Hwa-sung Kim

Implementation of Third Party Based Call Control Using Parlay Network API in SIP Environment

The communication network is in a transition toward the NGN (Next Generation Networks), which can support both of voice and data at the same time, according to the explosive demand of new services. The NGN allows the third-party application provisioning by defining the networks as layers of Services, Distributed Processing Environment and Transport. The Service layer can further be divided into Application and Service Component layer. In order to realize the third-party application provisioning, the Parlay Group has adopted an open Parlay API approach as an interface between the Application and the Service Component layer. Using Parlay API, the third parties may build and deploy the new applications at the Application layer exploiting the service components within network operators’ domain. In this paper, we presents the implementation details about the two-party call setup and release using the third party service logic based on Parlay API Rel. 3.0., where SIP is used as a signaling protocol in Transport layer.

The problems in digital watermarking into intra-frames of H.264/AVC

This paper intend to show the affect of the intra-prediction on the typical digital watermarking method and the fact that the watermarking method has very low effectiveness when it is performed for the intra-frames of H.264. The target watermarking method was the one for imperceptibility and robustness and was assumed to be performed during the intra-compression process by the H.264 technique. Also this method was assumed to insert watermark data and to extract it for certification if needed. The problem is that the resulting data from the re-engineering of the watermark insertion process to extract the watermark data is different from the one before. We experimentally showed that it stems from the intra-prediction itself. That is, we showed that the resulting image data from only compression without watermarking changes if it is re-compressed by the same conditions as the first compression and it is because the intra-prediction modes as well as the coefficient values change. Also, we applied one blind and one semi-blind watermarking methods to show that the typical attacks after watermarking makes this problem much more serious and lowers the effectiveness of the watermarking method dramatically. Therefore we concluded by considering the experimental data that a typical watermarking method which has been researched so far cannot guarantee the effectiveness of intra-frame watermarking and it is highly required to developed a new kind of methodologies.

QoS negotiation for IPTV service using SIP

This paper addresses QoS negotiation algorithm for IPTV services by using SIP. IPTV is defined as multimedia services such as television/video/audio/text/graphics/data delivered over IP based networks managed to provide the required level of QoS/QoE, security, interactivity and reliability by the ITU-T IPTV FG. As stated in its definition, IPTV provides the required level of QoS/QoE. To achieve this, IPTV service frameworks should be able to negotiate QoS/QoE with users or customers and SIP is one of the most proper methods for the SLA negotiation.

A fast handover mechanism for IPv6 based WiBro system

In wireless broadband Internet (WiBro) system, the issues for the IP-mobility support are critical factors. In order to provide the session continuity during the handover, FMIPv6 (mobile IPv6 fast handover) was introduced by IETF, which reduces the handover latency by enhancing the mobile IPv6 protocol. FMIPv6 can be beneficial to real-time applications. However, the FMIPv6 protocol has problems to be used for WiBro system, owing to difficulty in utilizing the layer 2 handover information. In this paper, we propose a mechanism that can provide effective fast handover in IPv6 based WiBro system. By integrating layer 2 and layer 3 handovers efficiently, our proposed mechanism minimizes the handover latency and eliminates the packet loss during handover. The simulation study shows that the proposed scheme achieves loss-free packet delivery and low latency

A global mobility scheme for seamless multicasting in Proxy Mobile IPv6 networks

Recently, Proxy Mobile IPv6 (PMIPv6) has been drawing attention as a mobility management protocol to effectively use the limited wireless resources. And, there have been some researches to apply PMIPv6 to multicasting, which is core technology of Internet broadcast system. However, PMIPv6 based multicasting cannot support the global mobility directly between different PMIPv6 domains because PMIPv6 is basically designed for local mobility in single PMIPv6 domain. Moreover, PMIPv6 based multicasting causes the disconnection of services because it does not solve problems of packet loss during binding and group joining procedure. In this paper, we propose a global mobility scheme that supports the seamless multicasting service in PMIPv6 networks. The proposed scheme supports the global mobility due to the addition of extra signalling messages between LMAs. Also, it achieves low latency because it performs fast binding and group joining procedure. We present the simulation results which show that the proposed scheme achieves the global mobility with low latency through the NS-2 simulation.

