Reliable end-to-end delivery service is one of the most important issues for wireless sensor networks in large-scale deployments. In this paper, a reliable data transport protocol, called the Data Forwarding Protocol (DFP), is proposed to improve the end-to-end delivery rate with minimum transport overhead for recovering from data loss in large-scale wireless sensor environments consisting of low speed mobile sensor nodes. The key idea behind this protocol is the establishment of multi-split connection on an end-to-end route, through the Agent Host (AH), which plays the role of a virtual source or a sink node. In addition, DFP applies the local error control and the local flow control mechanisms to multi-split connections, according to network state. Extensive simulations are carried out via ns-2 simulator. The simulation results demonstrate that DFP not only provide up to 30% more reliable data delivery, but also reduces the number of retransmission generated by data loss, compared with the TCP-like end-to-end approach.

A wireless sensor network is comprised of a large number of battery-limited sensor nodes communicating with unreliable radio links. The nodes are deployed in an ad hoc fashion and a reverse multicast tree is formed in the target domain. The sink node disseminates a query and collects responses from the sensors over pre-established links. Survivability in wireless sensor networks reflects the ability of the network to continue to detect events in the case of individual node failures. We present a sender initiated path switching algorithm that enables the immediate sender to change the packet's route dynamically when its parent on the reverse path is down. The overall effect of path switching on the survivability is analyzed as a measure of reliable event delivery. Using independent battery capacities, an analytical model of a multihop network is derived. The model is used to predict the maximum network lifetime in terms of total transmitted messages; which is in turn used to verify the correctness of our simulations. The results have revealed that dynamic path switching has a better performance than static multipath routing and salvaging schemes. It has also been shown that the proposed approach enhances reliability up to 30% in some topologies.