g), layer-1 signaling (DCI indication), and timer. Compared to RRC signaling, DCI indication offers better latency for active BWP change (2 ~ 3 ms instead of 10 ~ 15 ms) and less signaling overhead at the cost of higher modem complexity. To illustrate how the modem's operation bandwidth affects its power consump- tion, the mixed signal circuits block in Figure 13.1 is expanded and shown in Figure 13.14. When the operation bandwidth is scaled down, the function blocks of A/D (analog-to-digital) converter, D/A (digital-to-analog) converter and baseband unit can use a lower voltage and/or a lower clock rate due to less data sample for processing. When the PDCCH monitoring periodicity is scaled up (i.e. longer periods, and hence slower), RF circuits can be turned off until the next PDCCH monitoring occasion and other function blocks can either be turned off or use a lower voltage and clock rate. To improve the modem power efficiency by BWP operation, the 5G NR modem should be designed to enable dynamic voltage/clock rate adjustment (because the power consumed by a semiconductor chip is proportional to the applied clock rate and the 13 5G Modem Design Challenges Voltage Voltage Voltage converter 5G NR Voltage Clock RF circuits Baseband unit Antennas converter Clock Clock Clock Figure 13.14 Function blocks in 5G NR modem. Table 13.7 System-level evaluation assumptions. Parameters Assumptions Deployment scenario Dense urban (clustered 21 macro cells, ISD = 200 m) Users per cell Carrier frequency 4 GHz FTP traffic model 4 packets per second, packet size = 1.75 MB Video traffic model H.264 (3840p X 2160p, 30 fps) Buffered video length: 1 S DRX configuration On duration: 8 ms Inactivity timer: 100 ms Retransmission timer: 4 ms Long cycle: 160 ms Short cycle: 40 ms Short cycle timer: 0 ms ISD: Inter-site distance. square of the applied voltage) and reduce additional energy required for turning on/off of function blocks for more frequent on/off transitions. To illustrate how bandwidth adaptation improves the power efficiency