电子科大 无线传感器网络课件 wsn_chapter_2_传感器与执行器精选.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * idlestart-up statespeed-up state Example: Low Reliability The actor advertises low reliability (rrth) Some sensors switch to the speed-up state (probabilistically) and select as next hop the closest node to the actor ? reduce latency Some sensors switch to the aggregation state (probabilistically) and select as next hop the closest node already in the da-tree ? reduce energy consumption idlestart-up statespeed-up stateaggregation state Example: High Reliability The actor advertises high reliability (rrth) Comparison between the optimal solution of the event-driven clustering problem and the energy consumption of start-up, speed-up, aggregation configuration with varying event ranges (60 sensors; 4 actors) Sensor-Actor Coordination Start-up (speed-up) configuration: all nodes are in the start-up (speed-up) state Sensor-Actor Coordination Comparison of the energy consumption of different configurations The energy consumption in the aggregation configuration is much lower that in the start-up and speed-up configuration Comparison of average number of hops for start-up and speed-up configuration. The speed-up configuration shows paths with lower delay (less hops) Sensor-Actor Coordination Actor-Actor Coordination Objective: Selecting the best actor(s) in terms of action completion time and energy consumption so as to perform the action! Challenges: Which actor(s) should execute which action(s)? How should multi-actor task allocation be done? Actor-Actor Coordination Model DEFINITIONs: Overlapping Area: Area can be acted upon by multiple actors Non-Overlapping Area: Area can be acted upon only by one actor Action Completion Time Bound: The maximum allowed time from the moment when the event is sensed to the moment when the action is completed Power Levels: Discrete levels of power for performing the action ? A higher power level corresponds to a lower action completion time! Actor-Actor Coordinat