MMSE Based Block Diagonalization for Cognitive Radio MIMO Broadcast Channels

• Published in: IEEE transactions on wireless communications Vol. 10; no. 10; pp. 3139 - 3144
• Main Authors: Lee, Kyoung-Jae, Lee, Inkyu
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; block diagonalization (BD); Blocking; Channels; Cognitive radio; Design engineering; Downlink; Exact sciences and technology; Interference; Matrix decomposition; MIMO; minimum mean-squared error (MMSE); multi-user MIMO; Plutonium; Radio; Radiocommunication specific techniques; Radiocommunications; Receivers; Receiving antennas; Signal to noise ratio; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Wireless communication; Performance evaluation; MIMO system; Multiple access; Diagonalization; multi-user MIMO; Transmission channel; block diagonalization (BD); Downlink; Cognitive radio; Algorithm; Mean square error; minimum mean-squared error (MMSE); Simulation; Broadcast channels; Signal to interference plus noise ratio; Radio communication; Software radio
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2011.081611.101853

In this paper, we present a linear precoder design for cognitive radio (CR) multi-user multiple-input multiple-output (MU-MIMO) downlink systems where unlicensed secondary users (SUs) can simultaneously utilize the same spectrum used by a licensed primary user (PU). Although a zero-forcing block diagonalization (ZF-BD) precoder is extended to the CR network with the PU, a transmit power boost problem occurs. Therefore, we propose a regularized BD precoder method based on the minimum mean-squared error (MMSE) criteria subject to the interference power constraint under a predetermined threshold for the PU. As a result, the proposed CR-MMSE-BD scheme improves the signal-to-interference-plus-noise ratio at each SU's receiver, compared to the ZF-BD based method. The simulation results demonstrate that the proposed algorithm outperforms the ZF based technique for CR MU-MIMO downlink systems.