Real-Time Routing for Internet of Things: A Survey on Techniques and Protocols

The Internet of Things (IoT) is a wireless network consisting of interconnected objects. Lately, IoT has become the inevitable future for most if not all technologies related to human life. In IoT, various heterogeneous devices are connected in a Wireless Sensor Network. For that energy-efficient routing, optimization plays a very important aspect for network performance in IoT. The technique and devices in IoT require routing protocols that fit in an environment like low power and lossy networks (LLNs), which rise great routing challenges. Most of the applications of the IoT are real-time applications with time constraints that work on sensing the environment, processing the data, and sending back the results sufficiently quickly to affect the environment before a deadline. Unfortunately, in many emergency cases, like in the case of large data traffic, which leads to network congestion and also causes delay and packet loss. That is why there is a vital need to analyze the routing protocols for IoT under real-time constraints. The purpose of this paper is to provide insight into the various state of the art work of the worldwide researchers about routing protocols for the Internet of Things (IoT) under real-time environment, and we explain extensively used routing protocols in real-time IoT, by first state the routing challenges in a real-time IoT, followed by a complete survey of the variant routing protocols and techniques.