• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.901-908
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• 2012

In an intelligent automated manufacturing environment, an administrator may use M2M (Machine-to-Machine) communication to recognize machine movement and the environment, as well as to respond to any potential dangers. However, commonly used wireless protocols for this purpose such WLAN (Wireless Local Area Network), ZigBee, and Bluetooth use the same ISM (Industrial Science Medical) band, and this may cause frequency interference among different devices. Moreover, an administrator is frequently exposed to dangerous conditions as a result of being surrounded by densely distributed moving machines. To address this issue, we propose in this paper to employ a location-based frequency interference management using fingerprinting scheme in industrial environments and its advanced localization schemes based on k-NN (Nearest Neighbor) algorithms. Simulation results indicate that the proposed schemes reduce distance error, frequency interference, and any potential danger may be responded immediately by continuous tracing of the locations.

• Journal of KIISE:Information Networking
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• v.36 no.3
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• pp.184-190
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• 2009

WiBro has advantages when both WLAN and 3G UMTS are adopted. Much research is being carried out in this area. However, the WiBro specification does not consider end-to-end security. Hence, another security protocol has to be adopted to support secure communication. Most previous research only focused on WiBro MAC performance improvement or security. In this paper, we adopt a security protocol such as IPsec, TLS, and DTLS, well known end-to-end security protocols, to make full use of WiBro in the IP network. Using NS-2 we simulated the adoption of end-to-end security protocol and evaluated performance and usability. Simulation shows DTLS had some performance advantages. All the protocols, TLS and IPsec are also suitable for use in WiBro.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1926-1934
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• 2013

M2M (Machine-to-Machine Communication) refers to technologies that allow wired and wireless systems to communicate with other devices with similar capabilities. M2M has special features which consist of low electricity consumption, cheap expenses, WAN, WLAN and others. Therefore, it can communicate via a network. Also, it can handle itself without a person's management. However, it has a wireless-communicate weakness because of the machine-communicate request, and also it is difficult to administrate and control each other. So In this Paper, It suggests the safety protocol between Device, Gateway and Network Domain in M2M environment. Proposed protocol is based on ID-Based encryption's certificate and creates session key between the Access Server and the Core Server in the Network Domain. It uses that session key for sending and receiving data in mutual, and adds key renewal protocol so it will automatically update discern result. a comparative analysis of the existing M2M communication technologies and PKI-based certificate technology is compared with the proposed protocol efficiency and safety.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.280-282
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• 2005

In this paper we propose several mapping schemes for streaming video generated by state-of-the-art H.264 codec over IEEE 802.11e enabled wireless LANs. The schemes take advantage of both 802.11e's QoS mechanism and some novel features of the H.264 codec, so as to protect the most important information in terms of visual quality and reduce distortion under network congestion. The proposed methods are evaluated by means of the H.264 reference software codec, network simulation, and objective video quality measurements. Results show that the proposed methods achieve a robust and error resilient H.264 video streaming over wireless LANs than traditional best-effort streaming.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.277-280
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• 2004

A wireless LAN(WLAN) is a local area network without wires. WLANs have been around for more than a decade, but are just beginning to gain momentum because of falling costs and improved standards. This paper presents the state of the arts and analyses the patent information of wireless local area network technology.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.12
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• pp.50-59
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• 1997

A wireless LAN medical information transmission system is useful for patients who need mobility in a local area environment. This paper proposes a method using WLAN(wireless local area network) and implements a stand-alone system with MAC(meidum access control) layer protocol referenced IEEE 802.11 draft standard. The system consists of a 8bit-microprocessor which handles media access control protocol and a WL100(GEC Plessey) chip which takes care of phsical layer specific routines and uses a RF module DE6003(GEC Plessey). The major features of the implemented system are the CSMA/CA protocol used a consecutive DATA-ACK trasmission method which yields more effective bandwidth allocation for asyncronous traffic transmission and the modified PCF protocol for time-bounded traffic transmission, which operates in ad-hoc network topology apart from IEEE 802.11 draft standard confirm PCF mode operate in infrastruture topology.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.216-222
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• 2009

This paper proposes an integrated mobile sink networks management system which can monitor and control various kinds of wireless lan access points, located in many different areas divided by their managing groups, from multi-vendors, and their operations in networks. The proposed system has the center-local interoperability structure cooperating with local-center servers which can perform the same operations as the central servers for wireless lan access points from multi-vendors and wireless lan centric management features. For this purpose, we propose a new way of data design, messaging policy, and hierarchical system structure such that we can achieve stable and consistent management methods for various wireless access points on distributed networks.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1363-1366
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• 2005

텔레매틱스 무선접속기술은 텔레매틱스 단말기와 텔레매틱스 서비스 사업자간 정보를 전달하기 위한 무선채널을 제공하는, CDMA 기반으로 활용되고 있다. 또한 다양한 텔레매틱스 서비스를 제공하기 위해 DSRC, WLAN, DMB 기술이 활용되고 있다. 본 논문에서는 텔레매틱스 서비스를 제공 받기를 원할 때 그 서비스를 제공할 서버를 발견할 수 있고 서비스 위치탐색 기능을 제공할 수 있는 Ad-hoc 이라는 환경에서 다양한 텔레매틱스 서비스를 할 수 있는 네트워크 모델을 Ad-hoc 망을 적용해서 효율적으로 무선 네트워크 접속을 할 수 있는 텔레매틱스 네트워크 모델을 제안하고자 한다

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.189-192
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• 2006

무선 네트워크 환경에서의 미디어 전송은 채널의 패이딩 현상 및 채널 잡음 등으로 인한 다량의 패킷손실과 전송지연의 변동으로 급격한 화질 열화를 발생시킨다. 이러한 채널 변동이 심한 무선 네트워크 환경에서 성공적으로 미디어를 전송하기 위해서 FEC (Forward Error Correction), ARQ (Automatic Repeat reQuest) 및 인터리빙을 사용하여 오류를 복구한다. 하지만 각각의 오류제어 모드는 채널 상황 및 오류 패턴에 따라 효율성이 다르기 때문에, 채널 상황에 적응적으로 변경할 수 있는 기법이 필요하다. 본 논문에서는 무선채널 변동을 송 수신측의 피드백 정보를 통해 측정하고 이에 따라 유동적으로 가장 적합한 오류제어 모드를 선택하여 패킷손실을 최소화하는 네트워크 적응형 전송오류제어 기법인 NASTE(Network-Adaptive Selective Transport Error control)를 제안한다. 제안된 기법의 성능을 검증하기 위해 IEEE 802.11g 무선랜 환경에서 NASTE 를 구현해서, MPEG-2 미디어 전송할 때 발생하는 패킷오류를 복구함으로써 전체적인 전송률 개선을 검증한다.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.463-471
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• 2011

Cooperative communications using relays in wireless networks have similar effects of multiple-input and multiple-output without the need of multiple antennas at each node. To implement cooperation into a system, efficient protocols are desired. In IEEE 802.11 families such as a/b/g, mobile stations can automatically adjust transmission rates according to channel conditions. However throughput performance degradation is observed by low-rate stations in multi-rate circumstances resulting in so-called performance anomaly. In this paper, we propose active relay-based cooperative medium access control (AR-CMAC) protocol, in which active relays desiring to transmit their own data for cooperation participate in relaying, and it is designed to increase throughput as a solution to performance anomaly. We have analyzed the performance of the simplified AR-CMAC using an embedded Markov chain model to demonstrate the gain of AR-CMAC and to verify it with our simulations. Simulations in an infrastructure network with an IEEE 802.11b/g access point show noticeable improvement than the legacy schemes.