bols 36 symbols mobile = 0.71 ms = 0.43 ms = 0.41 ms = 0.32 ms broadband UE Capability 2 for 5 symbols 5.5 symbols 11 symbols low latency UE = 0.36 ms = 0.19 ms = 0.19 ms the requirement for receiver processing is approximately 0.2 ms and for transmitter processing 0.19-0.36 ms. For mobile broadband UE, the requirement is 0.17-0.57 ms depending on the subcarrier spacing. These processing time requirements are sub- stantially tighter than in LTE Release 8, where more than 2 ms was allowed for UE processing. The practical processing times can be lower than the minimum 3GPP requirements. We assume for simplicity in the following text that 5G UEs are just fulfilling 3GPP processing time requirements. We also assume that the processing time in the base station is half of the processing time in the UE. There are no 3GPP requirements defined for the network element processing times. 5G latency is impacted by the TTI size. Table 10.8 and Figure 10.10 show the latency values with full TTI transmission. TTI size is a function of the subcarrier spacing: a larger subcarrier spacing has a shorter TTI, leading to shorter latency. We assume 10 5G Performance Table 10.8 Two-way latency with different subcarrier spacing and full TTI transmission with UE capability 1. Delay component 15 kHz 30 kHz 60 kHz 120 kHz Downlink transmission (ms) 0.125 Uplink transmission (ms) 0.125 Downlink frame alignment (ms) 0.125 0.0625 Uplink frame alignment (ms) 0.125 0.0625 UE processing - reception (ms) UE processing -transmission (ms) BTS processing - reception (ms) BTS processing - transmission (ms) Transport and core (ms) Total (ms) Round trip time 15 kHz 30 kHz 60 kHz 120 kHz Downlink transmission Uplink transmission Frame alignment Scheduling UE processing - RX UE processing - TX BTS processing - RX BTS processing - TX Transport and core Figure 10.10 Two-way latency with different subcarrier spacings and full TTI transmission with UE capability 1. here continuous transmission and reception, which means FDD, and UE processing capability 1. Th