Timing Advance (TA)

Technical Explanation

Because UEs are located at varying distances from the base station, uncompensated uplink signals would arrive at different times, destroying OFDM orthogonality. The gNodeB calculates round-trip delay and commands the UE to advance its transmit timing by TA. 5G NR quantizes TA in fine steps of 16 x 64 x Tc (approx. 0.52 microseconds at 15 kHz SCS).

Key Functions

• Offsets UE transmit timing earlier than nominal downlink frame boundary
• Ensures simultaneous symbol arrival from all cell UEs within the cyclic prefix
• Quantized in fine increments scaling with subcarrier spacing