re for lower latency for small packet transmission. IoT evolution is summarized in Figure 14.2. The items are described in more detailed later in this chapter. IoT operation on top of LTE networks started from Release 8 using Category 1 devices that were available from 2015. Cat-1 is similar to Cat-4, but the peak data rate is limited to 10 Mbps. The initial smartphones had Cat-4 modems with 150 Mbps rates, and the latest smartphones are already Cat-20 with 2 Gbps capability. The lower peak rate in Cat-1 allows some costs to be saved in the baseband. Cat-1 was simple from the network point of view because it was compatible with Release 8 and could be deployed without any network upgrades. IoT device cost and power consumption were optimized in Release 12 with Cat-0 with a lower data rate of 1 Mbps, single-antenna reception, and half duplex RF. All ear- lier LTE devices were mandated to have two-antenna reception, while single-antenna reception can simplify the RF section of IoT devices. Another RF simplification was half duplex, which means that there is no simultaneous transmission and reception for the IoT device. The network has normal FDD operation with simultaneous uplink and 14.2 loT Optimization in LTE Radio downlink, but transmission and reception for a single IoT device are scheduled SO that they do not occur at the same time. The advantage is that a half-duplex device does not need to have a duplex filter at all, reducing the cost and power consumption. Cat-0 was never implemented in practice because there were already more substantial IoT improvements in the pipeline in Release 13. Cat-M in Release 13 brought narrowband RF with 1.4 MHz bandwidth. All earlier LTE devices had to support 20 MHz bandwidth. NB-IoT took it even further with 200 kHz bandwidth. The benefit of narrowband RF is lower cost for the implementation, reduced power consumption, and higher power spectral density for extended coverage. The 1.4 MHz bandwidth was relatively simple for LTE specifications because the smallest LTE bandwidth 