Title: Interference alignment for MIMO cognitive networks: a complex FDPM-based subspace tracking approach

Authors: Bin Zhu; Jianhua Ge; Jing Li; Xiaoye Shi; Yunxia Huang

Addresses: State Key Laboratory of Integrated Services Networks, Xidian University, No. 2, South Taibai Road, Xi'an, Shaanxi 710071, China ' State Key Laboratory of Integrated Services Networks, Xidian University, No. 2, South Taibai Road, Xi'an, Shaanxi 710071, China ' State Key Laboratory of Integrated Services Networks, Xidian University, No. 2, South Taibai Road, Xi'an, Shaanxi 710071, China ' State Key Laboratory of Integrated Services Networks, Xidian University, No. 2, South Taibai Road, Xi'an, Shaanxi 710071, China ' Southwest Communication Institute, No. 6, Chuangye Road, Chengdu, Sichuan 610041, China

Abstract: Interference alignment (IA) for multiple-input multiple-output (MIMO) cognitive networks is considered by modelling the unlicensed secondary transmitter-receiver pairs which coexist with the licensed multi-antenna primary user as a K-user MIMO interference channel. Starting from investigating the constraint conditions of IA scheme in MIMO cognitive networks, a practical IA algorithm is developed by using a subspace tracking approach based on the complex fast data projection method (FDPM). In the proposed algorithm, first, each secondary transmitter aligns its transmitted signal into the null space of the channel matrix from itself to the primary user without causing any interference to the primary user. Then secondary transmitters and receivers, requiring no channel knowledge of secondary networks, alternately design the precoding and postprocessing matrices through a training period which exploits the complex FDPM-based minor subspace tracking, thus eliminating interference among secondary users. Moreover, the case where secondary transmitters have partial knowledge of channels from themselves to the primary user is also discussed. Simulation results reveal that the proposed algorithm can achieve a high sum rate performance while requiring low computational complexity.

Keywords: interference alignment; subspace tracking; fast data projection; multiple-input multiple-output; MIMO cognitive networks; sum rate; simulation.

DOI: 10.1504/IJES.2013.057089

International Journal of Embedded Systems, 2013 Vol.5 No.3, pp.166 - 174

Received: 09 Nov 2012
Accepted: 26 May 2013
Published online: 19 Jul 2014 *

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