# Enhancing the Reliability of Cellular Internet of Things through Agreement
## 2 Related Work
### The Network Structure  
In addition to traditional human-to-human or human-machine communication, the IoT has become a new trend [21]. In the related applications of the IoT, low-cost sensors, actuators, and other similar devices will automatically generate, exchange and process data, and take actions based on common goals. Many applications can be provided through the IoT, such as healthcare, smart grid, traffic management, smart cities, agricultural systems [22], environmental monitoring, etc. The 5G has been marked as the Internet promoter of all people and everything. It is estimated that by 2021, there will be more than 28 billion connected CIoT devices (CIoT PUs), of which more than 15 billion CIoT PUs will be connected from machine to machine. This makes providing IoT communications be one of the most important tasks of 5G. The CIoT has gradually become one of the key conversion technologies in 5G systems, which allows millions of CIoT PUs to connect to a single base station (BS) [6]. CIoT technology is a new technology, specifically tailored for CIoT PUs. CIoT PUs are small and can run on battery power or the grid, depending on the deployment mode. They may have a GPS receiver to obtain location information, or they may use cellular signals to determine location. The main connection for these CIoT PUs is through remote cellular signals. The main purpose of this CIoT PU is sensing and reporting. because of the wide range of services and the use of cheap hardware, these CIoT PUs are densely deployed and cover many applications. CIoT with MEC is one of the most developed and popularized technologies in the 5G cellular system. It enables all CIoT PUs to connect to the Internet. The characteristics of CIoT PUs include: low power consumption, support for a longer transmission range, and have been developed to implement IoT in dense and remote areas [21]. With the increase in deployment density of CIoT PUs and the diversification of related applications, high-reliability services in cellular networks have become increasingly challenging. In this research, the high reliability of deploying CIoT using MEC will be ensured. In this study, the MEC-based CIoT (MECIoT) is used to provide a highly flexible and reliable CIoT platform. The physical infrastructure of MECIoT used in this study with its densely deployed CIoT PUs is shown in Figure 1. In Figure 1, all these CIoT PUs are connected to 5G BS. This connection is called the _Access Network_. Then, all 5G BSs are connected to the MEC through the _Transport Network_ and send the information obtained from the CIoT PU to the MEC PU. Finally, the MEC PU is connected to the _Core Network_ to transmit the information processed in the MEC PU to the Cloud PU. The structure of MECIoT is shown in Figure 2. MECIoT contains three tiers: _Access-tier_, _MEC-tier_, and _Cloud-tier_. Figure 1: The physical infrastructure for intensive deployment of cellular Internet of Things (CIoT) processing units (Pus). The _Access-tier_ is constructed by CIoT PUs; each CIoT PU is responsible for sensing and reporting sensor data required by CIoT applications. Figure 3 shows the dense deployment using CIoT PUs. All these CIoT PUs are connected to the BS through the _Access Network_. Then, all BSs are connected to the _MEC-tier_ through the _Transport Network_, so that the MEC PUs in the MEC cloud can obtain the data required to provide specific applications. The deployment of CIoT PUs can be divided into two categories: static and dynamic. In static deployment, all CIoT PUs are deployed according to the plan, and CIoT PUs do not need to have mobile capabilities, such as smart grid monitoring, bridge monitoring, and pollution monitoring applications. In dynamic deployment, all CIoT PUs are deployed in an unplanned manner, so CIoT PUs need to have the ability to move. For example, smart transportation systems must be able to grasp the dynamic status of various smart vehicles. A set of MEC clouds are constructed as _MEC-tier_.