# An Eccentricity Based Data Routing Protocol with Uniform Node Distribution in 3D WSN
## 2 Related Works  
A significant number of researches on routing protocol for WSNs have been proposed in the last few years. The low energy adaptive clustering hierarchy (LEACH) [13] is a pioneer work of clustering-based routing protocols in homogeneous WSNs and gives birth to many protocols. The idea of LEACH is clustering of nodes and periodic data gathering. For this, each node elects itself as a CH with a certain probability \(p\) and the role of CH rotates periodically among the nodes. To be a CH, each node generates a random number interval of 0 and 1. If the number is less than or equal to the threshold value \(T(n)\), it is elected as a CH. After the CH nodes election, each CH node broadcasts an advertisement message over the network within a radio range \(R\). Upon receiving the advertisements from the elected CHs, a nearest CH node is selected to form a cluster by calculating the distance followed by sending a join message to the selected CH. A CH node then fixes the TDMA schedule and broadcasts the message to its CMs. A CH node acts as a local BS that receives and aggregates data from CMs and sends the aggregated data directly (single-hop) to the BS. Once the set of nodes \(C\) is elected as CHs at time \(t_{\text{i}}\), in next round, a new set \(C^{\prime}\) is elected as CHs at time \(t_{\text{i+d}}\). Although it distributes the energy consumption of nodes equally, it leads to additional routing overhead, resulting in excessive use of limited energy of a CH node due to unequal CMs. Its single-hop communication strategy constructs the network less scalable. Meanwhile, it does not consider the residual energy of nodes in CHs election that cause a shorter steady state and network lifetime. Inspired from LEACH, many protocols have been proposed to improve the network lifetime. EADEEG [14] is a novel distributed clustering-based routing algorithm. It considers the ratio of the residual energy of neighbor nodes and the residual energy of the node itself during a CH node election. It achieves equal CHs distribution over the network, which prolongs the network lifetime. The drawbacks of this protocol are less scalable as LEACH and it cannot deal with the _'isolated points'_ during inter-cluster communication in some cases. To solve this problem, a distributed energy saving clustering and routing algorithm called BPEC has been proposed in [15]. Itlects a CH node by two different quality functions such as primary probability and subsidiary probability. Its primary probability function is similar to EADEEG and the subsidiary probability considers the node's degree in addition. It can solve the _'isolated points'_ unlike the EADEEG and can keep all the CH nodes connected during inter-cluster communication. To extend the network lifetime a degree further, a lifetime maximization algorithm has been proposed in [16]. It considers residual energy of nodes and the required transmission energy of path towards the BS during CH nodes election. It distributes the load of the nodes almost evenly, so that the energy consumption of the nodes is distributed equally. In [17], the authors proposed a \(k\)-connected overlapping method in clustering. It selects CH nodes on the basis of available energy status of the nodes that enhances the network lifetime. [18] is a link aware clustering-based routing algorithm. It adopts a clustering metric based on predicted transmission count, unlike considering residual energy in CH nodes election. This method determines a reliable and energy-efficient path in routing to prolong the network lifetime. In [19], the authors proposed an energy-aware distributed clustering (EADC) based routing protocol that can prolong network lifetime significantly. To distribute the CHs equally over the network, it partitions the network into CHs competition regions defined by \(R_{\text{c}}\). CH nodes are elected in each of the regions, so that the clusters have the approximate number of members and coverage area.