Turning 5G wireless communication into a widespread reality will require the use of mmWave frequencies. However, there are many of us RF engineers out there that have spent much of our careers working in the sub-6 GHz range, which actually has quite different needs than mmWave. Therefore, it is critical to get a handle on the key differences between working in this range and mmWave frequencies.
Three Key Differences Between Sub-6 GHz and mmWave Operations
First and foremost, the rules and specifications, such as those defined by the 3GPP Specification 3GPP TS 38.104 V17.2.0 (2021-06), are different for mmWave. At a high level, this specification defines the frequency ranges where 5G can operate – FR1 (4.1 GHz to 7.125 GHz) and FR2 (24.25 GHz to 52.6 GHz). It also highlights a variety of additional performance requirements that are important to understand when building mmWave base stations and small cells including base station classes, differences in channel bandwidths, and how to test for and handle unwanted emissions.