ssociated NPUSCH is at least 8 ms. Upon completion of the transmission of NPUSCH, the UE monitors NPDCCH to check whether NPUSCH was received correctly by the base station, or a retransmission is required [4,14]. 6.4.2 Physical, Logical, and Transport Channels NB-IoT physical, transport, and logical channel structure are similar to LTE, with the exception that there is no physical uplink control channel in NB-IoT and the UCI content is carried in NPUSCH. In the downlink, NB-IoT provides the following physical signals and channels. Unlike LTE, these NB-IoT physical channels and signals are primarily multi- plexed in time [6]. NPBCH Internet of Things DL-SCH UL-SCH Transport channels Physical channels NPBCH NPDSCH NPDCCH NPUSCH NPRACH Figure 6.22 NB-loT channel structure [6]. NPDCCH NPDSCH The NB-IoT includes the following channels in the uplink: NPRACH NPUSCH NPRACH is a newly designed channel since LTE PRACH uses a bandwidth of 1.08 MHz, which is more than NB-IoT uplink bandwidth (Fig. 6.22). 6.4.3 Cell Search and Random-Access Procedure Synchronization is an important aspect in cellular network operation. When a UE is pow- ered on, it needs to find and camp on a suitable cell. For this purpose, the UE must synchro- nize to downlink symbol, subframe, and frame timing, as well as to the carrier frequency. In order to synchronize with the carrier frequency, the UE needs to correct any frequency offset that is present due to local oscillator inaccuracy, and to perform symbol timing align- ment with the frame structure from the base station. In addition, due to the presence of mul- tiple cells, the UE needs to detect a particular cell on the basis of an NB-PCID. As a result, a typical synchronization procedure consists of determining the timing alignment, correcting the frequency offset, obtaining the correct cell identity, and the absolute subframe and frame number reference. The NB-IoT technology is intended to be used for low-cost UEs and at the same time, to provide extended coverage for UEs deployed in environme