Performance Evaluation and Low-Complexity Detection of the PHY Modulation of LR-FHSS Transmission in IoT Networks

Long-range frequency-hopping spread spectrum (LR-FHSS) is a new transmission protocol introduced under the long-range wide area network (LoRaWAN) specifications to tackle the issue of extremely long-range and large-scale internet of things (IoT) deployment scenarios. Unlike the other LoRaWanscheme, i.e., the one based on the chirp spread spectrum (CSS) modulation, the physical layer of LR-FHSS exploits a 488 Hz Gaussian minimum shift keying (GMSK) modulation. In this paper, we investigate and model the FHSS-GMSK modulation and evaluate its bit error rate (BER) performance in the LR-FHSS system using simulations. We also propose a low-complexity GMSK signal detection scheme that can be used at the gateway (GW) of an IoT network with a massive number of IoT end devices (EDs). Using computer simulations, we show that our proposed detector can offer a tradeoff between the complexity of the receiver and the bit error rate (BER) performance.