# Performance Evaluation of a Mesh-Topology LoRa Network
## 4 Current Research
Asexpected, the nodes in a next-ring hop network topology closest to the gateway showed the highest power consumption due to payload aggregation. Optimal-hop routing showed the best distribution of power consumption among the nodes, minimising bottlenecks in the network. A 96% reduction in power consumption was observed in nodes far from the gateway. Meshtastic [23; 24] is a LoRa-based mesh ad hoc networking standard aimed at peer-to-peer communication for long-range off-grid communication without a centralised gateway. Meshtastic adopts Carrier-Sense Multiple Access with Collision Avoidance (CSMA/CA) and uses flooding for multi-hop messaging. The focus of the Meshtastic research is more aimed at ad hoc P2P mesh networks, compared to the gateway-centric approach in this research. However, the Meshtastic research is ongoing and supports the argument for the research and development of a mesh-based LoRa network. The LoRa Alliance proposed a multi-hop strategy which could be used to enable add-hoc multi-hop networking, based on the existing LoRaWAN protocol, which is outlined in [9]. The proposed solution relies on Wake On Radio (WOR) frames to keep relay nodes in a low-power state for the majority of the time and only scan the channel periodically to detect any nodes which need to relay packets. This mechanism relies on the LoRa channel activity detector discussed in Section 3.2. The efficacy of the proposed solution has not yet been proven through simulations or empirical testing for large-scale deployments. Similar to [9], the research in [25] also proposes a multi-hop LoRa network, which is based on extended LoRa preambles and LoRa CAD. The authors provided a discrete-event cross-layer simulator based on LoRaEnergySim [26] and validated the results with a real-world test bench. The focus of the proposed multi-hop LoRa protocol is energy efficiency in a small-scale deployment. Based on the described low-node-count and low-throughput use case, the asynchronous protocol is perfect, as no overhead is needed for the synchronization mechanisms. The authors of [27] investigated the Optimizing Link-State Routing Based on Load Balancing (LB-OLSR) protocol as an approach for constructing LoRa distributed two-hop networks. The network relies on Multipoint Relay (MPR) nodes to forward messages from end-nodes to the central gateway. The study relies on a simulation model to validate the proposed mechanism. Although the work focuses on optimizing the construction of a LoRa distributed two-hop network, limited details are provided on the implementation of such a network in an LPWAN context. Another load balancing routing optimisation algorithm is proposed in [28]. The researchers used a UCB1 multi-armed bandit reinforcement-learning-based routing mechanism for multi-hop networks. The authors set up a reward function to balance fairness (evenly spread energy consumption among relay nodes), reliability (prioritize choosing paths with the smallest path-loss), and route length (minimize latency). The network was simulated in LoRaEnergySim, and the results showed an improvement, compared to a random route selection approach, in energy consumption, package delivery ratio, latency, and the number of hops. The research is promising; however, the model is currently limited to a single data rate, and there is no discussion regarding packet scheduling to reduce power consumption.