Time-Delay-Estimation-Liked Detection Algorithm for LoRa Signals Over Multipath Channels

LoRa promises long range reliable communication for the Internet of Things (IoT). However, multipath fading severely affects LoRa’s BER performance. In this letter, we propose a simple detection algorithm for the frame-based LoRa PHY signals mainly composed of a preamble and a variable-length PHY-payload. We first prove that detecting the frame-based LoRa signals over multipath fading channels can be formulated as a Time-delay-estimation (TDE)-liked problem. Based on this, a cyclic cross-correlation implemented by a matched filter is utilized to detect the LoRa signals. Additionally, the proposed TDE-liked detection algorithm is insensitive to the integer frequency offset due to the nature of implying a differential operation. The simulation results indicate that, the proposed algorithm significantly outperforms the existing detection algorithms for the LoRa signals over multipath fading channels. Under the multipath fading channel, the BER performance of the proposed algorithm is slightly inferior to that in the AWGN channel while the existing scheme fails to work.