The emergence of Internet-of-Things (IoT) has led to the development of
new energy efficient and long-range wireless technologies, which are
necessary for the successful realization of IoT applications. Within
this context, long range (LoRa) has emerged as one of the prominent low
power wide area network (LPWAN) technologies that is envisioned to
accommodate the future IoT requirements. However, current LoRa
frameworks suffer from limited network capacity, particularly in dense
deployments. Consequently, power domain-superposition modulation
(PD-SPM) is integrated with LoRa to alleviate the aforementioned
problem. In this paper, the error rate performance of a LoRa-enabled
PD-SPM system is investigated over Rayleigh fading channels.
Specifically, symbol error rate (SER) expressions are derived to
characterize the performance of an arbitrary number of users under
extreme fading conditions. Furthermore, Monte Carlo simulations are
presented to validate the analytical framework.