Clustering-Based Layering Approach for Uplink Multi-Hop Communication in LoRa Networks

LoRa is the most popular low-power wide-area networking (LPWAN) technology, and typically it uses LoRaWAN as the MAC layer. Usually, LoRaWAN forms a single-hop network. LoRa supports customization of transmission parameters, such as, bandwidth, spreading factor, and coding rate. Hence, a single-hop LoRaWAN network's coverage can be increased at the expense of higher energy consumption and lower data rate. However, there are a few issues: (i) there is an upper bound on a single-hop network's coverage, (ii) high throughput and large coverage can not be achieved simultaneously, and (iii) most importantly high energy consumption is generally not an option in IoT use cases. Here, a multi-hop uplink communication scheme is presented that exploits LoRa's ability to customize its transmission parameters and combine it with a novel routing protocol to eliminate the mentioned shortcomings. In simulation-based studies the proposed protocol uses LoRa's fastest data rate setting, however its coverage is lower than the LoRa's PHY layer setting recommended in LoRaWAN specification. Hence, a network's coverage is extended through multi-hop communication. Results have shown that the proposed uplink multi-hop communication scheme outperforms LoRaWAN and a state-of-the-art routing protocol for low-power wireless networks. The proposed protocol demonstrated nearly 20 times higher packet delivery ratio, and 60% lower energy consumption.