, depending on the carrier frequency. Assuming d is constant, Eq. (7.4) can be transformed to: L() = 0 log(d) + log(f) - 147.56 = K2 + 20 log(f) where K2 = 0log(d) - 147.56 In other words, doubling the carrier frequency from f to 2f, leads to: = 0log(2.f) = K2 + log(f) + 20 log(2) = K2 + log(f) + 6.02 => That is, a path loss increases in 6 dB. 7 NG-RAN Deployment Considerations This shows that technology advantages designed to increase the maximum coupling loss (MCL) (e.g. NB-IoT MCL increase from 144 dB of GSM to 164 dB) can be lost quickly, once a certain technology is being deployed on higher frequency bands without taking care of proper network planning with appropriate inter-NG-RAN site distances. The examples above are just simple considerations based on the free space propagation formula (FSPF). Even though the FSPF isn't applicable for wave propagation in urban areas, it allows the estimation of the number of base stations required for the cellular deployments, independent of the technology used. Detailed channel modeling for different NG-RAN deployment scenarios is avail- able in 3GPP TS 38.901 (3GPP TS 38.901), which can be used to further refine the back-of-the-envelope calculations shown above. 7.4.3 5G Frequency Ranges Currently the frequencies being considered for NG-RAN across the world include low, mid- dle, and high frequency ranges. The propagation characteristics for each of these ranges are different and justify different kinds of NG-RAN deployment architecture. In the lower ranges, a typical coverage of a macro cell is around 2-2.5 km. In the middle range, it is around 1-1.5 km and in high ranges (mm Wave) it is around 100-500 m. In terms of bandwidth, lower frequency ranges offer tens of MHz of bandwidth, middle ranges up to 100 MHz of bandwidth, and mmWave several 100 MHz of bandwidth. This is illustrated in Table 7.1. In other words, lower bands provide larger coverage with lower bandwidth, while higher bands provide larger bandwidth with lower coverage. These characteristics lead to diffe