# Wireless Mesh Networking: An IoT-Oriented Perspective Survey on Relevant Technologies
## 7 Ongoing and Future Developments
### General Considerations and Future Technologies Developments  
Besides the general analysis on different wireless technologies carried out in Sections 3-6, it is of interest to understand how each wireless mesh technology suits the requirements of different applications. As shown in Figure 15, the majority of the analyzed mesh protocols, but the IEEE 802.11, are characterized by the absence of intermediate ISO/OSI layers between L2 and L7, as also shown, in a comparative way, in Figure 16.  
Figure 15: Mesh protocols stacks and abstraction middleware for traffic harmonization. In Figure 17, we present a comparative overview of the considered wireless technologies. More in detail, the following relevant metrics are considered. 1. **Coverage (dimension: [m\({}^{2}\)])**: intended as the area which can be covered using a mesh network based on the analyzed technology. 2. **Range (dimension: [m])**: intended as the transmission range of a single node in the mesh network. 3. **Scalability**: intended as the capability of a mesh network, based on used wireless technology, to scale. 4. **Data Rate (dimension: [b/s])**: measured on single nodes. 5. **Network topology**: intended as the degree of complexity reachable building different network topologies. 6. **Battery Life (dimension: [days])**: measured on single nodes. 7. **Power Consumption (dimension: [W])**: measured on single nodes. 8. **Latency (dimension: [s])**: intended as the capability of a technology to obtain low latencies among nodes communications. 9. **Deployment**: intended as the complexity to deploy a mesh network based on the specific wireless technology. The values shown in Figure 17 have been obtained analyzing relevant works appeared in the literature--namely [79, 80, 81, 82, 83, 84, 85, 86, 87]--and normalizing each data in order to directly compare (through adimensional values) the communication technologies presented in the paper. In detail, each axis of the chart in Figure 17 corresponds to each of the 9 metrics. For each axis, we indicate a value \(v_{i,k}\), with \(i\in[1,9]\) identifying the performance metric and \(k\in[1,4]\) corresponding to each analyzed communication technology. Each value \(v_{i,k}\) corresponds to the average value of the \(k\)-th technology with respect to the \(i\)-th metric and is obtained as follows (the single values for each technology and performance metric are reported in Appendix A):  
\[v_{i,k}=\frac{\sum_{h=1}^{N_{ref_{i,k}}}\left(v_{i,k}^{[h]}/v_{i,k}^{\max} \right)}{N_{ref_{i,k}}} \tag{1}\]  
where: \(N_{ref_{i,k}}\) is the number of considered references [79, 80, 81, 82, 83, 84, 85, 86, 87] for the \(k\)-th technology with information on the \(i\)-th metric; \(v_{i,k}^{[h]}\) is the value found in the \(h\)-th reference of the list; and \(v_{i,k}^{\max}\) is the maximum  
Figure 16: Comparison among the analyzed communication protocols, based on data rate and transmission range. Minimum and maximum values (with average) are indicated for each performance metric. value found in all references. It follows that, by definition, \(v_{i,k}\leq 1\). In this way, it is possible to obtain the radar plot in Figure 17, where each metric is in the range \((0,1)\). As can be observed from Figure 17, the results show that a unique solution for all scenarios does not exist. However, the the radar plot can help in choosing the most suitable technology, considering the constraints of the application scenario at hand. For the transmission protocols analyzed in Sections 3-6, in the case of a target application where low-rate communications are acceptable, the most suitable mesh protocol that can be adopted is LoRa, due to its long-range capability, battery life and power consumption, even through it requires the presence of a backbone infrastructure, in terms of Network Servers and gateways. As an alternative, both Thread and Zigbee can be seen as adequate mesh technologies, especially in terms of scalability and power consumption.