Won Ryu

A New Mechanism for Seamless Mobility Based on MPLS LSP in BcN

We propose a new mobility management scheme using Label Switched Path (LSP) of Multi Protocol Label Switching (MPLS) for seamless service in Broadband Convergence Network (BcN) in Korea, and verify that the proposed scheme has lower latency time than the existing ones through the separation of control plane from data plane for handover signaling.

A scalable network-based mobility management framework in heterogeneous IP-based networks

This paper proposes a mobility management scheme to provide a mobile node with high-quality handovers among heterogeneous wireless access networks. The proposed scheme employs a signaling architecture to support fast and reliable delivery of control messages by separating a control plane from a data transport plane in the core network. The proposed scheme is based on the network-based mobility management framework which requires the minimum modifications on terminal devices. With interaction between Layers 2 and 3, the proposed scheme accelerates the handover control procedures. It also enables a mobile subscriber to select a target network for a vertical handover with consideration of not only wireless signal strength but also user preference and quality-of-service status. The proposed scheme addresses the well-known problems of the Mobile IP-based approaches, triangular routing and bottleneck at the home agent, since it establishes a data tunnel for a mobile node along the shortest path between two different access networks. The simulation and experimental results indicate that our scheme provisions more efficient performance than the existing approaches in terms of handover latency, data packet loss, data delivery latency and load balancing.

IPTV Systems, Standards and Architectures: Part II - Heterogeneous Networks and Terminal-Aware QoS/QoE-Guaranteed Mobile IPTV Service

We describe two main technical challenges in terms of the network and application levels for mobile IPTV service. To support a multimedia- streaming application service over a mobile network environment, we present the IP/MPLS-based NGN architecture with fixed and mobile convergence and its challenge, which is basically to support QoS for mobile IPTV ser vice. To meet the challenges for application source levels, we focus on the relationship of user terminals and video streaming sources to support user-perceived QoE, based on high- quality service between heterogeneous terminals. The techniques to meet these challenges depend on the characteristics of media processing and terminal capabilities, such as LCD panel size, resolution, video coding, and so on, in the heterogeneous network environment. To have a relationship between the two different levels, the significant factors mentioned previously are required to deliver the bandwidth coupled with a user profile to provide QoS/QoE in assured seamless mobile IPTV service on client devices.

Transmit Beamforming Based Inter-Cell Interference Alignment and User Selection with CoMP

Recently, two types of coordinated multiple point transmission (CoMP) technologies - joint processing and transmission (JPT) and coordinated scheduling and beamforming(CSB) - have been proposed to the latest cellular communication standard named as a Network MIMO, to improve the performance of cell-edge users who suffer strong ICI. In this paper, we investigate an ICI cancelation employing a user selection algorithm associated with CoMP-CSB, which is more practically used for cellular networks. Under the partial channel state information (CSI) and no data sharing condition, each base station (BS)concentrates more on the direction of the interference to users located at the adjacent cells during the user selection process.

Multi-objective Optimization Model for Partner Selection in a Market-Oriented Dynamic Collaborative Cloud Service Platform

In this paper, we propose a promising multi-objective (MO) optimization model for partner selection in a market-oriented dynamic collaboration (DC) platform of Cloud providers (CPs) to minimize the conflicts among providers that may happen when negotiating among providers. The model not only uses their individual information (INI) but also past collaborative relationship information (PRI) for partner selection which is seldom considered in existing approaches. A multi-objective genetic algorithm (MOGA) called MOGA-IC is also proposed to solve the model as the model is NP-hard. The algorithm is developed using two popular MOGAs- NSGAII and SPEA2. The experimental results show that MOGAIC with NSGA-II outperformed the MOGA-IC with SPEA2 in finding useful Pareto optimal solution sets. In addition, other simulation experiments are conducted to verify the effectiveness of the MOGA-IC in terms of satisfactory partner selection and conflicts minimization.

