Generic Iterative Downlink Interference Alignment

Won-Yong SHIN
Jangho YOON

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B    No.5    pp.834-841
Publication Date: 2015/05/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.834
Type of Manuscript: PAPER
Category: Fundamental Theories for Communications
Keyword: 
beamforming,  interference alignment (IA),  iterative algorithm,  leakage of interference,  multi-cell downlink network,  

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Summary: 
In this paper, we introduce a promising iterative interference alignment (IA) strategy for multiple-input multiple-output (MIMO) multi-cell downlink networks, which utilizes the channel reciprocity between uplink/downlink channels. We intelligently combine iterative beamforming and downlink IA issues to design an iterative multiuser MIMO IA algorithm. The proposed scheme uses two cascaded beamforming matrices to construct a precoder at each base station (BS), which not only efficiently reduce the effect of inter-cell interference from other-cell BSs, referred to as leakage of interference, but also perfectly eliminate intra-cell interference among spatial streams in the same cell. The transmit and receive beamforming matrices are iteratively updated until convergence. Numerical results indicate that our IA scheme exhibits higher sum-rates than those of the conventional iterative IA schemes. Note that our iterative IA scheme operates with local channel state information, no time/frequency expansion, and even relatively a small number of mobile stations (MSs), unlike opportunistic IA which requires a great number of MSs.