Cross-network cross-interface relaying via LoRa-ZigBee synergy: Enabling energy-efficient delay-constrained communication across low-power IoT networks

Abstract

The rapid expansion of the Internet of Things (IoT) ecosystem has propelled widespread deployment of distributed low-power wireless networks, among which ZigBee stands out for diverse innovative applications. However, energy-efficient cross-network communication remains challenging, as existing solutions like multi-hop ZigBee and one-hop LoRa entail trade-offs between communication delays and deployment costs. To tackle these issues, we propose a novel cross-interface relaying paradigm that utilizes a star topology within each ZigBee network and designates a relay node with an additional LoRa interface to bridge networks via a central LoRa gateway. Compared with existing methods, this approach reduces energy consumption and costs while improving scalability. To implement this paradigm while balancing energy conservation with delay guarantees, we introduce a Cross-network Cross-interface Relaying (CCR) scheme, which jointly schedules LoRa and ZigBee transmission behaviors to minimize energy consumption under delay constraints. CCR uses a scheduling framework that breaks down end-to-end delay constraints into link-level constraints, enabling global optimization of transmission parameters and dynamic adaptation to link quality variations. The effectiveness of CCR is demonstrated through extensive field tests on a prototype implemented on Raspberry Pi 3B+. Results show that CCR reduces energy consumption by 55.4% and 39.1% compared with an advanced LoRa communication protocol and a state-of-the-art cross-interface relaying scheme, respectively, while ensuring that 98.7% of packets satisfy their delay constraints. These findings highlight the potential of CCR for efficient and reliable cross-network communication in large-scale IoT deployments.