TY - JOUR
T1 - Layered Downlink Precoding for C-RAN Systems with Full Dimensional MIMO
AU - Kang, Jinkyu
AU - Simeone, Osvaldo
AU - Kang, Joonhyuk
AU - Shamai, Shlomo
N1 - Funding Information:
This work was supported in part by the Institution for Information and Communications Technology Promotion of the Ministry of Science, ICT, and Future Planning of South Korea through the ICT R&D Program under Grant B0101-16-1372.
Publisher Copyright:
© 2017 IEEE.
PY - 2017/3
Y1 - 2017/3
N2 - 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.
AB - 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.
KW - Cloud radio access networks (C-RAN)
KW - Fronthaul compression
KW - Full-dimensional multiple-input multiple-output (FD-MIMO)
KW - Layered precoding
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U2 - 10.1109/TVT.2016.2572199
DO - 10.1109/TVT.2016.2572199
M3 - Article
AN - SCOPUS:85015726642
SN - 0018-9545
VL - 66
SP - 2170
EP - 2182
JO - IEEE Transactions on Vehicular Communications
JF - IEEE Transactions on Vehicular Communications
IS - 3
M1 - 7478143
ER -