ingent delay requirements (e.g., HARQ protocol) or the functions where performance is proportional to latency (e.g., radio channel and signal measurements at physical layer or random access control). Radio-specific functions in the lower MAC can perform scheduling-related processing and reporting. They can also control activities of the configured UEs and report statistics periodically or on-demand to the upper MAC. This option will allow traffic aggregation/distribution from/to NR and LTE transmission points. Moreover, it can facilitate the management of traffic load between NR and LTE transmission points. In this option, the requirement for fronthaul bandwidth and latency can be relaxed depending on the load across access and core net- work interface. It allows efficient interference management across multiple cells and enhanced coordinated scheduling schemes such as multipoint transmission/reception. Option 6: In this option, the physical layer and RF functions are implemented in the DU, whereas the upper protocol layers are located in the CU. The interface between the CU and the DUs carries data, configuration, and scheduling-related information, as well as measurement reports. This option will allow centralized traffic aggregation from NR and LTE transmission points, which can facilitate management of traffic load between NR and LTE access nodes. The fronthaul requirements in terms of throughput are reduced as the payload for this option are transport block bits. Joint transmission and scheduling is also possible in this case since MAC sublayer is centralized. This option may require subframe-level timing synchronization between MAC sublayer in the CU and physical layer in the DUs. Note that round-trip fronthaul delay may affect HARQ timing and scheduling. Option 7: In this option as shown in Fig. 1.27, the lower physical layer functions and RF circuits are located in the DU(s). The upper protocol layers including the upper physical layer functions reside in the CU. There are multiple realizations of this op