Cracking the Pilot Contamination Nut
Communication Systems (KS),
Department of Electrical Engineering (ISY),
Linköping University (LIU),
When Thomas Marzetta introduced the Massive MIMO concept in a seminal article from 2010, he concluded that "the phenomenon of pilot contamination impose[s] fundamental limitations on what can be achieved with a noncooperative cellular multiuser MIMO system." More precisely, he showed that the channel capacity converges to a finite limit as the number of base stations goes to infinity. The value of this limit was determined by the interference level in the channel estimation phase. There are hundreds of papers on IEEEXplore that deals with the pilot contamination issue, trying to push the limit upwards and, particularly, achieve higher performance for a given number of antennas. Advanced semi-blind estimation schemes have been proposed and new resource allocation schemes.
But was pilot contamination really a fundamental limitation to start with? In this talk, I will demonstrate that it is rather easy to prove the opposite. You don't need a sledgehammer to crack the pilot contamination nut, but simple optimized signal processing tools will do. The lesson learned is that we must stop prioritizing analytical tractability over realistic system modeling when considering the fundamental limits.
Emil Björnson received the M.S. degree in Engineering Mathematics from Lund University, Sweden, in 2007. He received the Ph.D. degree in Telecommunications from KTH Royal Institute of Technology, Sweden, in 2011. From 2012 to mid 2014, he was a joint postdoc at the Alcatel-Lucent Chair on Flexible Radio, SUPELEC, France, and at KTH. He joined Linköping University, Sweden, in 2014 and is currently Associate Professor and Docent at the Division of Communication Systems. He teaches Master level courses on communications and is responsible for the Master programme in Communication Systems.
He performs research on multi-antenna communications, Massive MIMO, radio resource allocation, energy-efficient communications, and network design. He is on the editorial board of the IEEE Transactions on Communications (since 2017) and the IEEE Transactions on Green Communications and Networking (since 2016). He is the first author of the textbooks “Massive MIMO Networks: Spectral, Energy, and Hardware Efficiency” (2017) and “Optimal Resource Allocation in Coordinated Multi-Cell Systems” from 2013. He is dedicated to reproducible research and has made a large amount of simulation code publicly available.
Dr. Björnson has performed MIMO research for more than ten years and has filed more than ten related patent applications. He received the 2016 Best PhD Award from EURASIP, the 2015 Ingvar Carlsson Award, and the 2014 Outstanding Young Researcher Award from IEEE ComSoc EMEA. He has co-authored papers that received best paper awards at the conferences WCSP 2017, IEEE ICC 2015, IEEE WCNC 2014, IEEE SAM 2014, IEEE CAMSAP 2011, and WCSP 2009.