Efficient Data Gathering In Mobile Sensor Networks

Wireless sensor networks (WSNs) extend Internet from virtual world to real phys-ical world to satisfy people's ubiquitous needs for networks and have huge potential for applications. In traditional WSNs. one-hop neighboring sensors of a sink deplete their battery power faster due to more data rela3r. that may cause energy holes problem. To address this issue, some mobility schemes in WSNs are proposed to achieve even energy depletion. According to the movement objects, mobile WTSNs can be classified into two categories:sink mobility and node mobility, in which'mobility'plays different roles in different application scenarios.This dissertation focuses on how to design efficient data gathering schemes in mo-bile WSNs to improve the network performance and makes the following contributions.(1) The path selection problems in delay-guaranteed sensor networks with a mobile sink are considered to meet the delay requirement and minimize the energy consump-tion of entire network. According to the limitation on road infrastructures, the optimal problems arc formulated respectively in scenarios with constrained path and uncon-strained path. And a series of path selection schemes are proposed correspondingly.(2) An optimal partition scheme of overlapping time in path-constrained sensor networks is proposed. Aiming at the scenarios with two nodes and multiple nodes overlapping, the optimal problems based on data equilibrium are analyzed and formu-lated to minimize the variance of amount of data from each node, which is useful for evaluation of monitored information. And a two-phase communication protocol with equilibrium information diffusion is designed to control the information collection.(3) A series of novel destination choosing methods and routing schemes are pro-posed in path-constrained WSNs to improve the network performance (energy con-sumption or network lifetime) under the condition that network throughput are max-imized. An enhanced two-phase communication protocol with good scalability is de-signed to implement the proposed data gathering schemes.(4) An opportunistic routing scheme with bounded message copies is proposed in WSNs with node mobility. In the scheme, the information about speed and residual energy is utilized to allocate the number of copies between the corresponding pair nodes, that avoids the blind spraying of message copies and improves the performance of dclivciy probability, overhead ratio and network lifetime.