Dynamic addition and deletion of device in N-screen environment

Multimedia applications are gaining popularity over smart devices. Sharing and using multimedia contents among multiple devices is a hot issue in N-screen environment. In this paper, we are going to investigate how the same stream can be shared by distinct bit rates devices and how several streams can be managed to different devices. We propose control architecture of group communication using Group Information Control Server (GICS) and group agent (GA) that assure the delivery of contents to the different bit rates devices on addition or deletion in N-screen environment. In our architecture, the is responsible to check the receiving capabilities of a new device with already stream receiving devices whether to group this device with the stream receiving devices or delete some device from the group and group with the new device and start a separate stream. We present results that show our proposed architecture improves network throughput and reduces streaming server load.

Downlink Transmit Beamforming for Inter-Cell Interference Mitigation with BS Cooperation

The capacity of downlink multiple-input multiple-output (MIMO) cellular network is significantly limited by inter-cell interference (ICI), especially at the cell boundary. In this paper, we propose an ICI cancelation employing a user selection algorithm associated with CoMP-CSB, which is more practically used for cellular networks. Under the partial channel state information (CSI) and no data sharing condition, each base station (BS) concentrates more on the direction of the interference to users located at the adjacent cells during the user selection process. Although it is obvious that there are trade-offs between the ICI mitigation and the number of simultaneous scheduled users in terms of system capacity, the simulation results show that our proposed algorithm achieves higher sector throughput and is more robust against the ICI when the system is limited by interference.

Performance of an efficient method for association admission control in public wireless LAN systems

The paper generally relates to the field of wireless local area networks (WLANs), and, more particularly, to AP selection and association methods for the performance of a station. IEEE 802.11 WLAN is widely deployed and used as an emerging service to connect to the high-speed Internet in the public wireless environment. However, if there are many users in a hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism, especially when it is used in the public environment. We suggest an efficient association method using beacon or probe response frames based IEEE 802.11 and analyze the performance of stations. A station selects an AP using the information of the capability region in a beacon or a probe response frame. An association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the APs states to access with a radio channel; the station then selects and associates with the AP. Further, it is possible to improve the efficiency of network management.

Radio Resource Allocation for Scalable Video Services Over Wireless Cellular Networks

Good quality video services always require higher bandwidth. Hence, to provide the video services e.g., multicast/broadcast services (MBSs) and unicast services along with the existing voice, internet, and other background traffic services over the wireless cellular networks, it is required to efficiently manage the wireless resources in order to reduce the overall forced call termination probability, to maximize the overall service quality, and to maximize the revenue. Fixed bandwidth allocation for the MBS sessions either reduces the quality of the MBS videos and bandwidth utilization or increases the overall forced call termination probability and of course the handover call dropping probability as well. Scalable video coding (SVC) technique allows the variable bit rate allocation for the video services. In this paper, we propose a bandwidth allocation scheme that efficiently allocates bandwidth among the MBS sessions and the non-MBS traffic calls (e.g., voice, unicast, internet, and other background traffic). The proposed scheme reduces the bandwidth allocation for the MBS sessions during the congested traffic condition only to accommodate more calls in the system. Instead of allocating fixed bandwidths for the MBS sessions and the non-MBS traffic, our scheme allocates variable bandwidths for them. However, the minimum quality of the videos is guaranteed by allocating minimum bandwidth for them. Using the mathematical and numerical analyses, we show that the proposed scheme maximizes the bandwidth utilization and significantly reduces the overall forced call termination probability as well as the handover call dropping probability.

Mobile SCTP with Bicasting for Vertical Handover

The mobile Stream Control Transmission Protocol (mSCTP) can be used to support IP handover. This paper proposes an extension of mSCTP with bicasting for vertical handover across heterogeneous wireless access networks, in which the data packets of mSCTP are bicast to the old and new IP addresses in the vertical handover region. From the ns-2 simulation results, it is shown that the proposed scheme can provide better performance than the existing mSCTP.