Slot Allocation Algorithms for Minimizing Delay in Alarm-driven WSN Applications

Energy-efficiency and latency requirements in alarm-driven Wireless Sensor Networks often demand the use of TDMA protocols with special features such as cascading of timeslots, in a way that the sensor-to-sink delay bound can stay below the duration of a single frame. However, this single TDMA frame should be as small as possible. The results presented in this paper, point to the conclusion that a largest-distances-first strategy can achieve the smallest single frame sizes, and also the lowest frame size variations. A quite simple distributed version of this algorithm is presented, which obtains the same results of its centralized version. Simulations also show that this discipline presents the best results in terms of sensor-to-sink slot distance, even if they require a few more slots than breadth-first in multi-frame scenarios.