CSIT-Free Multi-Group Multicast Transmission in Overloaded mmWave Systems

In this paper, we investigate the downlink multi-group multicast (MGM) transmission problem in overloaded mmWave systems. In particular, the conventional MGM beamforming requires substantial computational complexity and feedback (or pilot) overhead for acquisition of channel state information at the transmitter (CSIT), while simultaneous interference management and multicast beamforming optimization across multi-group inevitably incurs a significant rate loss. To address this, we propose a CSIT-free MGM (CF-MGM) transmission that eliminates the need for a complex CSIT acquisition. A deterministic CSIT-free precoding and proposed closed-form power allocation based on max-min fairness (MMF) allow each user to detect the common multicast stream completely canceling the inter-group interference with a significantly low complexity. Simulation results demonstrate the superiority and scalability of the proposed CF-MGM for the achievable rate and increase of users in a group outperforming the existing CSIT-based methods.