Summary:
It was observed in this subsection that D2D
communication can result in increased power efficiency of
the network. A common technique to achieve this is to
dynamically switch between cellular and D2D modes. The
authors in [54] and [59] propose heuristic algorithms to solve
the mode selection problem, while [57] employs the bruteforce technique. The performance of the method in [57] is thus better than those in the other two, but it also requires
much more computations.