This research paper addresses on a secured wireless communications network (WCN) based on WiMAX infrastructure for smart grid applications. The proposed infrastructure consists of WiMAX base stations (BSs) enhanced by edge computing to assimilate the various types of smart grid applications (real time applications and non-real time applications) like wide area monitoring and control (WAMC), video surveillance, tariffs, alarm, and demand side management (DSM). The current work adopts a robust cybersecurity model for the suggested WCN and discusses the possible threats and attacks on the security model. The results indicated that, the WCN based on decentralized processing and self-powered can handle the adopted applications of smart grid successfully. Further, the results explained that the ciphering technique of cybersecurity model does not break the requirements of real time applications' system performance in terms of latency and received data reliability.