up to Geostationary Orbit and even beyond. This lecture describes the benefits of GNSS signals for space users and their specific user and application needs. Particular attention is paid to the interoperable GNSS Space Service Volume (SSV) which can significantly enhance the GNSS signal availability for satellites at altitudes above 8000 km. Concepts allowing for Deep Space Navigation are outlined in this lecture.
Dr. Todd Walter
Todd Walter is a Research Professor in the Department of Aeronautics and Astronautics at Stanford University. He received a B.S. in physics from Rensselaer Polytechnic Institute and an M.S. and Ph.D. in Applied Physics from Stanford University. His research focuses on implementing high-integrity air navigation systems. He was one of the principal architects of the Federal Aviation Administration’s (FAA) Wide Area Augmentation System (WAAS) safety processing algorithms, including development of the original ionospheric estimation and confidence bounding algorithm. He also advises the FAA on alternate means to exploit satellite navigation signals to provide services more efficiently. He has received the Institute of Navigation’s (ION) Thurlow and Kepler awards. He is also a fellow of the ION and has served as its president
- GNSS Effects for Aviation
This lecture describes the use of Global Navigation Satellite Systems (GNSS) to support air navigation. Particular attention will be paid to challenges that can affect the availability and safety of GNSS based navigation. The currently operating systems that augment the Global Positioning System (GPS) will be described. These are Aircraft Based Augmentation Systems (ABAS), Ground Based Augmentation Systems (GBAS), and Satellite Based Augmentation Systems (SBAS). They support differing flight operations and different regions of operations. Each method is described in detail and how it overcomes the challenges to provide suitable guidance.
- Cyber Security for Civil Navigation
The effects of radio frequency interference (RFI) is one of the largest challenges facing satellite navigation. RFI can overwhelm the desired signals and lead to a loss of navigation. Even more concerning, is the possibility that undesired signals can be interpreted as the intended signals, leading to corrupted positioning that may go undetected by the user. This latter spoofing threat may be inadvertent or part of a deliberate attack. The navigation community is working on several powerful technologies to overcome these dangers. These solutions include internal receiver validity checks, advanced receiver autonomous integrity monitoring (ARAIM), antenna based detection, and comparison to other sensors (such as accelerometers). ARAIM combats spoofing, because it is difficult to simultaneously replace all of the received signals with counterfeit signals. However, all of these approaches have limitation. The lecture will describe the threats as well as the trade-offs between the various proposed solutions.