Events for December 04, 2015
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Communications, Networks & Systems (CommNetS) Seminar
Fri, Dec 04, 2015 @ 11:00 AM - 12:00 PM
Ming Hsieh Department of Electrical and Computer Engineering
Conferences, Lectures, & Seminars
Speaker: Yi Ouyang, University of Michigan, Ann Arbor
Talk Title: A Common Information Based Multiple Access Protocol Achieving Full Throughput and Linear Delay
Series: CommNetS
Abstract: Multiple access communication has played a crucial role in the operation of many networked systems, including satellite networks, radio networks, wired/wireless Local Area Networks (LANs), and data centers. One important feature of multiple access communication is its decentralized information structure. In general, when multiple users share the communication system, coordination among them is essential to resolve collision issues. In the absence of a centralized controller, it is challenging to design efficient user coordination mechanisms.
We consider a typical slotted multiple access communication system where multiple users share a common collision channel. Each user is equipped with an infinite size buffer and observes Bernoulli arrivals to its own queue. In addition to the local information, all users receive a common broadcast feedback from the channel. The feedback indicates whether the previous transmission was successful, or it was a collision, or the channel was idle. The objective is to design a transmission protocol that effectively coordinates the users transmissions under the above described information structure.
In this talk, we propose a common information based multiple access protocol (CIMA) that uses the common channel feedback to coordinate users. In CIMA, each user constructs upper bounds on the lengths of the queues of all users, including itself, based on previous transmission strategies and the common feedback. Since the upper bounds are common knowledge, users can coordinate their transmission through these common upper bounds to avoid collision. We prove that without knowledge of any statistics, CIMA achieves the full throughput region of the collision channel. We also prove that the CIMA protocol incurs low transmission delay; the delay is upper-bounded by a linear function of the number of users.
Biography: Yi Ouyang received the B.S. degree in Electrical Engineering from the National Taiwan University, Taipei, Taiwan in 2009. He is currently a Ph.D. candidate in Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor, MI, USA. His research interests include stochastic scheduling, decentralized stochastic control and dynamic stochastic games with asymmetric information.
Host: Dr. Ashutosh Nayyar
Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248
Audiences: Everyone Is Invited
Contact: Annie Yu
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Integrated Systems Seminar Series
Fri, Dec 04, 2015 @ 02:00 PM - 03:30 PM
Ming Hsieh Department of Electrical and Computer Engineering
Conferences, Lectures, & Seminars
Speaker: Prof. Andreas G. Andreou, IEEE Fellow, Johns Hopkins University
Talk Title: BRAINWAY: Cognitive Computing using Energy Efficient Physical Computational Structures, Algorithms and Architecture Co-Design
Series: Integrated Systems Seminar
Abstract: The BRAINWAY project in my lab is aimed at the design of an energy efficient Cognitive Processor Unit (CogPU) that combines Ultra-Low-Voltage (ULV) circuit techniques with brain-inspired chip multiprocessor network-on-chip (NoC) architecture, in 3D CMOS technology. The design of the CopPU architecture is based on the recently developed mathematical framework for architecture exploration and optimization, where neurons are abstracted as arithmetic units, processing information using stochastic or deterministic unary representations. Data in the system represent probabilities a choice that is well suited for probabilistic inference and machine learning. Such highly energy efficient CogPU inference engine will provide an energy efficiency gain of about x65 by using ULV techniques and massive parallelism, a gain of about x10 by relying on its SOC 3D DRAM, and a gain of about x15 by relying on new memory based Bayesian inference computational structures. This yields an estimate aggregate improvement factor in energy efficiency of about x10000, roughly four to five orders of magnitude with respect to present day state-of-the-art. Preliminary results from fabricated chips in the Global Foundries 55nm technology confirm our estimates and to the best of our knowledge these are the first CMOS computer architecture that computes natively with probabilities. I will discuss the design and experimental results from sub-systems of the architecture, representing processing units for exact and approximate Bayesian inference, multi-variate function approximation, including circuit details for mixed signal vector-vector multiplier units, physical random number generators and probability approximators
Biography: Dr. Andreas G. Andreou is a professor of electrical and computer engineering, computer science and the Whitaker Biomedical Engineering Institute, at Johns Hopkins University. Andreou is the cofounder of the Johns Hopkins University Center for Language and Speech Processing. Research in the Andreou lab is aimed at brain inspired microsystems for sensory information and human language processing. Notable microsystems achievements over the last 25 years, include a contrast sensitive silicon retina, the first CMOS polarization sensitive imager, silicon rods in standard foundry CMOS for single photon detection, hybrid silicon/silicone chip-scale incubator, and a large scale mixed analog/digital associative processor for character recognition. Significant algorithmic research contributions for speech recognition include the vocal tract normalization technique and heteroscedastic linear discriminant analysis, a derivation and generalization of Fisher discriminants in the maximum likelihood framework. In 1996 Andreou was elected as an IEEE Fellow, "for his contribution in energy efficient sensory Microsystems."
Host: Hosted by Prof. Hossein Hashemi, Prof. Mike Chen, and Prof. Mahta Moghaddam. Organized and hosted by SungWon Chung.
Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248
Audiences: Everyone Is Invited
Contact: Elise Herrera-Green
