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2012 -13 Seminars


Understanding 'Informational-Friction' for Green Communication and Computation

Pulkit Grover
Assistant Professor, ECE
Carnegie Mellon University

Abstract
Just as there is friction when an object is moved on a surface, there is friction when information is moved on a link, whether wirelessly, through cables, or through on-chip wires. Surprisingly, this ``informational friction'' has been mostly ignored in fundamental study of communications, computer science, and even physics. But informational friction matters: it is one of the major reasons why there is energy consumed in today's Information and Communication Technologies (ICTs), such as the data-centers, laptops and personal computers, and networking equipment. ICTs themselves are slated to soon consume > 15% of the total electricity generated in the world. I will start with a fundamental approach to this energy consumption problem. I will first motivate and present a model of information-frictional losses in computation and communication. Focusing on communication systems, frictional losses are incurred not only in transmission across the communication channel, but also in processing at the transmitter and the receiver. In today's short-distance communication systems (e.g. in data-centers, or even on-chip information transfer), processing energy dominates transmit energy. Even so, the existing theory of information focuses almost exclusively on the transmit energy. I will describe how our informational-friction model helps us adapt traditional information theory results to include this computation power. This adaptation is leading us to a new fundamental understanding of "green" communication and computation that combines ideas from Shannon's information theory, thermodynamics, and computer science. I will discuss how this fundamental understanding has the potential to significantly reduce energy consumption in data-center ethernet, chip-to-chip and on-chip communication (I/Os), indoor wireless, etc., even without accounting for energy reductions with technology improvements.