Optimal Design of Random Unitary Beamforming for Energy Efficiency in MIMO Broadcast Channels

Jae Hong Kwon, Young Chai Ko, Sung Sik Nam

Research output: Contribution to journalArticlepeer-review


Random unitary beamforming (RUB) achieves multiuser diversity gain over multiple-input multiple-output broadcast channels with partial channel state information (CSI). RUB can asymptotically achieve the same growth of rate as the optimal dirty paper coding or sub-optimal zero-forcing beamforming, which need full CSI at the transmitter. In this paper, we propose energy efficient RUB systems that select the optimal number of streams and transmission power to maximize energy efficiency (EE). In contrast to other beamforming schemes that use full CSI, optimizing RUB in terms of EE is a difficult task due to the CSI constraints. To solve this problem, we first select the EE-optimal number of streams and transmission power by using the statistical characteristics of RUB, which have been studied in previous works. Next, based on partial CSI feedback from users, we propose the method whereby the transmitter of RUB can adaptively control the transmission power. Simulation results demonstrate that our proposed systems can improve the EE performance of RUB and that the analytical results derived in this paper are accurate.

Original languageEnglish
Article number7968426
Pages (from-to)12865-12877
Number of pages13
JournalIEEE Access
Publication statusPublished - 2017 Jul 5

Bibliographical note

Publisher Copyright:
© 2013 IEEE.


  • Random unitary beamforming
  • energy efficiency
  • joint optimization
  • power control

ASJC Scopus subject areas

  • General Computer Science
  • General Materials Science
  • General Engineering


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