Optimal diagonal precoder for multiantenna communication systems

Zhiyong Yan, Kon Max Wong, Zhi Quan Luo

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


In this paper, we examine a multiantenna single-user wireless communication system fitted with a QR-based successive cancellation receiver (QR receiver). Initially, our consideration is confined to uncoded binary phase shift keying (BPSK) signals transmitted through independent and identically distributed (IID) Rayleigh fading channels and to the design of an optimum precoder for the transmitter. For minimum feeding back of the channel state information (CSI) to the transmitter from the receiver, we stipulate the precoder to be in the form of a power loading square diagonal matrix. We proceed to develop the theory for the design of this diagonal matrix based on the minimization of the lower bound of the average bit error rate (BER) of transmission. The design obtained provides substantially lower error rates than most of other existing schemes under the same environment. The corresponding gain in signal-to-noise ratio (SNR) can be several decibels. To further improve the performance, we extend the design to include an optimal detection order of the received bits using an iterative approach. This iterative process proves to have fast convergence and results in a design providing significant SNR gain. We also propose a subchannel dropping scheme for cases in which SNR is low, and when the minimum BER precoder is equipped with this scheme, its average performance can be substantially superior to the Vertical Bell Laboratories Layered Space-Time (V-BLAST) detection. We extend our design of the optimum precoder to quadrature amplitude modulation (QAM) modulation scheme and similar performance gain has been observed.

Original languageEnglish (US)
Pages (from-to)2089-2100
Number of pages12
JournalIEEE Transactions on Signal Processing
Issue number6
StatePublished - Jun 2005

Bibliographical note

Funding Information:
Manuscript received September 10, 2003; revised July 12, 2004. The third author was supported by an NSF grant. The associate editor coordinating the review of this manuscript and approving it for publication was Dr. Martin Haardt.


  • Diagonal precoder
  • MIMO


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