Bit allocation schemes for MIMO equal gain precoding

Chi Liang Chao*, Shang-Ho Tsai, Terng-Yin Hsu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We design equal gain precoders with scalar quantization in MIMO systems with limited feedback, which do not require the predefined codebook. In such precoders, bit allocation can be used to quantize the precoding vector/matrix to further improve the system performance. There are two conventional bit allocation schemes. One is the uniform bit allocation and the other is the optimal bit allocation obtained by using exhaustive search. The uniform bit allocation is simple but turns out to have obvious performance degradation. On the other hand, the exhaustive search method leads to the optimal performance. However, its computational complexity is extremely high and may be somewhat impractical to be realized. In this paper, we propose two bit allocation schemes for the MIMO equal gain precoder with scalar quantization. Both of the proposed methods are with low complexity and their performance is close to the optimal scheme. Consequently, the proposed bit allocations provide good trade-off between performance and complexity.

Original languageEnglish
Article number5725208
Pages (from-to)1345-1350
Number of pages6
JournalIEEE Transactions on Wireless Communications
Issue number5
StatePublished - May 2011


  • Bit allocation
  • MIMO
  • equal gain precoder
  • limited feedback
  • scalar quantized (SQ)


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