  Energy harvesting (EH) from ambient radio-frequency (RF) electromagnetic
waves is an efficient solution for fully autonomous and sustainable
communication networks. Most of the related works presented in the literature
are based on specific (and small-scale) network structures, which although give
useful insights on the potential benefits of the RF-EH technology, cannot
characterize the performance of general networks. In this paper, we adopt a
large-scale approach of the RF-EH technology and we characterize the
performance of a network with random number of transmitter-receiver pairs by
using stochastic-geometry tools. Specifically, we analyze the outage
probability performance and the average harvested energy, when receivers employ
power splitting (PS) technique for "simultaneous" information and energy
transfer. A non-cooperative scheme, where information/energy are conveyed only
via direct links, is firstly considered and the outage performance of the
system as well as the average harvested energy are derived in closed form in
function of the power splitting. For this protocol, an interesting optimization
problem which minimizes the transmitted power under outage probability and
harvesting constraints, is formulated and solved in closed form. In addition,
we study a cooperative protocol where sources' transmissions are supported by a
random number of potential relays that are randomly distributed into the
network. In this case, information/energy can be received at each destination
via two independent and orthogonal paths (in case of relaying). We characterize
both performance metrics, when a selection combining scheme is applied at the
receivers and a single relay is randomly selected for cooperative diversity.
