5G standards progress and challenges

The 3GPP standardization process for the fifth generation of wireless networks, 5G, has been in full gear since early 2016. Perhaps one of the most ambitious standardization goal in wireless history; encompassing diverse characteristics such as massive broadband connectivity, massive (and densely) connected devices, and ultra reliable and low latency connection. In this paper, we review the progress of physical layer signaling design for 5G such as waveforms, multiple-input multiple-output (MIMO) technologies, and above 6GHz considerations. We also discuss key challenges in physical layer design as well as hardware design aspects.