A Novel Approach to Enhance the Robustness of LoRa-Like PHY Layer to Synchronization Errors

The Internet of Things (IoT) finds widespread applications spanning from consumer services such as smart home or domotic to strategic use cases, including infrastructure or energy management. Different technologies have been proposed to support IoT and this paper aims at considering the Long Range one (LoRa). The LoRa physical layer is based on the chirp spread spectrum (CSS) technique where the bit error rate can strongly degrade in the presence of synchronization errors. To alleviate this constraint, we propose a modification of the LoRa physical layer which we refer to as differential CSS (DCSS) associated to an original synchronization algorithm. The main contribution of this paper is to propose a receiver, based on this original synchronization algorithm associated to the DCSS technique, able to demodulate the received signals without performing a complete frequency synchronization and by tolerating some timing synchronization errors. In addition, our receiver has no limitation on the maximum carrier frequency offset as it is actually the case in the deployed LoRa receivers.