Cognitive Hybrid Division Duplex for Two-Tier Femtocell Networks

Tuesday, September 11, 2012

With the exponential increase in high rate traffic driven by a new generation of wireless devices, data is expected to overwhelm cellular network capacity in the near future. Femtocell networks have been recently proposed as an efficient and cost-effective approach to provide unprecedented levels of network capacity and coverage. However, the dense and random deployment of femtocells and theiruncoordinated operation raise important questions concerning interference pollution and spectrum allocation. Motivated by the flexible subchannel allocation capabilities of cognitive radio, in this talk we present a cognitive hybrid division duplex (CHDD) which is suitable for heterogeneous networks in future mobile communication systems. Specifically, this CHDD scheme has a pair of frequency bands to perform frequency division duplex (FDD) on the macrocell while time division duplex (TDD) is simultaneously operated in these bands by the underlaid cognitive femtocells. By doing so, the proposed CHDD scheme exploits the advantages of both the FDD and TDD scheme: operating FDD at the network level manages inter-tier interference while operating TDD at the femtocell level provides femtocells the flexibility of adjusting uplink and downlink rates. Using tools from stochastic geometry, we analyze the network performance and provide a methodology on how to design optimal switching mechanisms for cognitive TDD operation of femtocells. Finally, an open access policy for the CHDD scheme is proposed, which is shown to improve the performance of macrocell transmission.


Marios Kountouris received the Dipl.-Ing. in Electrical and Computer Engineering from the National Technical University of Athens, Greece in 2002 and the M.S. and Ph.D. degrees in Electrical Engineering from the Ecole Nationale Supérieure des Télécommunications (ENST) Paris, France in 2004 and 2008, respectively.His doctoral research was carried out at Eurecom Institute, France, and it was funded by Orange Labs, France. From February 2008 to May 2009, he has been with the Department of ECE at The University of Texas at Austin as a research associate, working on wireless ad hoc networks under DARPA’s IT- MANET program. Since June 2009, he has been an Assistant Professor at the Department of Telecommunications at Supélec (Ecole Supérieure d’Electricité), France. Dr. Kountouris has published several papers and patents, all in the area of communications, wireless networking, and signal processing. He has served as technical program committee member for several top international conferences and has organized several workshops on heterogeneous and small cell networks. He is currently an Editor for the EURASIP Journal on Wireless Communications and Networking. He also received the Best Paper Award in Communication TheorySymposium at the IEEE Globecom conference in 2009. He is a Member of the IEEE and a Professional Engineer of the Technical Chamber of Greece.