A Novel Residual Carrier Frequency Offset Estimation Approach for LoRa Systems

Long Range (LoRa) technology is gaining considerable academic and commercial traction because of its potential for low power consumption, long transmission distance and wide coverage. In this paper, we focus on the effect of residual carrier frequency offset (RCFO) on LoRa systems, and fill in the blank of efficient estimation and compensation algorithm. We first provide mathematically description of the LoRa signal with RCFO and derive the modulus of the correlation function between the RCFO precompensated upchirp in preamble and the local upchirp. Then, we propose an efficient RCFO estimation algorithm based on the Golden Section Search. The simulation results show that compared with the traditional method, our method achieves higher accuracy of the RCFO estimation and restore the Bit Error Rate (BER) to an acceptable level after compensation.