Layered Downlink Precoding for C-RAN Systems with Full Dimensional MIMO

Jinkyu Kang, Osvaldo Simeone, Joonhyuk Kang, Shlomo Shamai

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The implementation of a cloud radio access network (C-RAN) with full dimensional (FD) multiple-input multiple-output (MIMO) is faced with the challenge of controlling the fronthaul overhead for the transmission of baseband signals as the number of horizontal and vertical antennas grows larger. This paper proposes to leverage the special low-rank structure of the FD-MIMO channel, which is characterized by a time-invariant elevation component and a time-varying azimuth component, by means of a layered precoding approach, to reduce the fronthaul overhead. According to this scheme, separate precoding matrices are applied for the azimuth and elevation channel components, with different rates of adaptation to the channel variations and correspondingly different impacts on the fronthaul capacity. Moreover, we consider two different central unit (CU)-radio unit (RU) functional splits at the physical layer, namely, the conventional C-RAN implementation and an alternative one in which coding and precoding are performed at the RUs. Via numerical results, it is shown that the layered schemes significantly outperform conventional nonlayered schemes, particularly in the regime of low fronthaul capacity and a large number of vertical antennas.

Original languageEnglish (US)
Article number7478143
Pages (from-to)2170-2182
Number of pages13
JournalIEEE Transactions on Vehicular Technology
Issue number3
StatePublished - Mar 2017

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Computer Networks and Communications
  • Automotive Engineering


  • Cloud radio access networks (C-RAN)
  • Fronthaul compression
  • Full-dimensional multiple-input multiple-output (FD-MIMO)
  • Layered precoding


Dive into the research topics of 'Layered Downlink Precoding for C-RAN Systems with Full Dimensional MIMO'. Together they form a unique fingerprint.

Cite this