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Wireless Sensor Networks (WSNs) consist of several sensor nodes, each of which may collect, receive and transmit data. In recent years, WSNs have emerged as essential technologies due to their ubiquity in applications such as the military, smartphones, disaster management, healthcare monitoring, and other surveillance systems. The inability to send data from the sensor node promptly and the impossibility of new data reaching the node's queue indicate of network congestion. The packet will be either discarded or delayed, which will cause more data loss, longer transmission delays, reduced network throughput, and lower network quality of service. To address this problem, this paper proposes an efficient and novel Firefly Algorithm-optimized Fuzzy-PID (FA-Fuzzy-PID) controller for congestion control in Wireless Sensor Networks (WSNs). The proposed control technique used a fuzzy control algorithm to overcome the standard PID controller's slow optimization parameter, low calculation accuracy, and limited adaptability.

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This research work conducted a design and simulation of an ultra-low power all-optically tuned nonlinear ring resonator-based add-drop filter. The purpose of this study is to investigate a CMOS-compatible nonlinear material system for an optical filter with temperature resilience, polarization insensitivity, and fast and energy-efficient tunability. The all-optical tunability was achieved using an optical pump that photo-excites the high nonlinear Kerr effect in the device material system. A three-dimensional multiphysics approach was used, combining the electromagnetics and thermo-structural effects in the filter. Hybrid graphene on an ultra-rich silicon nitride ring resonator-based filter enabled the realization of an ultra-high tuning efficiency (0.275 nm/mW for TE mode and 0.253 nm/mW for TM mode) on a range of 1.55 nm and thermal stability of 0.11 pm/K. This work contributed to the existing literature by proposing (1) the integration of a high Kerr effect layer on a low loss, high index contrast, and two-photon absorption-free core material with an athermal cladding material system and (2) the use of a cross-section shape insensitive to polarization. Moreover, the tuning mechanism contributed to the realization of an all-optical on-chip integrable filter for Dense Wavelength Division Multiplexing systems in the less occupied L band.

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