• Journal of Communications and Networks
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• v.7 no.2
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• pp.126-134
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• 2005

Reducing energy consumption in mobile hosts (MHs) is one of the most critical issues in wireles/mobile networks. IP paging protocol at network layer and power saving mechanism (PSM) at link layer are two core technologies to reduce the energy consumption of MHs. First, we investigate the energy efficiency of the current IEEE 802.11 power saving mechanism (PSM) when IP paging protocol is deployed over IEEE 802.11 networks. The result reveal that the current IEEE 802.11 PSM with a fixed wakeup interval (i.e., the static PSM) exhibits a degraded performance when it is integrated with IP paging protocol. Therefore, we propose an adaptive power saving mechanism in IEEE 802.11-based wireless IP networks. Unlike the static PSM, the adaptive PSM adjusts the wake-up interval adaptively depending on the session activity at IP layer. Specifically, the MH estimates the idle periods for incoming sessions based on the exponentially weighted moving average (EWMA) scheme and sets its wake-up interval dynamically by considering the estimated idle period and paging delay bound. For performance evaluation, we have conducted comprehensive simulations and compared the total cost and energy consumption, which are incurred in IP paging protocol in conjunction with various power saving mechanisms: The static PSM, the adaptive PSM, and the optimum PSM. Simulation results show that the adaptive PSM provides a closer performance to the optimum PSM than the static PSM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3B
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• pp.214-219
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• 2011

The IMS (IP Multimedia Subsystem) is used for providing multimedia services to network provider. The IMS is composed of many nodes, depending on their function. According to the status (fault, performance, etc.) of each node, we need to provide dynamic routing algorithm. In this paper, we propose a dynamic routing algorithm for management of the IMS nodes using SNMP based on FCAPS (Fault, Configuration, Accounting, Performance and Security) in the IMS network.

• Journal of Internet Computing and Services
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• v.22 no.5
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• pp.9-16
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• 2021

Recently, the traffic volume of mobile communications increases rapidly and the small-cell is one of the solutions using two offload schemes, i.e., local IP access (LIPA) and selected IP traffic offload (SIPTO), to reduce the end-to-end delay and amount of mobile data traffic in the core network (CN). However, 3GPP describes the concept of LIPA and SIPTO and there is no decision algorithm to decide the path from source nodes (SNs) to destination nodes (DNs). Therefore, this paper proposes a dynamic mobile data traffic offload scheme using small-cells to decide the path based on the SN and DN, i.e., macro user equipment, small-cell user equipment (SUE), and multimedia server, and type of the mobile data traffic for the real-time and non-real-time. Through analytical models, it is shown that the proposed offload scheme outperforms the conventional small-cell network in terms of the delay of end-to-end mobile data communications and probability of the mobile data traffic in the CN for the heterogeneous networks.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.334-336
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• 2002

이동성 지원 프로토콜에서 사용자의 이동에 따른 위치 등록 부담을 줄이려는 노력으로 IP 페이징에 대한 관심이 커지고 있다. IETF(Internet Engineering Task Force)에서는 IP 페이징 프로토콜을 개발하기로 결정하여 seamoby 워킹그룹에서 이를 담당하도록 하고 HAWAII와 Cellular IP에서의 몇몇 IP 페이징 프로토콜이 제안되었다. 그러나 이는 미리 정의된 페이징 영역을 사용하기 때문에 호스트에 최적화된 페이징 영역을 만들기 어렵다. 본 논문은 페이징 영역을 결정하는데 중요한 요소인 크기와 모양을 설정하기 위하여 각 이동 호스트가 자신의 이동을 캐쉬하고 셀간 이동 횟수가 많이 발생하는 지역에서는 캐쉬된 내용에 근거하여 자신의 페이징 영역을 설정한다. 또한 이동 호스트의 방문이 거의 일어나지 않은 지역은 네트워크에 의해 설정된 페이징 영역을 적용하여 호스트에 의한 페이징 영역과 이중모드로 동작한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.4-6
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• 2003

MANET(Mobile Ad hoc NETwork)은 기간망(infrastructure network)에 대한 의존 없이 필요에 따라 노드(node)들이 자발적으로 임시적인 네트워크를 형성해 데이터를 주고 받는 형태이다. 지금까지 MANET에 관한 대부분의 연구는 노드들이 네트워크에 합류하기 전에 IP주소를 할당받는다는 가정하에 이루어졌다. 기존의 네트워크에서는 IPv4주소의 부족으로 모든 노드에게 영구적으로 IP주소를 할당 할 수 없어 동적으로 IP주소를 할당할 필요가 있을 때 DHCP를 이용해 노드들에게 IP주소를 할당했다. 그러나 MANET의 경우 노드의 이동성으로 인해 중앙집중화 된 DHCP 서버로의 접근을 항상 보장할 수 없다 그러므로 본 논문에서는 MANET의 노드들에게 유일한 IP주소를 동적으로 할당하기 위한 토큰-기반 동적 주소 할당 프로토콜을 제안하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1203-1206
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• 2008

