• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.182-185
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• 2004

Wireless sensor networks use battery-operated computing and sensing devices. And It can be expected to be deployed in an ad hoc networs. MAC is different from traditional wireless MACs such as IEEE 802.11 in almost every way. so self-configuration and power saving in sensor network are very important goals, while per-node fairness and latency are less important. In this paper, so we use a given prototype for efficient energy conservation to reduce power consumtion that is one of the important character in sensor network and compare energy consumption and collision with IEEE 802.11 MAC. Finally we conclude the paper and analyze it.

• Journal of Advanced Navigation Technology
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• v.15 no.1
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• pp.54-60
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• 2011

The development of wireless sensor networks (WSN) can be motivated by several types of applications. However, these applications demand an energy-efficient WSN that can prolong the network lifetime and can provide high throughput, low latency and delay. Designing wireless sensor networks with the capability of prolonging network lifetime catch the attention of many researchers in wireless system and network field. Contrasts with Mobile Ad Hoc Network system, Wireless Sensor Networks designs focused more on survivability of each node in the network instead of maximizing data throughput or minimizing end-to-end delay. In this paper, we will study part of data link layer in Open Systems Interconnection (OSI) model, called medium access control (MAC) layer. Since the MAC development of energy aware MAC Protocol for wireless sensor layer controls the physical radio part, it has a large impact on the overall energy consumption and the lifetime of a node. This paper proposes a analytical approach that tries to reduce idle energy consumption, and shows the increasement of network end-to-end arrival rate due to efficiency in energy consumption from time slot management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.647-656
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• 2012

TDMA MAC protocol in MANET requires precise network synchronization between nodes though network topology changes continuously due to node mobility and the effect of propagation environment. In this paper we propose in-band cross-layer network synchronization architecture for TDMA-based MANETs. In the proposed architecture TDMA MAC protocol and proactive routing protocol cooperate closely to rapidly detect network partition and merge caused by node mobility and to precisely maintain network synchronization. We also implement the proposed synchronization architecture in OPNET simulator and evaluate the performance of it in various simulation scenarios. Simulation results show that our architecture stably maintains network time synchronization in both network partition and merge situations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1496-1501
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• 2013

IEEE 802.11 has become the main technology in wireless network. However, performance anomalies, especially in terms of fairness, arise in its use in ad hoc networks. Two independent emitters nodes can easily monopolize the medium, preventing other nodes to send packets. This paper proposes the modified (m,k)-firm scheme which is based on T-MAC to improve fairness. The basic idea is to assign higher priorities to nodes that are closer to a dynamic failure so as to improve their chances of meeting their deadlines. The simulation result shows that the proposed scheduling scheme helps improve the fairness of the DCF.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.458-458
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• 2004

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.481-485
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• 2012

차량 통신 네트워크(VANET, Vehicular Ad Hoc Network)는 운전자 안전 정보 및 ITS(Intelligent Transp ortation System) 서비스를 지원하기 위해 IEEE 1609.4와 IEEE 802.11p를 활용한다. 그러나 차량 노드들의 숫자가 증가할 경우에는 트래픽 경합 문제(Traffic Contention Problem), 숨은 터미널 문제(Hidden Terminal Problem), 전송 지연 문제, 경합으로 인한 패킷 손실 문제, 처리량 감소 문제, MAC의 동적 채널 할당 방법 등 많은 문제점이 발생한다. 따라서 본 논문에서는 IEEE 1609.4와 IEEE 802.11p 기반 차량 통신 네트워크의 특징을 살펴봄으로써 기존 제안되었던 차량 통신 네트워크를 위한 MAC 및 멀티채널 기술의 특징의 장단점을 분석한다. 또한 분석된 문제점을 해결하기 위한 연구 방향을 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.184-191
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• 2008

NanoQplus, which is an embedded operating system for wireless sensor networks (WSNs) and developed by Electronics and Telecommunications Research Institute (ETRI), provides programmer-friendly preemptive multi-threading programming technique, but it has poor network protocol stack, as compared to TinyOS, one of the famous operating systems for WSNs. In this paper, we apply dynamic MANET on-demand routing (DYMO) protocol, which is being standardized in Internet Engineering Task Force (IETF), to NanoQplus. Since DYMO has been proposed for mobile ad-hoc networks (MANETs) and MANETs have less resource restrictions than WSNs, the basic DYMO protocol cannot be applied to WSNs without modifications. Moreover, coherence with MAC protocol should be considered in order to eliminate redundant data between MAC and network layers. Thus, we propose a modified version of the basic DYMO protocol for NanoQplus. The experimental results from a real sensor network test-bed show that the DYMO implementation using NanoQplus works efficiently in WSNs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.300-302
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• 2022

In this paper, We propose a mobility model-based resource collision avoidance technique that can share radio resources without resource collision between UAV in a FANET environment. The proposed technique tries to reduce the occurrence of resource collisions by estimating UAV mobility based on information obtained from GPS devices installed in UAV. Through simulations, The performance was compared with the contention-based protocol, and it was confirmed that the proposed algorithm can reduce resource collisions.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1593-1608
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• 2009

If a certain relay node in multi-hop wireless networks might become a malicious node that does not cooperate with other nodes or a selfish node, network throughput will be dramatically decreased. Most of existing ad hoc routing protocols assuming that the nodes will fully cooperate with other nodes do not resolve the problem of network performance degradation due to malicious and selfish nodes. This paper presents the CARE (Cooperative Ad hoc routing protocol based REputation) scheme incorporating the reputation management that can achieve a multi-hop wireless network with high throughput performance. The proposed scheme provides the horizontal cross-layer approach which can identify misbehaving malicious, selfish nodes dropped out of the hop-by-hop based packet processing in the network and then set up an optimal packet routing path that will detour misbehaving nodes. And the vertical cross-layer approach contained in the CARE scheme attempts to improve the quality of routing paths by exploiting the quality of link information received from the MAC layer. Besides, it provides high TCP throughput by exploiting the reputation values of nodes acquired from the network layer into the transport layer. A case study on experiments and simulations shows that the CARE scheme incorporating vertical and horizontal cross-layer approaches yields better performance in terms of the low rate of packet loss, fast average packet delivery time, and high TCP throughput between end-to-end nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11B
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• pp.792-803
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• 2005

Ultra wide band (UWB) technology will be applied in the high rare wireless personal area networks (WPANs) for its high rate, low power, and innate immunity to multipath fading. In this paper, a power aware multi-hop packet relay MAC protocol in UWB based WPANs is proposed and a power aware path status factor (PAPSF), which is derived from SINR and power resource condition of each device, is used to select a suitable relay node. Compared with relaying by piconet coordinator (PNC), which is easily chosen by other ad hoc routing protocol, the new scheme can achieve hi임or throughput, decrease the time required for transmitting high power signal and we can easily distribute the battery power consumption from PNC to other devices in the piconet to prevent the PNC device using up its battery too fast and finally avoid PNC handover too frequently.