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TopIntroduction
The development of Internet associated with the problem of communication between users or devices and environment. The users can access the consistency of data in his/her devices from different environments. The network with computing devices connected at any place, anytime, anywhere with any object is Ubiquitous Networks (UNs). This allows user to access and exchange information or data at anytime, anyplace, and anywhere in different environments through the use of broadband and mobile devices (Pallapa, 2010). The management of ubiquitous network includes core network, access network, ubiquitous appliances, and sensors. The prime focus of ubiquitous computing is used to create intelligent products that are connected, making communication and the exchange of data easier and less obtrusive (Kevin & Jairo, 2010).
Due to the above requirements of UNs, so need of data synchronization, which is one of the important issues of ubiquitous computing environment which provides assurance of data consistency among devices, i.e., allows users to access application on any device without any conflicts in the data stored. The purpose of data synchronization is to provide services to the users with convenience and continuous updating of data available at various devices without any conflicts. Data synchronization allows user device independent for accessing ubiquitous services over UNs. Various applications are running on user mobile devices/nodes, such devices are needed for data synchronization mechanisms for accessing the services through its servers (Aaqif & Mureed, 2012).
Figure 1 illustrates the layout of proposed UN, which has four layers like physical layer, network layer, ubiquitous computational layer, and application layer. The physical layer of the UN is associated with heterogeneous wireless sensor networks, mobile adhoc networks, and vehicular adhoc sensor networks, etc., the network layer or Internet layer is comprised with ubiquitous network nodes for computing ubiquitous services. The access points such as base stations, sensors, controllers and gateways are used as network administrators to access ubiquitous services continuously without any interrupt. The ubiquitous nodes hold the information from the network for computing and processing of ubiquitous services. The ubiquitous computing layer consists of a set of the following functions for services to users such as resource management, fault tolerance, data synchronization, context aware, and ubiquitous service. An application layer has ubiquitous applications which are accessed by users at different application sectors like agriculture, health monitoring, transportation, disaster management, landmine detection, robotic landmine detection, water catchment, eco-system monitoring and so on. Finally end user can access the ubiquitous services using a mobile device. The objective of the UN is used to provide distribution of communication infrastructure and wireless technologies throughout the environment to enable continuous service to users at any time, and anywhere through the use of broadband and mobile devices.
The following sections describe the issues and challenges in UNs, the cognitive agent approach, the classifications of data synchronization algorithms are used in UNs, the proposed data synchronization model in UNs using cognitive agent approach, and finally concluding remarks of the paper.
TopIssues And Challenges In Ubiquitous Networks
The major issues and challenges that affect the design and performance of ubiquitous network are as follows (Franklin, 2001; Jaydip, 2010; Stajano, 2009; Upkar, 2010):