• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2178-2187
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• 2015

Bluetooth Low Energy (Bluetooth LE) is a representative break-through communication technology for wireless personal area networks on nowaday. In this environment, most of significant performance should be aiming to energy efficiency due to the policy for manufacturing light-weighted communication devices derived from requirement of world IoT market, and many researches have been developed to satisfy this requirement. While Bluetooth LE has been leading the low power communication technology required from the current market by employing duty cycle and frequency hopping approaches, it couldn't address the problem of reliability on broadcast transmissions. The main goal of this paper is aiming to addressing this problem by suggesting a new method. Furthermore analytic evaluations would also be proceeded to find objective results in the view point of broadcast transmission efficiency from Master device.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.797-800
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• 2011

The objective of MPEG Media Transport (MMT), which is on going standard, is to develop efficient delivery of media over packet based networks in an adaptive, progressive, download/streaming fashion over various IP based networks, including terrestrial, satellite and cable broadcast networks. In this paper we introduce utilization of signal strength information based on Cross Layer Design(CLD) to efficient multimedia delivery over wireless network in which in practice the wireless conditions can vary significantly. Many recent studies have shown that a significant improvement in wireless video throughput can be achieved by utilizing signal strength information on CLD [1][2]. Despite of its usefulness, however, it was difficult to employ signal strength information in rate adaptation applications due to different representation of signal strength information for each underlying wireless network. To that end, we proposed syntax and semantics of signal strength information in such a way that the information can be interpreted in the unified way. The proposed signal strength information was proposed for the MMT standardization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.641-644
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• 2016

Unlike wired networks, broadcasting in wireless networks can transmit data at once to several nodes with a single transmission. For omnidirectional broadcast to a node in wireless networks, all adjacent nodes receive the data at the same time. In this paper, we propose a greedy algorithm to solve the minimum power broadcasting problem of minimizing the total transmit power on broadcasting in wireless networks. We apply two matrices to the proposed algorithm: one is a distance matrix that represents the distance between each node, the other is an adjacency matrix having the number of adjacency nodes. Among the nodes that receive the data, a node that has the greatest number of the adjacent node transmits data to neighbor preferential. We compare the performance of the proposed algorithm with random method through computer simulation in terms of transmitting power of nodes. Experiment results show that the proposed algorithm outperforms better than the random method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.310-313
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• 2011

Broadcasting nature of wireless communications makes it possible to apply opportunistic network coding (OPNC) by overhearing transmitted packets from a source to sink nodes. However, it is difficult to apply network coding to the topology of multiple relay and sink nodes. We propose to use relay node selection, which finds a proper node for network coding since the OPNC alone in the topology of multiple relays and sink nodes cannot guarantee network coding gain. The proposed system is a novel combination of wireless network coding and relay selection, which is a key contribution of this paper. In this paper, with the consideration of channel state and potential network coding gain, we propose relay node selection techniques, and show performance gain over the conventional OPNC and a channel-based selection algorithm in terms of average system throughput.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.110-113
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• 2011

최근 스마트폰에서 Wireless AP를 이용한 대형 쇼핑센터 또는 주차장에서의 실내 측위 어플리케이션들이 등장하고 있다. 하지만 이 어플리케이션들은 측정된 RSSI와 frequency를 이용한 Friis공식으로 거리 환산을 하여 삼각측량법으로 측위를 하게 되는데, 이 방법은 거리를 구함에 있어 오차가 심하여 실제 위치 측정이 Room level정도만 가능하다. 따라서 이에 대한 오차를 줄여 실시간으로 사용자의 위치를 파악하고 주변 정보와 최단거리 등을 알려주는 서비스가 앞으로 상당수의 쇼핑센터 또는 실내 놀이동산 등의 실내 문화공간에서 사용 될 수 있을 것으로 예측되므로 이에 대한 연구 필요성이 강조 되고 있다. 이에 본 논문은 장애물이 많은 실내에서의 위치기반 서비스에 있어 좀 더 정확한 위치정보 제공에 대한 제안 방안이다. 이를 위하여 여러 실험과 안드로이드 기반의 데모 프로그램 작성을 통하여 연구 개발 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.291-296
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• 2008

Wireless network technologies are becoming more widely used in industrial environment. The industrial communication system requires a real-time delivery of messages. The sensors periodically senses the physical environment and wants to deliver the data in real-time to the sink. This paper proposes a real-time protocol for periodic messages on wireless sensor and actor networks to be used in industrial communications. The proposed protocol delivers the data message using the shortest path from the source and the nearest actor. The protocol considers the energy consumption by reducing the number of broadcast messages during flooding. We have evaluated the performance of the proposed protocol using QualNet simulator. The simulation results show that the data messages have been delivered in real-time and the number of broadcast messages is reduced from 90% to 35% compared the existing protocols.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.1-8
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• 1994

In this paper, we have analyzed the performance of a BRAM (The Broadcasting Recognizing Access Method) protocol, as a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) scheme, which is widely used in wireles LAN systems. We have selected a Fair BRAM protocol among CSMA/CA schemes, considering the fairness of channel usage and the simplicity of the protocol. We have compared the performance of BRAM protocol to that of CSMA/CD. to research the characteristics of BRAM in wireless LAN system. In order to analyze the performance of this system, we have set up an imbedded Markov chain and calculated state transition probabilities. Then we have calculated steady state probabilities and finally derived the throughput of a Fair BRAM moder. To verify our analysis, we have simulated practical models. Then, we have found that analytic results are very close to simulation ones. Our analysis of the BRAM protocol will be expected to be very helpful to design and evaluate a MAC (Media Access Control) protocol in wireless LAN systems.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.291-294
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• 2004

Wireless sensor network을 위 한 MAC(Medium Access Control) layer를 low-rate WPAN을 목적으로 한 IEEE 802.15.4 사양에 따라 구현하고 검증하였다. 센서 네트워크의 노드는 배터리로 동작하므로 에너지 소모가 가장 큰 걸림돌이 된다. power saving을 위한 몇 가지 방법을 포함한 IEEE 802.15.4 MAC protocol을 구현함으로써 wireless sensor network에 적용 가능함을 보였다.

• Journal of Broadcast Engineering
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• v.7 no.1
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• pp.66-75
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• 2002

In this paper, a new wireless internet service for TV is proposed using the detection of a mobile agent of each mobile company Especially. new broadcasting programs like as music charts. quiz games can be serried by a mobile internet phone. In this proposed system, all mobile protocols( WAP, ME. W3C) are supported by one server based on the mobile agent detection of URL over the existed wire and wireless internees.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.71-79
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• 2007

The communicative behaviors in Wireless Sensor Networks(WSNs) can be characterized by two different types: routing and broadcasting. The broadcasting is used for effective route discoveries and packet delivery. However, broadcasting shorten the network lifetime due to the energy overconsumption by redundant transmissions. In this paper, we proposed a algorithm that remove redundant forward nodes based on Dominant Pruning method using 2-hop neighbors knowledge. Simulation results show that the proposed algorithm appears superior performance in respect of the number of forward nodes and the network lifetime.