dWidth Part (BWP) adaptation, an effective mechanism to reduce the modem's power consumption resulting from wide bandwidth usage in 5G NR. 13.2 High Data Rate, System Flexibility, and Computational Complexity Table 13.1 Impact of 5G NR features on modem design. NR Features High data rate and Low latency and Multi-RAT Modem impacts system flexibility flexible timing coexistence bandwidth Computational complexity Control flow complexity Modem architecture Power consumption Table 13.1 illustrates how the key 5G NR features contribute to impacting the modem. For example, multi-(Radio Access Technology) RAT coexistence primarily impacts the modem architecture. This chapter exposes the many challenges facing the 5G NR modem design and the solutions implemented to address those. Each part in this chapter focuses on one key NR feature (column in Table 13.1) and its associated modem impacts (rows in Table 13.1) with a particular emphasis on the main challenge to overcome. First, high data rates and system flexibility are discussed, focusing on tackling the associated computational complexity issue. Then, low latency and flexible frame structure are addressed from the main standpoint of control flow complexity. Thereafter, multi-RAT coexistence and the challenge it poses on modem architecture are debated. Finally, NR wide bandwidth operation is analyzed in relation to power consumption. High Data Rate, System Flexibility, and Computational Complexity The IMT-2020 requirements for 5G specify a target peak data rate of 20 Gbps for down- link (network to mobile device) [1], a 20-fold increase compared to the IMT-Advanced requirement (1 Gbps). In addition, IMT-2020 requirements target a threefold increase in spectrum efficiency compared to IMT-Advanced. To meet the above requirements, higher-layer Multiple Input Multiple Output (MIMO) schemes as well as flexible reference signal configurations to minimize the system overhead are cornerstones of the 5G NR design. This part elaborates on how the complexity in the device scales a