ion by oxygen. The absorption, however, has only a marginal impact on the cell range since the attenuation is below 10 dB/km. Assuming a typical cell range of clearly less than 1 km shows that the worst-case oxygen absorption is just a few decibels. Since the presence of oxygen is fairly consistent at ground level, its effect on 60 GHz radio propagation can be easily modeled. Weather-related attenuation is even more insignificant at those bands. Even heavy rainfall of 25 mm per hour causes just 5 dB/km attenuation and makes only a very small percentage contribution to the aggregate attenuation in the 60 GHz oxygen absorption region. More details about millimeter wave measurements can be found in Chapter 13. Mid-Band Spectrum at 3.3-5.0 GHz and at 2.6 GHz Spectrum at 3.3-5.0 GHz, also known as the C-band, is the mainstream spectrum for 5G and provides a nice combination of high bandwidth, wide area coverage, and global availability. This spectrum is emerging as a core band for 5G. Figure 4.9 illustrates 3GPP frequency variants in 3.3-4.2 GHz and the typical global allocations. Many countries have - and will - allocate up to 400 MHz of spectrum at 3.4-3.8 GHz, while other countries are able to allocate only a part of that spectrum. Those allocations fall into the 3GPP band n78 covering 3.3-3.8 GHz. More spectrum is expected to be available later at 3.8-4.2 GHz, which is covered by the 3GPP band n77. Japan already allocated spectrum at 3.8-4.1 GHz in 2019. Some regulators reserve a part of the 3.5 GHz spectrum for local and regional use for industrial networks. The target is that this part of the spectrum can be utilized locally 4 Spectrum 3.3 GHz 3.8 GHz 3GPP n78 500 MHz 3.3 GHz 4.2 GHz 3GPP n77 900 MHz 3.4 GHz 3.8 GHz Europe 400 MHz 3.4 GHz 3.6 GHz China 200 MHz 3.55 GHz 3.7 GHz USA CBRS 150 MHz 3.4 GHz 3.7 GHz Korea 300 MHz 3.4 GHz 3.6 GHz 4.1 GHz Japan 200 MHz (4G) 500 MHz Figure 4.9 Global spectrum allocation at the 3.3-4.2 GHz band. in the factories or other similar cases to provide private networks for ultra-