Supporting heterogeneous traffic in wireless sensor networks

We consider an energy-aware packet transmission node that supports packets of two types: real-time packets and non real-time packets. Several energy-aware packet scheduling schemes are explored and discussed. Using the average delay of non real-time packets and the rejection rate of real-time packets as performance metrics, a scheduling scheme for this purpose is proposed. It is composed of two scheduling stages. In the early stage, each packet type is scheduled independently on the per type basis. They are then merged using PGPS into the second stage where the transmission speed for each packet is assigned. The packets are then transmitted using dynamic modulation scaling (DMS). The method has been evaluated using simulation and compared against one in which energy savings schemes are not incorporated. The result shows that not only does it provide a fair share of bandwidth (low rejected packets for real-time packets and low delay for non real-time packets) between these streams, but it also saves the overall transmission energy, particularly in the light load case, where as much as 90% savings can be obtained.