• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.198-201
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• 2015

The prompt and accurate location determination of the nodes of the wireless indoor shipboard networks is crucial to forming the stable wireless shipboard sensor networks. To this end in this paper it can be achieved through the measurement of the bi-directional channel qualities among the nodes after the locations of the sensor nodes temporarily placed. For the 1st stage the piconet-type sensor networks are considered to measure the channel qualities between a specific node and the cluster node which is the master node. After finishing the 1st stage measurement the nodes needing the relay nodes are selected and the measurement action goes into the 2nd stage. In the 2nd stage the measurement between a candidate relay node and the node needing a relay node starts to begin. After the 2nd stage the relay nodes to connect to the cluster node are fixed and the information delivery paths between a node and the cluster head are established. In this paper the measurement results in the realistic environment are gathered and analysed to show that the measurement procedure can be applied in the wireless indoor shipboard networks.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.39-44
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• 2009

In this paper, we propose and develop software controllable mobile controller contents using bluetooth concepts. The main features of the propsed system are as follows. Bluetooth communication is used for between smart phone and bluetooth. We develop two kinds of programs, clients and server, in which clients requests bluetooth communication and server responds. It's controllable to move toward the previous page and next page, and GUI environments can give efficient user oriented services. The results of performance evaluation show relatively good performances in view points of prices, functions, and portability.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.2
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• pp.33-42
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• 2004

Controlling household devices using an infra-ray (IR) has a limitation since the IR signal cannot only be extended, but also cannot be transmitted over the physical barrier. Using a radio frequency (RF) may overcome these shortcomings. Bluetooth is one of the emerging RF_based standard protocols for short-range wireless communications among various control devices. In this paper, we describe a control system for household appliances using Bluetooth under embedded Linux environment. The control system consists of a centralized main controller and geographically scattered wallplates. Some of the challenges and lessons learned will be outlined in the presentation. As a result of this research, we found that the Bluetooth is a promising technology for realizing wireless control systems for household appliances.

• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.1-7
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• 2004

In addition to wired communication technology, wireless communication technology has been driving communication revolution nowadays. Bluetooth technology carries out data/voice communication making pico-net and the various application services are supported by access network connected to public network. This paper presents educational software development of bluetooth protocol stack including HCI, L2CAP, RFCOMM, SDP and profiles including GAP, SPP, GEOP, FTP. This software which supports programming environment of these protocol monitoring and emulation is implemented basically step by step for education based on H connected to the bluetooth device through RS-232-C, UART or USB cable. Application program coded by Visual C is operated over the firmware loaded on the bluetooth device connected to the PC. Additionally ftp and chatting function are developed to enhance educational efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.237-241
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• 2005

In Bluetooth version 1.0, the frequency hopping algorithm was such that there was one piconet, using a specific frequency, resolving the frequency depending on the part of the digits of the device clock and the Bluetooth address. Basic pattern was a kind of a round-robin using 79 frequencies in the ISM band. At this point, a problem occurs if there were more than two devices using the same frequency within specific range. In this paper, we proposed a software-based adaptive frequency hopping method so that more than two wireless devices can stay connected without frequency crash. Suggested method was implemented with HDL(Hardware Description Language) and automatically synthesized and laid out. Implemented adaptive frequency hopping circuit operated well in 24MHz correctly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.467-476
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• 2003

In this paper, we propose an efficient MAC scheduling algorithm for supporting Bluetooth scatternet operations. Our proposed algorithm improves overall performances of scatter mode［2, 3] and considers QoS requirements of each link of the bridge node of a scatternet. Scatter mode is based on time division scheduling and provides every links of a scatternet with fair service opportunities. However, since each Bluetooth devices has various traffic characteristics. fair allocation of service opportunities is not efficient and may cause extravagance of wireless resources. Therefore, we propose a new efficient inter-piconet scheduling algorithm compliant with the current Bluetooth specification［1］, and demonstrate its improved performances via computer simulations.

• Journal of information and communication convergence engineering
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• v.12 no.2
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• pp.109-115
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• 2014

This paper presents a concurrent channel time allocation scheme used in the reservation period for concurrent transmissions in 60-GHz wireless personal area networks (WPANs). To this end, the proposed resource allocation scheme includes an efficient method for creating a concurrent transmission group by using a table that indicates whether individual streams experience interference from other streams or not. The coordinator device calculates the number of streams that can be concurrently transmitted with each stream and groups them together on the basis of the calculation result. Then, the coordinator device allocates resources to each group such that the streams belonging to the same group can transmit data concurrently. Therefore, when the piconet coordinator (PNC) allocates the channel time to the individual groups, it should allow for maximizing the overall capacity. The performance evaluation result demonstrates that the proposed scheme outperforms the random grouping scheme in terms of the overall capacity when the beamwidth is $30^{\circ}C$ and the radiation efficiency is 0.9.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.604-611
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• 2007

In this paper, we present an analysis of the throughput when there are multiple piconets and WLAN sharing the ISM bands. The analysis takes channel propagation characteristics and the capture effect. We also propose an algorithm which can be used to reduce the amount of channel scanning. By using traffic prediction of the interfering WLAN, we are able to maintain a reasonable performance in terms of fraction of time channel is wasted due to collisions or unused channel. Through computer simulation, we demonstrate that the proposed algorithm achieves reduced scanning frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.411-417
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• 2008

This paper proposes BSFP (Bluetooth Scatternet Formation Protocol), which establishes a multi-hop bluetooth scatternet. BSFP independently operates on each bluetooth device, does not require any information on neighbor devices at the very beginning, and can establish a scatternet even though all the devices are spreaded beyond the bluetooth transmission range. BSFP is composed of the following three stages; 1) Init stage to investigate neighbor nodes, 2) Ready stage to establish a scatternet using gathered local information at each node, and 3) Complete stage to use the determined scatternet links. In BSFP, the scatternet formation time does not significantly affected by the number of bluetooth devices and a robust mobile ad hoc network is formed because BSFP formulates a scatternet with many adjacent links to neighbor devices.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2B
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• pp.133-142
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• 2007

WPANs are formed in relatively small area and a PNC that serves as a central control device plays an important role in the operation and organization of a piconet. Typical applications of WPANs are security system and health monitoring system. In these type of systems, guaranteeing realtime service is very important, and communications cannot take place when the PNC malfunctions. Thus, in this situation, it is necessary to elect a new PNC as soon as possible. For this reason, we propose distributed PNC election scheme that considers not only QoS support but also network connectivity to avoid possible network partition. Simulation results show proposed mechanism can select PNC with guaranteeing QoS and connectivity for a limited period.