## 4 Review of the Routing Protocols
### Link Quality-Based Routing Protocols Comparison
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt}} \hline \hline
**Protocols** & \multicolumn{2}{c}{**Comparison Parameters**} \\ \cline{3-3}  & **Methods** \\ \hline AnyBody [146] & \(\bullet\) & Overall, the protocol works in five steps, i.e., density computation, cluster-head construction, backbone network setup, routing path setup and neighbour discovery \\ \hline LEACH [147] & \(\bullet\) & The cluster heads aggregate and compress the data and forward it to the base station \\  & \(\bullet\) & Each node uses a stochastic algorithm at each round to determine whether it will become a cluster head in this round \\ \hline HIT [148] & \(\bullet\) & To minimise energy consumption, parallel processing is used for intra-cluster and inter-cluster communication modes. At the start, one node is selected as the cluster head, and later, further cluster heads are selected. Time division multiple access (TDMA) scheduling is used in HIT to send data to upstream and downstream nodes \\ \hline LEACH-M [105] & \(\bullet\) & LEACH-M supports sensor nodes’ mobility in WSNs by adding membership declarations to the LEACH protocol \\  & \(\bullet\) & LEACH-Mobile outperforms LEACH in terms of packet loss in a mobility-centric environment \\ \hline LEACH-EE [109] & \(\bullet\) & It prolongs the network lifetime and reduces energy consumption by first gathering data by cluster head; then, an optimal multi-hop path that leads to the base station is formed among the cluster heads. In this way, the problem of cluster heads consuming more energy is solved. \\ \hline AZM-LEACH [110] & \(\bullet\) & Improved version of BIOCOMM providing better delay performance in the multi-hop scenario. \\ \hline LEACH-GA [107] & \(\bullet\) & The ant colony approach is used. \\  & \(\bullet\) & The core idea is to evaluate cluster heads’ current residual energy and location information from the perspective of the overall network in real-time; a single ant traverses all nodes at once, forming a dendritic multi-hop path. While the path is rebuilt, low-energy nodes select an energy-saving path, and high-energy nodes increase energy consumption as a consideration to prolong the network lifetime. \\ \hline LEACH-IACA [149] & \(\bullet\) & A multi-hop routing algorithm LEACH-GA (LEACH-Genetic Algorithm) improves the cluster heads’ single-hop system in the LEACH routing protocol of heterogeneous wireless sensor networks. In this protocol, the cluster heads provide the shortest path link with SINR. \\  & \(\bullet\) & The cluster heads that are far away from SINR communicate with SINR through the transit cluster heads. \\  & \(\bullet\) & In fact, those who are near SINK can communicate with it directly. \\  & \(\bullet\) & From this point, the LEACH algorithm can be improved to be an algorithm with a SINR-centred multi-hop tree cluster link. \\ \hline EB-MADM [150] & \(\bullet\) & The energy budget based multiple attribute decision making (EB-MADM) algorithm for cooperative clustering is used for dynamic cluster selection. \\  & \(\bullet\) & Provides energy efficiency. \\ \hline BAN-Trust [151] & \(\bullet\) & An attack-resilient malicious node detection scheme (BAN-Trust) is brought into the current system; it can identify malignant attacks on BANs. \\  & \(\bullet\) & In this BAN-Trust scheme, malignant nodes are identified according to the nature acquired through the nodes on their own and the approvals shared by various nodes. \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Comparative analysis of cluster protocols. candidates, as recommended by the ZigBee standard [163], IETF 6 LoWPAN WG [130] and IETF ROLL WG [139], etc. Two ways are used to measure the link quality, including packet-based techniques and radio-hardware-based techniques [164]. Packet-based techniques compute the link quality using a number of received and estimated packets in a specified time [165]. Control packets are used to implement this approach [166]. As the packet-based technique maintains the state information, it needs more processing time, memory and energy [167].