J Nicholas Laneman - US grants

Populating our world with networks of sensors requires fundamental understanding of tech-
niques for connecting and managing sensor nodes with a communication network in scalable
and resource-e .cient ways.The proposed research involves a comprehensive program of sensor
network architecture,design,evaluation,and implementation that integrates research expertise
in the areas of wireless networking and multiuser communications and provides numerous op-
portunities for enhancing student research and education in the area of sensor networks,at both
undergraduate and graduate levels.
The dominant trend in sensor network practice is to consider a dense collection of tiny sensor
nodes with limited computation and communication capabilities,all connected via a .at,or
ad hoc,wireless network.Yet theoretical studies in multiuser communications suggest that
substantially improved performance can be obtained through sophisticated coordination among
nodes,requiring more versatile radios,hierarchy,and perhaps even sparse wired connectivity.
Thus,the objectives of the proposed research are to:1)identify network architectures that
permit the implementation of sophisticated transmission schemes that have been theoretically
studied,2)analyze such schemes in the context of sensor networks and design new ones adopting
a cross-layer approach and 3)implement these schemes and verify their behavior on a real
testbed.
The intellectual merit of the project lies in the improved understanding of an important
emerging class of wireless networks,and in the attempt to unite theory and practice.Clos-
ing the widening gap between theoretically proposed strategies and practically implemented
ones is crucial to understanding and improving the performance and lifetime of these resource-
constrained networks.Through a rigorous analytic approach,contributions to the emerging area
of network information theory are expected,leading to substantial advances in energy-e .cient
and delay-constrained protocol design.
The broader impact is manifested in part through an e .ort to integrate teaching and research.
Experimentation on a hardware platform plays an integral role in both research and education.
It will be used for veri .cation,as well as for undergraduate and graduate projects that provide
students with hands-on experience in a real sensor network testbed.This project will enable
the acquisition of the necessary hardware.Two newly developed graduate courses on multiuser
communications and wireless networking will bene .t greatly from this project.It is anticipated
that by such close linking,research and education cross-fertilize each other within the framework
of this proposal.Further,since the proposed architectures and related issues carry over to other
important classes of networks,the .ndings from this research will have an impact on a much
broader class of wireless networks,including multihop cellular networks,that may soon become
signi .cant for a major part of our society.The broader impact will also be felt through a broad
dissemination of results and through current and future interactions with other universities.
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Multihop transmission is increasingly being incorporated into modern wireless communication networks. These networks are central to our nation's future communications and monitoring infrastructures. The
basic motivation for multihop is that transmissions occur over shorter distances -- and therefore with higher received signal strength -- via many intermediate nodes rather than over longer distances -- and
therefore with lower received signal strength -- between the source and destination of the information. However, multihop transmission involves complex interactions among channel coding at the physical
layer, distributed channel access at the link layer, and multihop routing at the network layer. These techniques have been studied largely in isolation by different communities, whereas this project
focuses on their interaction, especially in delay-constrained scenarios.

This research involves models for general wireless multihop networks, and develops tradeoffs for transmission along an individual routes of up to M + 1 nodes. Transmission between the end nodes can occur in a single hop, or up to M hops. Multihop transmission increases the received signal-to-noise ratio (SNR) at intermediate nodes; however, this observation does not take into account the important practical issues of power and bandwidth allocation, end-to-end delay, error propagation, or interference induced by other transmitters. Among other results, preliminary research indicates that the benefits of multihop are eroded by these issues, especially for high spectral efficiency, i.e., high data rates relative to the available bandwidth. The investigators take a comprehensive look at multihop transmission from the point of view of communication theory, mathematical networking, and networking practice, with the goal of offering solutions that will impact a major part of our society.

