Orthogonalized spatial multiplexing for closed-loop MIMO systems

Heunchul Lee, Seokhwan Park, Inkyu Lee

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)


In this paper, we propose a novel spatial multiplexing (SM) scheme for transmission over flat-fading multiple-input multiple-output (MIMO) channels, which allows simple maximum- likelihood decoding at the receiver with small feedback information. We begin with a real-valued representation of the complex-valued system model, and show that we can achieve orthogonality between transmitted signals by applying a proper rotation to transmitted symbols. Compared with other closed-loop methods, the proposed scheme significantly reduces the processing complexity at both transmitter and receiver as well as the feedback overhead. We also combine the proposed orthogonalization method with antenna-selection techniques, and then discuss a criterion based on the minimum Euclidean distance between received vectors for selecting the optimal subset of multiple transmit antennas. Using geometrical properties of the receive constellations, we also present a simple antenna-selection metric for the proposed SM systems. Simulation results demonstrate that our SM system performs close to the optimum closed-loop system with much-reduced complexity.

Original languageEnglish
Pages (from-to)1044-1052
Number of pages9
JournalIEEE Transactions on Communications
Issue number5
Publication statusPublished - 2007 May


  • Closed-loop multiple-input multiple-output (MIMO) systems
  • Maximum-likelihood decoding (MLD)
  • Spatial multiplexing (SM)
  • Transmit-antenna selection

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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