Simultaneous wireless information and power transfer (SWIPT) technique is a
popular strategy to convey both information and RF energy for harvesting at
receivers. In this regard, we consider a two-way relay system with multiple
users and a multi-antenna relay employing SWIPT strategy, where splitting the
received signal leads to a rate-energy trade-off. In literature, the works on
transceiver design have been studied using computationally intensive and
suboptimal convex relaxation based schemes. In this paper, we study the
balanced precoder design using chordal distance (CD) decomposition, which
incurs much lower complexity, and is flexible to dynamic energy requirements.
It is analyzed that given a non-negative value of CD, the achieved harvested
energy for the proposed balanced precoder is higher than that for the perfect
interference alignment (IA) precoder. The corresponding loss in sum rates is
also analyzed via an upper bound. Simulation results add that the IA schemes
based on mean-squared error are better suited for the SWIPT maximization than
the subspace alignment-based methods.Comment: arXiv admin note: text overlap with arXiv:2101.1216