Graduate School and Research Center in Digital Sciences

Seminar: CM Seminar

Hossein A.Moghaddam (Univ. Oulu, Supelec)

Communication systems

Date: January 8, 2016

Location: Eurecom - salle Shannon

Title: Decentralizing the Optimal Multi-cell Beamforming with QoS Quarantees via Large System Analysis Speaker: Hossein A.Moghaddam (Univ. Oulu, Supelec) Abstract: The deployment of low power nodes (e.g., micro- or pico-cells, as well as relay nodes) within the basic macro-cell coverage is foreseen to be a widely used solution in the future to cope with the ever increasing mobile traffic demands. The close proximity of transmitting nodes and different power classes of low-power nodes and macro-cells results in challenging inter-cell interference (ICI) scenarios. Coordinated beamforming has been recognized as a promising scheme to improve the system performance by controlling or exploiting inter-cell interference. Due to dependency of inter-cell coordination on backhaul message exchanges, the backhaul imperfections such as limited link capacity and latency may restrict the achievable gains specifically when the number of antennas (N), the number of users (K) and the number of cells (L) are large or in a fast fading scenario. We address the coordinated beamforming problem where the objective to minimize the total transmit power in a multi-cell network. The problem has received great attention in the last years and is gaining renewed interest nowadays due to the emerging research area of green multi cellular networks. The decentralized coordination has been realized in the literature by exchanging messages related to the instantaneous inter-cell interference (ICI) values via a backhaul link in handshaking fashion which suffer from above mentioned imperfections. A possible way out to the above issues relies on conducting the analysis in large system regime in which N and K grow large with a given ratio K/N. Tools from random matrix theory are used to compute deterministic approximations for ICI values, which only depend on the channels statistics and the spatial load. Given the approximation of ICI values, we propose a quality of service guaranteed non-iterative fully decentralized solution to compute approximations of the optimal beamforming vectors in finite regime. Bio: Hossein A.Moghaddam received his M.Sc. (Tech.) degree in wireless communication engineering from the University of Oulu, Finland, in 2013. He worked as a research assistant at Department of Communication Engineering (DCE) and Centre for Wireless Communications (CWC), University of Oulu, during his Master's Thesis preparation. He began studying for his doctoral degree in January of 2014 and his research is focused on applications of random matrix theory for wireless communication. He is currently (until March, 2016) a visiting researcher at SUPELEC, France.

CM Seminar