However, unlike its predecessors, the fifth generation will empower more than smartphones and tablets, but fixed-wireless access (FWA) broadband delivery, autonomous vehicles, the “Factory of the Future”, connected cities, and dozens of applications within the broad umbrella of IoT. It’s a tall order, and delivering on all this presents enormous technological challenges, of which three, millimeter-wave operation, small cells, and artificial intelligence, stand out.
For example, even though carrier aggregation, more spectrally-efficient modulation schemes, and spectrum sharing will help, 5G along with Wi-Fi and other services will ultimately consume nearly all that remains of the available spectrum below 6 GHz. After that, there’s nowhere to go but up in frequency, possibly even to 95 MHz, for which even the FCC in the U.S. is on board (Figure 1). In the spirit of Field of Dreams, the commission is evaluating the viability of allocating more than 21 GHz of unlicensed spectrum between 95 GHz and 3 THz. The hope is that if spectrum is available “they will come”. After making the announcement, FCC Chairman Ajit Pai noted the limitations of this new frontier but touted the “mammoth swaths of airwaves” available.
However, for anyone who’s developed components and systems in this region such a plan probably seems comical at best and impossible at worst considering its immense challenges. That is, there are good reasons why, except for microwave links, satellite communications, and some military systems, millimeter wavelengths have remained uninhabited. But the commitment by the wireless industry illustrates just how much bandwidth the industry believes it will need to handle the disparate services that 5G will eventually provide. Why else would this or any other industry take it upon itself to operate in a region of the spectrum that is inherently inhospitable to the transmission and reception of electromagnetic energy?