In the modeling and performance characterization of communication channels, the mathematical framework of information theory has contributed significantly to both conceptual understanding as well as technology development. Despite its magnificent success for certain applications, there are many applications, particularly in delay-constrained and many network scenarios, in which classical
> information theory has offered fewer insights, or otherwise the available insights have not been fully integrated into existing systems. One of the drawbacks of the classical theory is its reliance on long coding blocklengths. We believe that application of information theory to modern applications can be accelerated by a "finite blocklength" information theory that is general enough to handle a wide class of important channel models but not so complex and subtle so as to be essentially unusable by system designers.
This research centers around activities for developing a general framework of finite blocklength information theory for modern communication systems and networks. The guiding objective is to develop suitable abstractions of communication channels and coding strategies in terms of a single random variable called the mutual information density rate, rather than its expectation. The anticipated abstractions will enable characterization of performance and architectural evaluation by network designers as well as facilitate orders of magnitude speedups in network simulation. The
technical approach is comprehensive, leveraging theoretical analysis, computer simulation, and testbed experiments. Opportunities for integration of research and education have been identified, and substantial cross-fertilization is expected.

It is well documented how cooperative links can offer considerable performance gains at the physical layer, but it is unclear what kind of network support would be required to attain the sought gains. Cooperative links violate the simple collision model for broadcast transmission, a model that has been instrumental so far in allowing the parallel evolution of communication theory and network theory.
Recognizing the absence of a correct taxonomy to use cooperative links at the network and multiple access layer, the objective of this collaborative project is to investigate theoretically and experimentally the interplay between a cooperative decentralized physical layer and the wireless network architecture as a whole. More specifically, the project will develop viable link abstractions, multiple access protocols, end-to-end network transport models, appropriate algorithms to support the introduction in wireless mobile networks of two technologies that are rapidly advancing: 1) cooperative transmission, that consists of multiple network nodes operating as a decentralized multi-antenna modem and, 2) distributed source coding, that allows the decentralized compression of correlated observations and, thus, is relevant to the design of a decentralized receiver.
The project will also use the GNU software radio platform to test cooperative links and assess their feasibility and degradation when facing real limitations of transceiver synchronization, carrier offset, clock jitter and computation delays.
Algorithms and theoretical results will be disseminated through the standard tools of research publications. Experimental results will be also documented online where the software will be shared to serve as an educational tool as well as to foster new technological advances in mesh networks.
This project will bring future wireless networks closer to achieving the physical limits of communications.

Engineering - Electrical (55)

The project is creating a new approach for teaching systems engineering within the electrical engineering (EE) curriculum. The approach makes use of a hardware/software platform and accompanying curricular innovations to bring a more engaged, hands-on, exploratory focus to what is probably the most convention-bound component of a typical undergraduate electrical engineering education. Unlike previous attempts to create a less abstract and more engaging systems engineering curriculum, which focused almost entirely on software tools (e.g., MATLAB), the proposed project is creating a hardware/software platform and using that platform to vertically integrate key systems concepts across the undergraduate curriculum. The platform is letting students explore systems applications using a variety of hardware devices such as signal generators, filters, A/D and D/A converters, sensors, and a microprocessor. The platform contains an interface to a student's MP-3 player and cell phone to bring home the relevance of the systems perspective to modern technology. To allow students to see the signals they are generating and manipulating, the platform includes a suite of visualization software. The project is being evaluated using an assortment of tools including an established signals and systems concept inventory along with the analysis of student products and enrollments numbers. The investigators are disseminating their results by posting their material on a website, by publication and presentation in engineering education venues, and through the investigators connection with the signals and systems concept inventory community. Broader impacts include the dissemination of the material, the focus on Hispanic students, and the outreach effort to high school students.

Communication across networks with feedback and relays is an important, challenging, and largely open problem in information and communication theory. Systematic and scalable communication algorithms will enhance reliability, decrease coding complexity or delay, impart robustness to communication schemes by exploiting diversity, and in some cases increase the achievable communication rates. Since all modern communication systems employ multiple feedback mechanisms, a better understanding of communication feedback is imperative.

