Frame structure: 10ms frame, 1ms subframe, slots

The Three-Level Time Hierarchy

The 5G NR frame structure organizes time into three nested levels. A radio frame spans 10 milliseconds and is divided into ten subframes of 1 millisecond each. Each subframe contains two-to-the-mu slots, so higher numerologies pack more slots into the same subframe duration. A slot always contains fourteen OFDM symbols under normal cyclic prefix or twelve symbols under extended CP, which is available only with mu equals two. The System Frame Number counts from 0 to 1023 and then wraps, creating a 10.24-second cycle broadcast in the MIB.