  Multicast device-to-device (D2D) transmission is important for applications
like local file transfer in commercial networks and is also a required feature
in public safety networks. In this paper we propose a tractable baseline
multicast D2D model, and use it to analyze important multicast metrics like the
coverage probability, mean number of covered receivers and throughput. In
addition, we examine how the multicast performance would be affected by certain
factors like mobility and network assistance. Take the mean number of covered
receivers as an example. We find that simple repetitive transmissions help but
the gain quickly diminishes as the repetition time increases. Meanwhile,
mobility and network assistance (i.e. allowing the network to relay the
multicast signals) can help cover more receivers. We also explore how to
optimize multicasting, e.g. by choosing the optimal multicast rate and the
optimal number of retransmission times.
