2 research outputs found
Simultaneous Wireless Information and Power Transfer in a Two-User OFDM Interference Channel
In this paper, we study the Simultaneous Wireless Information and Power
Transfer (SWIPT) in a Single-Input Single-Output (SISO) two-user Orthogonal
Frequency Division Multiplexing (OFDM) Interference Channel (IFC). We assume
that the transmitters are non-cooperative and have perfect knowledge of the
local Channel State Information (CSI). We show that the necessary condition for
the optimal transmission strategy at high SNR is for the energy transmitter to
transmit its signal by allocating its transmit power on a single subcarrier.
Accordingly, we propose a one-subcarrier selection method for the energy
transmitter and identify the achievable rate-energy region. In addition, we
further enlarge the achievable rate-energy region by enabling a basic form of
transmitter cooperation where messages are exchanged to inform the energy
transmitter about the subcarriers unutilized by the information transmitter
Multi-tone Signal Optimization for Wireless Power Transfer in the Presence of Wireless Communication Links
In this paper, we study optimization of multi-tone signals for wireless power
transfer (WPT) systems. We investigate different non-linear energy harvesting
models. Two of them are adopted to optimize the multi-tone signal according to
the channel state information available at the transmitter. We show that a
second-order polynomial curve-fitting model can be utilized to optimize the
multi-tone signal for any RF energy harvester design. We consider both
single-antenna and multi-antenna WPT systems. In-band co-existing communication
links are also considered in this work by imposing a constraint on the received
power at the nearby information receiver to prevent its RF front end from
saturation. We emphasize the importance of imposing such constraint by
explaining how inter-modulation products, due to saturation, can cause high
interference at the information receiver in the case of multi-tone signals. The
multi-tone optimization problem is formulated as a non-convex linearly
constrained quadratic program. Two globally optimal solution approaches using
mixed-integer linear programming and finite branch-and-bound techniques are
proposed to solve the problem. The achieved improvement resulting from applying
both solution methods to the multi-tone optimization problem is highlighted
through simulations and comparisons with other solutions existing in the
literature