Full Professor, Electrical engineering
Erik Agrell's publication list with downloadable articles
Erik Agrell's tables of binary block codes
Erik Agrell's database of sphere packings
Erik Agrell received the Ph.D. degree in information theory in 1997 from Chalmers University of Technology. In his Ph.D. thesis, he analyzed the Voronoi diagrams of various geometrical structures, in particular binary block codes and lattices, and developed Voronoi-based source encoding and channel decoding algorithms.
Erik had two postdoctoral positions in 1997–1999, with the University of Illinois at Urbana-Champaign and the University of California, San Diego, where he collaborated mainly with Profs. Alexander Vardy and Kenneth Zeger. During this happy period, he investigated properties of constant-weight binary codes and derived new bounds on their sizes, and together with Thomas Eriksson he developed a family of fast search algorithms for lattices, based on the so-called sphere decoder.
In 1999, Erik was back at Chalmers University of Technology, but this time at Campus Lindholmen, teaching in the bachelor's programs of applied electrical and computer engineering. This is where he began to appreciate how nonideal models and hardware limitations influence the system performance, and therefore they should also influence the system design. There is an intricate tradoff between practically useful problem statements and theoretically feasible problem solutions.
Erik joined the Communication Systems Group at the the department of Signals and Systems in 2001, first as an Associate Professor, from 2003 with the title of "docent", and since 2009 as a Professor. In 2002–2007, he was program director for the international Master's program Digital Communication Systems and Technology, and he led its development into a new program, Communication Engineering, according to the Bologna model. He has had the pleasure of teaching in Introduction to Communication Engineering and Digital Communications on the Master's level and in the Ph.D. course Error Control Coding.
Erik's general research interests are in digital communication theory, including coding and information theory. More specifically, his research follows two main tracks: the fundamental and the crossdisciplinary.
The fundamental track includes modulation theory, error-correcting coding, bit-interleaved coded modulation, multilevel coding, and cognitive radio. Much of this research can be formulated as the (joint or separate) optimisation of constellations, bit-to-symbol mappings, codes, and probability distributions, to improve the performance of a point-to-point communication system (in terms of bit rate, power consumption, spectral efficiency, and/or reliability). His favorite mathematical tools include optimisation theory, matrix algebra, stochastic processes, transform theory, and multidimensional geometry (especially lattices and other sphere packings).
In 2003, Erik spent a coffee break with Prof. Magnus Karlsson of the Photonics Laboratory at the department of Microtechnology and Nanoscience. Although Erik prefers tea, this did not prevent the coffee break from opening up a whole new research area at Chalmers. Both Erik and Magnus had for some time, from different viewpoints, been puzzled by the apparent absence of advanced digital communication theory in the development of optical communications. Communication theorists, at Chalmers and worldwide, were very much tuned to wireless applications, by tradition more than by any apparent technical reason. Conversely, the past progress in fiber-optical communications relied largely on hardware improvements, by designing better fibers, amplifiers, transmitters, and receivers. There was practically no interaction between the two fields. Magnus and Erik decided to do something about it. Beginning as a modest pilot study, the collaboration between the two departments expanded, by external funding and the recruitment of qualified researchers, into what is since 2010 recognized as a research centre at Chalmers: FORCE, the Fibre-Optic Communications Research Centre, headed by Prof. Peter Andrekson. Erik is the research area leader for fibre-optical communications at Signals and Systems.
Within the FORCE environment, Erik nurtures the crossdisciplinary track of his research interests: applying digital communication theory to fiber-optical communication systems. For example, designing coding and modulation schemes for joint transmission over both lightwave polarizations offers substantial power gains over independent transmission in the two polarizations, and it gives rise to challenging optimisation problems in a four-dimensional signal space. His other optical research interests include joint wavelength- and polarisation-division multiplexing transmission, spectrally efficient transmission over the optical intensity channel, and characterisation and mitigation of nonlinear phase noise.
Published: Mon 27 Jan 2020.
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