## 1 Motivation
Another approach is using the multipathstrategy to improve the network performance by increasing the throughput [13]. A detailed survey of multipath routing and its energy efficient impact on network along with research challenges is explained by [PERSON] _et al._[14]. In this paper, we have targeted the issue of improving network throughput from the aspect of energy conservation for routing and its related functionalities. Though the proposed scheme can work with any clustered network designing algorithm, here we have exploited the proposed architecture in MCDA since it is a state-of-the-art network architecture. The literature is rich in cluster-based routing protocols that mostly encompasses: (i) cluster design; (ii) route establishment and (iii) CH rotation processes. Cluster design consists of CH selection, cluster member affiliation to cluster heads and time slot assignment for communicating the sensed data to the CH. All the proposed algorithms for the same either accomplish these processes with central control of BS [10] or with a locally controlled distributed style [15]. Both techniques have their pros and cons. The cluster design part from the point of view of the aforementioned three steps is out of the scope of this underlying article. The second (route establishment) and third (CH rotation) steps are covered comprehensively in this article. In exploiting the architecture of MCDA, we offer suitable algorithms for routing (inter-cluster and intra-cluster) and CH rotation. All nodes in the first tier (first layer) may act as forwarding nodes for the second tier CHs. The cluster heads of each subsequent layer communicate with the CHs of the preceding layer either directly or through intermediate nodes. These intermediate nodes have once acted as decision  
Figure 1: The various roles of nodes during their lifetime in a clustered network architecture. maker nodes in the election of the CH during the cluster design process. Threshold levels are introduced for the node energy to initiate the process of CH rotation. This role is transferred to the most energy carrying nodes in two steps: load balancing and load transferring. These strategies in collaboration with the MCDAs' architecture work well to provide reliability (safe and stepwise role transfer), fault tolerance (higher density node selection for CHs and for decision maker nodes and thus for the forwarding node), better throughput and improved network lifetime (balanced network utilization, less inter node communication, removing hot spot area in the neighbor of BS, _etc._). Hence, based on this discussion, we can summarize the contributions of our work as follows:  
1. Proposed algorithms, some of whose components have been implemented and evaluated in our previous work [11, 16] are used to exploit the MCDA architecture to get the maximum advantages out of a clustered WSN. 2. In a flat network architecture, the information of optimal forwarding nodes among the available forwarding node set is kept in a neighbor table. The proposed strategy _i.e._, Energy Aware Routing (EAR) has successfully implemented the same idea in clustered networks with suitable customization and modification by considering the energy awareness aspect. Enlisting candidate decision maker nodes in a neighbor table during the cluster design process, introduction of two threshold levels of CH energy are the major ones among these. 3. Same style of Forwarding Node (FN) selection as mentioned in a previous point is subjugated for the CH and FN rotation strategy as well. This helps a good deal in conserving energy and hence in improving the network lifetime. Rest of the paper is organized as follows: a comprehensive literature survey of the state-of-the-art techniques and comparative analysis is presented in Section 2. Section 3 explains the proposed solution, followed by comparative analysis of the proposed technique with competing algorithms in Section 4. Conclusions and references are given in later sections.