Approximate BER Performance of LoRa Communication Under Carrier Frequency Offset

For LoRa communication in high speed mobile scenarios, the carrier frequency offset (CFO) can be decomposed into integer and fractional parts. The fractional offset spreads part of the energy across different frequency bins in demodulation, which can be modeled as energy leakage from the right bin. Therefore, the interference caused by CFO can be formulated as a Gaussian distribution, then the simple bit error rate (BER) approximation is derived with Gaussian Q-function and algebraic formulas. We verified the approximate expression through Monte Carlo simulations. Moreover, experiment results show that a high spreading factor leads to severe energy leakage and may result in BER reduction.