# Energy-Efficient LoRa Routing for Smart Grids
## 2 Literature Review
in SG WSNs utilising an SPOCC-centred HSA-PSO algorithm & Limited to SG outdoor transmission; security enhancement was identified as an impending factor, but not addressed in this paper \\
[31] & Fuzzy multi-criteria clustering and bio-inspired energy-efficient routing (FMCB-ER) & Hierarchical WSN protocol with FMCB-ER & As the complex algorithm, EPO, for route optimisation from the CHs to the sink nodes requires a large amount of computational power, it is impossible on low-power sensors Tested on fixed sensor nodes; the genetic algorithm was applied only to the source sensor nodes \\
[32] & Ticket-based routing (TBR) & Ticket-based QoS routing optimisation utilising G.A. for WSN applications in SGs Enhanced BEST-MAC protocol for WSN utilising optimum CH selection & Ticket-based QoS routing optimisation utilising G.A. for WSN applications in SGs Enhanced BEST-MAC protocol for WSN utilising optimum CH selection & Ticket-based QoS routing  
An upgraded version of LEACH, designated LEACH-C [38], allows the formation of clusters using a centralised clustering method. LEACH-C improves the network performance by distributing CHs around the network to build better clusters. The probability calculation takes into account the residual energy of the nodes. Thus, the nodes with higher energy have a greater chance of being picked as CHs. The modified LEACH protocol [39] is a well-known WSN clustering protocol. The basic idea is to make the clustering process dynamic by randomly selecting the CH and allowing the nodes to join the CH that is geographically nearest to them. The chosen CHs form the basis of this network's topology, which is inefficient since it ignores the residual energy at each node. A novel two-CH method for minimal energy consumption was proposed by [40] in that one CH lies closer to the BS and the other CH is selected randomly depending on the energy constraints. The randomly selected CH transmits the data to the nearby BS. As a result, the two CHs ensure the minimum energy loss in the network. Heterogeneous-aware routing protocols such as the stable election protocol (SEP) and distributed energy-efficient clustering (DEEC) have been introduced. The SEP [41] comprises heterogeneous nodes to boost the network's stability and longevity. The SEP has two types of nodes: normal nodes (NNs) and advanced nodes (ANs). Among these nodes, the AN acts as a CH because it has a higher estimated energy than the NN, stabilising the energy between CH and non-CH nodes. The hotspot problem is one problem with direct communication. This happens because the CH to the sink node uses much energy, which affects the lifetime of the network. The SEP functions similarly to LEACH and does not account for residual energy in determining the CH rotating process or election probability, which are directly tied to the node's initial energy. DEEC [42] is used for heterogeneous WSN applications. As opposed to the SEP, in DEEC, the ratio between each node's remaining energy and the network's average energy is considered for the CH selection. The remaining energy of the nodes in the network may not be uniform. Sensor nodes with the maximum residual energy have a better probability of becoming CHs when compared to other nodes. This gives a more excellent performance for the residual energy, node lifetime, and network lifetime than the SEP and LEACH in a heterogeneous WSN with a multi-level environment. DEEC cannot be used when the BS is placed far from the sensor nodes since it assumes the BS is positioned in the middle of the WSN. The enhanced DEEC proposed by [43] balances the WSN energy and extends its lifetime using a priority queue. In a smart grid communication network, a WSN has been considered in several works. For smart homes and cities, smart metring, and smart markets, the wireless technologies used can be integrated with a WSN for multipath routing [44].