  In this paper, existing results regarding the fundamental limits of
simultaneous energy and information transmission in wireless networks are
reviewed. In point-to-point channels, the fundamental limits on the information
rate given a minimum energy rate constraint are fully characterized by the
notion of information-energy capacity function introduced by Varshney in 2008.
In a centralized multi-user channel, the fundamental limits on the information
rates given a minimum energy rate constraint are described by the notion of
information-energy capacity region introduced by Fouladgar and Simeone in 2012.
Alternatively, in a decentralized multi-user channel, the authors have recently
introduced the notion of information-energy Nash region to describe these
fundamental limits. All these fundamental limits reveal the intrinsic trade-off
between the two conflicting tasks of information and energy transmission.
