Kyungkoo Jun

Agent-based resource discovery

Presents a distributed discovery method allowing individual nodes to gather information about resources in a wide-area distributed system made up of autonomous systems linked together by a network technology substrate. We introduce an algorithm and a model for distributed awareness and a framework for the dynamic assembly of agents monitoring network resources. Whenever an agent needs detailed information about the individual components of another system, it uses the information gathered by the distributed awareness mechanism to identify the target system, then creates a description of a monitoring agent that is capable of providing the information about remote resources, and sends this description to the remote site. There, an agent factory dynamically assembles the monitoring agent. This solution is scalable and is suitable for heterogeneous environments where the architecture and the hardware resources of individual nodes differ, where the services provided by the system are diverse, and where the bandwidth and latency of the communication links cover a broad range.

MAC Scheduling Scheme for VoIP Traffic Service in 3G LTE

3G Long Term Evolution, which aims for various mobile multimedia services provision by enhanced wireless performance, proposes the VoIP-based voice service through the PS domain. When delay and loss-sensitive VoIP traffic flows through the PS domain, more challenging technical difficulties are expected than in the existing 3G systems which provide the CS domain based voice service. Moreover, since 3G LTE, which adopts the OFDM as its physical layer, introduces Physical Resource Block (PRB) as the unit for the transmission resources, it becomes necessary to develop new types of resource management schemes. This paper proposes a MAC layer PRB scheduling algorithm for the efficient VoIP service in 3G LTE and shows the simulation results regarding its performance. The key idea of the algorithm consists of two parts; dynamic activation of a VoIP priority mode for the voice QoS satisfaction and adaptive adjustment of the VoIP priority mode duration in order to minimize the performance degradation induced by its priority mode application.

The Bond Agent System and Applications

In this paper we present the basic design philosophy of the Bond agent system, the multi-plane agent model and the component-based architecture implementing the model. We discuss several applications of Bond agents: resource discovery, an adaptive video service, a workflow management system, a system of agents for remote monitoring of web servers, and a network of PDE solvers.

Experiments for a Collaborative Haptic Virtual Reality

In this paper, we present preliminary results of our ongoing networked virtual reality project by discussing the implementation and performance of a networked haptic game. In this game, online players feel like handling a real basketball since they are able to feel the sense of touch by using haptic interfaces. One of challenging issues in this implementation is haptic data transmission over the Internet to allow online multi-user play. Since haptic information is extremely sensitive to delay and jitter, the provision of timely transmission is critical. We carry out experiments to compare the performance of the haptic data transmission when using UDP (User Datagram Protocol) and TCP (Transmission Control Protocol), and observe that neither UDP nor TCP is able to satisfy QoS (Quality of Service) requirements of the haptic transmission. As a further study, we plan to investigate some alternative haptic data transmission schemes.

An aspect-oriented approach to distributed object security

In this paper we present a security framework for Bond, a message-oriented distributed object middleware for network computing. Bond Security Framework, BSF, allows developers to exercise performance-security tradeoffs and use the security model best suited for a specific application and for a given environment. BSF consists of an extensible core and a set of well-defined security interfaces. Any Bond object can become a secure object when extended with a dynamic property called bondSecurityContext.

An Experimental Study on the Performance of Haptic Data Transmission in Networked Haptic Collaboration

In this paper, we present preliminary results of our ongoing networked virtual reality project by discussing the implementation and performance of an experimental haptic collaboration system; a networked haptic basketball game. In this game, online players feel like handling a real basketball since they are able to feel the sense of touch by using haptic interfaces. One of challenging issues in this implementation is haptic data transmission over the Internet to allow online multi-user play. Since haptic information is extremely sensitive to delay, jitter, and loss, the provision of timely transmission is critical. We carry out some experiments to compare the performance of the haptic data transmission under various delays, jitters, and losses of packets for two models; one is the position transfer model and the other is the force transfer model. We observe that loss of packets may reduce the force feedback in the Position Transfer Model and jitters are more sensitive than delays for both models.

Dynamic Bandwidth Allocation Scheme for Video Streaming in Wireless Cellular Networks

In this paper, we propose a novel dynamic bandwidth allocation scheme for the downlink real-time video streaming in the wireless cellular networks. Our scheme is able to maximize the bandwidth utilization, while satisfying the required packet loss probability, a QoS constraint, by dynamically determining the amount of bandwidth to be allocated at each unit time interval by measuring the queue length and the packet loss probability. The simulation results show that, without the need of a priori knowledge about the traffic traces, our scheme is able to achieve the same level of performance as what can be accomplished with the pre-calculated effective bandwidth in terms of the bandwidth utilization and the packet loss rate.

Structural Biology Metaphors Applied to the Design of a Distributed Object System

In this paper we present the basic ideas of a distributed object middleware for network computing. We argue that when building complex systems out of components one can emulate the lock and key mechanisms used by proteins to recognize each other.

Packet QoS Aware AMC Selection for 3G LTE of Evolved Packet System

3GPP evolved packet system (EPS) is an all-IP based system that supports various access networks such as LTE, HSPA/HSPA+ and non-3GPP networks. Recently, the support of IP flows with packet level QoS profiles has been added to the requirements of the EPS. This paper proposes an adaptive modulation and coding (AMC) scheme that supports the QoS of such IP flows in the 3G LTE access network of the EPS. Defining the retransmission as a critical factor for QoS, the proposed scheme applies different maximum packet error probability P max to each packet when selecting the AMC transmission mode. In determining P max , the QoS constraints as well as channel condition are considered, balancing two objectives: the satisfaction of the QoS and the maximization of spectral efficiency. Simulations show that it is able to reduce both delay violation and retransmission, while improving throughput in comparison with an existing scheme.

An Integrated Haptic Data Transmission in Haptic Collaborative Virtual Environments

Haptic collaboration virtual environment (HCVE) is an enhanced virtual reality space with haptic interface support. HCVE users are connected together over the network and are able to work together by using sense of touch, i.e. haptics as well as audio and visual interfaces. In HCVE, the communication of haptic data is challenging because of time-varying network conditions and extremely high data rate. To mitigate such difficulties, we propose a linear prediction algorithm and a buffering scheme which is an integrated scheme for haptic data transmission. The prediction algorithm is to minimize the negative effects from network delay, loss and jitter, while the buffering scheme is to easily synchronize haptic interaction. For the evaluation of our proposed schemes, we build an experimental test bed for HCVE. As the result, we observe that our schemes are effective in improving the quality of haptic experiences. The quantitative measurement results are presented.