Abstract: Internet of Things (IoT) has been recognized as a part of future internet and ubiquitous computing. It creates a true ubiquitous or smart environment. It demands a complex distributed architecture with numerous diverse components, including the end devices and application and association with their context. A key technology in the realization of IoT systems is middleware, which is usually described as a software system designed to be the intermediary between IoT devices and applications. The middleware for IoT acts as a bond joining the heterogeneous domains of applications communicating over heterogeneous interfaces. This paper presents the current gap and future directions in this field by a comprehensive review of the existing middleware systems for IoT and the Open Source Middleware Tools for the Internet of Things.

Keywords: 4G/LTE, Smart antennas, traffic light, DoA, AoA, OTSAT, GLT, TTP, MI.