Low-Power Wake-Up Signal Design in 3GPP 5G-Advanced Release 19
Sebastian Wagner
TL;DR
The paper addresses the challenge of reducing idle power in 5G IoT devices by introducing and detailing the Low-Power Wake-Up Signal (LP-WUS) and LP-Synchronization Signal (LP-SS) in 3GPP 5G-Advanced Release 19. It outlines the practical operation in RRC_IDLE/INACTIVE, signaling (SIB1) and DRX configurations, and dives into the PHY design, including encoding, multi-symbol OOK modulation, ZC-based wake-up sequences, and sequence encoding, alongside LP-SS-based measurements. A key contribution is the comparative analysis of receiver architectures (envelope vs coherent detection) and a cross-section with IEEE 802.11ba, with findings showing coherent detection offers superior performance at the cost of higher complexity, while ED remains attractive for ultra-low-power scenarios. The numerical evaluation demonstrates the trade-offs among ED, CD-S, and CD-L receivers, highlighting the potential for a hybrid receiver approach in practice, and discusses implications for 6G WUS design, focusing on balancing power efficiency with reliable paging and synchronization.
Abstract
The Low-Power Wake-Up Signal (LP-WUS) and Low-Power Synchronization Signal (LP-SS), introduced in 3GPP 5G-Advanced Release 19, mark an important advancement toward power-efficient IoT communications. This paper provides a comprehensive overview of the LP-WUS procedures in the RRC_IDLE and RRC_INACTIVE states and summarizes the key physical-layer design aspects. The LP-WUS is intended to be detected by a low-power energy detector (ED), allowing the main radio (MR) to remain switched off, thereby enabling substantial power savings compared to conventional 5G paging mechanisms. As such, LP-WUS is considered the baseline for 6G WUS design. Furthermore, different receiver architectures are evaluated, highlighting the inherent trade-offs between power-saving gains and coverage performance.