• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.5
• /
• pp.271-280
• /
• 2014

In wireless sensor networks, there have been two methods for sensing continuously moving object tracking: user-query based method and periodic report based method. Although the former method requires overhead for user query rather than the latter method, the former one is known as an energy-efficient method without transferring unnecessary information. In the former method, a virtual tree, consisting of sensor nodes, is exploited for the user querying and sensor reporting. The tree stores the information about mobile objects; the stored information is triggered to report by the user query. However, in case of fast moving object, the tracking accuracy reduces due to the time delay of end-to-end repeated query. To solve the problem, we propose a query relaying method reducing the time delay for mobile object tracking. In the proposed method, the nodes in the tree relay the query to the adjacent node according to the movement of mobile object tracking. Relaying the query message reduces the end-to-end querying time delay. Simulation results show that our method is superior to the existing ones in terms of tracking accuracy.

• Information and Communications Magazine
• /
• v.11 no.8
• /
• pp.60-77
• /
• 1994

This paper presents a survey of video coding schemes which use wavelet transform for the videophone on very low bit rate commun ication chan nel( ego 10 Kbps Public Service Telephone Network). Firstly, we introduce the standardization efforts to make the low bit rate videophone architecture and the typical application of low bit rate video coding scheme. Secondly, we summarize the several requirements on videophone, delay, encoder/decoder complexity, low bitrate, and progressive transmission capability. Third, we review the basic theory of wavelet transform without much mathematics. We compare the wavelet transform with short-time fourier transform and subband filters. Fourth, we summarize the video coding schemes proposed so far, and evaluate them with Ule requirements. Lastly, we conclude with fu¬ture research directions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.2B
• /
• pp.144-156
• /
• 2003

Internet/Intranet has been continuously enhanced by new emerging IP technologies such as differentiate service(DiffServ), IPSec(IP Security) and MPLS(Multi-protocol Label Switching) traffic engineering. According to the increased demands of various real-time multimedia services, ISP(Internet Service Provider) should provide enhanced end-to-end QoS(quality of service) and security features. Therefore, Internet and Intranet need the management functionality of sophisticated traffic engineering functions. In this paper, we design and implement the performance management functionality for the guaranteed end-to-end QoS provisioning on MPLS-based VPLS(Virtual Private LAN Service). We propose VPLS OAM(Operation, Administration and Maintenance) for efficient performance management. We focus on a scheme of QoS management and measurement of QoS parameters(such as delay, jitter, loss, etc.) using VPLS OAM functions. The proposed performance management system also supports performance tuning to enhance the provided QoS by re-adjusting the bandwidth of LSPs for VPLS. We present the experimental results of performance monitoring and analysis using a network simulator.

• Journal of information and communication convergence engineering
• /
• v.8 no.2
• /
• pp.223-227
• /
• 2010

In this paper, we present a QoS-aware MAC protocol (QA-MAC) for cluster based wireless sensor networks (WSNs). QA-MAC is a TDMA-based scheduling protocol that minimizes the energy consumption in multi-hop WSNs and provides Quality of Service (QoS). A dynamic scheduling algorithm according to the number of member nodes, node traffics, and traffic priorities is suggested. The selected cluster head allocates time slots for all member nodes in the first TDMA schedule period of each round. During the second schedule period in each round, the cluster head makes a schedule for all data transmission. The proposed QA-MAC (QoS-Aware MAC) could save energy, reduce transmission delay, and support QoS.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.5
• /
• pp.1108-1130
• /
• 2013

Wireless Body Area Networks (WBANs) are becoming increasingly important to solve the issue of health care. IEEE 802.15.6 is a wireless communication standard for WBANs, aiming to provide a real-time and continuous monitoring. In this paper, we present our development of a modified Markov Chain model and a backoff model, in which most features such as user priorities, contention windows, modulation and coding schemes (MCSs), and frozen states are taken into account. Then we calculate the normalized throughput and average access delay of IEEE 802.15.6 networks under saturation and ideal channel conditions. We make an evaluation of network performances by comparing with IEEE 802.15.4 and the results validate that IEEE 802.15.6 networks can provide high quality of service (QoS) for nodes with high priorities.

• Journal of the Korea Computer Industry Society
• /
• v.5 no.9
• /
• pp.841-850
• /
• 2004

In this paper under the distributed system for efficient distribution resource to system's each node must be designed to get right decision making. Thus we considered computing time to estimate fault such as delay on communication network, communication period and other decision making. Aiso, using direct communitation mode improve the availity of total system.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.11
• /
• pp.1946-1958
• /
• 2011

Wireless Sensor Network (WSN) is made up of a number of sensor nodes and base stations. Traffic flow in WSN appears self-similar due to its data delivery process, and this impacts queue length greatly and makes queuing delay worse. Active queue management can be designed to improve QoS performance for WSN. In this paper, we propose self-similar traffic rate estimating algorithm named Power-Law Moving Averaging (PLMA) to regulate packet marking probability. This algorithm improves the availability of the rate estimation algorithm under the self-similar traffic condition. Then, we propose an adaptive Proportional Integral algorithm (SSPI) based on the estimation of the Self-Similar traffic rate by PLMA. Simulation results show that SSPI can achieve lower queue length jitter and smaller setting time than PI.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2001.10a
• /
• pp.354-358
• /
• 2001

Cosim (Hardware and Software Co-Simulator) is a JavaBeans-based simulation tool fur validating systems architecture and estimating performance of web applications. Cosim has four components: Modeler, Translator, Engine and Scenario. Users start from Modeler to describe systems architecture in UML(Unified Modeling Language) deployment diagram, and then specify hardware & software performance parameters such as execution delay, network topology, and frame size. All information specified on Modeler are sent to Translator, and then automatically converted to Java programs. Scenario is responsible to run the Java program and produce results in text reports and graphs. Developers can reduce development time and cost by validating systems architecture of web applications before the actual deployment.

• International Journal of Control, Automation, and Systems
• /
• v.4 no.1
• /
• pp.70-76
• /
• 2006

The objective of this paper is to propose a reference model of a fire detection and monitoring system using MS/TP protocol. The reference model is designed to satisfy the requirements of response time and flexibility. The reference model is operated on the basis of BACnet, a standard communication protocol for building automation systems. Validity of the reference model was examined using a simulation model. This study also evaluated the performance of the BACnet-based fire detection and monitoring system in terms of network-induced delay. Simulation results show that the reference model satisfies the requirements of the fire detection and monitoring system.

• International Journal of Internet, Broadcasting and Communication
• /
• v.5 no.2
• /
• pp.18-22
• /
• 2013

Mobile IPv6 (MIPv6) is a host-based protocol supporting global mobility while Proxy Mobile IPv6 (PMIPv6) is a network-based protocol supporting localized mobility. This paper makes its focus on how to reduce the longer delay and extra cost arising from the combination of authentication, authorization and accounting (AAA) and PMIPv6 further. Firstly, a novel authentication scheme (Proxy-AAA) is proposed, which supports fast handover mode and forwarding mode between different local mobility anchors (LMAs). Secondly, a cost analysis model is established based on Proxy-AAA. From the theoretical analysis, it could be noted that the cost is affected by average arrival rate and residence time.