Optimal precoding for orthogonalized spatial multiplexing in closed-loop MIMO systems

Young Tae Kim, Heunchul Lee, Seokhwan Park, Inkyu Lee

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


In this paper, we propose a new precoding algorithm for orthogonalized spatial multiplexing (OSM) systems over flatfading multiple-input multiple-output (MIMO) channels. The OSM scheme was recently introduced for closed-loop MIMO systems which allows single symbol decodable maximum likelihood detection. To further improve the performance of the OSM system, we propose a new precoding method by maximizing the minimum Euclidean distance between constellation points in the effective channel. In order to efficiently identify the parameters of a precoder which maximizes the minimum distance, we introduce a partitioning approach. Through analysis, it is shown that one real value parameter and two bits are required for feedback information for precoding in 16-QAM systems. Simulation results demonstrate that our algorithm provides 9dB and 7.5dB gains at a bit error rate (BER) of 10-4 over the conventional OSM systems for 4-QAM and 16-QAM, respectively. We also confirm that the performance of the proposed scheme is the same as that of the optimum closed-loop MIMO systems in terms of the minimum distance. Consequently, our precoding algorithm significantly improves the system performance with a small increase of feedback amount.

Original languageEnglish
Article number4641965
Pages (from-to)1556-1566
Number of pages11
JournalIEEE Journal on Selected Areas in Communications
Issue number8
Publication statusPublished - 2008 Oct


  • Closed-loop MIMO system
  • Limited feedback
  • ML receiver
  • Minimum Euclidean distance
  • Precoding design

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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