نمونه متن انگلیسی مقاله
Wireless Sensor Network (WSN) localization is an important challenge, because A strong relationship between aggregation sense data and the location of data's origin. Software Defined Networks (SDN) technique is support localization algorithm and take into account all network's limitations and constraints. By making use of global network knowledge provided by SDN controller, the results of previous studies show that considerable improvement in network performance can be achieved. This paper explores the recently proposed localization algorithms and discusses the simulation results for each method used in Software Defined Wireless Sensor Networks (SDWSN) to find the best way to localized nodes with the highest accuracy and lowest energy consumption. This paper also present Software defined networking paradigm and WSNS challenges which solved by SDWSNs.
Wireless sensor networks (WSNs) have taken a lot of attention in recent years. WSN considered as the fundamental of smart environment, it acts as interface between the real world and smart systems. Sensor nodes have been used in wide applications such as monitoring, tracking and security applications . WSN is a group of distributed and autonomous sensor for monitoring the physical environment .
Wireless sensor network is the backbone of Internet of Things (IoT). Under the heterogeneous environment, a large number of sensors are connected together used to aggregate large amount of data. IoT network in the case of a smart city must be scalable with any number of devices and different technology in anytime, and because the wide application areas and difference of technology among the devices, incorporating WSN becomes challenging .
Sensor’s location awareness has a great interest in many wireless systems. Actually, sensing data without knowing the sensor location is meaningless .
In distributed localization the nodes gather the measurement with various methods and determine the distance between neighbors and anchor nodes . Due to different requirements and network constraints, such as battery consumption, computational resources, link technology and radio transmission range, Authors like Junior et al. in  proposed a model based on Software Defined Networking (SDN) paradigm, in which a controller have a global view of the network and it has the ability to choose a suitable allocation algorithm, also takes into account when choosing the requirement to be fulfilled, Such as extending the network lifetime, improving processing power of applications or reducing the quantum of data exchanged in the network.
In this paper, we have presented the concept of SDN and highlighted its advantages that brings to traditional WSN management, the global overview of control plane allows to improved network performance during localization. Researchers are primarily interested in reducing energy and increasing the accuracy when calculating nodes location.
Researchers proposed several localization algorithms in SDWSNs and the simulation results showed that some algorithms succeeded in increasing the accuracy of the location calculation with less energy consumption.
Other localization techniques like Trilateration, Maximum likelihood estimation and the Linear Least Square Localization algorithm are fail to increase accuracy and moving the computational operations from data plane to control plane, it’s just wasted energy and increase the load on SDN. However, this field need more work to exploit the centralization nature in SDWSN to increase accuracy of localization estimation and increase the lifetime.