Controlled mobility for performance enhancements in wireless sensor networks

The objective of this thesis is to investigate the role of controlled node mobility for enhancing data collection and energy performance in wireless sensor networks. The goal is to develop joint mobility and packet routing protocols, and to study the associated tradeoffs from a network design standpoint. An understanding of these tradeoffs help in formulating design guidelines that can be applied to network deployments. Specific contributions of the thesis are as follows.;First, for networks with mobile sensors and static base stations, a new paradigm for extending network life has been explored by introducing energy-aware node mobility along with an adaptive packet routing protocol. A fully distributed and localized mobility control and packet routing framework for collective extension of network lifetime was developed. Via analytical modeling and simulation experiments it was established that using cooperative and energy-aware node mobility, it is feasible to significantly extend a sensor network's operating life even in situations where the energy cost of physical node movement is modeled as high as up to four orders of magnitude larger than the energy cost for packet transmissions. The investigated paradigm in this part of the thesis applies to networks with mobile sensors such as terrestrial and aquatic robotic micro-vehicles with sensing abilities.;The second part of the thesis deals with networks with static sensors and mobile sinks which correspond to applications such as Unmanned Air/Ground Vehicles (UAV, UGV) based data collection from unattended static sensor units. In this part of the thesis, a generalized analytical formulation for mobile sensor based data collection has been developed with varying levels of static sensor to mobile sink multi-hop routing, which is parameterized as a hop-bound factor k. The key concept is to appropriately adjust the extent of multi-hop routing and the corresponding sink trajectory by varying the hop bound factor k. The main result is that for given sensor data rates and node density, there are clear bounds to the extent of multi-hop routing that can be sustained in a network. In other words, to maintain data collection stability from delay and capacity standpoints, the extent of multi-hop routing (hop-bound factor k) needs to be within a feasible range---rendering data collection with static sink often infeasible.;This result was experimentally validated by developing a Network-Assisted Data Collection (NADC), which is a distributed and location-unaware sink navigation and data routing protocol. Finally, the NADC framework was extended for networks with spatially heterogeneous data generation rates, and the routing feasibility results were validated for such scenarios.