MMSE-based MIMO cooperative relaying systems: Closed-form designs and outage behavior

Changick Song, Kyoung Jae Lee, Inkyu Lee

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


In this paper, we investigate minimum mean squared error (MMSE) based amplify-and-forward cooperative multiple antenna relaying systems where a non-negligible direct link exists between the source and the destination. First, we provide a new design strategy for optimizing the relay amplifying matrix. Instead of conventional optimal design approaches resorting to an iterative gradient method, we propose a near optimal closed-form solution which provides an insight. As relay systems with a direct link incur a non-convex problem in general, we exploit the decomposable property of the error covariance matrix and a relaxation technique imposing a structural constraint on the problem. Next, we study the error performance limit of the proposed scheme using diversity-multiplexing tradeoff analysis, which leads to several interesting observations on MMSE-based cooperative relaying systems. Finally, through numerical simulations, we confirm that the proposed solution shows the performance very close to the optimum with much reduced complexity and the analysis closely matches with simulation results.

Original languageEnglish
Article number6280246
Pages (from-to)1390-1401
Number of pages12
JournalIEEE Journal on Selected Areas in Communications
Issue number8
Publication statusPublished - 2012


  • Closed-form design
  • DMT analysis
  • Direct link
  • MIMO
  • MMSE
  • Relay

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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