An Adaptive Data Rate scheme for multi-hop forwarding in LoRaWAN networks

LoRaWAN (Long Range Wide Area Network) is experiencing widespread adoption in smart cities and industrial sites owing to its peculiar features, including easy deployment and low power consumption. However, the single-hop architecture of LoRaWAN presents scalability limitations in situations requiring multi-hop forwarding, such as during infrastructure breakdown, notably given the interoperability issues with other communication standards. Multiple studies have suggested dual-hop or multi-hop solutions to address this limitation, nevertheless, certain technical specifications that LoRaWAN relies on, such as adaptive data rate (ADR), still present challenges. The ADR mechanism dynamically optimizes data rate and transmission power. These parameters are controlled by complying with the network server (NS) based on signal-to-noise ratio (SNR), or by the device through the adaptive data rate (ADR) scheme. In a multi-hop scenario, the NS is unable to assess the signal quality to determine the best transmission parameters for the device. Moreover, the ADR scheme does not incorporate any alternative multi-path forwarding strategies. In this paper, we introduce a multi-hop adaptive data rate (MH-ADR) mechanism that relies solely on the device’s strategy to optimize transmission parameters. This mechanism leverages alternative multi-path routes to ensure the highest achievable data rate. Simulation results demonstrate that in a multi-hop scenario, the proposed mechanism preserves higher data rates for most of the simulation time compared to basic ADR.