The 39 GHz bands are under investigation, but significant public support and research have not materialized. Nonetheless, this band features some characteristics that may make it a compromise for wider adoption. The FCC has proposed 39 GHz for potential mobile use. Verizon, while focusing on 28 GHz for its initial field trials in 2017, has access to 39 GHz via its business relationship with XO Communications, which owns substantial 39 GHz licenses. Still, public support and acknowledgment of 28 GHz and 73 GHz research are more visible than that for other frequencies.
To capitalize on the promise of mmWave for 5G, researchers must develop new technologies, algorithms and communications protocols. The fundamental properties of the mmWave channel are different from current cellular models and are relatively unknown. The importance of building mmWave prototypes cannot be overstated, especially in this early timeframe. Building system prototypes demonstrates the viability and feasibility of a technology or concept in a way that simulation alone cannot (see Figure 3). mmWave prototypes communicating in real time, over the air, in a variety of scenarios will unlock the secrets of the mmWave channel and enable innovation, technology adoption and proliferation.
