On the topic of RTT and delivery ratio in query driven Wireless Sensor Networks

Emerging new applications of Wireless Sensor Networks (WSNs) place new and complex requirements on existing systems and continuously propel new research topics. With the proliferation of WSNs in domains such as process control, automation and related domains, the need to establish reliable communication with low latency is becoming intensely expressed. Taking into account WSNs as low power, low cost and low reliability infrastructures, the process of establishing Quality of Service (QoS) support for WSNs is a non-trivial task. Furthermore, the majority of the scientific work focuses on simulations so there is a need to perform experimental measurements on contemporary hardware solutions used in WSNs for comparison. This paper evaluates WSN application for access control system where sensor nodes are query driven and the network follows star topology configuration. Considering specific network configurations, this paper investigates reliability and delay for round-trip communication - RTT. The emphasis is placed on the analysis of network performance from the sensor node point of view. Analysis is performed through simulation and experimental validation of a WSN deployed within the proposed testbed. The investigation of influence of network parameters on the proposed metrics for critical network conditions using simulation results in higher losses, reduced reliability and high values of RTT that needs to be avoided for real network deployment. Finally, comparison of simulated and experimental results yields a conclusion that the simulation does not accurately represent experimental data, and more accurate simulation model of WSN nodes should be proposed in order to mitigate the observed discrepancies.