there is no PSS/SSS present at that frequency. The 20 ms SS block periodicity is four times longer than the corresponding 5 ms periodicity of LTE PSS/ SSS transmission (see Fig. 4.31). The longer SS block period was selected to improve the NR network energy efficiency and to reduce the layer-1 overhead. The disadvantage of a NR SS/PBCH block locations in time and frequency (configurable locations based on subcarrier spacing, frequency range, and other higher layer parameters) SS block periodicity Offset relative to center frequency RF carrier center frequency Frame = 10 ms Frame = 10 ms Frame = 10 ms Frame = 10 ms LTE PSS, SSS, and PBCH locations in time and frequency (fixed timing, periodicity, and frequency Locations) Frame = 10 ms Frame = 10 ms- Frame = 10 ms Frame = 10 ms RF carrier center frequency PSS/SSS periodicity (5 ms) PBCH periodicity (40 ms) Figure 4.31 Comparison of LTE and NR synchronization and broadcast channel transmission timing. New Radio Access Physical Layer Aspects (Part 2) 483 OFDM symbol Case A (SCS = 15 kHz) Case B (SCS= 30 kHz) Case C (SCS 30 kHz) Case B (SCS 30 kHz) Coexistence 0.125ms Case D (SCS= 120 kHz) Case E (SCS 240 kHz) Figure 4.32 Structure and timing of SS/PBCH block transmission with various numerologies [6,31]. longer SS block period is that a device must pause at each frequency for a longer time in order to conclude that there is no PSS/SSS at the frequency. However, this is compensated by the sparse synchronization raster relative to LTE, which reduces the number of frequency-domain locations at which a device must search for an SS block. The maximum number of SSBs within an SS burst set is 4 for frequency ranges up to 3 GHz, 8 for 3-6 GHz, and 64 for above 6 GHz in order to achieve a trade-off between coverage and layer-1 overhead. Furthermore, the number of actually transmitted SSBs could be less than the maximum number. The position(s) of actually transmitted SSBs can be sig- naled to the UEs in order to assist their RRC_CONNECTED or RRC_IDLE mode measure- ments and to