ABSTRACT: Intercell interference is the major limiting factor in wireless multi-cell networks. Recently, it has been shown that significant performance gains can be achieved by cooperation between base stations. Different degrees of cooperation are possible: From full cooperation, where multiple base stations form a virtual antenna array, to weak cooperation, where base stations take into consideration the interference caused to users in neighboring cells. In this work, weak cooperation in the form of interference management is investigated. The base stations are equipped with multiple antennas, while the mobile terminals only have a single antenna. Due to the spatial degrees of freedom, a base station can serve multiple users simultaneously. The base stations perform beamforming, user group selection, and scheduling, while the terminals treat interference as noise. The corresponding resource allocation problem is cast as a utility maximization problem, which includes common performance objectives such as arithmetic mean, geometric mean, and max-min of achievable user rates. Due to interference, the resulting utility maximization problem is a nonconvex optimization problem. Still, after a suitable reformulation, the problem can be solved to global optimality using the framework of monotonic optimization. In other words, we provide a framework for computing the jointly optimal beamforming, user selection, and scheduling strategy for each base station, under an arbitrary utility objective. (Joint work with Johannes Brehmer from TUM)
SPEAKER: Wolfgang Utschick completed several industrial education programs before he received the diploma ('93) and doctoral degrees ('98) in electrical engineering, both with honors, from Technische Universitaet Muenchen (TUM). In this period, he held a scholarship of the Bavarian Ministry of Education for exceptional students. From '98 - '02, he co-directed the Signal Processing Group at the Institute of Circuit Theory and Signal Processing at TUM. From '00 to '02, he was consulting in 3 GPP standardization in the field of multi-element antenna systems. In 2000, he was a visiting researcher at ETH Zurich and in 2005, he was a guest professor at the University of Edinburgh. In 2002, Dr. Utschick was appointed Professor at TUM where he is head of the Fachgebiet Methoden der Signalverarbeitung (Associate Institute for Signal Processing). He gives courses on Signal Processing, MIMO Systems, Stochastic Processes, and Optimization Theory (Crosslayer Design, Ressource Allocation) in the field of Wireless Communications. He holds some 10 patens in the field of multiantenna signal processing and has authored and co-authored more than 200 technical articles in international journals and conference proceedings. Dr. Utschick is editor of the Springer book series "Foundations in Signal Processing, Communications and Networking". Dr. Utschick serves as a coordinator and spokesman of the new German wide DFG focus program "Communications over Interference limited Networks" (COIN) which is devoted to topics as cooperative communications, crosslayer design, ad-hoc wireless networks. He is a senior member of the VDE and of the IEEE where he serves as an associate editor for T-SP since '09. From '06 to '09, he was an associate editor for T-CAS 1 and T-CAS 2. Dr. Utschick is recipient of the 2007 Award of the German Informationstechnische Gesellschaft (Award of the German Society for Information Technology).