QoS Mesh Routing Protocol for IEEE 802.16 based Wireless Mesh Networks

This paper proposes QoS Mesh routing protocol for IEEE 802.16 based wireless mesh networks. QoS Mesh Routing Protocol proposed in this paper is a proactive hop-by-hop QoS routing protocol. The goal of our protocol is not only to find routes from a source to a destination node, but also optimal routes that satisfies QoS requirements, given in terms of bandwidth and delay as default QoS parameters. In this paper, we first analyze possible types of routing protocols that have been studied for MANET and show proactive hop-by-hop routing protocols are the most appropriate for wireless mesh networks. Then, we present a network model for IEEE 802.16 based wireless mesh networks and propose a proactive hop-by-hop QoS routing protocol. Through our simulation, we represent that our routing protocol outperforms QOLSR protocol in terms of end-to-end delay, packet delivery ratio and routing overhead.

Cross-layer based Fast Handover Mechanism for Seamless Macro-mobility Support in WiBro Networks

With the recent increase in demand for high data rate services in wireless communications, the Mobile Broadband Wireless Access (MBWA) techniques are gradually in the limelight. One of these technologies is the WiBro (Wireless Broadband Internet) system. The WiBro consists of IP-based backbone networks, which will be ultimately deployed by IPv6 based technologies due to the ALL-IP trend. In such IP based MBWA systems, it will be needed to offer the efficient mobility management protocol on network layer based on IPv6 as well as MAC layer, because the mobile subscriber stations moving at vehicular speed are able to move beyond a current subnet at any time. From this point of view, we propose an efficient IPv6 based fast handover scheme for seamless inter-domain mobility support over WiBro networks considering cross-layer approach. In this paper, we also present the simulation results which show that the proposed scheme achieves the loss-free and low latency through the NS-2 simulation.

A proxy mobile IP based layer-3 handover scheme for mobile WiMAX based wireless mesh networks

In this paper, we present a proxy mobile IP based layer-3 handover scheme for mobile WiMAX based wireless mesh networks. Mobile WiMAX provides two types of layer-3 handover schemes: MIP based handover and PMIP based handover. MIP based handover incures the long handover latency because mobile nodes generate a lot of handover messages in wireless area. On the other hand, PMIP based handover decreases the handover latency by reducing the number of handover messages, because a mobile node does not participate in handover procedure. However, conventional PMIP based handover still has latency overhead, because of message exchanges between PBU and PBA after completing the layer-2 handover. Hence, we propose a new layer-3 handover method that does not bring about packet losses while achieving lower handover latency than conventional layer-3 handover scheme. Simulation results show that the proposed scheme achieves loss-free and low handover latency during the layer-3 handover.

A location inference algorithm based-on smart phone user data modelling

Human life is rapidly changing around the world in terms of smart phones as the number of users is increasing in a surprising rate and the recent development of remarkable performances. And, there is wide range of smart phone services available based on the location information. However, levels of location based services currently provided are not satisfactory due to the GPS error rate. Though there have been many studies offering measurement technologies based on a variety of network infrastructure or technologies to compensate GPS errors, there still exist disadvantages such as large error rates indoors, energy consumption and need of additional infrastructure. Nowadays, location inference study using available user log data on smart phones, not the measurement technology based on a network, is being made to improve these shortcomings. Smart phone has a variety of user log data. Also, it can obtain variety of information about the surrounding environment around the user using the embedded hardware sensors. These user log and collected sensor data can be modelled as an ontology model then meanings of the information can be apprehended to infer the user location. This paper presents an algorithm to infer user location through an ontology modelling of the collected sensor data and the logged user information such as time, day of the week, location, and kind of applications used by user.

The effect of decentralized resource allocation in network-centric warfare

We propose a decentralized combat model for the network-centric warfare. The troops (military units or weapon platforms) of Green (friendly) forces perform their own threat evaluation, decision making, and weapon allocation in order to encounter enemy forces. Although they cooperate with each other for the operational success, their dynamic behavior can be modeled by a set of decentralized optimization problems where each force adopts its best strategy of weapon allocation according to the assessed threat. Adopting the game-theoretic approach, we prove that the dynamic combat model achieves a unique equilibrium at which both forces maintain the balance of fighting strength. Moreover, we study the property of the equilibrium and show that the total weapon consumed by the Green forces is strictly larger than an optimal allocation.