## 1 Introduction  
Modern life has become increasingly convenient with the development and deployment of Information technology (IT) in nearly all areas of life. In particular, the Internet of Things (IoT) is a way to provide services to users using a convergence of both information produced by humans together with that obtained from everyday objects by networking all things and equipment. It is expected that this will play a part in a new service ecosystem capable of judging situations independently, performing tasks without human intervention, and providing information collected through the interactions between many different objects. Ubiquitous technology, which has been identified as a key element of the IoT, has developed rapidly based on Wireless Sensor Networks (WSNs) [1]. IoT is well known as a new communication system for the physical world and Internet connection via WSNs [2]. Accordingly, there is a trend to move from individual small WSNs to multiple large-scale networks in which multiple WSNs are integrated and share information. The role of WSNs has changed from simple surveillance and gathering of information to more critical tasks. As a result, plans for how to process and share large amounts of sensor data and maintain quality of service (QoS) guarantees are being developed [3]. There are several projects underway in the United States, Europe, Japan, and other locations to realize ubiquitous computing based on the IoT, in which all objects are networked and can exchange information [4]. In Korea, a wide range of projects and demonstrations have been initiated under the leadership of the government. There is a lot of research underway to solve a variety of related obstacles to implement the IoT, such as methods for autonomic networking configuration among tens of thousands of nodes, what fusion method should be used for a large-scale heterogeneous network, what exchange method is most efficient for dynamic autonomic data, methods for processing of uncertain data without affecting the reliability of network information, and other service-related issues such as software theoretical modeling to provide comprehensive intelligence services to users and Service Delivery Schemes [5,6]. However, the most important problem being researched is how to effectively implement the IoT by inter-networking heterogeneous subnets using different infrastructures while considering the cost and quality of service (QoS) of each component and network. The three most significant components of the IoT are the Internet, mobile networks, and WSNs [7, 8, 9]. A wide range of commercial services using existing IP-based networks and mobile networks have been already offered. There are relatively few issues in configuring the IoT, since each company can offer a reasonable quality-adjusted price for basic service while a variety of research projects are ongoing to improve product quality [10,11]. On the other hand, current WSN studies are being conducted on a variety of devices and applications, and commercialization has begun in sectors such as ubiquitous computing for healthcare and smart homes. However, there has been few research reported thus far on totally integrated ubiquitous computing models; thus, there is no management plan, which creates a difficult situation for quality management and coordination. WSN QoS management and improvement are thus urgent problems for IoT configuration [12]. WSNs deliver a data-below topology consisting of a tree structure centered on a sink with wireless communications to the sink. A large Ubiquitous Sensor Networks (USN), consisting of different types of WSNs integrated together, has a polynuclear structure and has a much higher probability ofexperiencing congestion due to its Multi-Sink, Multi-Event and Mobile Sink characteristics. Communications over wireless networks are generally not reliable compared with those over wired channels [13]. Due to these characteristics, there is a high probability of congestion in the network around the sinks.