Novel medium access protocols for LoRa internet of things networks

Alahmadi, Hanan Jabr

Abstract

LoRa, which stands for Long Range, is a network technology that provides a long transmission range while maintaining a low power consumption profile, enabling a wide range of Internet of Things (IoT) applications such as smart cities, smart monitoring, and smart agriculture. However, due to the nodes’ ALOHA-based access method, reliable performance in high-density networks may be difficult to achieve, limiting such networks’ scalability. Moreover, the Duty Cycle (DC) restrictions imposed on nodes and gateway transmissions to regulate the access to the unlicensed shared ISM band can further constrain network scalability. Furthermore, LoRa networks provide multiple configurable transmission parameters that greatly affect the performance of the overall network. To the best of our knowledge, the optimal combination of these parameters that can allow orthogonal simultaneous transmissions to be successfully decoded by the gateway has not been reported in the literature. Motivated by the aforementioned challenges, this thesis aims to address the main challenges of LoRa networks and conceive comprehensive solutions considering all these challenges such that the network scalability and the energy efficiency are maximized. The main contribution of this thesis is the proposing of decentralized approaches that optimize the network performance without burdening the network with extensive control packets from the network server. To address the challenges mentioned earlier, the thesis first develops a distribution algorithm, named Sensitivity-Aware LoRa (SAL), for LoRa transmission parameters that maximize the network scalability by minimizing the Packet Error Rate (PER). The main contribution of SAL algorithm is doubling the available DC by considering channels from all sub-bands. Then, an autonomous Time-Division Multiple Access (TDMA) protocol named Sector-Based Time-Slotted (SBTS-LoRa) was proposed to minimize the collisions resulting from the ALOHA random channel access and hence improving the network scalability. The collision rate of SBTS-LoRa was enhanced by 49% compared to the legacy Lo- RaWAN. After that, the SBTS-LoRa was enhanced to consider the dynamic and relatively short time frame sizes, which are presented in the autonomous Adaptive Frame Size (ATS-LoRa) MAC protocol. The main novelty of the proposed protocol is that the time frame size depends on the node density, which uses common transmission parameters to avoid collisions among them. According to that, the network throughput was enhanced three times compared to the SBTS-LoRa protocol. Moreover, all the proposed protocols were evaluated in realistic environmental settings where large-scale and dense networks were considered.

Citation

Alahmadi, H. J. Novel medium access protocols for LoRa internet of things networks. (Thesis). Edinburgh Napier University

• Thesis Type: Thesis
• Deposit Date: Jan 6, 2025
• Publicly Available Date: Jan 6, 2025
• DOI: https://doi.org/10.17869/enu.2024.4043788
• Award Date: Oct 31, 2024