This research focuses on a deeper study of this topic by viewing it through the lenses of consensus algorithms and more general stochastic approximation algorithms. This approach yields scalable and robust algorithms for cases of extreme relevance to modern communication systems, e.g., network scenarios with noisy feedback. A confluence of problems, techniques and tools from information theory and distributed dynamic systems are utilized, with a potential transformative impact on both fields. In addition to analytical techniques and simulations, the team also utilizes facilities and experience realizing novel communication algorithms in a wireless network testbed based upon software-defined radios.

Any impact on the problem of communication across networks with noisy feedback will have immediate applications to most modern communication systems. Moreover, this research furthers the unification of the two aspects and research communities relevant to a more general information theory - one that considers both the transmission of data (classical information theory), as well as its utilization (classical dynamical systems). An emphasis on organizing special sessions in conferences, offering new graduate courses, including undergraduates in the experimental research, mentoring minority students, and furthering outreach to high school students interested in engineering is an integral part of the project.

Computer Engineering (32)

The objectives of this project include construction of a hardware and software prototype of a customizable wireless educational WIPER platform. This platform allows teachers and students to emulate real-world devices by plugging in the desired modules such as different radio technologies, sensor types, and other components typically found in wireless systems. From the software perspective, WIPER automatically recognizes the inserted modules and provides programmers access to library functions that facilitate rapid development of wireless applications. The WIPER programming environment is extensible and offers an easy-to-use graphical programming interface.

The project provides instructors with a tool for rapid development of wireless networks and systems with minimal learning curve. Besides this new learning platform, the project provides novel learning materials for the WIPER platform.

The WIPER platform can be used in courses such as computer networks, sensor networks, mobile computing, or wireless communications. The PIs leverage the WIPER platform to further raise interest in wireless systems and recruit students from underrepresented groups. The PIs work with Notre Dame's Innovation Park to explore commercialization opportunities to provide educators with access to the WIPER platform.

The FCC released its National Broadband Plan citing the exponentially growing demand for mobile data services and the critical need to better utilize the radio spectrum. Beyond retargeting certain frequency bands, the FCC is considering a paradigm shift of dynamic spectrum access (DSA) technology and policy. DSA allows 'secondary' radios to transmit in underutilized 'white space' provided they create minimal interference to 'primary' radios. Significant white space, as much as 85%, has been observed across time, frequency, and location. However, even in the TV bands, the challenge of inconspicuous utilization of white spaces has not yet been achieved by the two leading solutions, distributed spectrum sensing and centralized emitter databases.

This project focuses on a comprehensive approach to DSA based upon spectrum sensing that combines the following in a feedback loop: novel modeling of primary and secondary transmissions; design of optimal spectrum sensing algorithms and secondary access protocols based upon these models; and experimental validation within a testbed of software-defined radios. Preliminary results develop primary Markov models and optimal sequence detection algorithms for spectrum sensing that build upon the well-known Viterbi and forward-backward algorithms and expose fundamental limitations due to primary mismatch for the commonly used energy detector. The connections to trellis- and graph-based algorithms from the channel coding community should introduce a sizable new toolbox to DSA researchers. Secondary access protocols that take advantage of Markov process models for the primary users similarly exhibit improved performance tradeoffs between primary interference and secondary throughput. Collaborators in industry and regulatory bodies will be kept informed of the research results with an aim toward impacting DSA technology and policy development at national and international levels.

Wireless sensor-actuator networks (WSAN) are systems consisting of numerous sensing and actuation devices that interact with the environment and coordinate their activities over a wireless communication network. This project studies "resilience" in WSANs. A resilient system is one that maintains an active awareness of surrounding threats and reacts to those threats in a manner that returns the system to operational normalcy in finite time. This project's approach to resilient WSANs rests on two fundamental trends. One trend uses machine-to-machine (M2M) communication networks that promise wireless networking with greater peak bit-rates and reliability than previously possible. The other trend comes from recent ideas that use quantization and event-triggered feedback in a unified manner to reduce bit rates required by real-time control systems. This project will evaluate and demonstrate this integrated control/communication approach to resilience on a multi-robotic testbed consisting of unmanned ground vehicles. The testbed will integrate M2M communication hardware/software with a multi-robot control architecture addressing task coordination and platform stabilization.

