5G benefits to consumers and enterprises include higher data throughputs, lower latency, and increased network reliability. On the radio side, this is enabled by use of wider RF bandwidths—beyond 100 MHz—in the sub-6 GHz bands (like the popular C-bands), as well as higher-order modulation schemes (256 QAM). Both factors, when combined with stringent 3GPP-defined RF spectral compliance requirements, put pressure on RF designers for system-level optimization.
The 3GPP-defined base station classes are important, because they define the minimum RF requirements that the product needs to support. Examples include error vector magnitude (EVM) of the transmitted signal (which translates to modulation order) and adjacent channel leakage ratio (ACLR) and other unwanted signal transmissions (say, RF spurs) that define unwanted transmissions outside of the intended transmitted spectrum. These minimum RF requirements differ per base station class, generally being more relaxed for lower-power product classes (e.g., Local Area). In addition to 3GPP base station classes, we can define a market segmentation that outlines typical products that are deployed by managed network operators (MNOs) or private networks. There are no standardized definitions of these cell types, so keep in mind there is some fluidity in this definition. This paper considers relatively low-power base station classes (Femto, Pico, Micro).
