Low Power Wide Area Network Analysis: Can LoRa Scale?

TL;DR

This paper develops a stochastic geometry model to analyze the scalability of LoRa LPWA networks, revealing that interference significantly limits network growth more than spectrum constraints.

Contribution

It introduces a novel analytical framework capturing LoRa's unique features, enabling rigorous assessment of network scalability under interference.

Findings

Coverage probability decreases exponentially with more devices.

Interference from same spreading factor signals is a key limiting factor.

LoRa scalability is more constrained by interference than spectrum limitations.

Abstract

Low Power Wide Area (LPWA) networks are making spectacular progress from design, standardisation, to commercialisation. At this time of fast-paced adoption, it is of utmost importance to analyse how well these technologies will scale as the number of devices connected to the Internet of Things (IoT) inevitably grows. In this letter, we provide a stochastic geometry framework for modelling the performance of a single gateway LoRa network, a leading LPWA technology. Our analysis formulates unique peculiarities of LoRa, including its chirp spread-spectrum modulation technique, regulatory limitations on radio duty cycle, and use of ALOHA protocol on top, all of which are not as common in today's commercial cellular networks. We show that the coverage probability drops exponentially as the number of end-devices grows due to interfering signals using the same spreading sequence. We conclude that this fundamental limiting factor is perhaps more significant towards LoRa scalability than for instance spectrum restrictions. Our derivations for co-spreading factor interference found in LoRa networks enables rigorous scalability analysis of such networks.