- Massive multiple-input multiple-output (MIMO) is promising technology which scales up the current state-of-the-art MIMO by employing a large number of antennas at the base station that can help significantly improve the network capacity, and energy efficiency. This research proposal aims to investigate key research issues pertaining to physical-layer massive MIMO systems within the context of future 5G wireless cellular networks. Specifically, we plan to study various signal processing techniques, known as secrecy beamforming/precoding, in the downlink and relay channels that improve the physical layer secrecy. We also plan to study the effects of the intermediate relay agents as cooperative jammers in an effort to enhance the physical-layer security. The proposed ideas will have important contributions for Qatar because they tackle its wireless communication security capability. In particular, the proposed effort addresses fundamental challenges related to the defense of the Information and Communication Technology (ICT) infrastructure.