Lightweight Carrier Sensing in LoRa: Implementation and Performance Evaluation

In LoRa, leading communication technology for the Internet of Things (IoT), the so-called Class A devices are proposed for applications that require low energy consumption. However, the MAC layer of Class A devices is based on pure ALOHA, which performs poorly when the network includes a large number of devices. In this paper, we propose a Lightweight Carrier Sensing (LSC) mechanism for LoRa end devices, which does not include back-off and, thus, results in negligible overhead on end devices. LCS is based on the Channel Activity Detection (CAD) procedure already implemented at the hardware level in all modems based on the standard LoRa chipset. We first theoretically analyze the benefits of LCS on a simplified LoRa network to understand its benefits over pure ALOHA. We present the design and implementation of the proposed LCS and provide measurement results to demonstrate its feasibility in real-world LoRa networks. We have also implemented LCS in a detailed custom-build LoRa simulator to study LCS impact on network energy consumption and scalability in large-scale LoRa networks. Our results show that not only LCS supports more end devices, but also results in significantly lower energy consumption compared to ALOHA, thus efficiently improving network scalability without additional complexity or overhead.