Designing a reliable transport protocol is a new challenging area in Wireless Sensor Networks (WSNs). Traditional transport layer protocols (such as TCP and UDP) can’t directly be applied to the WSNs. Generally transport layer is responsible for congestion control and reliable packet delivery. Congestion is an essential problem in WSNs. It not only wastes the scarce energy due to a large number of retransmissions and packet drops, but also hampers the event detection reliability. Thus, to meet the Quality of Service (QoS) requirements of network applications, a reliable and fair transport protocol is mandatory. In this paper we present a reliable transport protocol for wireless sensor networks which not only controls the congestion in the network, but also provides reliability in packet delivery. The proposed model uses a rate control mechanism to adjust the transmission rate of each sensor node based on the congestion degree in the network. We use the time to recover packet loss as a congestion indicator. To use a node’s energy efficiently, we use a hop-by-hop NACK based reliability guaranty model. Simulation results, confirm the superiority of the proposed model.

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