VoIP 서비스에서 긴급통화 서비스는 사용자 단말의 위치 정보(Location Information)와 사용자 식별번호를 긴급 호에 실어 긴급 대응 센터에 보내는 서비스이다. VoIP 긴급통화 서비스를 위하여 긴급 호발생 시 위치를 획득하여야 하며, 이를 위해 본 논문에서는 RFC 4776기반의 DHCP 옵션 확장하여 VoIP 단말의 위치 정보를 획득하는 방법을 구현하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.747-754
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• 2016

DHCP(Dynamic Host Configuration Protocol) is a protocol for efficiency and convenience of the IP address management. DHCP automatically assigns an IP address and configuration information needed to run the TCP/IP communication to individual host in the network. However, existing DHCP is vulnerable for network attack such as DHCP spoofing, release attack because there is no mutual authentication systems between server and client. To solve this problem, we have designed a new DHCP protocol supporting the following features: First, ECDH(Elliptic Curve Diffie-Hellman) is used to create session key and ECDSA(Elliptic Curve Digital Signature Algorithm) is used for mutual authentication between server and client. Also this protocol ensures integrity of message by adding a HMAC(Hash-based Message Authentication Code) on the message. And replay attacks can be prevented by using a Nonce. As a result, The receiver can prevent the network attack by discarding the received message from unauthorized host.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.558-564
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• 2007

3G Long Term Evolution, which aims for various mobile multimedia service provision by enhanced wireless interface, proposes VoIP-based voice service through a Packet Switching (PS) domain. As delay and loss-sensitive VoIP traffic flows through the PS domain, more challenging technical difficulties are expected than in Circuit Switching (CS) domain based VoIP services. Moreover, since 3G LTE, which adopts the OFDM as its physical layer, introduces Physical Resource Block (PRB) as a unit for transmission resources, new types of resource management schemes are needed. This paper proposes a PRB scheduling algorithm of MAC layer for VoIP service in 3G LTE and shows the simulation results. The proposed algorithm has two key parts; dynamic activation of VoIP priority mode to satisfy VoIP QoS requirements and adaptive adjustment of the priority mode duration in order to minimize the degradation of resource utilization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.1-10
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• 2007

We propose a new approach to accommodate bidirectional asymmetric traffic demands as well as unexpected dynamic internet traffic variation in the WDM mesh network by using optical networking technologies. In the proposed scheme, an intermediate node determines the optical path based on the switching statistics of IP router of the node which characterizes the Internet traffic variation, which in effect provides a dynamic and distributed traffic control over the network. It is expected to reduce the efficiency deterioration of RWA(Routing and Wavelength Assignment) due to the real-time variation of Internet traffic so that expandability and flexibility of the network can be enhanced. In this paper, we describe a methodology for traffic behavior analysis at a node, and the decision policy of the establishment/release of optical path. In addition, we evaluate the performance of the proposed scheme through the computer simulations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.71-81
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• 2008

In this paper, we propose a novel Globally Asynchronous, Locally Dynamic System(GALDS) bus and demonstrate its performance. The proposed GALDS bus is the bidirectional multitasking bus with the segmented bus architecture supporting the concurrent operation of multi-masters and multi-slaves. By analyzing system tasks, the bus architecture chooses the optimal frequency for each If among multiples of bus frequency and thus we can reduce the overall power consumption. For efficient data communications between IPs operating in different frequencies, we designed an asynchronous and bidirectional FIFO based on an asynchronous wrapper with hand-shaking interface. In addition, since systems can be easily expandable by inserting bus segments, the proposed architecture has advantages in IP reusability and structural flexibility As a test example, a four-segment bus haying four masters and four slaves were designed by using Verilog HDL. We demonstrate multitasking operations with read/write data transfers by simulation when the ratios of operation frequency are 1:1, 1:2, 1:4 and 1:8. The data transfer mode is a 16 burst increment mode compatible with Advanced Microcontroller Bus Architecture(AMBA). The maximum operation latency of the proposed GALDS bus is 22 clock cycles for the bus write operation, and 44 clock cycles for read.