  Radio-frequency energy harvesting constitutes an effective way to prolong the
lifetime of wireless networks, wean communication devices off the battery and
power line, benefit the energy saving and lower the carbon footprint of
wireless communications. In this paper, an interference aided energy harvesting
scheme is proposed for cooperative relaying systems, where energy-constrained
relays harvest energy from the received information signal and co-channel
interference signals, and then use that harvested energy to forward the
correctly decoded signal to the destination. The time-switching scheme (TS), in
which the receiver switches between decoding information and harvesting energy,
as well as the power-splitting scheme (PS), where a portion of the received
power is used for energy harvesting and the remaining power is utilized for
information processing, are adopted separately. Applying the proposed energy
harvesting approach to a decode-and-forward relaying system with the
three-terminal model, the analytical expressions of the ergodic capacity and
the outage capacity are derived, and the corresponding achievable throughputs
are determined. Comparative results are provided and show that PS is superior
to TS at high signal-to-noise ratio (SNR) in terms of throughput, while at low
SNR, TS outperforms PS. Furthermore, considering different interference power
distributions with equal aggregate interference power at the relay, the
corresponding system capacity relationship, i.e., the ordering of capacities,
is obtained.
