Within a PTW, the determination of the PFs and POs is done in the same way as for the non-eDRX. The NB-IoT supports stationary and low-mobility UEs as most of the NB-IoT nodes are sensors and devices that hardly move. Handover is not supported in NB-IoT, thus when an TeDRX Extended sleep Paging transmission window (PTW) DRX cycle Sleep Paging occasion (PO) Figure 6.25 Illustration of the correspondence of PO and PTW. Internet of Things 783 NB-IoT UE moves out of the coverage area of the serving cell, it will experience a radio link failure (RLF). As we mentioned earlier, an NB-IoT UE may support data transport via control plane. The UE may also support data transfer via the user plane, and when it does, the RRC connection reestablishment procedure is supported, which means that after an RLF is detected, the UE attempts to find a suitable cell through cell selection. If the UE finds a suitable cell, it will try to reestablish the connection on that cell and resume the data trans- fer. The RRC reestablishment intends to hide the temporary loss of the radio interface to the upper layers. The RRC reestablishment for a UE only supporting data transfer via the control plane was added in 3GPP Rel-14 [6,8]. 6.5 Implementation and Deployment Considerations The NB-IoT specifications meet a number of challenging requirements including a greater coverage area, longer device battery life, and lower device cost resulting from the small and intermittent data transmissions. The reduced peak data rate requirements make it possible to employ a simple radio and baseband processing in the receiver chain. With half-duplex operation of the NB-IoT, the duplex filter in a typical LTE device can be replaced by a sim- ple switch in addition to fewer oscillators for frequency synthesis. The use of simplified downlink convolutional coding instead of the LTE turbo code would allow a low- complexity baseband decoding process. The main candidate architectures are the zero-IF and low-IF receivers, which combine analog frontends and digital base