  Underlay in-band device-to-device (D2D) multicast communication, where the
same content is disseminated via direct links in a group, has the potential to
improve the spectral and energy efficiencies of cellular networks. However,
most of the existing approaches for this problem only address either spectral
efficiency (SE) or energy efficiency (EE). We study the tradeoff between SE and
EE in a single cell D2D integrated cellular network, where multiple D2D
multicast groups (MGs) may share the uplink channel with multiple cellular
users (CUs). We formulate the EE maximization problem with constraint on SE and
maximum available transmission power. A power allocation algorithm is proposed
to solve this problem and its efficacy is demonstrated via extensive numerical
simulations. The tradeoff between SE and EE as a function of density of D2D
MGs, and maximum transmission power of a MG is characterized.
