Power Efficiency
Power efficiency enhancement techniques for D2D-enabled
cellular networks is also a very interesting research topic.
Xiao et al. propose a heuristic algorithm for power
allocation in OFDMA-based cellular networks. They propose
a heuristic that performs power allocation and mode selection
using the existing subcarrier and bit allocation algorithms
in [55] and [56]. The heuristic first allocates the resources
for the cellular users and then performs resource allocation
and mode selection for D2D users. If the required power level
for D2D transmission is higher than a certain threshold, the
D2D pair communicates through the BS. Via simulations, they
show that the integration of their proposed heuristic with the
existing algorithms in [55], [56] improves the downlink power
consumption of the network around 20%
in comparison to the traditional OFDMA system without D2D.