Research Article QoS and QoE Aware N-Screen Multicast Service Ghulam Sarwar, Farman Ullah, and Sungchang Lee Department of Electronics and Information Engineering, Korea Aerospace University, Deogyang-gu, Goyang-si, Gyeonggi-do 412-791, Republic of Korea Correspondence should be addressed to Sungchang Lee; sclee@kau.ac.kr Received 17 December 2015; Accepted 29 March 2016 Academic Editor: Marco Anisetti Copyright © 2016 Ghulam Sarwar et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te paper focuses on ensuring the quality-of-service (QoS) and quality-of-experience (QoE) requirements of users having heterogeneous devices in a multicast session. QoS parameters such as bit rate, delays, and packet losses are good indicators for optimizing network services but fall short in characterizing user perception (QoE). In N-Screen service, the users have diferent devices with heterogeneous attributes like screen size, resolution, and access network interface, and the users have diferent QoE on N-Screen devices with the same QoS parameters. We formulate the objective function of the N-Screen multicast grouping to ensure the minimum user’s QoE with smaller bandwidth requirement. We propose a dynamic user reassignment scheme to maintain and satisfy the QoE by adapting the user’s membership to the varying network conditions. Te proposed schemes combine the available bandwidth and multimedia visual quality to ensure the QoS and QoE. In the network architecture, we introduce the functions of the QoS and QoE aware multicast group management and the estimation schemes for the QoS and QoE parameters. Te simulation results show that the proposed multicast service ensures the network QoS and guarantees the QoE of users in the varying network conditions. 1. Introduction Multimedia streaming is one of the fastest growing appli- cations and the last decade alone has witnessed a rapid development in the complexity of smart devices and commu- nication technologies. Te interactive advertisement bureau report states that about 69% of users have 4-Screens [1] active and about 90% of the users’ interaction is through Multi-Screen [2]. N-Screen, also termed as Multi-Screen, has diferent attributes such as network interfaces, media codecs, screen resolutions, computing, and storage. N-Screen service enables users to access and share the content from the same source through heterogeneous devices from any location and at any time [3, 4]. Te ubiquity of communication technologies and smart devices demands that users should be able to access their subscribed services through any of the available networks such as 3G, 4G, LTE, and WiFi, as well as through any device such as smart phones, laptops, desktops, and tablets. N-Screen multimedia service demands extensive bandwidth to ensure the quality of service (QoS). A lack of bandwidth could cause higher end-to-end delay, video jitter, and packet losses. Cisco forecasts that by 2019, 80% of the global IP data will be video trafc. Moreover, the heterogeneity of N-Screen devices raises new questions about the multimedia QoS and user’s experience on diferent terminals [4, 5]. Te challenges that come with a rapid increase in mobile video trafc and ensuring multimedia QoS and user’s quality of experience (QoE) on mobile devices can be addressed by either boosting the network capacity or by ofoading trafc from the core and backhaul networks [6]. Tis paper presents a novel N-Screen multimedia multicast scheme to minimize the trafc and ensure that the QoE requirements of all group users on their N-Screen devices are met. Te huge growth rates of multimedia services utilize higher bandwidth and cause congestion in the core network. IP multicast [7] is a technique designed to conserve the network bandwidth by sending a single stream to multiple hosts simultaneously which helps in reducing the core net- work trafc. Te multicast stream receiving nodes can have diferent capabilities and QoS and QoE requirements. IP mul- ticast synchronizes the content transmission rate to the worst channel conditions among the multicast users that cause the traditional bandwidth fairness problem. To improve fairness Hindawi Publishing Corporation Journal of Sensors Volume 2016, Article ID 8040138, 11 pages http://dx.doi.org/10.1155/2016/8040138