Routing Protocol with Unavailable Nodes in Wireless Sensor Networks

With the rapid development of modern microelectronic technology, wireless communication technology, signal processing technology, and computer network technology, wireless sensor networks (WSNs) has become one of the most important and the most basic technologies of information access (Jennifer Yick, 2008). WSNs have been widely used in military, environment monitoring, medicine care and transportation control. Routing protocol is one of the key support technologies in WSNs and the performance of routing protocols significantly impact the performance of the entire network (Khan & Javed, 2008). In wireless sensor networks (WSNs), some unavailable areas often are formed because some sensor nodes become unavailable due to energy exhausted, congestion, or disaster (Fang et al., 2006; Jafarian & Jaseemuddin, 2008). Multi-path routing protocol is one of the mechanisms to solve or alleviate the above problems. Data delivery over multiple paths can help balance network load and extend the life time of entire network. Generally, multiple paths in the routing protocols can be classified into two categories: disjoint multiple paths and joint multiple paths (Ganesan et al., 2001). Disjoint multiple paths can be furthermore classified into node-disjoint multiple paths and link-disjoint multiple paths. In the node-disjoint multiple paths, each path is independent and has no affect on each other. Apparently, it is better to choose node-disjoint multiple paths for data delivery in the designed routing protocol if possible. Most of multi-path routing protocols in wireless ad hoc networks are extended from classical single path routing protocols. For example, split multi-path routing (SMR) is based on the dynamic source routing (DSR) protocol and ad hoc on demand multi-path distance vector routing (AOMDV) extends the ad hoc on-demand distance vector routing (AODV) protocol (Lee & Gerla, 2001; Marina & Das, 2001). Similarly, as its special type, most of multi-path routing protocols in WSNs are extended from the ones in wireless ad hoc networks and at the same time take account of different factors such as energy, QoS, security, congestion, and etc. There are many papers to consider energy efficiency when designing multi-path routing protocols in WSNs (KIM et al., 2008). They mainly select multiple paths based on the link cost function consisting of both the node residual energy level and hop count. In (Huang & Fang, 2008), Xiaoxia Huang and Yuguang Fang proposed a probabilistic modeling of link state for wireless sensor networks. Based on this model, an approximation of local multi-path routing algorithm is explored to provide soft-QoS under multiple constraints, such as delay and reliability. Yunfeng Chen and Nidal Nasser proposed to select multiple paths between one 6