Interference alignment for a multi-user SISO interference channel

International audienceOur work addresses the single-input single-output interference channel. The goal is to show that although interference alignment is suboptimal in the finite power region, it is able to achieve a significant overall throughput. We investigate the interference alignment scheme proposed by Choi et al. (IEEE Commun. Lett. 13(11): 847-849, 2009), which achieves a higher multiplexing gain at any given signal dimension than the scheme proposed by Cadambe and Jafar (IEEE Trans. Inform. Theory 54(8), 2008). Then, we try to modify the IA design in order to achieve enhanced sum-rate performance in the practical signal-to-noise ratio (SNR) region. Firstly, we introduce a way to optimize the precoding subspaces at all transmitters, exploiting the fact that channel matrices in the interference model of a single-input single-output channel are diagonal. Secondly, we propose to optimize jointly the set of precoder bases within their associated precoding subspaces. To this end, we combine each precoder with a new combination precoder, and this latter seeks the optimal basis that maximizes the network sum rate. We also introduce an improved closed-form interference alignment scheme that performs close to the other proposed schemes

Downlink Cellular Interference Alignment

Cellular networks have been notoriously interference-limited systems in dense urban areas, where base stations are deployed in close proximity to one-another. Recently, a signal processing method called Interference Alignment has emerged, making use of the increasing signal dimensions available in the system through multiple-input multiple output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) technologies. In this report, we review the state of the art of interference alignment since its foundation, and we detail algorithms and baseline comparisons to make when applying interference alignment schemes to downlink cellular networks. We also propose a number of research directions of interest which are not yet answered in the current literature.Les réseaux cellulaires ont été l'exemple typique de réseaux dont les performances sont limités par les interférences, particulièrement dans les régions urbaines. Récemment, une nouvelle technique de traitement du signal appelée "alignement d'interférences" a été dévelopée, et permet d'utiliser les dimensions du signal reçu à travers les technologies MIMO (multiple input multiple output) et OFDM (orthogonal frequency division multiplexing) pour annuler tout ou partie de l'interférence reçue par les mobiles. Dans ce rapport, nous évaluons la littérature liée à l'alignement d'interférence et nous détaillons les algorithmes existants et leur application aux réseaux cellulaires en voie descendante. Nous proposons ensuite un ensemble de directions de recherche d'intérêt par rapport à l'état de l'art actuel