ts (k,l) in increasing order of k where k and l represent the frequency and time indices, respectively (see Table 4.3), New Radio Access Physical Layer Aspects (Part 2) 481 SS burst set periodicity (20 ms) SS burst set SS burst SS burst SS burst SS burst 5ms [Half frame] window Figure 4.30 SS block structure and timing [6,8]. within one SS/PBCH block [6]. The SSS sequence mapping to resource elements in the fre- quency domain is illustrated in Fig. 4.28. Furthermore, the time-frequency structure and timing of the SSS transmission are depicted in Fig. 4.29. 4.1.4.3 Synchronization Signal Blocks In NR, the primary and secondary synchronization signals are used by the UE for initial cell search and to obtain frame timing, Cell ID, and to find the reference signals for coherent demodulation of other channels. The PSS, SSS, and PBCH are time-multiplexed and trans- mitted in an SSB with the same numerology. One or more SS block(s) constitute an SS burst, and one or more SS bursts form an SS burst set as illustrated in Fig. 4.30. The SS burst sets are transmitted periodically. An SS block consists of four consecutive OFDM symbols. Regardless of the SS burst set composition, the transmission of SSBs within an SS burst set is confined to a 5 ms window to help the UEs reduce power consumption and com- plexity for radio resource management-related measurements. Fig. 4.31 compares the syn- chronization signals and broadcast channel transmission timings of LTE and NR. The SS block is transmitted periodically with a period which may be configured between 5 and 160 ms. However, the UEs performing initial cell search or handover can assume that the SS block is repeated every 20 ms. Each SS burst set is always confined to a 5 ms win- dow located either in the first or the second half of a 10 ms radio frame. This allows a UE that is searching for an SS block in the frequency domain to know the time duration it should pause at each frequency before retuning to the next frequency within the synchroni- zation raster, concluding that 