Research On Data Gathering Protocol For Optimizing Lifetime And Transport Delay Under Reliability Constraint In Multi-hop Cluster-based WSNs

The energy-efficient and reliable data transmission mechanism, determining how the sensed data are delivered to the base station by multi-hop routing, is one of the basic and key issues in the WSN research and has a critical influence on the communication performance and energy efficiency of the network. Focusing on the transmission characteristics of WSN, the research on energy-efficient and reliable data transmission theory and application technology is of great significance. Clustered wireless sensor network, as a kind of hierarchical WSN, has been verified the availability and high-efficiency in numerous research and applications. However, due to the complexity of cluster-base WSNs, there are few researches both with optimizing lifetime and transport delay under reliability constraint in clustered WSNs.In this paper, we propose a reliable data gathering protocol named SW-HBH-ARQ for clustered WSNs. Based on this approach, we analyze the transmission delay and energy consumption of the network theoretically and present an analysis strategy to meet the requirements of a sensing application through trade-offs between the network lifetime and source-to-sink transport delay under reliability constraint for cluster based WSNS. After this, a novel data-gathering protocol named Broadcasting Combined with Multi-NACK/ACK(BCMN/A) protocol, combining the energy efficiency and minimal delay under statistically reliable constraint, is proposed on the basis of SW-HBH-ARQ. The main characteristics of this protocol are as follows. In the intra-cluster data-gathering process, each cluster head broadcasts several NACK messages to notify the nodes whose data are not received properly to retransmit their data. This will ensure the nodes whose data are accepted validly not to do retransmission and reduce the energy consumption and transport delay. In the inter-cluster data-gathering process, cluster heads will send multiple ACK messages after receiving a data packet from other heads timely. We actually increase the number of ACK packets with this strategy, but the retransmissions of data packets that take a lager number of energy to forward are decreased at the same time. Therefore, the energy consumption is declined and the network lifetime and transmission delay are improved significantly.Simulation results are found to be consistent with our theoretical results, and demonstrate the BCMN/A protocol is potent in boosting energy efficiency and transport delay under reliability constraint, which will be instructive and meaningful to deployment and improvement for cluster-based WSNs.