Future broadband wireless systems are expected to provide huge user and overall bit rates in a reliable and secure way. This means a substantial spectral efficiency increase, which must be achieved while maintaining or even improving the power efficiency. To accomplish this, one needs to employ new transmission techniques, with the most promising ones based on the use of a large number of antennas. For this reason, massive MIMO (Multiple-Input and Multiple-Output) schemes, involving tens or even hundreds of antennas, will be a key component of current 5G, since they allow high capacity gains, while enabling significant power savings. Clearly, the evolution beyond 5G will involve even more antennas.

A new and revolutionary technique able to improve substantially the performance of wireless communication networks is to smartly changing the propagation characteristics of the wireless channel through the use of RIS (Reconfigurable Intelligent Surfaces), which are made of a large number of low cost passive reflecting elements able to independently change the amplitude and/or phase of the incident signal so as to achieve specific propagation effects. LIS (Large Intelligent Surfaces) are the natural evolution of massive MIMO schemes. They will employ many thousands of antenna elements, allowing huge capacity gains, as well accurate positioning and new physical layer security approaches. However, the implementation of these techniques involves considerable challenges.

In this talk we give an overview of potentialities and challenges of systems with a huge number of antennas. We start by making an overview on the evolution from MIMO to massive MIMO, and its extension to RIS and LIS and cell free systems. Then we present the main features of those systems, as well as the implementation constraints and challenges, as well as potential solutions.

Biography:

Rui Dinis received the Ph.D. degree from IST, Technical University of Lisbon, Portugal, in 2001 and the Habilitation in Telecommunications from FCT, Nova University of Lisbon (UNL) in 2010 where he is a Full Professor. Rui Dinis is also researcher at IT (Instituto de Telecomunicações). During 2003 he was a visiting professor at Carleton University, Ottawa, Canada. Rui Dinis is an IEEE ComSoc Distinguished Lecturer and an IEEE VTS Distinguished Speaker. He is or was editor at several major IEEE journals (IEEE TWC, TCOM, TVT and OJ-COMS) and at Elsevier Physical Communication and Hindawi ISRN Communications and Networking. He was also a guest editor for multiple special numbers in several journals. He was involved in the organization of IEEE conferences, namely several VTC and GLOBECOM, and is a member of several technical committees of IEEE Communications Society. Rui Dinis has been actively involved in several international research projects in the broadband wireless communications area. He has 30 PhD students (current and past), published 7 books, over 200 journal papers and book chapters and over 400 conference papers (of which 6 received best papers’ awards), and has over 20 patents. He was involved in pioneer projects on the use of mm-waves for broadband wireless communications and his main research activities are on modulation and transmitter design, nonlinear effects on digital communications and receiver design (detection, equalization, channel estimation and carrier synchronization), with emphasis on frequency-domain implementations, namely for MIMO systems and/or OFDM and SC-FDE modulations. He is also working on cross-layer design and optimization involving PHY, MAC and LLC issues, as well as indoor positioning techniques.