# Cross-Layer MAC/Routing Protocol for Reliability Improvement of the Internet of Things
## 1 Introduction  
The Internet of Things (IoT) is a system wherein many physical objects can be connected to the Internet using a wireless network. In this regard, different network architectures from heterogeneous communication technologies may be adopted depending on the nature of the services to be implemented (e.g., low data rate or high data rate), operational constraints (e.g., availability of external power sources), and coverage (e.g., long-range or short-range links). For example, if end-to-end communication is not possible due to power limitations and/or radio wave failures, mesh network and short-range communication technologies are preferred. In this case, multi-hop communication between devices can be used to pass information from the control center to the edge of the network. In this regard, the IEEE 802.15.4 standard [1] may be applied. Instead, star networks and long-distance communication techniques are preferred if direct and reliable links between the central hub and all nodes deployed in the coverage area are available. This topology can be adopted especially in most low-power wide-area networks (LPWANs) designed to interconnect battery-driven devices over long distances at low data rates. These technologies can be used in a wide variety of applications related to buildings, industrial automation systems, health care, smart grids, and security [1, 2]. A key concern of IoT is whether Internet protocol technology can be used in limited devices such as sensors and actuators. Devices used in IoT are devices with limited resources in memory, battery, bandwidth, and connectivity [3]. The Internet Engineering Task Force (IETF)formed a working group (WG) in 2013 and began standardizing activities to support the requirements of the IoT. As the IoT relates to various technologies, the IETF has working groups focused on four IoT areas-- that is, the Internet, applications, routing, and security. Typically, there are low power wireless personal area network (6 LoWPAN) WGs that have ended their current activities in the Internet area, constrained restful environments (CoRE) WG in the application area, routing over low-power and lossy networks (ROLL) WG in the routing area, and authentication and authorization for constrained environments (ACE) WG in the security area. The IETF WGs are actively working on standardizing IoT-based protocols to be used within low-power and lossy networks (LLNs) comprising wireless nodes with constraints in power and computing capacity. Another key feature that IETF pays attention to in IoT standardization activities is allowing a wide range of \"things\" to use interoperable technologies to communicate with each other. Here, \"things\" range from built-in sensors to complex machines (e.g., cars) or even large infrastructure (e.g., bridges). Currently, deployable IoT stacks can easily configure many additional protocols, including protocols not designed for IoT or IETF (e.g., ISO Standard Message Queuing Remote Transport (MQTT) or IETF Standard HTTP). This is mainly due to the fact that IoT is important and suitable for various numbers of definitions, design visions, and deployments [4]. Recently, as research on smart cities, a national strategic project, has begun in earnest, the scope of application of IoT technology is expanding even more. One of the goals of the smart city concept is to monitor, control, and manage resources such as electricity. In this regard, the starting point for many current smart city implementations in Europe is the public lighting system [5; 6]. In [7], the authors focus on the design of streetlight controllers to reduce power consumption and ultimately reduce public lighting costs. There are studies that have adopted IEEE 802.15.4 technology in smart city scenarios. In [8], the authors discuss simulators for evaluating the performance of IEEE 802.15.4 and IEEE 802.11 when applied to such scenarios. In [9], the authors investigate the deployment of wireless sensor networks at road intersections in some of the world's major cities.