Low-Complexity Pilot-Independent Time Synchronization for Zero-Padding-Based IoT Devices

Many Internet of Things (IoT) devices are small, battery-powered systems, requiring energy-efficient solutions to extend their operational life. To reduce communication energy consumption, we suggest zero-padding (ZP)-orthogonal frequency-division multiplexing (OFDM) as a more efficient alternative to its cyclic-prefix (CP)-OFDM counterpart. However, ZP-OFDM typically relies on pilot data for time synchronization, which can be prohibitively expensive for resource-constrained IoT devices. This article introduces a low-complexity, pilot-independent time synchronization method for ZP-OFDM. Thus, the proposed approach eliminates the need for pilot data which further enhances the energy efficiency of ZP-based signaling for IoT applications. Simulation results demonstrate that the proposed estimators achieve a high lock-in probability even in low SNR with low computational complexity, enabling the practical deployment of ZP signaling in IoT systems. Although the proposed methods cannot be directly integrated to the existing IoT technologies, such as ZigBee for physical implementation, they pave the way for practical implementations in future IoT technologies.