 thus, 5 MHz channel bandwidth is not achievable. It is to be noted that the 60 KHz SCS would allow channel bandwidths up to 200 MHz, but in the time frame of Release 15, there was no operator holding that would require such bandwidth. Therefore, it was decided to limit channel bandwidth at 100 MHz, man- date UEs to support 15 and 30 kHz SCS and all channel bandwidths, while 60 kHz SCS 12 5G RF Design Challenges Table 12.2 Supported channel bandwidths in FR1 and associated spectrum utilization. FR1 Channel BW (MHz) Parameters (kHz) CP-OFDM SU [#RB] DFT-s-OFDM SU [max#RB] CP-OFDM SU [max%] DFT-s-OFDM SU (max%) 242.5 312.5 382.5 452.5 522.5 592.5 552.5 692.5 Min guard band (kHz) is optional. 60 kHz SCS is only supported for bands >1 GHz as the lower bands do not require wide channel bandwidths. Filtering or windowing techniques have been introduced to obtain better spectrum confinement as already discussed in Section 12.2.1. One of the goals was to obtain bet- ter SU (the ratio of allocated RB bandwidth versus channel bandwidth) than for LTE, which is limited to 90% (for example, a 20 MHz channel has the maximum number of RBs of 100 which is 18 MHz). In Table 12.3, the number of maximum allocated RBs is provided for CP-OFDM versus SCS in the first set of rows; this was derived by simulat- ing the Adjacent Channel Leakage Ratio (ACLR), SEM, and the required guard band for both the UE and the BS. Given that different companies have used different spectrum confinement techniques, the end result is not always consistent within a few RBs. In the second set of rows, SU is derived for DFT-s-OFDM, which cannot always achieve the same SU as CP-OFDM because the number of RBs must meet the N RB = 2x X 3Y X 5 superscript(2) rule. In the next two set of rows, the SU in % is reported for CP-OFDM and DFT-s-OFDM. If for small channel bandwidths the result is similar, and for high SCS, sometimes lower than the 90% of LTE, for channel bandwidths above 40 MHz close to 98% SU is achieved. One particular aspect of NR waveforms is that 