A Stable Routing Framework for Tree-Based Routing Structures in WSNs

Achieving industry standards for transmission of data is an ultimate goal for wireless sensor network (WSN) designers. Such standards are difficult to attain due to the challenging communications environment in which WSNs operate where best transmission routes may change rapidly. In such dynamic environments, it is not only advantageous, but commonly necessary to change the used route for better performance. However, with so many changing routes, it is possible to introduce instability, which can hinder the provision of services. Route instability can be particularly detrimental in a tree-based routing structure. In these scenarios, it is beneficial to maintain more stable routes in the tree to preserve high standards. The focus of this paper is the development of a route stability framework, whereby currently used metrics are adapted to promote routes that achieve greater stability in highly dynamic network conditions. The central concept introduces neighborhood heuristics (NHs), a method of combining a sensor's routing metric with those of its neighbors to highlight both the quality of the current route and the quality of the routing options available to the sensor should its current route become unavailable. The additional information afforded by the new combined metric allows sensors to choose good quality routes that can better maintain quality despite the degradation of an upstream link. The NHs framework is implemented with the routing protocol for low power and lossy networks routing protocol. Experiments are conducted both in simulation and on an open public testbed, which compare routing stability using the expected transmissions (ETX) metric and ETX under the NHs stability framework (ETX-NH), showing a marked increase in route stability for ETX-NH over using ETX.