Energy Efficient, High-speed Communication in WSNs

Abstract: This thesis presents a set of feasible extensions for the low power, low delay ORW routing protocol. It introduces the capability of handling multiple concurrent bulk transfers including various application scenarios, e.g., cross traffic. The extensions added to the ORW protocol include a collision avoidance method applied beside thealready existing, well functioning collision detection technique. This collision avoidance method reduced the overuse of the ORW protocol’s collision detection method from a per packet basis to a per bulk transfer basis. This reduction in the frequency of collisions allowed a significant improvement in all the metrics in general, but especially in the transmission time and power consumption. Using the collision avoidance extension a bulk transfer was performed in a fraction of the time that would needed for a bulk transfer using the ORW base protocol, while the power consumed during this fraction of time was less accordingly. The second extension’s purpose was to stabilize the EDC routing metric used by the ORW protocol to estimate the duty-cycles needed for a packet to reach the sink from the given node. This extension was relevant in certain scenarios with high intra-path interference stemming from the high number of hops in the paths between the source and the sink nodes. The third, and last, extension forbade the duty-cycling during a bulk transfer for the nodes that were involved in the given bulk transfer. This extension aimed to mitigate the performance degradation that occurred at the case when a given node terminated its duty-cycle notwithstanding that an other node was sending packets to this given node. By applying these extensions it was possible to reach an almost 500% increase in the throughput with less than 25% of the power consumption during a bulk transfer on the Indriya testbed.