Hierarchical Control Structure for Provisioning N-Screen Services in Mobile Operator Network Ghulam Sarwar, Farman Ullah, and Sungchang Lee Department of Information & Communication Korea Aerospace University, Goyang, South Korea {sarwar,farman,sclee}@kau.ac.kr Abstract—In this paper, we propose hierarchical control ar- chitecture and request routing mechanisms to support N-Screen services and mobility of both sources and devices in hetero- geneous networks. N-Screen services enable users to manage their active sessions among multiple devices having different capabilities, access networks and locations. To support N-Screen services in mobile operator networks, we introduce new functions that maintain the list of active devices with their sessions and network parameters for efficient N-Screen session management. The system supports the terminal and personal mobility of both the sources and devices without affecting the overall multicast connections and minimizes the service disruption. We propose a hierarchical structure for request routing and content sharing that tries to add a user to an active session locally first. The system offloads the backhaul and core networks traffic by localized session adaptation and sharing and improves the scalability issue of existing centralized mobile network architecture. We focus on the physical placement of the new nodes and mechanisms for request routing. Simulation results show that the use of hierarchical adaptation nodes in mobile operator networks can significantly reduce network latency and traffic, and improve the system throughput. I. I NTRODUCTION N-Screen multimedia services, live streaming, video on demand and Massively Multi-Players Online Games demand extensive bandwidth to ensure QoS and delay constraints. Cisco forecasts a 13-fold increase in mobile video traffic by 2017 [4]. This challenge can be faced either by boosting the network capacity, or by offloading traffic from the core and backhaul networks [1]. Multimedia contents and smart devices are growing expo- nentially. A user needs to access and share the contents at any- time, anywhere and on any of his devices. N-Screen services enable users to share, split-share, transfer or retrieve-back their active sessions among their devices [2, 7]. Many researchers used SIP signaling and the concept of ’Virtual Device’ to manage multimedia sessions among user’s devices [5]. Luc et al. [3] proposed visualcasting architecture to enable session sharing with multiple tiled-display sites, but, performed visu- alcasting from the same bridge node. A user can get the list of his active devices registered in different networks from the N-Screen service and content management server (NSCMS). For localized session sharing, N-Screen service architecture includes a transcoding node in the networks. Mateiro et al. [6] proposed an agent-based multicast mechanism that supports terminal mobility of both sources and listeners within the network. Sharing contents from the same bridge node with multiple devices reduces the wired network traffic and content server (CN) processing load [2], but cannot help mobile networks as traffic to each user from the bridge node should traverse the PDN GW, core and backhaul networks. Moreover, the existing systems do not support N-Screen services, personal and terminal mobility of both sources and receivers, and seamless service continuity in heterogeneous networks. We use NSCMS, N-Screen service and cluster control agents that maintain the user’s profile, a list of active user’s devices and network parameters to enable N-Screen services, localized session sharing, and efficient session management in hetero- geneous networks environment. We introduce the N-Screen bridge node to offload traffic from the backhaul and core net- works, and to minimize the streaming server processing load. The simulation results show the effectiveness of hierarchical bridges in terms of network latency and throughput. II. GENERAL STRUCTURE FOR N-SCREEN SERVICE PROVISION IN MOBILE NETWORK The first important design choice is the physical placement of the N-Screen bridges in the mobile operator network. In order to enable resource saving, the bridges can only be placed where the content can be directly accessed in the network with Fig. 1. Structure for Provisioning N-Screen Services in Mobile Network 2014 IEEE International Conference on Consumer Electronics (ICCE) 978-1-4799-1291-9/14/$31.00 ©2014 IEEE 149