Course Description

Musics Doctoral School is pleased to announce the following course :

Distributed MIMO: theory, architecture and implementation

by François Quitin, Electrical and Computer Engineering Department, University of California, Santa Barbara

When?  November 6th, 2012 at 11.00 am
 
Where? Building C, 3rd floor,  OPERA service, ULB

Abstract:

MIMO systems have received tremendous attention from the research community in the last decade. By increasing the number of antennas at the transmitter and/or receiver, it is possible to increase communication range, link quality, reduce interference etc. The idea of Distributed MIMO (D-MIMO) is to exploit the potential benefits of MIMO with SISO terminals: different single-antenna terminals can be combined to create a “virtual” antenna array. In this talk, two particular sub-problems of D-MIMO will be investigated: distributed transmit (D-Tx) beamforming and distributed receive (D-Rx) beamforming.

The biggest challenges of D-MIMO systems are the different levels of synchronization that must be achieved among the different terminals to operate a virtual array, and the scalability to larger network sizes. Three types of synchronization are required: frequency, phase and timing. The frequency offset results from the fact that each node has its own local oscillator (LO), and small LO offsets between nodes may result in large LO frequency offsets. The phase synchronization is needed because the path lengths between the different nodes are unknown. The timing offset is due to the fact that each node has its own clock, and common time references are needed to align the clocks of all the nodes. Solutions for these problems must always take scalability into account: for larger networks, it is important not to drown the network with control messages.

For both the D-Tx and D-Rx beamforming, we will present architectures that are able to tackle the synchronization issues while maintaining scalability to larger networks. Synchronization is achieved with feedback-based strategies that are able to synchronize the nodes of the virtual array; even with low-quality local oscillators typically used for software-defined radios. The proposed architectures are investigated theoretically, and closed-form expressions for the limits of our architecture are deduced. Finally, for both D-Tx and D-Rx beamforming, the proposed architecture is implemented on our software-defined radio testbed. Our experiments show with appropriate design, the potential benefits of D-MIMO can be achieved with low-cost radios.

Biography :

François Quitin received his PhD degree in Electrical Engineering from the Université Libre de Bruxelles (ULB) and Université catholique de Louvain (UCL) in 2011. He is currently working as a post-doctoral researcher at the University of California, Santa Barbara.  He received the Alcatel-Bell Lucent 2012 award, the WoWMoM 2012 best demo award and the EuCAP 2009 best propagation poster award.

His research interests focus on the interplay between propagation channel and RF hardware for advanced wireless systems, like distributed MIMO, UAV-based communication networks and 60 GHz wireless systems.