earticle

영어

Wireless Sensor & Actuator networks take actuation decisions based on the data collected by the deployed set of sensor nodes. The method of data acquisition, leading to decision making, could be semi-automated or fully automated. In either case, the reliable delivery of information assumes critical importance since it has a direct impact on the decision making process for subsequent action by the actuator network. This paper presents in details a novel methodology “Layer Based Time Constrained Reliable Data Acquisition Mechanism” LTCRDM, which can be utilized for reliable delivery of information, sensed periodically or in response to a query, by the sensors deployed over a geographical area to a centralized sink where the decision for eventual actuation is taken. Since the latency and reliability requirements in a WSAN are stringent, the mechanism detailed attempts delivery of maximum packets with minimum latency to ensure that estimation of the sensed event is accurate leading to correct decision making. The methodology ensures relatively low packet loss as compared to standard packet delivery mechanisms with latency time constraints. The algorithm for dissemination of query (LQDM) in the deployed nodes is also presented. Authors have provided detailed algorithm, results of simulation and observations using IEEE 802.15.4 PHY & MAC as underlying layers. Experimental results over a test-bed are also presented. A critical analysis of the results is presented for comparison against the standard methodologies in vogue.