Previous generations of wireless technology have used lower-frequency bands of spectrum. To offset the challenges relating to distance and interference with mmWave, the wireless industry is also considering the use of a lower-frequency spectrum for 5G networks so network operators could use spectrum they already own to build out their new networks. Lower-frequency spectrum reaches greater distances but has lower speed and capacity than mmWave.
The lower frequency wireless spectrum is made up of low- and midband frequencies. Low-band frequencies operate at around 600 to 700 megahertz (MHz), while midband frequencies operate at around 2.5 to 3.5 GHz. This is compared to high-band mmWave signals, which operate at approximately 24 to 39 GHz.
MmWave signals can be easily blocked by objects such as trees, walls and buildings -- meaning that, much of the time, mmWave can only cover about a city block within direct line of sight of a cell site or node. Different approaches have been tackled regarding how to get around this issue. A brute-force approach involves using multiple nodes around each block of a populated area so that a 5G-enabled device can use an Air interface -- switching from node to node while maintaining MM wave speeds.