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LFCS seminar: David Tse and Pramod Viswanath

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  • LFCS Seminar
  • Upcoming events
When Nov 20, 2018
from 04:00 PM to 05:00 PM
Where IF 4.31/4.33
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Title: Deconstructing the Blockchain to Approach Physical Limits
Speaker: David Tse
The concept of a blockchain was invented by Satoshi Nakamoto to maintain a
distributed ledger for an electronic payment system, Bitcoin. In addition to its
security, important performance measures of a blockchain protocol are its
transaction throughput, confirmation latency and confirmation reliability. These
measures are limited by two underlying physical network attributes:
communication capacity and speed-of-light propagation delay. Existing systems
operate far away from these physical limits. In this work we introduce Prism, a
new blockchain protocol, which can provably achieve 1) security against up to
50% adversarial hashing power; 2) optimal throughput up to the capacity C of the
network; 3) confirmation latency for honest transactions proportional to the
propagation delay D, with confirmation error probability exponentially small in the
bandwidth-delay product CD ; 4) eventual total ordering of all transactions. Our
approach to the design of this protocol is based on deconstructing the blockchain
into its basic functionalities and systematically scaling up these functionalities to
approach their physical limits.
This is joint work with Vivek Bagaria, Sreeram Kannan, Giulia Fanti and Pramod
Viswanath. The full paper can be found at
David Tse received the B.A.Sc. degree in systems design engineering from
University of Waterloo in 1989, and the M.S. and Ph.D. degrees in electrical
engineering from Massachusetts Institute of Technology in 1991 and 1994
respectively. From 1995 to 2014, he was on the faculty of the University of
California at Berkeley. He is currently the Thomas Kailath and Guanghan Xu
Professor at Stanford University. He received the Claude E. Shannon Award in
2017 and was elected member of the U.S. National Academy of Engineering in
2018. Previously, he received a NSF CAREER award in 1998, the Erlang Prize
from the INFORMS Applied Probability Society in 2000 and the Frederick
Emmons Terman Award from the American Society for Engineering Education in
2009. He is a coauthor, with Pramod Viswanath, of the text Fundamentals of
Wireless Communication, which has been used in over 60 institutions around the
world. He received best paper awards from IEEE Information Theory,
Communications and Signal Processing societies, and is the inventor of the
proportional-fair scheduling algorithm used in all third and fourth-generation
cellular systems.
Title: Why Blocks and Why Chains; A First Principles (Re)Design of Blockchains
Speaker: Pramod Viswanath
Today's blockchains do not scale in a meaningful way. As more nodes
join the system, the efficiency of the system (computation, communication, and
storage) degrades, or at best stays constant. Furthermore, the security of
the permission less system imposes limitations on the core performance metrics
of throughput, latency and confirmation probability. We take a first principle
approach to the blockchain ecosystem addressing each of the various
components holistically. Our approach is characterized by seeking
fundamental limits (those prescribed by the physics of the underlying network) to
performance and designing algorithms that attain them. This research is
informed by decades of experience in information theory, coding theory,
algorithms, wireless communication and packet networks. This talk will highlight
key outcomes of this research program, including
Prism (a new consensus algorithm that guarantees information theoretically
optimal throughput, latency, reliability),
Spider (a new networking protocol for off-chain payment channels),
Polyshard (a new coded storage architecture), and
Dandelion (a new network privacy layer).
Bio: Pramod Viswanath received the Ph.D. degree in EECS from UC Berkeley in
2000. From 2000 to 2001, he was a member of research staff at Flarion
technologies, NJ. Since 2001, he is on the faculty at University of Illinois at
Urbana Champaign in Electrical and Computer Engineering, where he currently
is a professor. He is a coauthor, with David Tse, of the text Fundamentals of
Wireless Communication, which has been used in over 60 institutions around the
world. He is coinventor of the opportunistic beamforming method and codesigner
of Flash-OFDM communication algorithms adapted into fourth-generation cellular
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