D2D-Aided Multi-Antenna Multicasting in a Dense Network

Abstract

We consider the problem of multicast transmission in cooperative cellular systems, where a base station (BS) aims at conveying a common message to a set of user equipments (UEs) that are also connected with each other via device-todevice (D2D) links. Assuming statistical channel knowledge at the BS, we design a two-phase scheme that exploits multi-antenna transmission at the BS and D2D communications between the UEs to achieve a non-vanishing multicast rate when the number of UEs grows large. This represents a non-trivial extension of our previous work, which is restricted to the case of instantaneous channel knowledge at the BS (and is thus impractical for dense networks). Finally, we study the scaling of the resulting multicast rate as a function of the number of UEs and BS antennas for different practical scenarios.