2 research outputs found
Harvested Power Maximization in QoS-Constrained MIMO SWIPT with Generic RF Harvesting Model
We consider the problem of maximizing the harvested power in Multiple Input
Multiple Output (MIMO) Simultaneous Wireless Information and Power Transfer
(SWIPT) systems with power splitting reception. Different from recently
proposed designs, we target with our novel problem formulation at the jointly
optimal transmit precoding and receive uniform power splitting (UPS) ratio
maximizing the harvested power, while ensuring that the Quality-of-Service
(QoS) requirement of the MIMO link is satisfied. We assume generic practical
Radio Frequency (RF) Energy Harvesting (EH) receive operation that results in a
non-convex optimization problem for the design parameters, which we then solve
optimally after formulating it in an equivalent generalized convex form. Our
representative results including comparisons of achievable EH gains with
benchmark schemes provide key insights on various system parameters.Comment: 5 pages, 3 figures, accepted to IEEE CAMSAP 201
Optimal Channel Estimation for Hybrid Energy Beamforming under Phase Shifter Impairments
Smart multiantenna wireless power transmission can enable perpetual operation
of energy harvesting (EH) nodes in the internet-of-things. Moreover, to
overcome the increased hardware cost and space constraints associated with
having large antenna arrays at the radio frequency (RF) energy source, the
hybrid energy beamforming (EBF) architecture with single RF chain can be
adopted. Using the recently proposed hybrid EBF architecture modeling the
practical analog phase shifter impairments (API), we derive the optimal
least-squares estimator for the energy source to EH user channel. Next, the
average harvested power at the user is derived while considering the nonlinear
RF EH model and a tight analytical approximation for it is also presented by
exploring the practical limits on the API. Using these developments, the
jointly global optimal transmit power and time allocation for channel
estimation (CE) and EBF phases, that maximizes the average energy stored at the
EH user is derived in closed form. Numerical results validate the proposed
analysis and present nontrivial design insights on the impact of API and CE
errors on the achievable EBF performance. It is shown that the optimized hybrid
EBF protocol with joint resource allocation yields an average performance
improvement of over benchmark fixed allocation scheme.Comment: accepted for publication in IEEE Transactions on Communications, 17
pages, 17 figure