Describe the 5G NR frame structure and flexible numerology.

5G NR introduces flexible numerology to support diverse use cases. Subcarrier spacing (SCS): 15, 30, 60, 120, 240 kHz (μ = 0 to 4, SCS = 15 × 2^μ kHz). Slot duration scales inversely: 1ms at 15 kHz to 0.0625ms at 240 kHz, reducing latency. Frame structure: 10ms frame = 10 subframes, each 1ms. Slots per subframe = 2^μ. Each slot has 14 OFDM symbols (normal CP). Bandwidth parts (BWP) allow different numerologies within a carrier. Mini-slots (2, 4, 7 symbols) enable ultra-low latency. Cyclic prefix scales with SCS for consistent delay tolerance. FR1 (<7 GHz) supports 15-60 kHz; FR2 (mmWave) supports 60-120 kHz (data), 240 kHz (sync). Flexible slot formats with configurable DL/UL symbols support dynamic TDD.