Single-Symbol Iteration Based Delay-Locked Loop for 5G NR Positioning

High-accuracy positioning service is an important feature of 5G new radio (NR). Although delay-locked loop (DLL) has been widely adopted in traditional navigation systems where the spread-spectrum sequences are transmitted continuously, it can be hardly used in 5G NR positioning systems because the positioning reference signals (PRS) are transmitted discontinuously. To enable high-accuracy timing tracking based on 5G PRS, we propose a single-symbol iteration based DLL in this paper. Instead of tracking the timing with continuously transmitted spread-spectrum sequences, single-symbol iteration can converge to the optimal timing point within only one PRS symbol. Therefore, the single-symbol iteration scheme can be adopted well to high-accuracy positioning service in 5G NR. Simulation results are also shown in this paper to demonstrate the proposed scheme.