 and Corresponding Maximum Bandwidth Sub-carrier Cyclic OFDM Symbol OFDM Symbol Max BW quency Prefix/Guard Spacing (kHz) Duration (us) with CP (us) (MHz) Range Space (us) 66.67 71.35 33.33 35.68 16.67 17.84 16.67 17.84 CP length is based on the path delay information, and the BS and UE determine this information with synchronization signals (using the PSS and SSS frames). Hence, based on the path propagation delay details from each UE, 5G NR defines a CP for each transmission stream. An operator can choose to use different numerology values simultaneously in each cell to support different 5G use cases-services can utilize different OFDM numerologies, multiplexed on the same frequency channel. The caveat is that mixing different numerologies on a carrier can cause in- terference with sub-carriers of another numerology. Synchronization can eliminate the major source of the interference by coordinating the frame timing. Therefore, the synchronization accuracy re- quirements are even more stringent with 5G frame structure and time-slot duration than they were with previous generations of radio. 10.4.1 5G System Architecture In parallel to its work on aspects of the NR radio, 3GPP is working on the overall system architec- ture, including the 5G Core network (5GCN) and the 5G RAN. These components have the follow- ing responsibilities: The 5GCN is responsible for control functions like authentication and access, charging, end-to- end connection setup, mobility management, policy control, and many similar functions in the control plane of the mobile network. It is also responsible for the User Plane Function (UPF), although the core maintains a clear split between the user and control plane functions. The 5G RAN is responsible for all radio-related functionality, including scheduling, radio-re- source handling, transmission, coding, multi-antenna schemes, and SO on. The following section details the basic features of the 5GCN. A detailed treatment of the architec- ture is beyond the scope of this book because it is unn