lustrated in Figure 14.12. 14.6 Coverage Coverage optimization is one of the targets in LTE IoT design. Coverage can be measured as the maximum allowed path loss between the device and base station 14 Internet of Things Optimization Figure 14.13 NB-loT coverage target. 140 dB 150 dB 164 dB Multimedia Voice >1 Mbps >10 kbps >100 bps antennas. A good-quality data connection can be maintained with path loss values up to 130-140 dB and low-data-rate voice up to 145-150 dB. The target for IoT connectivity is a path loss up to 164 dB for a very-low-data-rate connection of only 100 bps = 0.1 kbps. The coverage extension is illustrated in Figure 14.13. In theory, the path loss can be improved by 20 dB when the data rate is reduced by 20 dB, that is, by a factor of 100. The practical solutions for coverage extension are narrowband transmissions with power boosting, repetition, and retransmission. Link budgets are needed to estimate the maximum allowed path loss. The path loss value can then be converted into the maximum cell radius based on the propagation models. We use the following assumptions for the link budget calculations: The base station transmission power is assumed as 32 dBm per 200 kHz for LTE-M corresponding to 40 W for 10 MHz, which is a typical case for low band LTE FDD. 35 dBm per 200 kHz is assumed for NB-IoT including power boosting. The UE transmission power is assumed as 23 dBm. The base station noise figure is assumed as 3 dB and for the UE 5 dB. The IoT data rate is relatively low when using extreme coverage. Figure 14.14 illus- trates the IoT data rate as a function of the path loss. LTE-M can support up to 161 dB path loss in the uplink, which is 5 dB more than the 3GPP target of 156 dB. NB-IoT can support even up to 167 dB path loss. We note that the data rate becomes very low at high path loss values. We also note that the uplink coverage is still the limiting fac- tor. The downlink data rate at 156 dB is 20 kbps with LTE-M and 5 kbps with NB-IoT, while the uplink data rate is just 0.8 kbps. The 