Recent years have witnessed a growing interest in the application of wireless sensor networks (WSN). Examples of such applications include environmental monitoring, disaster management, target tracking and border control. Typically sensors in such applications collect data about their surrounding and forward that data to a gateway (sink). Due to the limitation of the energy supply that these miniaturized sensors have, almost all of the proposed routing protocols aimed at energy efficiency as the ultimate objective and considered relaying data to a stationary gateway.
However, with the increasing interest in WSN applications, new protocols that can provide other performance guarantees such as end-to-end delay are needed. In this dissertation, we present a novel energy-aware mechanism for routing of delay-constrained data. The end-to-end delay bound is achieved by employing the Weighted Fair Queuing (WFQ) based packet scheduling technique in each sensor node. We have further extended the protocol to provide on-time delivery of delay-constrained data even when in-network data aggregation is performed at intermediate sensor nodes.
In order to further improve the performance of our proposed protocol, we exploited the gateway?s ability of moving to a new location. The aim is to enhance timeliness of real-time packets for the cases where it starts to diminish due to high volume of traffic. We have developed a novel relocation protocol for the gateway which periodically checks the
deadline miss rate for packets and triggers a relocation stimulus for the gateway if the gateway miss rate exceeds a certain threshold.
In addition to demanding certain performance guarantees, numerous WSN applications desire the mobility of the gateway node. We present a novel routing protocol for efficient and continual data delivery to a mobile gateway. The same mechanism for handling gateway mobility is then utilized and combined with WFQ-based scheduling in order to provide certain end-to-end delay bounds with a mobile gateway. The performance of all the proposed protocols has been verified through extensive simulations. |