• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.590-593
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• 2005

In this paper, it is analyzed a transmission time of ACL Packet in bluetooth wireless link. In order for segment to improve the transfer capability in bluetooth system, it is fragmented in TCP total messages that are coming down from upper layer and then the packets are sent one at time in baseband. And it is studied that transmission time for bluetooth wireless link according to DM1, DM3 or DM5 packet type in bluetooth piconet environment. From the results, we were able to obtain ACL packet transmission time, optimal TCP packet size and DM packet size.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1000-1002
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• 2005

In the Bluetooth piconet in which up to 7 slave devices can be connected simultaneously at one network instance, the wireless data expected to be sent over to the RF interface should be sliced by the unit of 1 micrometer, which is a requirement in the specification of the Bluetooth version 1.1. In this contribution, we have designed a digital low-pass filter which is able to slice the unstable analog signal fed from the RF interface to the Baseband, by the uniform unit of 1 micrometer, and is also capable of removing the possible noise which can be caused by the analog circuit system. The low-pass filter operated well in the various modes of the Bluetooth RF embedded Baseband chip such as sleep mode, normal mode, and high-speed mode at 12MHz, 24MHz, and 48MHz respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.838-846
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• 2003

In Bluetooth networks, the scatternet is defined as the internetworking of multiple piconets. Currently, Bluetooth standardization does not include the formation issue of scatternet by piconets. The existing formation algorithms of scatternet do not support the features of ad-hoc networks, which cause the performance degradation of systems when the nodes have certain degree of mobility. Therefore, as the formation of scatternet gets complicated, the throughput is lowered and the delay increases due to the inefficient architectural problems. In this paper, we propose the distributed formation scheme for bluetooth in scatternet, in which the nodes are spread out to form scatternet. Simulation results show that the proposed algorithm outperforms the conventional schemes.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10b
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• pp.285-290
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• 2007

본 논문에서 구현하고자 하는 유비쿼터스 컴퓨팅 응용에 필요한 위치 인식 시스템의 주 요소는 블루투스 프로토콜 스택(BlueZ)에서 제공하는 RSSI(Received Signal Strength Indicator) 값을 측정하는 블루투스 AP, 측정된 RSSI 값을 위치 인식 서버에 전달하기 위한 무선 AP 공유기 그리고, 받은 데이터로 위치 값을 측정하는 위치 인식 서버 및 Context Broker(고 수준의 상황 정보를 추론하는 서버 역할)로 이루어져있다. 전체적인 동작 시스템은 위치 값을 측정하고자 하는 이동 매제(마스터)를 중심으로 최대 여덟 개까지 네트워크가 가능한 블루투스 AP(슬레이브)장치로 구성된 피코넷(Piconet) 영역에서 삼각측량 필요에 적절한 세 개의 블루투스 AP를 RSSI값을 이용하여 분류 한 후 이동 매체의 위치를 측정한다. 그 결과로 나온 데이터는 피코넷 영역에서 가장 가까운 무선 AP 공유기를 거쳐서 위치 값을 측정하는 위치 인식 서버에 전달한 후, 그 결과 값으로 Context Broker에서 상황 정보를 추론해서 Community Manager에서 유비쿼터스 컴퓨팅 응용에 맞게 서비스를 구현한다. 또한, 위와 같은 시스템 내부 구조 된 데이터처리는 리눅스 운영체제 내에서 디바이스 드라이버와 사용자 프로그램으로 구현된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1262-1268
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• 2016

Bluetooth has been developed to be applied over the course of several versions in different environments. Especially low is moving to address the constraints, it gives a high utilization rate is faster than the Zigbee wireless LAN communication. To gather information on children's environmental copper transition to multiple versions. There is one limitation of Bluetooth requirements to effectively apply the information collected by Bluetooth. At the same time need to collect several information actions, Bluetooth can not connect to one of only seven Slave Master. In this paper, in order to take advantage of the many benefits of Bluetooth to gather the information by operating the Bluetooth operates in Beacon deliver packets of 168 bits, and the pairing between the master and slave unnecessarily generate a regular signal a large number of connections simultaneously Information We consider how to apply the effective policy that can be collected.

