Interference Alignment in Two-Cell LTE-Advanced Heterogeneous Networks

Fei YU  Lu TANG  Luxi YANG  Changchun ZHANG  Weiping ZHU  

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B   No.1   pp.126-133
Publication Date: 2015/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.126
Type of Manuscript: Special Section PAPER (Special Section on Quality of Diversifying Communication Networks and Services)
Category: 
Keyword: 
heterogeneous networks,  interference alignment,  two-cell,  degree-of-freedom,  

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Summary: 
In this paper, we address the issue of interference alignment (IA) in a two-cell network and consider both inter-cell and intra-cell interferences. For cell one, a linear processing scheme is proposed to align the inter-cell interference to the same signal dimension space of intra-cell interference. For cell two, we propose a distributed interference alignment scheme to manage the interference from the nearby cell. We assume that the relay works in an amplify-and-forward (AF) mode with a half-duplex and MIMO relaying. We show that the composite desired and interfering signals aggregated over two time slots can be aligned such that the interfering signal is eliminated completely by applying a linear filter at the receiver. The precoding matrix of the relay is optimized jointly with the precoding matrix of the base station (BS). The number of data streams is optimized jointly for every user terminal (UT). The degree of freedom (DoF) performance of the proposed scheme as well as the conventional cooperation scheme are derived for multiple antennas at both base stations, relay station and user terminals. Simulation results show that the proposed alignment scheme can achieve a better DoF performance.