tailieunhanh - Hybrid beamforming for relay-aided mmWave backhaul links

Massive multiple-input multiple-output (MIMO) and millimeter-wave (mmWave) technologies have emerged as a promising solution to enhance the backhaul wireless link in 5G Heterogeneous networks (HetNets). These mmWave backhaul links, however, are very susceptible to a significant path loss due to the blockage of the line-ofsight and massive antenna arrays may not be sufficient to alleviate such losses. To this end, relays are usually deployed to provide alternative routes that help boost links with high path loss. In this paper, therefore, we consider using relay base stations (RBS) in mmWave backhaul links between small cell base stations (SBS) and a macro-cell base station (MBS). It is assumed that the SBSs, the RBSs, and the MBS are all equipped with massive antenna arrays employing hybrid analog and digital beamforming. | Hybrid Beamforming for Relay-Aided mmWave Backhaul links Mostafa Hefnawi 1 Esmael Yahya 1 Jamal Zbitou 2 Mohamed Aboulfatah 2 Hassan Abdelmounim 2 1 Department of Electrical and Computer Engineering Royal Military College of Canada Kingston ON Canada 2 LMEET FST of Settat University Hassan 1 st Settat Morocco Abstract. Massive multiple-input multiple-output MIMO and millimeter-wave mmWave technologies have emerged as a promising solution to enhance the backhaul wireless link in 5G Heterogeneous networks HetNets . These mmWave backhaul links however are very susceptible to a significant path loss due to the blockage of the line-of-sight and massive antenna arrays may not be sufficient to alleviate such losses. To this end relays are usually deployed to provide alternative routes that help boost links with high path loss. In this paper therefore we consider using relay base stations RBS in mmWave backhaul links between small cell base stations SBS and a macro-cell base station MBS . It is assumed that the SBSs the RBSs and the MBS are all equipped with massive antenna arrays employing hybrid analog and digital beamforming. The analog beamformers are based on the selection of fixed multi-beams using a constrained eigenbeamforming scheme while the digital beamformers are based on the maximum ratio transmission and maximum ratio combining MRT MRC schemes that maximize the transmit and receive SINRs of the effective channels created by the actual channel and the analog beamformer. The performance evaluation in terms of the beampatterns and the ergodic channel capacity shows that the proposed HBF scheme achieves near-optimal performance with only 4 RF chains and requires considerably less computational complexity. Keywords Hybrid beamforming HetNets Relays Massive MIMO mmWaves. 1 Introduction Recently millimeter-wave mmWave massive multiple-input multiple-output MIMO technologies 1 2 3 4 5 6 have emerged as a promising solution to enhance the backhaul wireless link in 5G