On Energy Efficient Routing Protocols for Wireless Sensor Networks

The sensor nodes communicate together by wireless techniques, and these communication techniques are handled by routing protocols. The resource limitation and unreliable low power links between the sensor nodes make it difficult to design an efficient routing protocol. The sink may be either static or mobile in the network. In many scenarios, static sink causes hotspots, where the sensor nodes near to the sink die out soon due to transmission overhead. On the other hand, the mobile sink improves the lifetime of a network by avoiding excessive transmission overhead on the nodes that are close to the sink. Further, an attempt is made to resolve the issues of sensor nodes and sink mobility by proposing energy-efficient routing techniques for wireless sensor network. A multipath routing protocol (MRP) is proposed, which reduces the control overhead for route discovery and increases the throughput of the network. The proposed multipath routing protocol is designed to improve the lifetime, latency and reliability through discovering multiple paths from the source node to the sink. MRP is a sink initiated route discovery process, where source node location is known. In MRP, one primary path and number of alternate paths are discovered. The sink may receive redundant data due to densely deployed sensor nodes. Clustering the sensor nodes is an effective way to reduce the redundancy. The cluster head aggregates the cluster members’ data before transmitting it to the sink. A cluster based multipath routing protocol (CMRP) is proposed, where the clustering technique reduces the data traffic in the network, and multipath technique provides the reliable path. Although, the hotspot problem can be resolved with mobile sink, it makes the network dynamic. A tree-based data dissemination protocol with mobile sink called TEDD is proposed to overcome the above problems. TEDD manages the mobility of the sink and balances the load among the sensor nodes to maximize the lifetime. A sensor node initiates the tree construction and becomes the root node of the tree. Sensor nodes can send the data to the sink using this tree. It has been observed that the TEDD is a robust and energy-efficient protocol in themobile sink environment. The proposed dense tree based routing protocol (DTRP) is an extension of TEDD. The objectives of DTRP are to minimize the control overhead and reduce the path length. Both the objectives are achieved by reducing the number of relay nodes in the tree structure. DTRP resulted in, increased lifetime and reduced end-to-end latency. A clustered tree based routing protocol (CTRP) is designed to reduce thedata traffic in the network and efficiently manage the sink mobility. The traffic is reduced by the cluster head, which uses the aggregation technique. The number of cluster heads is restricted to the number of grids present in the network. The CTRP efficiently manages the load among the sensor nodes. The tree is constructed in the network using the cluster heads as vertices. The data can be transmitted to the sink through the tree structure. The CTRP is compared with the TEDD and DTRP in terms of energy efficiency, end-to-end latency, data delivery ratio and network lifetime. For the time-sensitive applications, a rendezvous based routing (RRP) with mobile sink is designed. Each sensor node can communicate with the rendezvous region. In RRP, two methods for data transmission are proposed. In the first method, source node directly transmits their sensory data to the rendezvous area. In the second method, the source node retrieves the sink’s current position and sends the data to the sink through intermediate nodes. The end-to-end latency and data delivery ratio are improved in the first proposed method. Whereas, the energy consumption and lifetime in the second proposed method are enhanced.