A new user selection measure in Block Diagonalization algorithm for multiuser MIMO systems

Riichi Kudo, Yasushi Takatori, Kentaro Nishimori, Atsushi Ohta, Shuji Kubota, Masato Mizoguchi

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Multiuser - Multiple Input Multiple Output (MU-MIMO) techniques were proposed to increase spectrum efficiency; a key assumption was that the Mobile Terminals (MTs) were simple with only a few antennas. This paper focuses on the Block Diagonalization algorithm (BD) based on the equal power allocation strategy as a practical MU-MIMO technique. When there are many MTs inside the service area of the access point (AP), the AP must determine, at each time slot, the subset of the MTs to be spatially multiplexed. Since the transmission performance depends on the subsets of MTs, the user selection method needs to use the Channel State Information (CSI) obtained in the physical layer to maximize the Achievable Transmission Rate (ATR). In this paper, we clarify the relationship between ATR with SU-MIMO and that with MU-MIMO in a high eigenvalue channel. Based on the derived relationship, we propose a new measure for user selection. The new measure, the eigenvalue decay factor, represents the degradation of the eigenvalues in null space compared to those in SU-MIMO; it is obtained from the signal space vectors of the MTs. A user selection method based on the proposed measure identifies the combination of MTs that yields the highest ATR; our approach also reduces the computational load of user selection. We evaluate the effectiveness of user selection with the new measure using numerical formulations and computer simulations.

Original languageEnglish
Pages (from-to)3206-3218
Number of pages13
JournalIEICE Transactions on Communications
Issue number10
Publication statusPublished - 2009 Oct
Externally publishedYes


  • Block Diagonalization
  • Channel capacity
  • Multiuser mimo
  • User selection

ASJC Scopus subject areas

  • Software
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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