Spatial Multiplexing with Limited RF Chains: Generalized Beamspace Modulation (GBM) for mmWave Massive MIMO

Shijian Gao, Xiang Cheng, Liuqing Yang

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Millimeter wave (mmWave) massive multiple-input multiple-output (mMIMO) has been recognized as a promising candidate for 5G communications for its capability of supporting Gb/s transmission. However, it is a common exercise to deploy a limited number of radio-frequency (RF) chains at mmWave mMIMO transceivers due to hardware complexity and cost. As a result, the potential multiplexing gain (MG), which is restricted by the smaller number of RF chains at the transmitter and receiver, is markedly compromised. In order to boost the MG and spectral efficiency (SE), we innovatively develop a novel index modulation termed as the generalized beamspace modulation (GBM). The acquisition of (sub-)beamspace is owing to a natural exploitation of the unique features of mmWave mMIMO. Based on the (sub-)beamspace, a complete GBM transceiver is designed and optimized. Unlike existing alternatives that are largely digital based, our GBM is tailored for the hybrid structure of mmWave mMIMO and can, thereby, realize efficient spatial multiplexing despite the limited RF chains. Extensive analyses and simulations have demonstrated remarkable superiority of GBM over existing counterparts in terms of the error performance and SE.

Original languageEnglish (US)
Article number8772188
Pages (from-to)2029-2039
Number of pages11
JournalIEEE Journal on Selected Areas in Communications
Issue number9
StatePublished - Sep 2019
Externally publishedYes

Bibliographical note

Funding Information:
Manuscript received December 1, 2018; revised April 8, 2019; accepted June 22, 2019. Date of publication July 25, 2019; date of current version August 19, 2019. This work was supported in part by the National Key Research and Development Project under Grant 2017YFE0121400, in part by the Major Project from Beijing Municipal Science and Technology Commission under Grant Z181100003218007, in part by the National Science and Technology Major Project under Grant 2018ZX03001031, in part by the National Natural Science Foundation of China under Grant 61622101 and Grant 61571020, and in part by NSF ECCS-1935915. This paper part has been presented in the IEEE Global Communications Conference (Globe-com), Abu Dhabi, UAE, December 9-13, 2018 [1]. (Corresponding author: Xiang Cheng.) S. Gao and L. Yang are with the Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80523-1373 USA (e-mail:;

Publisher Copyright:
© 1983-2012 IEEE.


  • Millimeter wave
  • generalized beamspace modulation
  • massive multiple-input multiple-output
  • multiplexing gain
  • spectral efficiency


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