MIMO broadcast channels based on SINR feedback using a non-orthogonal beamforming matrix

Jongrok Park, Hojae Lee, Sanghoon Lee

Research output: Contribution to journalArticle

7 Citations (Scopus)


The signal to interference plus noise ratio (SINR) feedback has been utilized in random beamforming (RBF) to select users for multiple-input multiple-output (MIMO) systems where a large number of users are required to obtain a multi-user diversity gain. However, if the number of users is not large enough, it may be difficult to obtain the performance gain and be easy to have a performance degradation conversely. To resolve this problem, it is necessary to find orthogonal random beams close to the channel matrix of selected users. In this paper, we present RBF using a non-orthogonal beamforming matrix (RBF NOBM), demonstrating an efficient search of random beams correlated with the channel matrix of selected users over a small number of users. For single user RBF using NOBM (SU-RBF NOBM) with two transmit antennas, the beamforming matrix for user data service is obtained through closed form expressions, and SU-RBF NOBM is then expanded to more than two transmit antennas. We also propose user selection algorithms for SU-RBF NOBM and multi-user RBF using NOBM (MU-RBF NOBM). Via simulation results, we demonstrate that the performances of RBF NOBM represent significant improvements compared to conventional beamforming schemes.

Original languageEnglish
Article number6226899
Pages (from-to)2534-2545
Number of pages12
JournalIEEE Transactions on Communications
Issue number9
Publication statusPublished - 2012 Jul 3

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

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