Séminaire ETIS : Alexandre Graell i Amat

Titre du séminaire et orateur

Wireless Distributed Storage with D2D Communication.

Alexandre Graell i Amat, Chalmers Univ. of Technology, Götenborg, Suède.

Date et lieu

Mardi 6 octobre 2015, 11h.

Université de Cergy-Pontoise, site de St-Martin 2, amphithéâtre des colloques.


The recent years have witnessed the explosion of services and applications such as social and media networks, video streaming, and cloud computing. With these applications comes the challenge to store and deliver massive amounts of data. The design of efficient and reliable storage and delivery systems to cope with this unprecedented increase of data has given rise to the emerging research area of distributed storage (DS), where data is stored over multiple individually (unreliable) storage nodes to globally provide reliability.

In the first part of this seminar we will explain the concept of DS. We will then focus on one of our recent results. In particular, we will consider DS for a wireless network where mobile devices arrive and depart according to a random process. Devices wish to download content (think about popular video files) from the network. Content is stored in a number of mobile devices, using an erasure correcting code. When requesting a piece of content, a user retrieves the content from the mobile devices using device-to-device communication or, if not possible, from the base station (BS), at the expense of a higher communication cost. We show that DS can reduce the overall communication cost with respect to the case where content is only downloaded from the BS.


Alexandre Graell i Amat received the PhD degree in Electrical Engineering from the Politecnico di Torino, Turin, Italy, in 2004. From September 2001 to May 2002, he was a Visiting Scholar at the University of California San Diego (UCSD), CA. During 2001-2004, he also held a part-time appointment at STMicroelectronics, Milan, Italy, as consultant on coding for magnetic recording channels. From March 2004 to December 2005, he was a Research Professor at the Universitat Pompeu Fabra, Barcelona, Spain. From 2006 to 2010 he was with the Department of Electronics of TELECOM Bretagne (former ENST Bretagne), Brest, France, first as a Postdoc and since October 2008 as an Associate Professor. In 2011 he joined the Department of Signals and Systems at Chalmers University of Technology, Gothenburg, Sweden, where he is currently an Associate Professor. His research interests are in the area of coding theory (in particular codes on graphs), distributed storage and optical communications.

Dr. Graell i Amat is currently serving as an Associate Editor for the IEEE TRANSACTIONS ON COMMUNICATIONS. He was the General Co-Chair of the 7th International Symposium on Turbo Codes & Iterative Information Processing, 2012. He received the Marie Curie Intra-European Fellowship of the European Commission and was awarded the IEEE Communications Society "2010 Europe, Middle East & Africa Region Outstanding Young Researcher Award”.