This project broadens its impact through organizations and programs on and around the Notre Dame campus that facilitate industrial engagement and technology transfer. The project will engage undergraduate and graduate students to support the project's testbed and algorithm development. The project will augment and re-organize Notre Dame's Cyber-Physical System (CPS) curriculum by integrating the results of this project into courses.

The new center site of the Industry/University Cooperative Research Center (I/UCRC) for Broadband Wireless Technologies and Applications at the University of Notre Dame will complement the existing center?s activities through a focus on emerging wireless technology, economics, and regulatory policy challenges. The site intends to develop a cohesive and integrative approach to broadband research challenges in areas including cellular data collection, analytics, & visualization; heterogeneous network modeling, analysis, and design; electromagnetic radiation exposure; spectrum sharing; vehicular communications; inter-machine wireless; crowd-sourced approaches and advanced circuitry.

The center site addresses an area of critical economic and has the potential to support development of broadband wireless as a platform for innovation as addressed in the White House PCAST Report. The center site at Notre Dame has the potential to link an even greater diversity of member companies across the broadband industry sector with university a broader base of discovery in this area. The site will provide early exposure to the concerns of and approaches employed in industry in students? education and career development. Underrepresented undergraduate and graduate students will be recruited to the program through existing mechanisms at the site such as the REU program in Experimental Research on Wireless Networking (ERWiN), in which more than 40% of the participants were from underrepresented groups over the last five years.

NDWI is conducting research in the area of emerging wireless technology, economics, and regulatory policy challenges. Addition of NDWI site to BWAC facilitates the transfer of knowledge from these areas to industry members. Close collaboration with industrial partners will ensure that problems of practical relevance are studied, resulting in direct technology transfer into innovative and practical wireless systems. The diverse research team, with expertise ranging from RF circuit design and electromagnetics, communication systems signal processing and coding, spatial statistics, visualization, and application development, will ensure that many critical aspects of wireless system design are addressed cohesively. Basic research will be combined with robust experimental validation from the hardware level up to large-scale field studies.

Techniques and solutions developed through NDWIs cooperative research program will potentially impact worldwide wireless standards, software and hardware components, and network deployments. The basic and applied research activities will involve undergraduate and graduate students in cutting-edge research, training them in multiple disciplines relevant to modern wireless networks. Early exposure to the concerns and the approaches in industry will be invaluable in students? education and career development. Several mechanisms will be utilized to attract underrepresented undergraduate and graduate students to the program, e.g., REU program in Experimental Research on Wireless Networking (ERWiN).

With the exponential increase in data consumption world-wide, the corresponding increase of associated power consumption in wireless communication systems is receiving significant attention and concern. This research effort examines wireless communication performance techniques and limits when simple low-power devices are used to transmit and receive signals. These devices, because of their simplicity, are constrained to transmit and receive "one bit" of information, and with extremely low power consumption. However, many of them can be used together and at very high speeds, giving an overall high effective data rate. The effort examines the potential power advantages of using such devices over conventional devices that are more capable but have much higher power consumption. The project pushes the boundaries on many areas of traditional linear systems and circuit theory, and will be integrated into undergraduate and graduate course offerings in linear systems, digital signal processing, circuit design, and microwave engineering. The results will be used to encourage discussion about how high data rates need not require a large power budget.

The design of wireless communication systems that rely on classical linear-system techniques runs into difficulties with high power-consumption of circuits at carrier frequencies above 20 GHz and with bandwidths above 2 GHz. Linear amplifiers, mixers, and high-speed analog-to-digital converters, and digital-to-analog converters in the transceiver chains become inefficient and expensive. This research effort examines wireless communication performance limits and techniques when a novel energy-efficient "transceiver cell" is used for the air interface. The transceiver cell exploits nonlinearities in its devices and circuits to obtain very low power consumption and ease of fabrication in a variety of technologies for wide bandwidths and at very high carrier frequencies. The cell comprises a transmitter and receiver capable of modulating and demodulating a single bit per symbol. The effort is transformative because it looks at maximizing bits/(second-Hz-Watt) in the trade-off of the performance of each cell versus the number of cells in a power-constrained system, by applying concepts from neural-networking systems of low-power nonlinear ``computational cells''.

