Massive MIMO (mMIMO) is crucial for meeting 5G’s use cases and promise for both performance and energy efficiency, so it is not surprising to witness rapid gains in shipments and deployments as 5G roll-out proceeds. The driving factors are clear enough – the potential to serve multiple users and devices simultaneously while sustaining high data rates and consistent performance efficiently, which makes it a strong fit for 5G, particularly the eMBB (enhanced mobile broadband) high speed use cases. Yet mMIMO was not originally envisioned to become such a major driver for 5G, having only broken into the cellular industry around 2006 on the back of a few research projects. It had already made its mark in WiFi and has roots…