  In this paper, we consider a prospective receiving hybrid beamforming
structure consisting of several radio frequency (RF) chains and abundant
antenna elements in multi-input multi-output (MIMO) systems. Due to
conventional costly full connections, we design an enhanced partially connected
beamformer employing a low-density parity-check (LDPC)-based structure. As a
benefit of the LDPC-based structure, information can be exchanged among
clustered RF/antenna groups, which results in a low computational complexity
order. Advanced message passing (MP) capable of inferring and transferring
information among different paths is designed to support the LDPC-based hybrid
beamformer. We propose a message-passing enhanced antenna and RF chain
selection (MARS) scheme for minimizing the operational power of antennas and RF
chains of the receiver as well as hybrid beamforming. Furthermore, sequential
and parallel MP schemes for MARS are designed, namely, MARS-S and MARS-P,
respectively, to address the convergence speed issue. A heuristic genetic
algorithm is designed for receiving hybrid beamforming, comprising gene
generation initialization, elite selection, crossover, and mutation.
Simulations validate the convergence of both the MARS-P and the MARS-S
algorithms. Due to the asynchronous information transfer of MARS-P, it requires
higher power than MARS-S, which strikes a compelling balance among power
consumption, convergence, and computational complexity. It is also demonstrated
that the proposed MARS scheme outperforms the existing benchmarks using the
heuristic method of fully/partially connected architectures in the open
literature by requiring the lowest power and realizing the highest energy
efficiency.
