Visitor Statistic
Mobility Modeling and Analysis
To study mobility per se, it is beneficial to have protocol-independent metrics that reflect the nature of the movement pattern. The routing performance is affected by the link status, and the link status between the nodes is in turn affected by the relative movement. Relative speed metric captures the magnitude of the relative movement and spatial dependence metric captures the angle of relative movement. These are two useful tools to analyze the mobility characteristics. Link duration, which is the average duration of a link existing between two nodes, is helpful in analyzing the connectivity graph.
Contact-based Resource Discovery and Query Resolution
provisioning of efficient query resolution and resource discovery. In many cases sensor networks are expected to be large-scale, and in some cases these sensors maybe installed on moving objects, rendering the query resolution problem even more challenging. Flooding techniques, including global flooding or expanding ring search techniques, may be very inefficient in large-scale networks, especially in wireless (spatial) networks where the diameter of the network tends to be quite high. More so is the case when queries are one-shot and frequent.
Robust Geographic Protocols and Services
Geographic protocols are very promising for wireless ad hoc and sensor networks. These protocols take advantage of the information of node locations to provide higher efficiency and scalability. We study geographic protocols to assess their robustness to non-ideal conditions corresponding to the real-world environments. Our current studies cover protocols that provide basic functions at the network-layer such as geographic routing, geocasting, and geographic-based rendezvous mechanisms. Several robustness issues are considered, such as lossy wireless channels, location inaccuracy, obstacles, node failures, and mobility. Our results are promising and show the discrepancy in performance when the protocols are evaluated in non-ideal realistic environments compared to the common ideal environments typically used. These results also show the inadequacy of the current protocols to be implemented as-is in real-world. By introducing simple fixes and strategies that take these conditions into account, we show that we are able to improve the performance significantly.