Secrecy sum-rates for multi-user MIMO regularized channel inversion precoding

Giovanni Geraci, Malcolm Egan, Jinhong Yuan, Adeel Razi, Iain B. Collings

Research output: Contribution to journalArticleResearchpeer-review

113 Citations (Scopus)


In this paper, we propose a linear precoder for the downlink of a multi-user MIMO system with multiple users that potentially act as eavesdroppers. The proposed precoder is based on regularized channel inversion (RCI) with a regularization parameter α and power allocation vector chosen in such a way that the achievable secrecy sum-rate is maximized. We consider the worst-case scenario for the multi-user MIMO system, where the transmitter assumes users cooperate to eavesdrop on other users. We derive the achievable secrecy sum-rate and obtain the closed-form expression for the optimal regularization parameter α-{LS} of the precoder using large-system analysis. We show that the RCI precoder with α-{LS} outperforms several other linear precoding schemes, and it achieves a secrecy sum-rate that has same scaling factor as the sum-rate achieved by the optimum RCI precoder without secrecy requirements. We propose a power allocation algorithm to maximize the secrecy sum-rate for fixed α. We then extend our algorithm to maximize the secrecy sum-rate by jointly optimizing α and the power allocation vector. The jointly optimized precoder outperforms RCI with α-{LS} and equal power allocation by up to 20 percent at practical values of the signal-to-noise ratio and for 4 users and 4 transmit antennas.

Original languageEnglish
Article number6253216
Pages (from-to)3472-3482
Number of pages11
JournalIEEE Transactions on Communications
Issue number11
Publication statusPublished - 2012
Externally publishedYes


  • MIMO systems
  • multi-user communications
  • physical layer security
  • precoding
  • Secrecy rate

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