WiMAX backhaul for environmental monitoring

In environmental monitoring, wirelessly connected sensors form local networks and collect data, which are sent to a central repository for further analysis and permanent stor- age. In this paper we empirically evaluate the use of xed WiMAX to backhaul data from an environmental monitor- ing application. We nd that aggregating sensor readings is crucial for taking full advantage of the WiMAX back- haul. We consider application-layer aggregation for scenar- ios where sensor communication is programmable or at least congurable. For scenarios where sensors cannot be modi- ed, we consider network-layer aggregation using a perfor- mance enhancing proxy. Finally, we consider the case where application- and network-layer aggregation are combined. Our results show that without aggregation, goodput is only a small fraction of the maximum achieved in our testbed. Furthermore, we examine the eect of dierent modulation