LoRa Preamble Detection Robust to Inter-channel Interference

LoRa is currently one of the most widely deployed technologies for low-power wide-area networks. Its physical layer has been extensively studied in the literature, especially regarding the demodulation and decoding aspects. However, preamble detection has received little attention, with only a few works offering performance evaluations. Due to the imperfect orthogonality of LoRa logical channels (spreading factors) and the near-far problem resulting from the lack of coordination between LoRa devices, it is crucial for the preamble detection method to be resilient to inter-channel interference. The current schemes fail to offer both a good preamble detection rate and a good immunity against false alarms caused by high-power interferers from other LoRa logical channels. In this paper, we develop a detection method able to offer close to optimal detection performance while showing an effective immunity to strong inter-channel interference. The performance is studied both analytically and through Monte Carlo simulations.