Smart versus Dumb Signal Processing for MMIMO and 5G

With the advent of Massive MIMO (MMIMO), we can finally exploit the spatial domain for more efficient communications and multiplexing. MMIMO is a theoretically very powerful technology, but with great power comes great responsibility for the engineers that implement the system. The signal processing used for channel estimation, multiuser detection in the uplink, and precoding in the downlink must be implemented in the right way, otherwise, we will not achieve the theoretical gains in practice. Dumb methods such as maximum ratio processing and eigenbeamforming have received a disproportionate attention by the community, probably because they are easy to analyze and implement. Moreover, semi-smart zero-forcing methods that work well in single-cell scenarios are also commonly applied in multi-cell scenarios, where they are far from optimal. In this presentation, I will explain what characterizes a smart signal processing design for MMIMO and how the spatial domain and spatial channel correlation ought to be utilized for interference suppression in 5G.