• Journal of Korea Multimedia Society
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• v.17 no.5
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• pp.573-581
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• 2014

The salient features of UWB(Ultra WideBand) networks such as high-rate communications, low interference with other radio systems, and low power consumption bring many benefits to users, thus enabling several new applications such as wireless universal serial bus (WUSB) for connecting personal computers (PCs) to their peripherals and the consumer-electronics (CE) in people's living rooms. Because the size of multimedia data frame, WiMedia device must transmit the fragment of MSDU. However, when the fragment of MSDU is lost, WiMedia device maintains active mode for the time to complete the transmission MSDU, and there is a problem that unnecessary power consumption occurs. Therefore we propose new power management scheme to reduce unnecessary power consumption of WiMedia devices in the case that the fragment is lost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.597-607
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• 2014

An integrated ship area network has functionality of remote control and autonomous management of various sensors and instruments embedded or boarded in a ship. For such environment, a wireless bridge is essential to transmit control and/or managing information to sensors or instruments from a central integrated ship area network station. In this paper, one of reliable schemes of wireless bridge using WiMedia distributed MAC (D-MAC) protocol is proposed to increase a communication reliability. Simulation results show that the proposed wireless bridge using WiMedia D-MAC protocol guarantees reliable communications between 2-hop devices.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.526-534
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• 2014

In this paper, for the WiMedia Distributed Medium Access Control (D-MAC) protocol based on UWB. performance degradation due to the Distributed Reservation Protocol (DRP) conflict problem caused by devices' mobility is analyzed. And a DRP relay protocol and a DRP conflict resolution (CR) are proposed to overcome the performance degradation at DRP conflicts. In order to give the loser device at DRP conflicts a chance to maintain resources, the proposed DRP relay protocol executed at each device helps the loser device reserve an indirect link maintaining the required resources via a relay node. Simulation results considering the mobile environment have indicated that the DRP relay combined with the CR prevent the throughput decrease even though mobility of devices increases.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.317-324
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• 2016

WiMedia provides the data rate of up to 1Gbps, but the transmission range is restricted to approximately 10 meters. When constructing a multi-hop WiMedia network to extend its coverage, conventional hop-based routing may not guarantee satisfactorily the required QoS. We propose two QoS routing techniques for the WiMedia-based wireless mesh network. The proopsed QoS routing reflects the characteristics of TDMA-based WiMedia MAC and develops QoS extensions separately for on-demand routing and table-driven routing. Through simulations, we identify that the QoS routing shows better performance than the hop-based routing. It also turns out that the QoS on-demand routing and the QoS table-driven routing show conflicting performance results depending on the transmission power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.389-391
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• 2012

현재에 있어서 무선네트워크의 중요성은 갈수록 높아지고만 있고 데이터를 처리함에 있어서 유선이 아닌 무선을 이용함으로써 사용자들의 간편성 및 신속성이 보장되어지고 있다. 하지만 현재 제안되고 있는 일반적인 무선네트워크인 ZigBee를 이용한 무선네트워크는 데이터 전송에 있어서 영상 등의 대용량의 데이터를 전송 할 경우 유선에 비해 디바이스 간 데이터 처리속도가 매우 낮다. 따라서 본 논문에서는 이러한 문제점을 극복하기 위해 ZigBee와 WiMedia의 결합을 통해 기존 무선 네트워크인 ZigBee를 이용하면서 디바이스간의 통신 방법 개선 및 통신속도향상 그리고 채널 상황에 능동적으로 대처할 수 있는 Distributed MAC프로토콜 기반의 릴레이 협력통신 방안을 제안한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.59-63
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• 2022

In recent years, research on smart factory wireless mobile communication technology that wirelessly remotely controls utilities is being actively conducted. The Wi-SUN(Wireless Smart Utility Network) Alliance proposed Wi-SUN protocol structure suitable for building a platform such as a smart factory as a new wireless communication standardization standard based on EEE802.15.4g/e. It analyzes the performance of the IEEE802.15.4e CSL(Coordinated Sampled Listening) Mode MAC(Media Access Control) in terms of power consumption and looks at considerations for efficient operation. Although CSL-MAC can dramatically reduce power consumption at the receiving end in an asynchronous manner, it has been found that the transmitting end has a disadvantage in that power consumption occurs due to an excessive wake-up sequence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.109-113
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• 2011

In intelligent subway systems, UWB-based WiMedia D-MAC Protocol can be considered to send and receive multimedia data which requires high data rate. However, network devices which do not exist within 10 meters, the limited communication rage, can not communicate with each other because WiMedia does not support multi-hop communications. In this paper, we developed the algorithm to select a relaying device for multi-hop routing on WiMedia networks. In the first step, each device acquires information of neighbors through beacon and decides whether it is a normal or relaying device using the acquired information. In the next step, all devices can create the 2-hop routing table using the information received via relaying devices and the whole routing table for all devices on networks, eventually.

• Journal of Korea Multimedia Society
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• v.12 no.3
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• pp.419-426
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• 2009

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. The WiMedia D-MAC fundamentally removes the problems of the centralized MAC revealed at IEEE 802.15.3 MAC, by adopting a distributed architecture. However, there is no completely distributed method for allocating fair data rates to all traffic streams by considering each stream's QoS parameter. In this paper, a novel fair distributed QoS admission control method is proposed. The proposed method is a fair, adaptive QoS provisioning method, by allocating time slots to devices according to the current traffic load condition, through executing only a proposed single satisfaction of QoS (SoQ) algorithm at each device.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.1
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• pp.53-59
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• 2007

Wimedia UWB(Ultra-Wideband) platform provides data rates up to 480Mbps in WPAN (Wireless Personal Area Network). Wimedia conformant devices access to the channels through superframe concept for communications. As the channel resource is limited, the optimal channel time required for each device needs to be estimated to share the resource efficiently among the devices. In this paper, we propose a scheme to estimate the required channel time in a super frame to satisfy the QoS of the application on a device. The channel time is estimated from the service rate which is computed from the TSPEC of the application. In the process of the estimation, we take the frame overhead for data transmission as well as the overhead due to the acknowledgement scheme, preamble, and MDSU size into consideration. We also analyze and compare the throughputs for different acknowledgement scheme, preamble, and MDSU size situations. The estimated channel time required for a given service rate is allocated in the unit of MAS(Medium Access Slot).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1369-1376
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• 2015

A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WiMedia Distributed-MAC(D-MAC) protocol is adopted for development of a seamless N-Screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU(One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a Dynamic Threshold-based Multicast(DTM) technology is proposed and analyzed. For this technology, a new Hard/Soft Vertical Region(HVR-SVR) based time slot allocation and a multicast resource reservation scheme are combined. From simulation results, proposed DTM scheme expands the number of time slots available for unicast and multicast realtime N-Screen reservations with various service time interval requests. Furthermore, it enhances performances in vewpoints of realtime N-Screen data reservation conflict and throughput.