• Journal of Korea Multimedia Society
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• v.15 no.4
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• pp.516-525
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• 2012

In this paper, an efficient technique for enhancing the QoS of multimedia service for an WiMedia network applying distributed cooperative medium access (D-MAC) protocol is proposed. D-MAC protocol has been proposed to support high-rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia supports all devices to be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However the WiMedia D-MAC can't prevent reduce the throughput degradation occurred by mobile nodes with low data rate. Therefore, a distributed cooperative MAC protocol for multi-hop UWB network is proposed in this paper. The proposed technique can intelligently select the transmission path with higher data rate to provide real-time multimedia services with minimum delay, thus enhances QoS of multimedia service.

• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.158-167
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• 2002

In this paper, it is analyzed that WAP packet transmission time to improve performance of WAP using SAR-QT algorithm in Bluetooth channel. The order for SAR-QT algorithm to improve the transfer capability, it is fragmented in WTP total messages that are coming down from upper layer and then the packets are sent one at time in baseband. And it is studied that transmission time for WAP over Bluetooth according to DMI, DM3 or DM5 packet type using SAR-QT algorithm in Bluetooth piconet environment. This SAR-QT algorithm decreases WAP packet transmission time of L2CAP baseband packets by sending packet that are spanning multiple slots. From the results, in WAP over Bluetooth channels, it is found out that WTP packet size ought to be increased to decrease transmission time of WAP packet. In addition, considering BER in wireless channel, optimal WTP packet size is achieved for WAP over Bluetooth in a Rician fading environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1086-1095
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• 2007

This paper proposes a novel non-coherent TOA estimation scheme using multiple correlation process on the existence of multiple simultaneously operating piconets (SOPs). Impulse radio-ultra wideband (IR-UWB) based on direct sequence spread spectrum (DSSS) using Gold sequence is employed in order to discriminate each piconet. In order to enhance the characteristic of correlation, this paper presents the method of multiple mask operation (MMO). The time of arrival (TOA) of direct line of sight (DLOS) path is estimated via two step coarse/fine timing detection. To verify the performance of proposed scheme, two distinct channel models approved by IEEE 802.15.4a Task Group (TG) are considered. According to the simulation results, it could conclude that the proposed scheme have performed better performance than the conventional method well even in densed indoor multi-path environment as well as in the existence of multiple SOPs.

• Journal of Korea Multimedia Society
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• v.7 no.11
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• pp.1610-1619
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• 2004

While researches and studies on short distance wireless communications have been actively carried out, studies on many applications of short distance wireless communications focusing on user-oriented Mobile device are also in progress. Since Bluetooth has several advantages that existing short distance communication does not have, studies on standardization have been carried out focusing on SIG, and IEEE has also jointly studied on this. Bluetooth is a short distance wireless communication technology that can be usefully applied to various kinds of applications. In this regard, this thesis presents payment system using Bluetooth, out of several application technologies of Bluetooth. This payment system is based on the scenario in which secure piconet is formed focusing on the user, the user gets in the car, fill up the gas at the gas station using his own Mobile device and pay The secure payment system presented in this thesis is designed to complement the weakness of existing Bluetooth in terms of security and to secure several requirements of security required for payment using short distance wireless communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9A
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• pp.837-843
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• 2006

IEEE802.15.3 and IEEE802.15.4 have defined the hybrid MAC protocols based on TDMA and CSMA where a multi-frame TDMA structure is employed so that multiple data frames can be transmitted within one timeslot to guarantee minimum delay bounds of isochroous traffic. However, TDMA has an intrinsic problem that cannot dynamically allocate optimal length of timeslot to each station. Therefore the idle timeslot can be produced by stations when each transmission queue is instantaneously empty during its timeslot, which would waste lots of timeslots especially in the multi-frame TDMA systems. In this paper, we propose a more flexible multiple-access scheme for the multi-frame TDMA system based on the concept of virtual slot which is accessible by every station with the highest priority for slot owner and lower priority for other stations. Finally, our simulation results from various environments show that proposed scheme can achieve magnitude improvement of total system throughput and average message delay by maximizing channel utilization.