Hybrid Beamformers Design for MIMO Relay Networks in Millimeter Wave

Abstract

Abstract-One of the challenges for the wireless networks is meeting the high demand for cellular data. One approach is to utilize the wide bandwidth provided by the millimeter wave (mmWave) frequencies. In this work, we propose using multiple relays to link two points in the outdoor mmWave environments. We use hybrid (analog and digital) beamformers in the Amplify-and-Forward (AF) half duplex relays to overcome the propagation losses usually arise in such environments. The design is based on the the widely known Orthogonal Match Pursuit (OMP) algorithm. Results show significant performance improvement for multiple relay links as compared to links with single relay. The results also discuss the influence of the array size and the number of RF chains on the overall performance.

Hybrid Beamforming and Relay Selection for End-to-End SNR Maximization in Single-User Multi-Relay MIMO Systems

“…Contrary to the aforementioned works on relay-assisted hybrid beamforming for different communication networks (e.g., [ 34 , 35 , 36 , 37 , 38 ]), this paper proposes a beamforming and relay selection simultaneously. Relay selection in a multi-hop transmission system is an essential design aspect to avoid performance degradation due to error propagation [ 40 , 41 ].…”

“…In [ 34 ], orthogonal matching pursuit (OMP) based solution proposed in [ 23 ] was extended to design the relay-assisted MIMO network with AF relaying protocol. The hybrid transceiver design proposed in [ 23 ] was further modified in [ 35 ] and [ 36 ] to design multi-relay MIMO systems. In [ 35 ], only the analog precoders/combiners were employed at relay nodes, while hybrid processing components were used at source and destination.…”

“…In [ 35 ], only the analog precoders/combiners were employed at relay nodes, while hybrid processing components were used at source and destination. In contrast to the hybrid precoding design in [ 35 ], the proposed algorithm in [ 36 ] used hybrid beamformers at all communicating nodes. In [ 37 ], the digital baseband processing component and the analog RF beamformer were designed separately for a single relay multi-user MIMO system by using pre-defined codebooks, and this approach was adopted to avoid intractable searching problem.…”

“…It is obvious from the obtained results that the proposed approach has a great potential to show good performance in sparse and rich scattering environments such as mm-Wave and Rayleigh fading channels, respectively. The existing works (e.g., [ 34 , 35 , 36 , 37 , 38 ]) only focus on the hybrid beamforming design for relay-assisted mm-Wave MIMO systems under different scenarios. With this perspective, there is a need to address relay-assisted MIMO communication in conjunction with a relay selection mechanism to enhance spectral efficiency of the system.…”

“…The existing works (e.g., [ 34 , 35 , 36 , 37 , 38 ]) only focus on the hybrid beamforming design for relay-assisted mm-Wave MIMO systems under different scenarios. With this perspective, there is a need to address relay-assisted MIMO communication in conjunction with a relay selection mechanism to enhance spectral efficiency of the system.…”