Evaluation of the BER Performance of LoRa Communication using BICM Decoding

The patented LoRa physical layer adopts FEC codes that are essentially derived from the simple (7,4) Hamming code. The underlying coding rates of transmitted LoRa signals could vary between 4/5 and 4/8. The inherent capabilities of such codes are restricted to a mere error detection for the (5,4) code configuration and limited to single error correction/double error detection when the (8,4) code setting is used. On the other hand, LoRa modulation could be categorized as a form of multi-dimensional orthogonal signaling. This renders the opportunity to apply Bit Interleaved Code Modulation (BICM) to received LoRa signals with the potential of maximizing the coding gains that could be attained from the simple FEC codes deployed within commercial LoRa chips. In this paper, we apply the concept of BICM to LoRa signals and investigate the associated BER performance within AWGN and Rayleigh channels. Furthermore, we explore the potential of applying iterative decoding (i.e., BICM-ID) in order to further enhance LoRa BER performance.