will be sent to it, it must monitor NPDCCH subframes and attempt to decode them, in order to detect a pending downlink trans- mission. The NPDCCH configuration for a UE is primarily defined by how often the UE should start to monitor NPDCCH subframes and the maximum number of subframes that it should monitor. These two parameters are denoted by NPDCCH period T and maximum NPDCCH repetitions Rmax (Fig. 6.15). In the example shown in Fig. 6.16, the NPDCCH period is assumed to start from a subframe at time t = 0. Therefore, the UE starts to monitor Table 6.3: Various NB-loT DCI formats [3]. DCI Format Size (bits) Content Uplink grant NPDSCH scheduling RACH procedure initiated by NPDCCH order Paging and direct indication 766 Chapter 6 Period (T) 12 Assigned repetitions (R = 4) Maximum repetitions (Rmax) 8 Nongap interval Gap interval Start of period = aT Offset: a = 0 UE1: Rmax = 2 UE3: Rmax 8 T= 16 a=3/8 Figure 6.15 Example NPDCCH configuration for an NB-loT UE and the use of an offset to create non- overlapping NPDCCH configurations (18,19]. NPDCCH subframes at the following time instances 0, T, 2T, While there are T sub- frames in one period, the UE monitors NPDCCH subframes for a maximum duration equal to Rmax subframes, alternatively referred to as the non-gap interval. The duration of the remain- ing T Rmax subframes are known as gap interval. Fig. 6.16 further shows that at the start of the second period, the UE has received four repetitions of the NPDCCH, which it would then start decoding to check for any relevant control information. The choice of Rmax, for a given period T, has the following implications. A large Rmax implies higher downlink signal-to-interference plus noise ratio (SINR), resulting in better downlink coverage. A large Rmax further indicates more opportunities to schedule the UE within period T. In heavy net- work loading scenarios, this may decrease the waiting time for the UE to be scheduled. The maximum number of scheduling opportunities per second can be represented by Rmax/T. A trade-o