This award is a planning grant for the Spectrum Innovation Initiative: National Center for Wireless Spectrum Research (SII-Center). The focus of a spectrum research SII-Center goes beyond 5G, IoT, and other existing or forthcoming systems and technologies to chart out a trajectory to ensure United States leadership in future wireless technologies, systems, and applications in science and engineering through the efficient use and sharing of the radio spectrum. The radio spectrum should be utilized to the greatest public benefit at national and global scales. Spectrum shortages, both real and perceived, are leading to conflicts between existing users and anticipated new uses ? some of which were not imagined when existing spectrum allocations were made decades ago. Many stakeholders seek to protect and advance their interests, with aspects of these interests overlapping and conflicting with each other. Hence, the public debate over the optimal model for managing spectrum is a complex interplay of technology, economics, law and regulation, policy, and the history of past successes and failures.

This project is aimed at the development of a comprehensive plan for an SII-Center which would help maintain and extend US leadership in future wireless technologies, systems, and applications in science and engineering through the efficient use and sharing of radio spectrum. The project team is led by the University of Notre Dame, with partners from Northwestern University, Clemson University, University of California, Berkeley, University of California, Los Angeles, New York University, and Stanford University. The team has an extensive record of successful research, as well as significant and relevant industry and implementation experience. The project seeks to develop plans for a multi-disciplinary center that emphasizes instrumentation of the radio spectrum; collecting and sharing accurate regulatory, usage, and economic data; and developing data-rich system designs and regulatory policies for more efficient spectrum utilization.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

The worldwide growth of wireless communication, navigation, and telemetry has provided immense societal benefits including mobile broadband data, Internet of Things, mobile healthcare, and intelligent transportation systems. This award is a grant to establish a Spectrum Innovation Initiative: National Center for Wireless Spectrum Research (SII-Center) to ensure United States leadership in future wireless technologies, systems, and applications in science and engineering through the efficient use and sharing of the radio spectrum. An SII-Center will promote transformative use and management of the electromagnetic spectrum, charting a trajectory to ensure United States leadership in future wireless technologies, systems, and applications in science and engineering through the efficient use and sharing of the radio spectrum. An SII-Center will also educate and develop an agile workforce needed to support industries of the future which rely heavily on wireless technologies.

This award funds the establishment of the first national center for wireless spectrum research, SpectrumX. The vision for SpectrumX is to be an inclusive multidisciplinary and increasingly interdisciplinary center that applies convergence research and team science to promote coexistence among disparate use cases in the radio spectrum, particularly including “public good” use cases for science and defense. In particular, SpectrumX will pursue its initial research strategy in scientific receiver hardware with interference measurement and mitigation capabilities; instrumentation of the radio spectrum in terms of advanced sensing networks; collecting and sharing accurate regulatory, usage, and economic data; flexible use rights that align incentives with efficient outcomes; and distributed, data-rich, and cloud-ready system designs for more efficient spectrum management and utilization. The project team is led by the University of Notre Dame, bringing together broad and synergistic research capabilities from a team of 41 founding researchers and staff from 27 universities, including 14 minority-serving or majority non-white institutions, and partnerships across industry, government, and academia. The Center will be an information and innovation hub connecting stakeholders. SpectrumX has a Broadening Participation plan aimed to increase awareness of cultural competence for all center participants to ensure that Diversity, Equity, and Inclusion are woven into the core of the Center’s values and culture. SpectrumX will develop spectrum-related curriculum for Grade 6 through master’s students and has an Education and Workforce Development Plan to offer flexible pathways for researchers and students from diverse backgrounds, disciplines, and levels of maturity to engage in spectrum innovation.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.