• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.607-608
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• 2013

무선 애드훅 네트워크에서는 무선링크의 성능을 표현하는 다양한 품질 척도가 있다. 그것은 노드가 움직임이 없는 상태에서 주변 무선 상태를 반영한다. 하지만 해상 환경에서는 선박의 이동성 뿐만 아니라 바람과 파고에 의해 선박이 움직이는 특성이 있다. 따라서 선박에 위치한 안테나의 흔들림을 유발하여 신호의 수신을 불안정하게 만든다. 본 논문은 선체운동에 따른 무선 링크 성능을 분석한다. 이를 위해 자이로 센서를 이용하여 서로 다른 해상 환경에서 선체운동을 측정 및 분석하고, 하드웨어 및 소프트웨어에 의한 무선 링크 안정화 방안을 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9A
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• pp.801-808
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• 2011

We propose MBAP(Multi-rate Broadcast Active Probing) technique to get the right measurements for link quality in Wireless Mesh Network (WMN). Most routing protocols for WMN make use of link quality-aware routing metrics, such as ETX(Expected Transmission Count) and ETT(Expected Transmission Time), while the hop count is usually used in MANET (Mobile Ad-hoc NETwork). A broadcast based active proving technique is adopted in the previous studies to get the ETX or ETT of a link. However this technique does not reflect the multi-rate feature of WLAN because it uses a single fixed transmission rate for broadcast which usually differs from the actual rate used in data transmissions. MBAP overcomes this shortage by exploiting various rate broadcast frames for probing. We implement MBAP on linux system by modifying WLAN driver and related kernel sub-systems. Experimental results show that MBAP can capture link quality more accurately than the existing techniques.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.99-111
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• 2010

In this paper as a follow-up to Paper I, the required fade margin derived in Paper I to preserve the same service quality has been examined by analyzing system and propagation characteristics as well as measured data. The comparison of the fade margin between simulated and measured results is also performed for the actual operating line-of-sight(LOS) and non-LOS links, and practical usefulness as an analysis tool is revealed by checking service quality of M/W system relevant to frequency reallocation. According to simulated and measured results, there was a little difference for LOS link between Mt. Moodung and Mt. Mangun, but a fairly good agreement was reached for non-LOS link between Andong KBS and transmitter site.

• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.905-916
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• 2004

Self-organizing hierarchical ad hoc network (SOHAN) is a new ad-hoc network architecture designed to improve the scalability properties of conventional 'flat' ad hoc networks. This network architecture consists of three tiers of ad-hoc nodes, i.e.. access points, forwarding nodes and mobile nodes. This paper presents a topology discovery and routing protocol for the self-organization of SOHAN. We propose a cross-layer path metric based on link quality and MAC delay which plays a key role in producing an optimal cluster-based hierarchical topology with high throughput capacity. The topology discovery protocol provides the basis for routing which takes place in layer 2.5 using MAC addresses. The routing protocol is based on AODV with appropriate modifications to take advantage of the hierarchical topology and interact with the discovery protocol. Simulation results are presented which show the improved performance as well as scalability properties of SOHAN in terms of through-put capacity, end-to-end delay, packet delivery ratio and control overhead.

• Convergence Security Journal
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• v.15 no.5
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• pp.29-35
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• 2015

The network security encryption type is divided into two, one is point-to-point, second method is link type. The level of security quality attributes are a system security quality requirements in a networked environment. Quality attributes can be observed and should be able to be measured. If the quality requirements can be presented as exact figures, quality requirements are defined specifically setting quality objectives. Functional requirements in the quality attribute is a requirement for a service function which can be obtained through the encryption. Non-functional requirements are requirements of the service quality that can be obtained through the encryption. Encryption quality evaluation system proposed in this study is to derive functional requirements and non-functional requirements 2 groups. Of the calculating measure of the evaluation index in the same category, the associated indication of the quality measure of each surface should be created. The quality matrix uses 2-factor analysis of the evaluation for the associated surface quality measurements. The quality requirements are calculated based on two different functional requirements and non-functional requirements. The results are calculated by analyzing the trend of the average value assessment. When used this way, it is possible to configure the network security encryption based on quality management.